ACKNOWLEDGEMENT

Data gathering has remained one of the most worrisome aspects of  Information delivery as this sometimes involves extensive travels and painstaking analysis of data necessary for project implementation.

Success in implementing this project is attributed to efforts of some Scientists who assisted in data gathering and subject analysis/classification of such data.  We appreciate immensely the literature contributions by Dr. G. C. Orkwor, data collection by Drs. Ogbe, F. and Jide  Olojede.  The assistance rendered by Drs. J.E.G. Ikeorgu, A. Udealor, F. O. Anuebunwa and U. J. Ukpabi in analysing and classifying some of the complex literature/data are equally memorable.

The valuable collections in yam literature placed at the disposal of visiting Scientists and Librarians at International Institute of Tropical Agriculture, Ibadan, Raw Materials Research Development Council, Abuja and College of Agriculture, Delta State University, Asaba were tremendously utilized with thanks.

Chief K. F. Okocha (Assistant Director --Information & Documentation)

INTRODUCTION

 “Bibliography of Yam Research” is one of the series of recent efforts to meet the challenges of information explosion.  It highlights the state of knowledge and research status quo of yam between 1990 and 2002.  It has the potentials to facilitate information access and transfer.  It is intended also to provide bibliographic control of the literature and check duplication of research.

It shall be the precursor to further abstracts/bibliographies on the commodity crops of the Institute’s mandate areas which shall be published annually in series.

The maiden edition though current, topical and timely, it is by no means in its present textual format a substitute to the likes of such electronic devices as TEEAL (The Essential Electronic Agricultural Library), AGORA (Access to Global On-Line Research in Agriculture) AGRIS (International Information System for Agricultural Sciences and Technology) and CARIS (Current Agric. Research Information System).

It is however an essential prelude that can be explored for future information technology advancement.

The collection lists over 200 current articles on yam research, each with a concise synopsis directly below the listed articles and covers twenty sub disciplines ranging from Agronomy to Yam Research.  Each article is classified under the author/s within each sub-discipline for ease of access and articles are numbered sequentially.  It also enjoys the peculiarity of listing works carried out in Nigeria.

It is intended to be a reference tool for agricultural scientists, policy makers and large holder Agricultural Entrepreneurs.

CONTENTS 

AGRONOMY

YR 01. Abudulai, M. and Quansah, C. (2002)

Alternative media to sawdust for minisett propagation of seed yam (Dioscorea spp,) – Tropical Science. 42, 47-51. (En. 11 ref. 2 tab.)

Savanna Agricultural Research Institute, P.O.Box 52, Temale, Ghana.

Minisetts from Dioscorea alata (water yam) and D. rotunda (white Guinea yam) were planted in Various media.  There are 78-92% sprouting in topsoil, rice husk and saw dust, but only 69% in river sand.  Sprout was 73-92% in mixtures that included topsoil and rotten palm fibre or rice husk.  D.alata had 88-96%  sprouting while  D.rotundata had 73-76%.

YR 02. Agbaje, G.O; Adegbite, A.A.; Akinlosotu, T.A. and Shoyinka, S.A. (2002)

Performance of new hybrid yam (Dioscorea rotundata poir) varieties under different cropping systems – African Journal of Root and Tuber Crops 5 (1) 8-11 (En. 14ref. 4 tab.) Institute of Agricultural Research and Training, Obafemi Awolowo University, P.M.B. 5029 Moore Plantation, Ibadan Nigeria.

Four hybrid yam varieties (TDr 89/02665, TDr 89/02565. TDr 89/00559, TDr 89/02677) and a local cultivar (TDr 93-1, ex-Abuja) were evaluated for tuber yield respond to mosaic diseases and soil borne pests under three yam-based cropping systems (sole yam, yam + maize, and yam + melon( in 1997 and 1998.

The results showed that tuber yields was significantly influenced by yam variety and cropping systems (P<0.05).  Differences in susceptibility to leaf mosaic virus between varieties showed similar trend in 1997 and 1998.

YR 03. Aighewi, B.A. Akoroda, M. O. and Asiedu, R. (1995)

Preliminary studies of seed yam production from minisetts with different thickness of cortex parenchyma in white yam (Dioscorea rotundata Poir). – In Root Crops and Poverty Alleviation Proc. 6^th Symp. Intern. Society for Tropical Root Crops – African Branch held at Lilongwe.  22-28 Oct. Malawi 22-28 Oct 1995 445-447 (En. 14 ref. 4 tab) Dept. of Agronomy, Univ. of Ibadan, Nigeria.

This paper reported the use of yam peels for seed yam production.  The yam peel consisted of cocky periderm, the cortex, a meristematic layes and varying amounts of ground tissue.  It is the source of meristematic cells which differentiate into sprouts (Onwueme 1978).

YR 04.  Asadu, C.L.A. and Akamigbo, F.O.R. (1996)

Performance of whole and cut-setts of white yam for ware yam production in Southeastern Nigeria – African Journal of Root and Tuber Crops. (ISTRC-AB) 1 (2): 1-43 (En, 13 ref. 6 tab.) Department of Soil Science , University of Nigerian Nsukka.

To assess the yields of similar sizes of seed yams and cut-tuber setts in the direct production of ware yams, three prominent yam-growing locations were selected in Southeastern Nigeria.  Results showed that the production of ware yams using cut-setts may only be encouraged in the subhumid environment of Zaki-Biam, particularly using cultivar “Agatu” and with fertilizer application.  The production of ware yams using cut-setts in both the forest savanna transition of Abakaliki and Riverine areas of Atani should be discouraged.

YR 05.  Aighewi, B. A., Akoroda, M. O. and Asiedu, R. (2002)

Seed yam (Dioscorea rotundata poir) production storage, and quality in selected yam zones of Nigeria – African Journal of Root and Tuber Crops 5 (1) 20-23 (En. 9 ref. 3 tab.) Department of Crop Production, University of Dschang, Dschang, Cameroon.  Department of Agronomy, University of Ibadan, Ibadan, Nigeria.

A survey was conducted to assess the current production and storage practice as well as the quality of seed yams in selected yam zones in Nigeria involving 299 farmers that were interviewed using a questionnaire.  Result showed over 57% of the farmers used only seed yams from their farms for propagation.  All farmers practised double harvesting in combination with some other traditional method of seed production between 50.0 and 65.0% of farmers from Asaba treated seed yams with purchased chemicals before planting to protect against yam beetle attack while in other locations less than 35.0% did any other form of treatment. Storage in situ or planting shortly after harvest was widely practised in Oyo North, Lokoja and Lafia areas.  In Asaba, storage was done for longer period.  In yam barns 47.0 – 90% of farmers had a combination of pests and rots on their seed yam.  The high level of loss and poor seed yams are favoured by current production and storage practises.

YR 06. Asadu, C.L.A., Akamigbo, F.O.R., Nweke F.I. and Ezumah, H.C.   (1996)

Evaluation of six cultivars of white yam (Dioscorea rotundata) across three yam-growing areas in Southeastern Nigeria. – The Journal of Agricultural Science . 127, 463-468. (En, 12 ref. 2 tab). Dept. of Soil Science, Univ. of Nigeria, Nsukka.

A split split-plot experiment was conducted in three major yam growing areas in South eastern Nigeria to assess the performance and yield stability of six cultivars of white yam (Dioscorea rotundata Poir).  The best location for yam production based on the overall performance of the cultivars, was the sub-humid Guinea Savannah, followed by the humid forest –regrowth and then the transitional Forest Savannah Zone.

YR 07. Dabels, V. Y, and Ikeorgu, J.E.G. (1999).

Germination trial of Yam Minisetts using different growth media. – Annual Report: National Root Crops Research Institute. 27. (En.).

This experiment sought to determine the best medium suitable for pre-sprouting the minisetts when compared with top soil.  Result showed the medium with the highest germination percentage was top soil (control) with 39% followed by the saw dust (37.3%), River sand (31.6%) sterilised soil (30.67%).  Soil treated with neem powder (30%) and rice husk (31.6%)  The Germination was generally low, this was attributed to so many factors, one of the main factors was the light incidence of rainfall (the experiment was rain-fed)  This led to the clogging of the growth media and the rotting of the minisetts.

YR 08.  Gyansa –Ameyaw, C.E.,  Hahn, S. K., Alvarez N.M. and Doku E.V. (1991)

Determination of Optimum sett size for white guinea yam (Dioscorea rotundata Poir.) seed yam production: trends in sprouting in the presprout nursery and field  performance. – Tropical Root Crops in a developing Economy. Proceeding of the Ninth Symposium of the International Society for Tropical Root Crops 20-26 Oct. 335-341. (En, 7 ref. 4 tab)

Six weight – classes of white guinea yam (Dioscorea rotundata Poir.)Setts – 2-5, 5.01-10, 10.01–20, 20.01-30, 30.01-40 and 40.01-50g-were presprouted in fresh, moist sawdust open air propagation beds.  The 2-5g and 5.01 classes were described as microsetts.

YR 09.  Igwilo Ndubuisi (1998)

Field performance of yam (Dioscorea spp.) Pieces in relation to surface area of periderm and sett thickness. – The Nigerian Agricultural Journal 29 78-94 (En, 9 ref. 6 tab.) Institute of Agric. Research & Dev.  Univ. of Port Harcourt.

In this experiment, yam minisetts were cut up into yam pieces with 2cm², 3cm² and 4 cm² Periderm surface. Result showed that in both yam varieties and both years the optimum sett thickness was 1cm in terms of sprouting and establishment leaf area development and tuber yield.

YR 10. Igwilo Ndubuisi, (1999)

Effect of progressive removal of ground tissue with increasing plant population on the growth and yield of yam (Dioscorea sp) grown from minisetts. - The Nigerian Agricultural Journal. 30, 19-31. (En, 12 ref. 8 tab.) Institute of Agricultural research and Development, Univ. of  Port Harcourt, Nigeria.

A field experiment was conducted in 1991 and 1992 to explore the possibility of using smaller yam pieces than the minisett (25g pieces) to multiply seed yams (Dioscorea sp.) which is a major cost item and a constraint in yam production.  Thinner setts yielded more than thicker setts with 0.5 cm – sett in Um 680 and a1 cm sett in obiaoturugo giving the largest tuber yields.

YR 11.  Ikeorgu, J.E.G., Anioke, S.C., Nwauzor, E.C. (1998)

Effect of tissue on Introduction of minisetts in minisett/maize/melon intercrop on yields of component crops – Annual Report 1997 and Programme of Work for 1998: National Root Crops Research Institute, Umudike. 40-42 (En. 2 tab).

The research was aimed at determining the optimum time to introduce minisett yam in an intercropping system for improved productivity.  Four different cropping systems were tried.  Findings showed that minisett can be introduced into maize and make up to 14 days after planting melon or maize.

YR 12. Ikeorgu, J.E.G., Ezulike, T.O., Nwauzor, E.C. (1998).

Effect of sett size on the seed yam size – Annual Report 1997 and Programme of Work for 1998. Umudike.  National Root Crops Research Institute. 39-40.

Yam minisetts of various sizes were planted to determine the effect size would have on yam yield.   Results showed that: to produce seed yams of 200-500gm 12-25g sett sizes of white yam and water yam may be used; to produce seed yams in the range of 501-1000g, 30-45gof both white yams and water yam may be used; to produce yams above 1000g, 40-50g of water yam, and 45-50g of water yam, and 45-60g of white yam may be used.

YR 13.  Ikeorgu, J.E.G. and Aniedu, O. C. (1999)

Effect of variety and size of minisetts on yield and size of minituber. – Annual Report: National Too Crops Research Institute, 23-26 (En. 3 ref. 3 tab.) NRCRI Umudike, PMB 7006, Umuahia, Abia State Nigeria.

Investigations were carried out on eight Dioscorea rotundata cv to determine varietal response to minituber production from minisetts and to access the most economic sett size to use for minituber production.  Result showed that the minituber technique of seed yam production has potentials to revolutionize the seed industry but will await the development of better techniques for sprouting.  Among the Land races, Nwopoko and Abi seem to be more promising while most of the hybrid yams responded to this technology

YR 14.  Ikeorgu, J.E.G. and Igbokwe, M. C. (1999)

Effects of various sizes of minitubers on seed yam size and yield – Annual Report: National Root Crops Research Institute 36-40 (En. 4 tab).

Trials were conducted in Umudike, Igbariam and Otobi Locations in 1999 to determine the final seed yam yield and size that would result from a given minituber size and thus to initiate a process of grading and predicting the seed yam sizes from minitubers using D. rotundata cv. Result showed that growing minitubers below 25g will  produced mostly  minitubers and seed yams not exceeding 200g, but with 26-50g minitubers farmers could produce about 45% seed yams of 200-500g with this cultivar.  Also using minituber of 51-75g, farmers will produce over 86% seed yams of 200-1000g.

YR 15.  Ikeorgu J.E.G. and Igwilo   (2000)

Development of off-season intercropped yam/vegetable production techniques in Nigeria. – Annual Report: National Root Crops Research Institute, Umudike 16-17 (En, 1 tab,) 

The aim of the study was to produce yams off-season in inland valleys, fadamas, flood Plaines or under irrigation so as to make fresh yams available year round.  Equally to integrate the production of vegetables  grown at this time in many peri-urban centres with yam production.  Results showed that the seed yam yields from the 25g minisetts of Nwopoko and Um 680 grown during the dry season of 1999/2000, suggests that optimal seed yam yields from this technology would be  achieved when the plots were both mulched and staked.

YR 16.Ikeorgu John E.G; Nwokocha, H. N. and Ikwelle M. C.   (2000)

Seed yam production through the yam minisett technique:  recent modifications to enhance Farmers’ adoption. – Potential of root crops for Food and industrial resources.  Twelfth Symposium of the International Society for Tropical Root Crops (ISTRC) held in Japan Sept. 10-16, 2000.  372-375 (En. 6 ref.) National Root Crops Research Institute, Umudike, P.M.B. 7006, Umuahia Abia State., Nigeria, West Africa.

This paper reported the progress so far made to modify the yam minisett technology and make it more acceptable resource-poor farmers preferred to intercrop to maximise total returns  from a unit area of land and satisfy their dietary requirements, the maize/cowpea , maize-soybean and maize/egusi melon, with yield depression of about 33%.

YR 17.  Kalu Obasi Nwankiti (1990)

Evaluation of new hybrid yams under sole cropping. – Annual Report 1997 and Programme of Work for 1998: National Root Crops Research Institute, Umudike (1998) 58-59 (En, 2 tab,) 

The aim of the research was to evaluate five new hybrid yam varieties – TDr 84/0625, TDr 87.00559, TDr 89/02677, TDr 90/00540 and TDr 93-1 – for agronomic characteristics and yield attributes.  Results showed that percentage establishment of the varieties, except one, was above 90%.  Average tuber weight was in the range of 0.50-1.11kg and yield range was 10.63-15.10 t/ha.  Only TDr 84/00625 yielded significantly lower than the other varieties.

YR 18.    Kainga, P. E. Opukeme K. I.,  Diegbegha J, and Emehute  J.K.U. (2001)

On Farm evaluation of 2 sett sizes of water yam, Dioscorea alata for the production of acceptable seed yam in Bayelsa State. – Proceedings of the 16^th Annual Zonal Research Extension farmer input, linkage systems (Refils) workshop South-East/South South Zones of Nigeria.  (2001) 82-83. (En, 1 tab.)  Bayelsa State Agricultural Development Programme, Yenegoa.

The objective of this trial was to select the best size for the production of acceptable seed yam in Bayelsa State.  Results showed that the 435g sett produced acceptable seed yams ranging between 200-600.  Therefore the 45g settsize is recommended for the production of acceptable seed yam in the State.

YR 19.  Ndegwe, N. A.,  Ikpe, F. N., Abosi, S. D., Jaja, E.T. (1990)

Effect of staking method on yield and its components in solecropped white Guinea yam (Dioscorea rotundata poir) in a high rainfall area of Nigeria. – Tropical Agriculture. 67 (1) 29-32 (En. 6 ref).  Rivers State University of Science and Technology  Institute of Agricultural Research & Training, Onne, Port  Harcourt, Nigeria.  (From field crop Abstracts  April (1990) 43 (A).

In field trials at Onne in 1985-86; a local Nwagba long tuber D. rotundata cultivar was grown without stakes of with 2-10 plants/stake (5000-2000 stakes/ha 20 plants to a netted rope platform supported by 4 strikes (2000 stakes/ha) or with 10 p[ants to a trellis supported by 2 stakes (1000 stakes/ha).  The number of tubers was not consistently affected by staking method although 2 plants/stake yielded approximately 15% more tubers than unstaked yams.

YR 20.  Obiazi, C.C.   (1995)

Sustainable supply of stakes for yam production. – Journal of Sustainable Agriculture 5 (3) 133-138 (En, 8 ref.) Department of Agriculture, Delta State University,  Abaraka, Nigeria.

This paper justified yam needs for stakes and shows how people from different parts of the world have been managing the practice of yam staking.  An advantage of on-Farm yam stakes procurement and an outlook into the future trend of yams stakes procurement are also examined.

YR 21.  Odurukwe, S.O. and Ikeorgu, J.E.G. (1991)

Effects of fertiliser and time of introduction of cassava in yam/maize/cassava intercrop on component yields. – Proceedings of the Ninth Symposium of the international society for Tropical Root Crops.  Held at Accra, Ghana 20-26 October 1991, 72-77.  (En. 7 ref. 4 tab.)

A study was conducted to investigate the most appropriate time to  introduce cassava into yam/maize/cassava mixture grown with and without inorganic fertiliser.  Results showed that delaying the introduction of cassava significantly increased yam tuber and maize grain yields but reduced cassava root yields significantly.  Cassava planted at the same time with yam and maize had a significantly higher mean total productivity than cassava introduced 28 days later or 56 days later.

YR 22.    Okezie, C.E,A. Okonkwo, S.N.C. and Nwoke, F.I.O. (1991)

Carbon source requirement for the culture of white yam (Dioscorea rotundata) embryos in vitro.  Tropical Root Crops in a Developing  Economy: Proceedings of the Ninth Symposium of the International Society for Tropical Root Crops Held at Accra Ghana 20-26 October 1991.  329-334 (En. 17 ref. 3 tab).

This study aimed at screening the carbohydrates available to us with a view to finding the appropriate ones as well as their optimal levels for the growth of D. rotundata embryos in vitro.

YR 23.    Okoli, O. O., Opara, M. U. and Anyaoha, C. O. (1999)

Effect of seed weight  on yield determinant, yield components and intra-plot variability in yield of yams (Dioscorea spp) – African journal of Root and tuber crops 3 (2) 44 – 48 (En. 6 ref. 43 tab) National Root Crops Research Institute, Umudike, P.M.B. 7006, Umuahia Abia State,  Nigeria.

Three experiments were conducted at the National Roots Crops Research Institute farm in Umudike for three years to investigate the influence of seed size on earliness of sprouting and survival till harvest and the consequence of these on yield and yield components of yams.  Also examined were the effect of seed size on multiplication ratio, intra-plot yield ranges and stand yield variability.   Results obtained showed that larger seeds sprouted earlier and had higher percentage sprouting and survival till harvest making for higher total yield. Smaller seeds, however, had higher multiplication ratios and lower intra-plot variability.

YR 24.    Okonkwo, J.C.  (1995)

Effects of pre-sprouting and planting depth of yam (Dioscorea spp) Minisett on Field establishment, Tuber yield and net income in the southern guinea savannah of Nigeria.  – The Nigerian Agricultural Journal 28 (I) 1-8 (En. 12 ref 4 tab.) National Root Crops Researach Institute, P.M.B. 7006, Umudike, Nig.

Studies were carried out to determine the effects of sprouting and planting depth of yam minisett on the field establishment, tuber yield and income.  Results showed a 16.5 percent minisett rot during pre-sprouting.  Minisett, cut from the head part of seed yam sprouted more than minisett from the middle or tail part.

YR 25.    Olasantan , F. O. (1990)

Effect of time of mulching on soil temperature and moisture regime and emergence, growth and yield of white yam in Western Nigeria. – Soil & Tillage Research 50, 215-221 (En, 9 ref. 5 tab.)  Department of Agriculture, Univ. of Agriculture, P.M.B. 2240, Abeokuta, Nigeria.

An On-farm trial was conducted in Nigeria to determine the effect of time of mulching on the hydrothermal regime and emergence, growth and tuber yield of white yam.  Results showed that mulching significantly improved emergence  and development of yam seedlings, and increased tuber yield. Results also showed that mulching immediately after planting in October or 4 week later did not improve emergence at 28 WAP as compared to mulching later in the season.

YR 26.    Orkwor, G.C. and Ekanayake I. J. (1998)

“Growth and Development” In Food Yams: Advances in Research (1998).  39-62 (En, 109 ref. 2 tab.)

Recent observations at the IITA have shown that sprouting does not

always initiate at the head end of the tuber (Aigbewi unpublished data).  There is a significant negative correlation between yam tuber yield and pre-emergence period in both D.rotundata and D. Cayenensis.

YR 27.    Orkwor, G.C. (1997)

Seed yam production technology: The yam minisett technique.- L’igname, plante s’eculaire et. Culture cl’avenir. Actes du s’eminnaire International Cirad-Inra-Orstom-Cornf. Montpellier, France.  87-92 (En, 20 ref). Research Institute Umudike, PMB 7006, Umuahia, Nig.

This paper reviews various methods of seed yam production using clonal materials with special emphasis on the yam minisett technique for massive seed yam production and the latest research developments for refining the yam minisett techniques.

YR 28.    Orkwor G.C., Nwachukwu, E.C., Dabels, V.A., Adeniji A.A., (2000)

Multilocational Evaluation of local land races and Hybrid yams. – Annual Report: National Root Crops Research Institute, Umudike 4-5. (En, 3 tab.)

This study was carried out in the IFAD/WECARD/IITA regional Yam Project for the development of technologies in yam production for poverty alleviation and enhanced food availability in West Africa. Result showed the superiority of the hybrid yams over the landraces of D.rotundata was significantly manifested in crop establishment, growth and tuber yield.

YR 29.    Orkwor, G.C.  (1997)

Yam Production in Nigeria – L’igname Plante Se’cculaire et Culture d’avenir.  Actes du seminaire international Cirad-Inra-Orstom-Corng. Mont pellier France.  81-85 (En, 19 ref) NRCRI, National Root Crops Research Institute, Umudike, P.M.B. 7006, Umuahia, Nig.

This paper reviewed production system, advances in research and areas that call for more research in the production of yam in Nigeria.  Nigeria is the world’s largest producer and consumer of food yams.  Global production of food yams is now estimated at 32.9 million metric tonnes per annum with about 96% of this coming from the West African zone and Nigeria alone accounts for about 70% of the world total.

YR 30.    Orkwor, G.C., Surma, D., Udensi, U.A.. Chukwu G.O. and Kwagbura, F.M.

(1999).  Pre-release multilocational trials of hybrid yams and land races in the Southern Guinea Savannah. – Annual Report: National Root Crops Research Institute 52-54 (En. 2 tab) NRCRI Umudike, PMB 7006, Umuahia, Abia State.

The objectives of the trial were to test the performance of the selected hybrid yam using land-races as checks in Southern Guinea Savannah and to determine which ecologies the hybrid yams  will perform well after the crop release.  Result showed that though drought and late rains affected sprouting and crop establishment at Zaki Biam, total tuber yield was comparable to that in Umudike  which had better and more stand establishment.

YR 31.    Orkwor, G.C., Okoli, O. O. Emehute, J.K.U., Ezeh, N.O.A. (1996)

Studies on the optimum plant population, depth of planting and best tuber portion of mother seed yam as planting sett in seed yam production using minisett technique – National Agricultural Research Project (NARP). Priority Research and REFILS Projects Report: National Root Crops research Institute, Umudike (1986) 4-12 (En. 5 ref. 7 tab).

The experiment showed that optimum production of normal size seed yam is at 60,000/ha.  With 25gm sett as planting material, ware yams of about 1000 gm or about are rarely produced.  There is       need to increase the size of planting setts above 25gm (30-40gm).

YR 32.    Orkwor, G.C.  and Asadu, C.L.A.  (1998).

Agronomy – In Food  yams: advances in research (edited by Orkwor, G.C. (et al) Ibadan, Nigeria, IITA/NRCRI 105-141 (En. 80 ref.) NRCRI Umudike P.M.B. 7006, Umuahia Nigeria.

The articles noted that yam require good fertile soil, adequate and well distributed rainfall and considerable labour input for agronomic operations such as land preparation, planting, staking, weeding, training the vines, harvesting and post-harvest handling and storage.  They also require large quantities of planting materials (seed yams) for ware and seed yam production.  Climatic factors such as water. (soil moisture), temperature light and photo period affect the growth and performance of yams.

YR 33.    Okwuowulu, P.A.   (1995)

Yield response of edible yam (Dioscorea spp) to time of fertiliser application and age at harvest in an ultisol in the humid zone of Southeaster Nigeria. – African Journal of Root and Tuber Crops 6-10 (En) 18 ref. 5 tab.) NRCRI Umudike, P.M.B. 7006, Umuahia.

The experiments were conducted to appraise the response of  six cultivars of edible yam to fertilizer application during certain stages of growth and to evaluate the effect of varying  age at harvest on their tuber yield.  Results showed significant differences among cultivars in percent survival tuber number, fresh weight yield and multiplication ratio.  Timing of fertilizer application significantly increased tuber yield. Harvest age also significantly affected the yield of tubers.

YR 34.  Okwuowulu, P. A. (1999)

Yam (Dioscorea spp) tuber – seed- tuber cycle approach for food yam propagation – Proceedings of the 32^nd Annual Conference of the Agricultural Society of Nigeria held at Fed. Coll. Of Agriculture Ishiagu 13-16 Sept. 1998 125-128.

The research was carried out to (I) ascertain the tuber yield potential of yam seeds and practical application (ii)  to develop the technique for farmers adoption, and iii for seed production and further work on new geno-types.  Results showed that seed yams from yam seeds gave high seed harvest multiplication ratio.

YR 35.   Okwuowulu, P. A., Nnodu, E.C., Udensi, U. A., Opara, M.U.A. (1999)

Some effects of time of fertilizer application and age at harvest on the storability of edible yams. – Proceedings of the 32^nd Annual Conference of the Agricultural Society of Nigeria held at Fed. Col. of Agric., Ishiagu 13-16 Sept. 1998) 58-63 (En, Tabs 13 ref).

Weight losses from yam tubers during storage in a traditional barn and in a modified indoor store differed significantly among six cultivars.  Sprouting and rotting of tubers also differed significantly.  Age at harvest significantly effected storability.  Tubers harvested 6 or 7 months after planting stored best.  Weight loss were lower in the traditional barn that in the modified store.

YR 36. Osiru, D.S.O. and Hahn, S.K. (1994)

Effects of mulching materials on the growth development and yield of white yam – African Crop Science Journal (Uganda) 2 (2) 153-160 (from Abst. On trop. Agric.) 20 (2) 1995 (En, 14 ref. ) IITA, Ibadan, Oyo Nigeria.

The effects of different mulching materials and staking on the growth, development and yield of white Yam (Dioscorea rotundata) were studied in Nigeria during 1985-1986.  Results showed that polythylene plastic mulch with white surface up was superior to all other treatments.  Suggesting that under tropical conditions farmers would obtain better seed yam yields through the white surface polyethylene plastic mulch.

YR 37.    Otu  O. I. And Agboola, A.A. (1991)

The suitability of Gliricidia Sepium in –situ . Live stake on the yield and performance of white yam (Dioscorea rotundata).  -  Tropical Root Crops in a developing  economy: Proceedings of Ninth Symposium of the International Society for Tropical Root Crops held at Accra Ghana 20-26 Oct. 1991, 360-366. (En 9 ref. 3 tab.)

The objective of this study were: To access the suitability of gliricidia shrub legume as in situ-live-stake on the tuber yield and performance of white yam.  Second, to evaluate the contributions of gliricidia prunings to weed suppression improvement of soil physical properties, and biomass production and to determine the role of gliricidia prunings on soil  fertility maintenance.

BIOCHEMISTRY

YR 38.    Bonire, J. J., Jalil, N.S.N, Lori, J. A. (1990) 

Sodium and Potassium content of two cultivars of white yam (Dioscorea rotundata) and their source soils.  Journal of the science of Food and Agriculture.   53 (2) 271-274 (En, 5 ref.) (From Field Crop Abs. July 1991 44 (7) ) Department of Chemistry, Ahmadu Bello University, Zaria, Nigeria.

Sodium and potassium were estimated in 2 cultivars (“Amara” and “Chika Kwondo”) of white yam (Dioscorea – rotundata) and their source soil from 3 Farms.  Results showed that K content of both cultivars was 100 times greater than that of Na.  The barks of both cultivars  were also richer in K than in Na. Less than 0.2% of the Na and K present in the soil was available to the plant for absorption.

YR 39.    Ezeike, G.O. and Obetta, S.E. (1995)

Mass and thermal diffusivity inter-relationsips for starchy food products (yam tissue) – African Journal of Root  and Tuber Crops 3 (1) 4-6 (En. 17 ref 2 tab.) Department of Agric. Engineering, University of Nigeria Nsukka, Nigeria.

Mass diffusivity, D. was determined experimentally for a yam (Dioscorea spp.) variety tissue using a custom made through circulation test dryer .  Test results showed mean values ranging from 0.0014015 cm²/min to 0.0025369 cm²/min. for different temperature conditions between 48^oc to 97^oc at varying levels of moisture content of between 45% to 133% dry basis.

YR.40.    Ilori, J. A., Bonire, J. J. and Jalil, N. S. N. (1994)

Difference in concentration of some mineral elements in the tissue and bark of white yam (Dioscorea rotundata). – Discovery and Innovation 6(1) 14-16 (En. 12 ref., 3 tab.) National Research Institute for Chemical Technology, PMB 1052, Zaria, Nigeria.

The difference in concentration of some mineral elements in the tissue and bark of two cultivars of white yam (Dioscorea rotundata) samples randomly from Kaduna State of Nigeria were reported.  The elements reported were determined by flame atomic absorption spectrometry and flame emission spectrometry.  The Ca, fe, mg and k contents were significantly different contrary to concentration of Cu, Na, Ni and Zn showed insignificant differences.  In both cultivars fe showed the highest bark/tissue ratio while K had the lowest.

YR 41.  Iwuoha. C.I. and Nwakanma, M.I.   (2002)

Effect of processing conditions on the physico-chemical properties of flours from cassava (Manihot esculenta crantz, sweet potato (Ipomoea batatas L. Lam.) and white yam (Dioscorea rotundata poir.) – 5 (1) 38-42 (En. 32 ref. 3 tab.) Department of Food Science and Technology, FUTO, P.M.B. 1526, Owerri, Imo State, Nigeria.

Tubers of cassava, sweet potato and white yam were fermented, boiled and baked.  Some physico-chemical properties of the processes tuber flours, were evaluated against the raw ones.  Results showed that the boiling effected the greatest increase in tapped bulk density of white yam (32.85%) while the least was in fermented cassava (7.31%).

YR 42.    Oluoha, U  (1990)

Purification and properties of phosphorylase from white yam tuber (Dioscorea rotundata).  – Biologia Plantarum  32 (1) 64 – 76 (En, 20 ref.) (From Field crop Abs. Oct. 1991 44 (10))  Department of Biochemistry. University of Benin, Benin City, Nigeria.

Glucan phosphorylase was extracted from D. rotundata tubers and purified 55 – Fold with specific activity of 360 nmo1/min mg protein and a yields of 41.5%. Result of the finding showed that enzyme showed normal michaelis-menten kinetics and was activated by AMP, AATP, ADP, ADP-Glucose, Ca and mg inhibited it.  It was active in the presence or absence of primer but unaffected by the addition of glycolytic intermediates or amino acids.  Using gel filtration, MW of the enzyme was 188000 and the extract contained 1 form.  Properties

of the enzyme indicated that phosphorylase from white yam tuber unctioned primarily as a starch degrading enzyme.

YR 43.    Osagie, A. U., Rees, T. AP (1990)

Sugar metabolism by Dioscorea tubers during sprouting – Journal of the Science of Food and Agriculture (1990) 52 (2) 171-177 (En, 15 ref.) (From Field Crop Abst. Feb. 1991 44 (2)) Botany School, University of Cambridge, Cambridge CB2 3EA, UK. 

When (1-14C ) – and (6-14C) Glucose were supplied to tubers of D. rotundata and D. bulbifera no significant labelling of Free Pentose was detected.  The 2 isotopes labelled the fractions that contained the organic acids, amino acids and protein almost equally.  Pentoses were not detected in significant amount when the sugar fractions were analysed.

YR 44.    Osagie, A. U.  (1999)

Chilling injury in yams: Effects on Organelle Membrane Fatty acids and cell wall Enzymes – Advances in yam Research Vol.2 : Production and Post-Harvest Technologies of the Yam tuber.  91-98 (En, 34 ref, 3 tab.)  Dept. of Biochemistry, University of Benin, Benin City, Nigeria.

Lack of change in lipid unsaturation in chill-injured Yam tuber organelles was therefore not unusual and indicates that some other mechanism is operated to account for the leakage of ions during chilling injury in these tubers.

YR 45.    Udoessien, E. I. and Ifon, E.T  (1992)

Chemical evaluation of some antinutritional constituents in four species of yam Tropical Science  32 (2) 15-119 (En, 18 ref. 1 tab) Dept. of Chemistry and Biochem., University of Cross River State Uyo, Nigeria.

Four yam species of the genus Dioscorea (D. alata, D. Cayenensis, D. rotundata and D.esculenta) were assayed for four antinutritional substances namely oxalate, phytate, total cyanide and tannin.  It was

Concluded that the levels of antinutritional constituents assayed in the species studied should not have any serious adverse effect on the nutritional value of the yams.  Most of these substances are significantly reduced during the preparation of yams for consumption.

YR 46.    Ukpabi. U. J.   (2000)

Effect of soil fertility on the starch and Alkaloid contents of Discorea dumetorum.  – Annual Report: National Root Crops Research Institute, Umudike (2000) 24-25 (En. 3 ref, 2 tab.)

The study aimed at investigating of variability in alkaloid and starch content of the crop’s tubers was effected by soil fertility.  Results showed that fertilizer treatment at the levels used in the experiment, did not significantly (P-0,5\\0 affect the starch and alkaloid content  of the D,. dumetorum tubers.  Moreso, it was observed that D. dumetorum like some varieties of D. rotundata was amenable to the minisett technology for tuber production.

BIOTECHNOLOGY

YR 47.    Asiedu. R.;  Ng. S.Y.C.; Virylstke, D., Terauchi, R., Hahn, S.K.  (1992)

Analysis of the need for biotechnology research on cassava, yam, and plantain. – Biotechnology: Enhancing Research on Tropical Crops in Africa 27-32 (En. 10 ref).  International Institute of Tropical Agriculture, P.M.B. 5320, Ibadan, Nigeria.

Cassava, yam and plantain have long growth cycles high perishability and slow multiplication rates of propagation materials, and they are subject to a number of biological Stress, which include diseases, insects, mites, nematodes and weeds.  Intensification of research is needed in cytogenetics, molecular genetics, in vitro culture, cryopreservation and disease diagnosis.

YR 48.  Bokanga, M.   (1992)

Constraints in food and nutrition research -  Biotechnology: Enhancing  Research on Tropical Crops in Africa. 33-38 (En, 17 ref).  International Institute of Tropical Agriculture, PMB 5320, Ibadan, Nigeria.

The paper highlighted 3 areas of food and nutrition research that will benefit from advances in biotechnology in Africa. The first, a development of starter cultures for African fermented foods and beverages for expansion, the second, on detoxification of cassava, and the third, on postharvest deterioration of cassava, yam, sweet potato plantain and banana.

YR 49.    Montell, S.H. and Boccon-Gibod, J.  (1997)

Progress towards the realization of biotechnological tools for genetic improvement of Dioscorea spp.- L’igname plantae seculaire et culture d’avenir.  Actes du S’eminnire International Cirad-Inra-Distom –Cornf. Montpellier France (1997) 163-180 (En, 82 ref) Dept. of Biological Sciences, Wye College Univ. of London.  Wye Ashford Kent Tn 25  5AH, UK.

This paper presented an overview of current progress in the development and deployment of cell suspension cultures for the production of steroids and for development of plant regeneration via somatic embryo genesis.

YR 50.    Ng. S.Y.C.  (1992)

Tissue culture of root and tuber crops at IITA – Biotechnology: Enhancing Research on Tropical Crops if Africa.  135-141 (En. 8 ref). International Institute of Tropical Agriculture, PMB 5320, Ibadan, Nigeria.

Virus-tested improved clones of cassava, yam and sweet potato have been distributed to national programmes for evaluation and testing.  Clonal germplasm is conserved by the in-vitro reduced growth storage method; plantlets can be kept in the same tube for 1-2 years.  In-vitro microtubers, production of yams is an alternative that could aid international distribution of virus-tested clonal materials.

YR 51.    Ng. S.Y.C., Ngu, M.A., Ladeinde, T.A.O.

Embryo culture of yams: germination and callus induction – Proceedings of the Fifth Triennial Symposium of the International Society for Tropical Root Crops – Africa Branch. (1992).  141-144 (En, 13 ref. 2 tab)

The response of embryos of  two yam species Dioscorea rotundata Poir and D. abyssinica Hochst to six different culture media and the incubation conditions was studied.  Callus formation was obtained at the concentration of 9 to 90 NM 2, 4-D.  In most treatments, root formation was obtained from callus.  Embryoid structure and plant regeneration were obtained at 18 UM 2, 4-D treatment in D. rotundata.

YR 52.    Nwachukwu, Emmanuel  C.  (2000)

Induced mutations and in-Vitro culture Techniques in the genetic improvement of the white guinea yam (Dioscorea rotundata Poir)  A Dissertation submitted to the Department of Crop Science, University of Nigeria, Nsukka (En, 75 ref. 38 tab).

This study examined the extent and type of variations exhibited in the white guinea yam using hybridisation, mutation induction and plant cell and tissue culture techniques.

YR 53.    Okezie, C.E.A; Okonkwo, S.N.C.  (1992)

Status of plant regeneration of yam – Biotechnology: Enhancing Research on Tropical Crops in Africa.  151-155 (En, 27 ref) Laboratory for Plant Cell and Tissue Culture and Biotechnology.  Department of Botany, University of Nigeria, Nsukka . Nigeria.

Current methods of improving yam are inadequate and thus plant scientist have begun to search for alternative regeneration techniques, using biotechnology methods. Somatic embryo genesis has been achieved in some species and somaclonal variants arising in culture could form a basis for yam improvement.

YR 54.    Okonkwo, S.N.C. and Okezie C.E.A. (1993)

Potential  non-tuber materials for yam propagation – Advances in yam Research Vol 2: Production and Post-Harvest Technologies of the yam tuber.  43-55 (En, 48 ref.) Department of Botany and Division of general studies, Unviersity of Nigeria, Nsukka, Nigeria.

This paper investigates the propagative methods of the following: vine cuttings, cell, tissue and organ culture, embryo culture, and true seeds.  The findings  revealed that extensive experiments with vine cuttings are necessary; to improve their cultural and management practices to achieve maximum tuber yield from them.

YR 55.    Pistorius, R. (1992)

Biotechnology in Nigeria, Cameroon, Gabon and Ghana: Biotechnology and Development Monitor No. 10, 6-9 (En, 3 ref).

The work examined the extent to which biotechnology is practised in Nigeria, Cameroon, Gabon and Ghana.  Results showed that out of 24 governmental research Institutes, about 10 are involved in biotechnology; 4 research centres report biotechnological activities in Cameroon; only one in Ghana.

BREEDING

YR 56.    Akorada, M. O. (1997)

Genetic selection in food yams: a century of sporadic efforts: L’igname Plante S’eculaire et culture d’avenir. Actes du S’eminaire Intenantional Cirad-Inra-Orstom – Cornf. Montpellier France.   107-116 (En, 35 ref. 5 tab.) TRIP, IITA, Ibadan, Nigeria.   

This paper, reviewed the progress made in different areas of research relating to the genetic selection of yams and suggest what still needs to be done towards obtaining the yam of the future.

YR 57.    Asiedu R., Bai, K. V., Teranchi, R., Dixon, A.G.O., Hahn, S.K.,

Thottapilly G. (1992)

Status of wide crosses in cassava and yam – Biotechnology: Enhancing Research on Tropical Crops In Africa 63-68 (En, 32 ref) International Institute of Tropical Agriculture, PMB 5320, Ibadan Nigeria.

Some crosses between cassava and its wild relatives had led to polyploids (crosses with M. glaziovli and M. epruinesa) and resistance to 2 major diseases, cassava mosaic virus (African cassava mosaic bigeminivirus) and cassava bacterial blight (Xanthomonas campestris pv. Manihotis) (crosses with M.glaziovili).  No barriers to interspecific hybridisation have been found in the genus manihot, but hybridisation between Dioscorea species was severely hampered by poor and erratic flowering.

YR 58.    Asiedu, R., Ng, S.Y.S.,  Bai, K.V., Ekanayake, .I. J. and Wanyera, Nim.

  (1998)         

Genetic improvement. – Food yams advances in research. (edited by Orkwor, G.C. et  al.)  Ibadan Nigeria, IITA/NRCRI, 63 – 104 (En. 159 ref.)

The article stressed the progress that has been made in understanding the reproductive biology of yam to make genetic improvement a viable option for enhancing its productivity.  The few yam breeding programme reported here have focused on clonal selections from land races and hybridisation on elite genotypes within and between species.

YR 59.    Bai, K. V. and Ekanayake, I.J. (1998)

Taxonomy, Morphology and Floral Biology) – Food yams: Advances in Research edited by Orkwor G.C. et al – Ibadan, Nigeria IITA/NRCRI 13-37 (En 80 ref, tab).

A review of the state of knowledge on taxonomy morphology and flowering behaviour of yam illustrates a sufficient and comprehensive database for successful yam improvement activities for the year 2000 to assist resource poor farmers in sub-Saharan Africa.

YR 60.    Edeoga, H. O. (2002)

Anatomical studies on the roots of some Dioscorea species (Dioscoreaceae). – African Journal of Root and tuber crops.  5(1) 33-37.  (En.25 ref. 1 tab).  Department of Biological Sciences, Federal University of  Agriculture, Umudike, PMB 7246, Umuahia, Abia State, Nigeria.

Anatomical studies on the roots of ten Dioscorea species were reported. An analysis of the features of the Internal arrangements of the leathery, non-storage root showed that these taxa posses vital characters that could be used in their description characterisation, recognition, identification and classification.

YR 61.    Hamon, P., Toure; Ng-Nq.,  Perrino P., Attere, F., Zedan, H. (1991)

New trends for Yam Improvement in the Dioscorea Cayenensis – rotundata complex. – Crop Genetic resources of Africa. Vol, II: Proceedings of an International Symposium, Ibadan, Nigeria, 17-20 Oct. 1988. 119-125 (En. Fr  6 ref) University  Nationale  FAST Genetique, 22 BP 582 Abidjan 01, Cote d’Ivoire.

Morphological and isoenzymatic data indicated that of the 20 varietal groups of cultivated yam, 15 are related to the annual wild species D.abyssinica and D.prachensilis, 1-2 are closely related to the semiperennial  D. mangenotiana, while the other 3 appear to be hybrids between perennial and annual wild species.

YR 62.  Mignouna, H. D.,Asiedu and Thottapilly G.  (1995)

Molecular taxonomy of cultivated and wild yams in West African – Root Crops and Poverty Alleviation: Proceedings of the Sixth Triennial Symposium of the International Society for Tropical Root Crops.  Held at Lilongwe, Malawi 22 – d28 October 1995, 429 (En) International Institute of Tropical Agriculture, (IITA), PMB 5320, Ibadan, Nigeria.

RAPD markets was used to study the taxonomy of 45 accessions of Guinea yams and some wild species belonging to the Enantiophyllum section leaf samples of cultivated and wild species were collected from various agro ecological zones of Nigeria. A total of 215 different fragments were obtained.  Result showed that cultivated yam varieties of D. rotundata used in this study have been domesticated from D. abyssinica because more than 95% of genetic similarly between the two species was obtained.

YR 63.    Ng.,  S.Y.C. .(1990)

In-Vitro tuberization in white yam (Dioscorea rotundata Poir) – IITA Research 1 (1) 11-13 (En. 17 ref)  IITA Ibadan Nigeria.

The article examines In-vitro processes in the tuberization of white yam.

YR 64.    NG. N.Q.  (1995)

Potential use of aerial tubers for water yam germplasm conservation and production.  – Root Crops and Poverty Alleviation: Proceedings of the sixth Triennial  Symposium of the International Society for Tropical Root Crops  AB 448 – 449 (En, 1 tab.) Genetic Resource Unit, IITA, PMB 5320, Ibadan, Nigeria.

A preliminary study was undertaken to assess the potential use of water yam (Dioscorea alata L.) aerial tuber as propagules for underground tuber production and for germplasm conservation.  Results showed that these aerial tubers produced vigorous plants with underground tubers similar in shape and texture to those of minisetts and ware yam planting setts.

YR 65.    NG.  S.Y.C. , Asiedu R. (1995)

Acclimatisation of in vitro plantlets of white yam (Dioscorea rotundata Poi): transition from culture tubes to field – Root Crops and Poverty Alleviation: Proceedings of the six Triennial Symposium of the international society For Tropical Root Crops.  Held at Lilongwe, Malawi 22-28 October, 1995.  435-438 (En, 11 ref. 5 tab.)  International Institute of Tropical Agriculture, Oyo Road, PMB 5320, Ibadan, Nigeria.

Studies were carried out to evaluate the suitability of an alternative transplanting medium locally available over two transplanting seasons using different genotypes of white yam (Dioscorea rotundata Poir).

YR 66.    Nwachukwu. E.C. and Obi, I. U. (2000)

Advanced yield trial of hybrid white yam clones.  Annual Report: National Root  Crops Research Institute, Umudike  9-11 (En, 8 ref. 2 tab).

A total of 500 hybrid white yam clones selected after a preliminary yield trial was  used.  The hybrid clones were planted out in the field using augmented randomised complete block design.  Result showed that tubers with high TSI values grow more in girth than those with low TSI values.

YR 67.  Nwachukwu E.C., Ene, L,S,O,, Mbanaso E. N.A. and Agbo,  F.M.O.  (1990)

Increasing variability in yams by induction of mutation using gamma rays. – Annual Report: National Root Research Institute (NRCRI) Umudike.  42-45 (En. 2 tab.).

The aim of the study was to establish the dose range of gamma radiation that will give high frequency of beneficial mutation.  Results showed that high dose of gamma radiation tended to inhibit sprouting and therefore the number of standards that established in the field to harvest in both setts from the head and tail regions of yam tubers.

YR 68.    Nwachukwu E. C. and Obi I. U.  (1999)

Clonal evaluation of MV₂  yam lines raised from gamma ray treated Obiaoturugo minitubers. – Annual Report: National Root Crops Research Institute 41-43 (En. 3 ref. 2 tab) NRCRI Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

The objective of this experiment was to determine the effect of gamma irradiation on treated minituber lines for shrubby, dwarfy and bunchy vegetation that may be cropped without staking.  Result showed that generally, increasing gamma ray disease decreased yield.  This effect was more pronounced on the stands raised from the gamma ray irradiated T. regions of the tuber.  However, gamma ray irradiation did not affect the tuber shapes at both generations.

YR 69.    Nwachukwu, E.C., Sonnino,A. and Mbanaso, E.N.A. (1996)

Influence of NAA concentration and of explant source of plantlet regeneration in white guinea yam (Dioscorea rotundata) Poir. – Journal of genetics and breeding.  50, 181 –184.

Different types of explant (Whole leaves, leaf segments, petioles and internodal stem pieces ) excised from in vitro growing seedlings of white guinea yam (Dioscorea rotundata pir) cv. Obiaoturugo, were cultured on MS medium supplemented with increasing concentrations of NAA.  At higher NAA concentrations all types of explant reached towards callus formation.  The induced call; developed plantlets when subcultured in MS medium supplemented with 2mg/1 BAP and 0.1 mg/1 NAA.  Direct regeneration from petioles and stem pieces and indirect regeneration through callus induction are both regarded as possible tools from Yam Improvement.

YR 70.    Nwachukwu, C.C. and  Obi I. U.  (1999)

Prelimnary yield trial of hybrid white yam clones – Annual Report: National Root Crops Research Institute 31-35 (En. 4 ref. 3 tab)

In the yam genetic improvement programme both mutation induction and hybridisation techniques were employed.  Here preliminary yield trial of third (3^rd) generation yam plants raised from gamma ray treated and untreated true yam seeds were presented.  Results showed the list of hybrid yam lines with mean tuber yields per stand of 0.5kg and above. Using selection index ration (SIR) for further elimination of lines with undesirable characteristics.   All lines with SIR value of 3 and below were eliminated.  From this trial, a total of 199 lines have been selected for further trial and selection.

YR 71.    Nwachukwu. E.C., Ene, L.S.O. and Mbanaso, E N.A.  (1991)

Mutagenensis in Yam: Effect of gamma dose on survivability of treated yam tubers (Dioscorea rotundata) – Annual Report, National Root Crops Research Institute, Umudike   30-31 (En.)

The objective of the study was to establish the dose-range of gamma rays that will give high frequencies of beneficial mutations with little generic damage using micro tubers.

YR 72.    Okoli, O. O.  (1993)

Propagation Techniques and prospects for breeding of yams (Diocorea spp) – Advances in yam Research  Vol2: Production and post Harvest Technologies of the yam tuber. (1993) 7-16 (En., 19 ref 5 tab) National Root Crops Research Institute.

The difficulty of obtaining uniform setts for yield trials led to the study of the effect of size of ‘seed’ on yield determinants, yield components total yield and intra-plot variability in two cultivars of D.rotundata poir.  Result indicated that larger tubers sprout earlier than smaller tubers.  (ii) attain maximum sprouting percentage earlier than smaller tubers; and  (iii)  have higher percentage survival at harvest than small tubers.  These determinants imply that larger seeds yield higher by producing,

YR 73.    Okoli, O. O. and Akoroda, M. O. (1995)

Providing seed tubers for the production of food yams. – African Journal of Root and tuber crops. 1 (1) 1-6 (En. 19 ref. 5 tab.) Dept. of Agronomy, University of Ibadan, Ibadan, Nigeria.

In the late 1970s, a method was developed for the production of seed tubers separate from the production of ware, food or table tubers.  The method now known as the minisett technique utilizes a small (20-50g) part of a whole non dormant tuber containing periderm and some cortex parenchyma.  The minisett was sown and the resulting tuber was sufficiently large to serve as a seed tuber that was suitable for the production of food tubers.

YR 74.    Orkwor, G. C., Udensi, U. A. and Chukwu G.O. (1999)

Pre-release multilocational trials of hybrid yams and land races in nationally co-ordinated research project (NCRP) AT Umudike forest Zone.  – Annual Report. National Root Crops Research Institute 49-51 (En, 2 tab.) NRCRI, Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

The objective of the trial were to evaluate the hybrid yams with popular land races as a check in a pre-release multiclocational trial in yam ecologies and to determine which zone the new materials perform optimally as a guide for recommendation to farmers after release.

Result showed that the hybrid yams tested have compare favourably well with two local best (land races) DRN 010 and 93-2 (Pepa) in crop establishment at Umudike.

YR 75.    Orkwor, G.C, Surma, D., Chukwu, G. O, Kwagbura F. M, Udensi U

               and Anumudu M. C.  (2000)

Pre-release multilocational trials of hybrid yams at Umudike and Zakibiam – Annual Report: National Root Crops Research Institute, Umudike. 12-15  (En, 6 tab).

Trials were conducted at Umudike and Zaki Biam in April and may to carry out the two years.  Result showed that hybrid yams however appear less tolerant to some pest and diseases at the locations.  In terms of tuber yield ware yam and seed yams, the hybrid yams performed significantly better than the land races at the two locations.

YR 76.    Segnou, Fotokun, C.A;  Akoroda, M. O.; Hahn, S. K.  (1993)

Studies on the reproductive biology of white yam (Dioscorea rotundata Poir).  In Euphytica Vol. 64(37) 197-203 (From Plant Breeding Abstracts, June 1993 63 (6 )

Investigations were conducted on the identification and distribution of yam natural pollinators, flowering patterns and hybridisation of D. rotundata at the International Institute of Tropical Agriculture, Nigeria.  Studies on the flowering pattern revealed that (1) male and female clones differed in their periods of flower initiation as well as the flowering duration; and (2) seed production and conventional breeding methods are feasible if staggered planting, ware and soil fertility could be managed to ensure that flowering periods of males and females nick and also extend flowering.

YR 77.    Segnou, C.A.F., Akoroda, M.O. and Hahn, S.K.   (1992)

Studies on the reproductive biology of white yam (Dioscorea rotundata poir).  Euphytica 64, 197-203 (En. 10 ref. 3 tab.) Institute of Agronomic Research (IRA) B.P. 13 Nyombe, Cameroon.

Investigations were conducted on the identification and  natural pollinators, flowering pattern and hybridisation of white yam (Dioscorea rotundata poir) at IITA, Ibadan, Nigeria.  Studies on the flowering pattern revealed that (1) male and female clones differed in their periods of flower initiation as well as the flowering duration (ii) Seed production and conventional breeding methods were feasible if staggered planting, water and soil fertility could be managed.

YR 78.    Terauchi, R.  (1992)

The use of chloroplast DNA analysis in yam phylogeny reconstruction – Biotechnology: Enhancing Research on Tropical Crops in Africa (edited by Thotttapilly,  G. et al) Wageningen, the Netherlands, CTA, 255-260 (En. 2q2 ref.)  IITA, PMB 5320, Ibadan. Nigeria.

Recently developed techniques of molecular genetics were summarised in this work.  These techniques offered opportunities for elucidating the phylogeny and origins of yam species.  This knowledge is important for an effective breeding and conservation of yams.

YR.79.  Terauchi, R., Chikaleke, V, A., Thottoppilly, G. and Hahn, S. K. (1993)

Origin and phylogeny of Guinea yams as revealed by RFLP analysis of chlorplast DNA and nuclear ribosomal DNA – IITA Research  (6) 1-6, (En, 34 ref.)  International Institute of  Tropical Agriculture (IITA) PMB 5320, Ibadan Nigeria.

Variation in CtDNA and nuclear & DNA was studied in 7 accessions at white yam (Dioscorea rotundata), 5 accessions of yellow yam (D. Cayenensis) 2 accessions of an intermediate type (D. rotaundata – D. Cayenensis) and 12 wild Dioscorea species.  Ten Mutational changes were detected among the 26 CtDNAS analysed, allowing their classifications into 5 chloroplast genome types, A-E.  No intraspecific variation was observed.

YR 80.    Terauchi; R., Chikaleke V.A.; Thottappilly G. Hahn, S.K.   (1992)

Origin and phylogeny of Guinea yams as reveal by RFLP anlysis of chlorplast DNA and nuclear robosomal  DNA – Theoretical and Applied Genetics (6-7) 734-75 (From Plant Breeding Abstracts, Sep. 1992 62(9).

The origin and phylogeny of the Guinea yams consisting of the white yam (Dioscorea rotundata) and the yellow yam. (D. Cayenesis), was investigated.  It was revealed that two cultivated species (D. rotundata and D. Cayenensis) display the same chloroplast genome type, type A, as the three wild species D. prachensilis, D. Liebrectitsiana and D.abyssinica.  Chloroplst genome types B.C.D. and E. were found in D. Miantiflora, C.burkilliana, S. Smilacifolia and D. togoensis, respectively.

 ECONOMICS

YR 81.    Adesimi, A. A. , Doss, C. R.  and Olson, C.    (1991)

Farm enterprise combination and resource use among smallholder farmers in Ijebu, Nigeria –Issues In African rural development. (En. 18 ref. 5 tab) Dept. of Agricultural Economics, Obafemi Awolowo University Ile-Ife Nigeria. 

A survey information was obtained over the course of the 1987 Crop year.  This study survey results and budgetary and linear programming analyses, add to the growing body of evidence that suggested that intercropping of subsistence food crops was more profitable, efficient and practical than the cultivation of food crops in segregated stands.

YR 82.    Anuebunwa, F. O.   (2000)

A bio-economic on-farm evaluation of the use of sweet potato for complementary weed control in a yam/maize/ egusi/cassava intercrop in pigeon pea hegderows in the rain forest belt of Nigeria. – Biological Agriculture and horticulture 18 95-102.  (En.  12 ref. 4 tab) NRCRI Umudike, PMB 7006,Umuahia, Nigeria.

The bio-economic on-farm evaluation was conducted on resource-poor farmers’ farms in the Orlu and Owerri agricultural zones in the rainforest belt of Nigeria in 1996 and  1997.  Result showed the yields of all the component crops except cassava were statistically similar.  The yield of yam and cassava were higher where sweet potato was introduced at 10 WAP than with two hand weedings.  It has both the Monetary value and benefit.  There were savings in labour, in the use of the Intervention and it offers opportunity that can reduce production cost and drudgery.

YR 83.    Anuebunwa, F. O.   (1992)

A bio-economic evaluation  Intercropping arrangements in a yam-cassava based cropping system in the rain forest belt of Nigeria.  -  Biological Agriculture and horticulture.  8, 251-260 (En. 18 ref. 4 tab.) NRCRI, Umudike, PMB 7006, Umuahia Abia State

A farm-level trial was conducted at Mgbidi and Umuowa in the Orlu Agric. Zone of Imo State, Nigeria.  The productivity of and income from single, alternative and double row intercropping arrangements for yam (Dioscorea rotundata(/maize (Zeamay)/Egusi (Gtrulus Vulgaris)/Cassava (Manihot esculenta crantz).  Intercrop were compared against the farmers’ intercropping arrangements. The alternate row arrangement was able to transform the farmers’ farm resources into a highest profit margin of 80.35% over the farmers’ intercropping arrangement.

YR 84.    Asumugha, G. N. and Chinaka, C. C.  (1998)

Socio-Economic and Cultural variables influencing adoption of yam minisett technique in three Eastern States of Nigeria. – Proceedings of the 32^nd Annual Conference of the Agricultural Society of Nigeria.   56-59 (En, 5 ref. 6 tab) NRCRI, Umudike. PMB 7006 Umuahia.

This study analyses some socio-economic variables identified to influence the adoption of the yam minisett technology developed at the National Root Crops Research Institute Umudike, Umuahia.  The Result of this study indicated that most farmers prefer intercropping the yam minisett with compatible crops with yam/maize/egusi/vegetable and cassava.  The finding also indicates that contact with  extension agency and availability of inputs such as minisett dust and fertilizer showed positive influence on the adoption of the yam minisett technique by the study farmers.

YR 85.    Asumugha, G. N.  and Obiechina, C. O.B.  (2001)

Comparative economics of minisett and traditional seed yam production technologies at the farm level in the eastern forest zone of Nigeria. – African Journal of Root and tuber crops 4 (2) 9-12 (En. 12 ref. 4 tab) National Root Crops Research Institute, Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

This paper compares the economics of minisett technology with traditional method of seed yam production at the farm level in the eastern forest zone of Nigeria.  Results showed that the minisett technology was more labour intensive utilizes a lower total operating cost and also gives           higher net operating margin when compared to the local method.  However, there were no significant differences between the two technologies in the labour required for planting weeding, staking,  harvesting and storage except that for sett preparation and transportation.

YR 86.  Chukwu, G. O. and Ikwelle, M.C.  (2000)

Yam: Threats to its sustainability in Nigeria – Palawija News 17(1) 1-7. (En. 9 tab.) NRCRI, Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

This paper reviewed the threats in yam production in Nigeria, Inspite of its socio-cultural importance and culminary roles and offers- Solutions to boost and sustain the productivity of Nigeria’s king of root and tuber crops.

YR 87.    Eboh, E.C.   (1992)

Socio-economic survey of land-use intensification indicators in Anambra State, Nigeria – Beitiage zur Trospischen Landwirtschaft und Veterinarmedizin (1992) 30:2, 221-228 (En.  5 ref) Department of Agricultural Economics, University of Nigeria, Nsukka, Enugu State, Nigeria. 

The study attempted to determine and explain the nature and level of land use intensification; and ascertain the status of the land-bases economy, changes to cropping systems and the dynamics of forest/bush product availability in Anambra State.  Results indicated fallow management to have been adversely affected by increased, land shortages, the risks of soil exposure, deterioration, and degradation.

YR 88.  Ezeh, N.O.A.   (1991)

Economics of yam storage in alternative environments improved versus traditional barns – Annual Report Umudike, National Root Crops Research Institute, Umudike.  (1991) 37 – 43 (En. 9 ref. 3 tab

Yam tubers stored under the traditional open barn environment have short shelf-lives due to rapid weight loss sprouting and infection by Pests and diseases.  It has also been asserted that the improved barn developed by NRCRI, Umudike is better than the traditional barn.  The study aimed at analysing the relative technical and economic efficiencies of the two alternative storage structures – the improved and the traditional yam barns.

YR 89.    Ezeh, N.O.A.  (1996)

Benefit-cost Analysis of Improvements in the Productivity of Yam Minisett Technique – National Agricultural Research Project (NARP), Priority Research And REFILS Projects Report:  National Root Crops Research Institute Umudike. 19-21)  (En. 3 ref, 1 tab)

The research was carried out to see if improvements can still be made to improve the productivity of yam minisett technique.  Results showed that improvements in the productivity are technically and economically feasible.

YR 90.    Ezeh, N.O.A.   (1992)

Economic appraisal of an improved yam storage barn – Tropical Science 32. 27 – 32 (En. 10 ref.) NRCRI, Umudike PMB 7006, Umuahia, Abia State, Nigeria.

This study evaluated the improved yam barn developed at the National Root Crops Research Institute, Umudike, Nigeria.  The barn structure was described.  Gross margin and capital budgeting analytical tools were used.  The result showed that, interms of minimising tuber weight loss, the barn had storage efficiencies and was also economically feasible.    

YR.91.    Ezeh, N.O.A.  (1998)

Economics of production and post-harvest technology – In Food yams: advances in research edited by Orkwor, G.C. etal – Ibadan, Nigeria, IITA/Nigeria, 187 – 214 (En. 13 ref, 19 tabs). NRCRI Umudike, PMB 7006, Umuahia, Abia State.

The article analysed the economic factors of yam production, cost and profit implication and also the economic of the post-harvest technology.

YR 92.    Ezeh, N.O.A.  (1990)

Economics of seed yam production from minisetts in Umudike: implications for commercial growers. – Annual Report.  National Root Crops Research Institute, Umudike.  34 – 41  (En.  7 ref.  5 tab.)

The study aimed at carrying out a detailed economic analysis of seed yam production using minisetts at Umudike, South-Eastern Nigeria.  Results showed that the estimated net income per hectare of seed yams and gross margin are negative.  The above findings showed that a commercially-oriented seed yam producer should strive to either minimise his resource inputs or maximise his yields.

YR 93.    Ezeh,  N.O..A. (1991)

Economics of seed-yam production from minisetts in Umudike in Southeastern Nigeria.  Implications for commercial growers: – Proceedings of the ninth Symposium of the International Society for Tropical Root Crops.  378 381 (En. 12 ref.  3 tab)

This study conducted a detailed economic analysis of seed-yam production from minisetts at Umudike, South-eastern Nigeria and examined the implications of the results for commercial operators.  Result showed that labour inputs of about 218 man-days/ha, or 86.3 man-days plus 9.4 tractor hours/t of seed yams were required.  The estimated gross margin per hectare and net income per ha are – 4472.16 Naira and – 5120.16 Naira respectively.  This suggested that at the current level of input management, tuber yield, and prices, seed yam production from minisetts at Umudike was unprofitable.

YR 94.    Ezeh, N.O.A.  (1992)

Economics of yam Flour Production: Implications for a research and development and promotion of yam based industries in Nigeria. -  Tropical Agriculture (Trinidad) 69 (1) 51-57  (En, 13 ref. 7 tab.)  National Root Crops Research Institute, Umudike P.M.B. 7006, Umuahia, Abia State, Nigeria.

The study examined the cost-effectiveness of an improved yam flour production technology  (from Dioscorea rotundata Poir) developed at the National Roots Crops Research Institute, Umudike, Nigeria.  Results showed that an estimated gross margin per tonne of about N4050 and a net processing margin (profit of about N3811 were realisable from the venture.  The results of this study have important implications for research and development (R&D) and promotion of small-scale yam-based industries in Nigeria.

YR 95.    Lev, L. S. and Shriver ( 1997)

A trend analysis of yam production area, .yield and trade (1961 – 1996). – L’igname, plante se’culaira et culture d’avenir.  Actes du seminaire international cirad – Inra – Orstom – coraf. Montpellier, France.  11-16,  (En, 6 ref. 11 tab.)  Agricultural and Resource Dept. Oregon State Univ. U.S.A.

This paper provided a trend analysis of yam production, area yield and trade statistics for the period 1961-1996.  The analysis was conducted at the world, region and individual country levels.

YR 96.    Ndegwe, N. A   (1990)

Economic returns from yam/maize intercrops (1990) with various stake densities in a high-rainfall area.  – Tropical Agriculture. 69 (2)  171-175  (En, 7 ref. 7 tab.)  Rivers State University of Science and Technology, Institute of Agricultural Research and Training, P.M.B. 5345. Port Harcourt.

The profitability of producing yam (Dioscorea rotundata Poir) with 0-5000 stakes ha^-1 when intercropped with maize in a high-rainfall area in Nigeria was examined. Results showed that tuber yield and weight tuber decreased with lesser numbers of stakes ha^-1.  Production cost was highest with 5000 stakes ha^-1 and lowest in unstaked yams.  Trailing six stands stake^-1, gave the best net return (48%) in sole yam but two stands stake^–1 gave the best (22.4%) in intercropped yam.

YR 97.    Nweke, F.I.  Okorji, E.C.,  Njoku, J. E.,  King. D. J.  (1992)

Elasticities of demand for major Food items in a root and tuber based food System: emphasis on yam and cassava in South-eastern Nigeria. – Resource and Crop Management Research Monograph. (ii) 20  (En. 19 ref.  8 tab)  International Institute of Tropical Agriculture, P.M.B. 5320 Ibadan, Nigeria.

The objective of this paper was to ascertain the future of yam in South Eastern Nigeria by estimating and comparing the expenditure – elasticities of demand of yam with those of other staples.  Results showed that overall expenditure elasticities of demand for yam was greater than unity. Expenditure elasticities of demand for cassava were relatively high but low for cereals in relation to those for a root and tuber crops.

YR 98.    Onwueme, I. C. and Charles, W. B.   (1994)

Tropical root and tuber crops: production, perspectives and future prospects – FAO plant production and protection paper   FAO No. 126, 240  (En.)  Fed. Univ. of Tech. Owerri,  Imo State Nigeria.

Attention was focused on the significant role of tropical tuber crops in the economy of developing countries.  The objective was to provide Information which will assist government officials and policy-makers in acquiring resources for research and development.  The botany and ecology, cultivation, occurrence of pests and diseases, harvesting storage, processing, utilisation and socio-economic characteristics (including perspective, problems and future prospects) for a cassava, yam sweet potato and cocoyam were reviewed.

YR 99.    Orkwor, G.C. and Adeniji, A. A.  (1997)

Production constraints and available technologies for food yam (Dioscorea spp.) Production to Nigeria. – L’gname plantae s’eculaire et culture d’avenir.  Actes du s’eminaire international cirad – Inra – Drstom – Coraf.  Montepellier France. 409 –413. 

This paper discussed production constraints and reviewed available technologies developed to ameliorate these constraints so far for sustainable food yam production in Nigeria.

YR 100. Orkwor, G. C,   (1998)

The importance of yams – In Food yams: advances in Research  (edited by Orkwor, G.C. et al) Ibadan, Nigeria, IITA/NRCRI. 1-12 (En. 33 ref.) NRCRI Umudike, PMB 7006, Umuahia, Nigeria.

The article examined the Socio-Cultural and economic significance of yams.

YR 101. Ugwu, B. O.  (1996)

Yam and cassava productions as income-generating activities for households.  -  African Journal of Root and Tuber Crops. (ISTRC-AB) 1 (2): 1-43 (En, 5 ref.)  National Root Crops Research Institute, (NRCRI), Umudike, P.M.B.7006, Umuahia, Nigeria.

The aim of this research is to compare the roles of yam and cassava as sources of cash income for the producing households.  Result showed that in cassava producing areas, cassava production generated more cash income and benefited more household than yam production.  Cassava has a wider ecological adaptation than yam but both are cash crops in their respective producing areas.

ENTOMOLOGY

YR 102. Atu, U. G.  (1993)

Cultural practices for the control of termite (Isoptera) damage to yams and cassava in South-eastern Nigeria.  International Journal of Pest Management 39 (4) 462-466 (En, 8 ref. 5 tab.) Crop Production Department, Federal University of Technology, PMB 1526. Owerri, Nigeria.

Seed-bed  types,  Fertilisers cassava stem portions, Planting time and yam cultivars were studied for the incidence of termites in cassava and yam fields.  Results showed that planting cassava on ridges reduced the incidence of termites and significantly (P<0.05) increased tuber yield.  NPK mg (12:12:17:2) suppressed termites in yam and improved yield significantly.  Delay in harvesting yam tubers increased termite infestation.  Chinese yam showed the greatest resistance to termites.

YR 103. Echendu, T.N.C. and Alozie, S. O. (1990)

Susceptibilities of some yam cultivars to damage by Decadarchis Miniscula (Walsingham) Iepidoptera Tineidae) in Southeast Nigeria – Beitr.trop. Landwirtsch. Vet. Med. 28 (1990) H.1,  63-67  (En, 13 ref.  4 tab.)

This paper reported studies on the varietal susceptibilities of the difference yam cultivars currently recommended by the National Root Crops Research Institute to D. Miniscula.  The research also examined effect of storage structures currently in use and some biochemical changes with insect attack.

YR,104.  Emehute, J.K.U.  (1995)

Degradation of dried yam chips by Araecerus fasciculatus Degeer as influenced by Storage containers Pakistan Journal of Zoology  27 (2) 181 – 183 (En.) NRCRI, Umudike, PMB 7006, Umuahia, Abia Stte, Nigeria.

Handmade mini-baskets, mini-jute bags and polyethylene bags 20 and Um thick, were evaluated for their effectiveness for protecting dried yam chips against infestation by Aracerus fasciculatus in the laboratory at 26.5-30.5^oc and 60.0-85% RH.  After 7 months, the 130 UM polyethylene bags were undamaged.  Weight loss and infestation was significantly greater in the baskets and jute bags than in the Polyethylene bags.  Feeding loss was 32.8, 21.1, 5.9% and zero for the baskets, Jute bags and 20 and 130 Um thick polyethylene bags rep.   A fasciculatus did not survive in yam floor.

YR 105.Emehute, J.K.U., Odurukwe, S.O., Udealor, A., Ibedu, M. A..  (1998)

On-farm Evaluation of Sumithion 2.5D for the control of yam beetle – Annual Report 1997 And Programme of Work for 1998: National Root Crops Research Institute, Umudike 48  (En. 1 tab)

Research was conducted to evaluate under farmers’ condition, the effectiveness of Sumithion 2.5D for the control of yam beetle with a view to making firm recommendation.  Three treatments – Sumithion 2.5D.  Aldrin and the control were compared.  Results showed that tuber yield and unattacked yam tubers from Sumithion treated plots were better than in Aldrin and control plots.

YR 106. Emehute, J.K.U., Ikotun, T., Nwauzor, E. C. and Nwokocha, H.N.  (1998)

Crop Protection – In Food Yams advances in research edited by Orkwor, G.C. etal – Ibadan, Nigeria, IITA/NRCRI, 143 – 186 (En. 146 ref. 4 tab.) NRCRI, Umudike, PMB 7006, Umuahia, Abia State.

The article mentioned, described the numerous yam pests and diseases.  Their symptoms, distribution, economic importance and control.

YR 107. Emehute, J.K.U., Odurukwe, S.O., Nnodu, E.C., Nwauzor, E and

              Okwuowulu, P.A.  (1991).

Chemical control of crickets and beetles in Bori, Rivers State – Annual Report: National Root Crops Research Institute Umudike,  50-57 (En, 3 ref 5 tab.)

Six chemicals at manufacturer’s recommended rates were compared against untreated control in 1988.  The chemicals were tested at 3 application times.  Results showed that percentage damage by insects mostly crickets was as low with sumithion as with aldrin dust;  control with these two chemicals were significantly better than with other chemicals.

YR 108.  Emehute, J.K.U. and Echendu N.T.C.  (1992)

Susceptibility of stored yam tubers (Dioscorea spp) to infestation by Araecerus fasciculatus Degeer. – Tropical Science.  32 (1), 99-103.  (En. 10 ref)  National Root Crops Research Institute, Umudike PMB 7006, Umuahia, Nigeria.

Two species  of Dioscorea were used to study the effects of yam tuber periderm and cortex in relation to the susceptibility of stored yam tubers to Araecerus fasciculatus in the laboratory at a mean ambient temperature of 28.4^oc  and PH of 82.0%. Infestation was more severe when the cortex was cut open.  Protection afforded by the periderm differed signifiantly within and between the species of Dioscsorea and was greater in D.alata  cv Um680 than in 2 cultivars of D.rotundata.

YR 109.  Enyinnia, T.,  Emehute, J.K.U.  (1998)

On-Station validation of new dust formulation for dressing yam minisetts for enhanced establishment. – Annual Report 1997 and Programme of Work for 1998:  National Root Crops Research Institute, Umudike  47 (en. 1 tab)

A new dust formulation prepared by NRCRI was compared with Apron-plus as seed dressing materials for yam minisetts.  Results showed that the new dusts formulation protected minisetts against soil pests better than Apron and control.

YR 110.  Ezulike, T. O., Egwuatu, R. I.   (1993)

An investigation into the alternate host plants of green spider-mite, Mononychellus tanajoa in tropical rain  forest of South Eastern Nigeria. – Pakistan Journal of Zoology.) 25: (1) 83-85 (En, 14 ref.) National Root Crops Research Institute, Umudike  P.M.B. 7006, Umuahia, Abia State. Nigeria,

The research was carried out to check the incidence of tetranychid Monochellus tanajoa which has become the major arthropod pests of cassava in Nigeria since 1979.  Cultivated cassava supported large numbers of Mononychellus tanajoa, but no mites were found on weed species of the family Euphorbiaceae to which cassava belongs.  It was concluded that the host range of M. tanajoa was restricted to species of Manihot and that control strategies should concentrate on the species.

YR 111.  Green, K. R., Sangoyomi, T. E. and Amusa, N. A.  (1995)

Importance  of Rhizoctonia solani as a pattrogen of yam (Dioscorea spp) in Nigeria – Root Crops and poverty Alleviation:  Proc. Of the Sixth Triennial Symposium of the International Society for Tropical Root Crop.  Held at Lilongwe Malawi 22-28 Oct. 1995  412-418 (En, 12 ref. 5 tab).  Plant Health Management Division, IITA, Ibadan.

Preliminary Studies showed that R.. Solani was one of the Organisms causing severe symptoms of stem die-back and leaf blackening that were observed on yams propagated from true seeds at IITA.  Hence the objectives of the present investigation were to elucidate the biology of Rhizoctonia on yam .

YR 112.  Green K. R.  (!995)

Distribution and severity of foliar diseases of yam (Dioscorea spp) in Nigeria – Root Crops and poverty Alleviation: Proceedings of the Sixth Triennial Symposium of the International Society for Tropical Root crops – African Branch, held at Lilongwe Malawi.  22-28 October 1995  439 – 444.  (En. 18 ref. 4 tab.)   Plant Health Management Division, IITA, PMB 5320, Oyo Road, Ibadan.

This paper highlighted the major Findings from preliminary analysis which indicated that the severity of foliar disease was lowest in the northern guinea savannah and highest in the humid  forest zone, suggesting  a positive relationship with rainfall levels.

YR 113.  Morse S.,  Acholo M.,  McNamaira, N.,  Oliver R.  (2000)

Control of storage insects as a means of limiting yam tuber fungal rots. – Journal of stored Products Research  36 37-45 (En. 13 ref. 6 tab) International Development Centre, Reading University, 2 Earley Gate, Reading RG6   6AU. UK.

This study examined whether insect damage inflicted on yam tubers during storage in specialised barns was an important agent in the incidence of fungal disease.  Results showed that treatment of tubers with insecticide dust (Actellic 2% Dust ai= Pirimphosmethyl) significantly reduced Fungal infections resulting from insect attack during storage.  More so physical damage required during harvest appeared to be ameliorated by the insecticide, resulting in significantly fewer fungal lesions. Results suggested that insecticide treatment of yam tubers prior to storage could provide a relatively cheap and effective means of preservation.

YR 114.  Simons, S.A. and Green, K.R. (1994)

Quantitative methods for assessing the severity of anthracnose on yam (Dioscorea alata):- Tropical Science.  34 (2) 216 – 224 (En. 17 ref,) Dept. of Agric.  University of Reading, P. O .Box 236 Reading RG6  2AT, UK,

Two methods which have been used  successfully to assess the severity of yam anthrancnose in this studies showed that the individual leaf method provided detailed information on the incidence and severity of athrancnose on yam.

EXTENSION

YR 115.  Asiabaka, C. C. (1992)

The attitude of farmers towards the yam minisett technology in Imo State of Nigeria – Proceedings of the fifth Triennial Symposium of the International Society for Tropical Root Crops.  372 – 374 (En, 10 ref.  2 tab.) School of Agric. & Agric. Technology.  Federal University of Technology, Owerri, Nigeria.

The study focused on the perception and attitude of farmers in Imo State, of Nigeria, towards yam minisett technology.  Nineteen attitude statements were used to elicit Farmers’ attitude towards the technology. Findings indicated that respondents had a positive attitude towards the technology. Farmers perceived that late delivery of farm inputs, scarcity of fertilisers, input subsidy and small plot Adoption Technique (SPAT) strongly influenced their attitude towards the technology.

YR 116.  Chikwendu, D. O., Chinaka, C.C. and Omotayo, A, M,  (1995)

Adoption of minisett technique of seed yams production by farmers in the eastern forest zone of Nigeria – Discovery and Innovation   367-375. (En. 17 ref) National Agricultural Extension and Research Liaison Services, ABU, Zaria Nigeria.

The yam minisett technique was appraised among farmers in the structured questionnaires.  The findings showed that while 78.8% of the farmers were aware of the technique, only 48.8% actually practised it.  Age, household size cooperative membership, tenurial status and the intensity of extension contact were significant determinants of the adoption of the technique.  Among the constraints to adoption of the technique were scarcity of complimentary inputs, lack of funds and tedious and technical nature of the procedures involved in the technique.

YR 117.  Erhabor, P. O., Omoregie, E. M. and Idachaba, F.S.  (1994)

The state of agricultural research and its commercialisation in Nigeria.  Tropenlandwirt 95, 173-183 (En. 9 ref. ) Dept. of Agric. Economics, University of Agriculture Makurdi, Benue State  Nigeria.

Hybrid maize and minisett yam and yam pounding equipment are presented as case studies of insufficient utilization of these improved technologies.  Suggestions aimed at improvement of information dissemination of technologies are listed.

FARMING SYSTEMS

YR 118.  Anuebunwa, F.O.  (1994)

On-farm evaluation of yam staking material alternatives in a yam-cassava bases cropping system in the forest–savanna mosaic belt of Nigeria. – Biological Agriculture and Horticulture  10, 179-188 (En, 26 ref 6 tab) Nigeria Umudike PMB 7006, Umuahia, Abia State, Nigeria.

A two year farm level trial (1989-1990) was conducted in Ikom and Ogoja agricultural zones of Cross River State, Nigeria.  Live guinea corn (Sorghum bicolour L. CV KSV8) and maize (Zea Mays L CVTZSRW) as yam staking materials alternatives were compared against the farmers conventional wood stakes.  Result showed the use of live guinea  for staking 200g yam sett size with a cost outlay advantage of 25.03%, gave the highest profit margin also potential acceptability.  It offers opportunity that stimulates yam production.

YR 119.  Igwilo, N.  (1992)

Effect of height of stakes and intercropping with Okra (Abelmoschus esculentus) on the yield of yam (Dioscorea spp) grown from seed yams. – Beltr. Trop. Landwirtsch. Vet. Med.   30(4)  373 – 379  (En 9 ref  2 tab).  Institute of Agricultural Research and Development, University of Port Harcourt. PMB 5323, Port Harcourt,  Nigeria.

In 1989 and 1990 the yam varieties Obiaoturugo (D. rotundata) and UM 680 (D.alata) were grown sole or intercropped with Okra (Abelmoschus esculentus)  Result showed that intercropping with Okra and the height of stakes had no significant effect on the tuber yield of both yam varieties.  The height of the stakes had no effect on the yield of Okra.  Intercropping and the height of stakes did not affect the leaf area index (LAI) of yam and Okra.  Economic and ecological implications of these 4 results are discussed.

YR 120.  Igwilo, Ndubisi  (1998)

Effect of intercropping yam and maize on the performance of both crops using maize stalks as alternative supports for the yam vines – Proceedings of the 32^nd Annual Conference of the Agricultural Society of Nigeria.  209 –213 (En, 8 ref. 7 tab) Institute of Agricultural Research and Development, University of Port Harcourt.

This experiment was designed to explore the possibility of using maize stalks as alternative supports for yam vines in a yam/maize mixture.  The result suggested that it is not advisable to intercrop yam with maize.  Rather, the field should be partitioned between the yam crop and the maize crop and maize grown at optimum population in its own portion of 50,000 stands/ha instead of the 20,000 stands/ha used in this experiment.

YR 121.  Igwilo Ndubisi  (1998)

Yield of yam tubers grown from minisetts in relation to height of stakes and interrcopping with okra (Abelmoschus esculentus Moench) in the rain forest zone of Nigeria.  -  The Nigerian Agricultural Journal  29,  95 –105 (En., 12 ref. 5 tab.)  Institute of Agricultural Research and Development, University of Port Harcourt, Port Harcourt.

A study was conducted to explore the suitability of Okra for intercropping with yam minisetts  and of using stakes shorter than 2m for supporting the yam vines.  Results showed that yam and Okra were planted on the same dates.  In both years, the yields of the yam varieties were not significantly affected by intercropping. Or by height of stakes. Okra fruit yields were also not affected by the yams or by height of  stakes.

YR 122.  Igwilo Ndubisi  (1994)

Effect of staking and population of yam and removal of maize leaf and ear in a yam/maize:  Dry matter production and the mechanism of maize interference with yam yield.- The Nigerian Agricultural Journal  27(1) 73-82 (En, 8 ref. 6 tab)  National  Institute of Agric. Research and Dev. University of Port Harcourt.

Intercropping yam with maize caused a significant reduction in tuber and non-tuber dry matter yield of yam.  The reduction in the yield of yam was attributed to increase in soil physical impedance to yam root and tuber growth caused by aggressive root competitor of the fibrous root system produced and left behind by the maize component crop.

YR 123.  Ikeorgu, J.E.G., Anioke, S.C., Nwauzor, E. C.,  (1997)

Investigations on component crops for intaercropping compatibility with yam minisetts.  Annual Report 1997 and Programme of Work for 1998:  National Root  Crops Research Institute, Umudike.  37-39.  (En. 2 tab).    

Yam setts of appropriate weight and the desired space were intercropped with cowpea, yam barn, vegetable cowpea, bambara soyabean and groundnut. Results showed that sole yam cropping yields optimum results.  For purposes of increased total returns and to satisfy dietary requirements, intercropping was recommended too.

YR 124.  Oladokun, M.A.O. (1990)

Tree crop based agroforestry in Nigeria: a checklist of crops intercropped with cocoa-Agroforestry Systems.  II(3) 227-241. (En. 6 ref.)  Cocoa Research Institute, PMB 5244, Ibadan Nigeria.

A survey of cocoa farmers in Bendel, Ogun, Ondo and Oyo States of Nigeria, carried out in 1985, showed that almost all the farmers intercropped other crops with cocoa.  The intercrops include food crops such as plantain (921.3%)  cocoyam (85.7%) Cassava (51.3%), Yam (41.3%) Maize (38.9%), etc. and tree crops such as oil palm (71.5%), kola (.3%), Coffee(41.0%)  and other crops. Result showed that as many as six or more other crops could be intercropped with cocoa at the same time.

YR 125.  Unamma, Ray P.A. Anuebunwa, F. O., Oputa, C. O  (1990)

On-farm evaluation of different weed management alternatives in a yam-maize intercrop.  – Nigerian Journal of Weed Science .  59-66.  (En 7 ref. 3 tab).

Alternative weed management strategies involving the use of alachlor (2-chloro – 2, 6 – dietyl – N – (Methoxymethyl) acetanilide) at 2.0kg ai./ha, chlorambea (3-amino – 2,5- dichlorobenzoic acid) at 3.4kg ai./ha and Fluometurol (1, -dimethyl – 3 – (a,a,a, - trifluoro – m – tolyl) urea at 2.5kg ai./ha applied either singly or in combinations and the use of relatively high populations of low-growing crops, manual hoeing and combinations of these, were tested on white yam Dioscorea rotundata Poir cv. ‘Nwopoko’ intercropped with (i.c.w.) yellow maize (Zea mays L. cv. FARZ-Y).  For technical feasibility, economic viability and socio-cultural acceptability.  Generally, all the weed control alternatives gave yields that were as good as, or significantly better than the above.

YR 126.  Wariboko, C., Harry, G. I. And Dan-kalib, L.A.,  (1996)

On-farm evaluation of the effect of introducing soybeans into yam/cassava/maize intercrop on productivity in Rivers State. – Proceedings of the 10^th Annual Farming Systems Research and extension Workshop in South-Eastern Nigeria (1996)  117-118 (En, 1 tab)  Rivers State ADP, Port Harcourt, Rivers State.

This trial was aimed at introducing soybean into the yam/cassava/maize crop mixture with a view to increasing productivity and income of the resource poor farmers.  Results indicated that inclusion of soybeans in the mixture did not significantly affect the yield of yams and maize. The root yield of cassava was significantly higher when soybeans was introduced in the crop mixture.

GENETIC RESOURCES

YR 127.  Chukwu, G. O., Chukwu, K. E. and Mbanaso E. O..   (2002)

Indigenous knowledge of conserving biodiversity in yams in Nigeria  - Proc. 36^th Ann. Conf. Agric. Society of Nigeria F.U.T.  Owerri     121-124  (En. 10 ref. 1 tab,)  National Root Crops Research Institute, Nyanya sub-station, P. O. Box 9682, Garki, Abuja.

A survey was undertaken in the root crop belt of Nigeria to document indigenous knowledge of conserving biodiversity in yams.  Result showed that farmers adopted integrated approach.

YR 128.  Vernier P., Orkwor, G. C. and Dossou, A. R.  (2003).

Studies on yam domestication and Farmers’ practices in Benin and Nigeria – Outlook on Agriculture.  32  (1)  35 – 41  (En, 11 ref. 6 tab) CIRAD T70/16, 34398 Montpellier cedex 05, France.  E-mail:  Philippe,vernier @Cirad  Fr.

The objective of this paper was to present information gathered in the different regions of Benin and Nigeria in order to give an overview of the techniques of domestication of yam in this region, considered to be the centre of dissemination of Guinea yams.  Results showed that actual practices of domestication are tending to decline, in particular where yam production is mostly market-oriented, and this endangers the future of D.rotundata, a species representing about 90% of the cultivated yams in the world, and which is a major component of food security in Western Africa.

MECHANIZATION

YR. 129  Aiyelari, E. A. and Akoroda, M. O.   (1996)

Determination of some yam tuber properties relevant to the design of  mechanical harvesters – African Journal of Root and tuber crops (ISTRC – AB) 1 (2): 1-43 (En, 12 ref. 2 tab).  Agronomy Depart; University of Ibadan, Ibadan Nigeria.

The study examined five sites and five cultivars with varied cultural conditions.  For physical aspects and orientation of tubers of white yam grown in ridges in relation to the design of mechanical harvesters.  Results showed that the study has provided the required design data on the common width of tuber growth combined with knowledge of the probable size and location of tubers in the soil.

YR 130.  Akubuo, C. O. , Odigboh, E. U. and Anazodo U.G.N.   (1993)

Design of a two-row Automatic seed-yam Planter. – Advances in yam Research Vol.2:  Production and Post Harvest Technologies of the yam tuber 25-33 (En, 8 ref. 2 tab)  Department of Agricultural Engineering, University of Nigeria, Nsukka, Nigeria.

This paper discussed  the design and performance testing of a prototype automatic seed yam planter.  The planter also has a version for planting minisetts for seed yam production.  Results showed that the present design has the potential to the problem of mechanising  the planting of seed yams.  The highest planting rate of 0.82 ha/ was obtained at 3.51 km/h on a well prepared field with the tractor operating in the second lowest gear.

YR 131.  Nwandikom, G. I.  (1990)

Yam tuber resistance to mechanical damage: - Agricultural mechanization in Asia, Africa and Latin America.  (1990) 21 (2)  33-36  (En, 15 ref) (From Field Crop Abstracts. Oct. 1990, 43 (10).  School of Engineering and Engineering Technology, Fed. University of Technology, Owerri, Nigeria.

The bulky nature and high moisture content of yam tubers make them vulnerable to mechanical damage during production, handling and storage operations.  The contribution of modulers of deformability, bioyield strength, rupture strength and density of yam tuber in predicting failure conditions under dead and impact loading were briefly presented.

YR 132.  Nwandikom, G.I., Ozara, N., Opara C.C., Olowonibi, M.M., Obiakor, S.I., Ozumba, I. C., Kamalu, A.R., Olajide, D. O., Oye, T. J. (1998).

Survey of existing  tools. – Annual Report 1997 and Programme of Work for 1998: National Root Crops Research Institute, Umudike (12998) 54 (En,)

The project was aimed at surveying existing tools for planting and harvesting yams;  Literature review was conducted at IITA, NRCRI, NIAM and University of Ibadan.  Questionnaire on existing tools for planting and harvesting yams was administered on farmers.  Results showed that no machine was identified for planting/harvesting yams.  Only hand tools were available.

YR 133.  Nwandikom, G.I., Ozara, N., Opara, C.C., Olowonibi, M.M., Obiakor, S.I.,Ozumba, I.C. Kamal, A.R. Olajide, D.O., Oye, T. J.  (1998)

Identification of farmers’ felt need for planting and harvesting yams.  – Annual Report 1997 and Programme of Work for 1998: National Root Crops Institute, Umudike (1998) 54 (En).

The research was aimed at identifying farmers’ needs and to collect field data for designing yam planter and harvester.  To achieve this, questionnaire was administered on farmers.  Results showed that design of a yam planter and harvester was in progress.

YR134.  Nwokedi, P. M., Anazoda, U.G.N.,  Obi, I. U. and Onwualu, A.P.  (1992)

Regression models for predicting soil compaction and tillage machinery effects on yam cultivation – Trends in Agricultural Engineering. Proceedings of Engineering held in Prague 15-18 Sept. 1992,  368 – 372 (En, 7 ref.)

Four tillage systems were evaluated for yam cultivation in a sandy –clay loam  subjected to 4 levels of soil compaction, in the humid rain forest zone of Nigeria.  The finding indicated that compaction levels were provided by different machinery weights and traffic.  Regression models developed showed linear relationships between soil properties and yam sprouting and yield.

YR 135.  Odigboh, E. U. and Akubuo C. O.  (1991)

A two-row automatic minisett yam planter – Journal of Agricultural Engineering Research  50, 189-196.  (En. 9 ref. 2 tab), Dept. Agricultural Engineering, University of Nigeria, Nsukka .Enugu State

A two-row automatic minisett yam planter prototype was designed, constructed and tested.  Result showed that the planter achieved a field capacity of 0.34 to 1.32ha/h at the tested speeds of 1.90 to 7.35 km/h on a clean well prepared field with very few misses as a result of the near 100% metering efficiency.  The planter also makes acceptable sizes  of ridges, and places the minisett in ridges at within-row spacings and planting depths close to agronomically recommended values of 25cm and 4cm respective

 NEMATOLOGY

YR 136.  Fawole, B. and Osunlola, O. B.  (1999)

Comparative efficacy of thermotherapy and chemotherapy of control of root-knot nematodes meloidogyne spp in yam tubers. – African Journal of Root and tuber crops 3 (2) 38-40 (En. 10 ref 1 tab).  Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria.

Studies were carried out to determine the comparative efficacy of chemical disp and hot water treatment to disinfest  “seed” yam against meloidogyne spp.

Results indicated that though the nematicides mocap and nemagon were more effective in denematizing yam tubers, hot water immersion for 30 minutes at 50^oC may be a preferable control option for practical, ecological and economic reasons.

YR 137.  Nwauzor, E.C.  (1996)

Use of groundnut (Arachis hypogaea L.)  As an Intercrop For Nematode Control In Seed Yam Production by Minisett Techniques Final Report.  National  Agricultural Research Project (NARP) Priority Research and REFILLS Projects  22-26 (En, 2 ref) 2 tab)

The researcher inter-cropped specified groundnut varieties with nematode-susceptible yam varieties to see if this can effect nematode control in seed yam production by minisett technique.  Results showed that by intercropping  yam minisett (40,000/ha) with groundnut SAMNUT 10 at (160,000/ha) or 120,000/ha), nematode damage of seed yams will be reduced by about 60%.

YR 138.  Nwauzor, E., Odurukwe, S. O., Nnodu E. C., emehute J. K. U. and

 Okwuowulu, P.A.  (1991)

Investigations on level and time of application furadan 3G for optimum control of yam nematodes. – Annual Report: National Root Crops Research Institute Umudike.  58-62 (En, 4 ref. 2 tab.).

The study aimed at establishing optimum dosage of the nematicide as a result of very high incidence of nematode infection and storage rots observed in Bori.  Result showed that soil nematode population was reduced by application of furadan 3G. 

YR 139,  Nwauzor, E.C.,    (2000)

Studies on the Residual Effect of Neem leaves incorporated into the soil on nematode control in yam production.  – Annual Report: National Root Crops Research Institute, Umudike (2000) 18-21  (En. 2 ref. 3 tab) NRCRI, Umudike.

This paper reports on the effect of the residual neem leaves on soil nematode, population nematode infection of emanating yam tubers and yield of yam in subsequent cropping of same piece of land.  Result showed that minisett sprouting and establishment were not influenced by the residual neem leaves in the soil.  Yam tuber yield was  significantly higher in all neem-treated plots compared with control.

YR 140.  Nwauzor, E.C.   (2000)

Effect of integrating dry season tillage with groundnut intercrop on the control of nematodes in yam production – Annual Report: National Root Crops Research Institute, Umudike. (2000)  21-24  (En. 2 ref. 2 tab).

This paper reports on a two year trial, evaluating the efficacy and superiority of the combination of the two control measures (dry season tillage and groundnut inter crop) as against the individual measures for nematode control in yam production.  Result showed that the presence of groundnut, tillage either during dry season or wet season did not influence sprouting and establishment of yam minisett.  Yield of yams were significantly higher in plots that received dry season tillage than plots tilled at normal wet season period.

YR.141.  Nwauzor, E.C.     (1990)

Denematization of seed yams infected by root-knot nematode using bleach solution. -  Annual Report National Root Crops Research Institute (NRCRI) Umudike 46—48 (En, 3 ref. 1 tab.)

Most nematodes that attack yam tubers concentrate within the 1^st 1cm from the peridermal surface.  This work reports on the results of dipping nematode – infected yams in commercial bleach.  Result showed that after 3 months of storage, 93.3% of control tubers had rotted.  Rot incidence was reduced with increasing bleach concentration and longer dipping time.  Dipping in 30% bleach for 30 minutes produced the bests result.

YR 142.  Nwauzor, E. C.  (1999)

Control of nematodes in yam production by soil organic matter amendment using nematode – antagonistic plant (Neem) as green manure – Annual Report: National Root Crops Research Institute,  28-30  (En, ref. 2 tab.)

The objectives of this study were to find out the effect of incorporating fresh neem leaves in the soil during seed bed preparation on nematode control and performance of yam and to determine the optimum level of neem leaves for best results.

Results showed that incorporating neem leaves into the soil during seed bed preparation at the rate of 10-15T/ha will enhance tuber yield and less nematode – infested seed yams.

YR 143.  Onyenobi, F. I. and Silwood Centre for Pest management   (1993)

Evaluation of commercial pesticides for the Protection of Dioscorea Rotundata from Meloidogyne incognita at Cultivation – Advances in yam Research Vol. 2:  Production and Post-Harvest Technologies of the yama tuber 34-42 (En, 21  ref. 4 tab.) Department of Science Technology, Institute of Managements & Technology (IMT) Enugu Nigeria.

The pesticides currently used for yam protection in Nigeria were evaluated with vydate 100 (oxamyl), to determine the most effective treatment for root-knot nematode control.  Result showed that the overall assessment of the pesticides indicate  that  Vydate 10G is best at root-knot nematode control.  However, the yield of yam harvest from Furadam 5G, and marshal 3D treatments were more though not statistically significant.

PATHOLOGY

YR 144.  Acholo, M., Morse, S., Macnamara, N., Flegg, L and Oliver, R. P. (1997)

Aetiology of yam (Dioscorea rotundata) tuber rots held in traditional stores in Nigeria:  Importance of Fusarium spp and yam beetle. – Microbiological Research  152(3) 293 – 298 (En. 19 ref,) Diocesan Development Services,  P. O. Box 114, Idah, Kogi State, Nigeria.

The extent and causes of yam tuber rots were investigated  in Igala land. Nigeria.  Rots were found to be associated with prior physical damage in almost all cases.  Numerous fungal species were isolated from the infected lesions of which fusarium spp. Predominated not Betryodiplodia theobromae as previously reported.

YR 145.  Akem, C. N., Asiedu, R. (1992)

Distribution and severity of yam anthracnose in Nigeria. – Proceedings of the Fifth Triennial Symposium of the International Society for Tropical Root Crops. – Africa Branch, Uganda.  Nov. 22-28 (1992) 297-301.  (En.13 ref. 3 tab.)

Yam anthracnose was found in all 4 regions of the country in which yam production is concentrated. Disease severity was greatly influenced by the cropping systems of the fields.  Results showed that there were good correlations between the percentage of fields affected by anthracnose and mean DS in affected fields in each region.   Yam hectarage in the four regions did not correlate with either percentage of fields affected by anthracnose or mean DS.

YR 146.  Amusa, N.A.  (1997)

Fungi associated with anthracnose symptoms of yam (Dioscorea spp.) in South –West Nigeria and their roles in disease severity. – Crop research  13 (1) 177-183 Department of  Agricultural Biology, University  of Ibadan, Ibadan, Nigeria.

Five different fungi were found to be associated with the severe blight symptoms often encountered on yam foliage and stem. Pathogenicity test revealed that all the Fungal isolates were pathogenic on yam (TDa 289) leaves.  Although each isolates produced leaf spot of varying sizes, C. Pallescens and C. eragrostides induced leaf spots of 0.4 and 0.5 cm with yellow halo on leaves of D.alata (TDa 289), respectively.

YR 147.  Amusa, N. A. (2001)

Fungi associated with yam chips in storage and the effects on the chips nutrient composition. – Moor Journal of Agricultural Research.  2 (1)  35-39 (En, 20 ref.  3 tab,) Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation. PMB. 5029, Ibadan Nigeria.

The aim of this study was to determine the fungi associated with yam chips in storage and their effects on the nutrient composition on food value of the chips.  Results indicated that the wall surface of the storehouses were all contaminated with the Fungi, even if yams for processing were brought into store free of infection, during drying and storage, the possibility for contamination is high.

YR 148.  Ejechi , B. O. and Ilondu², M. E. (1999)

Control of yam tuber (Dioscorea rotundata) rot agent sclerotium rolfsii with camwood (Baphia nitida Lodd) sawdust extract. – Africa journal of Root and tuber crops 3 (2) 13-15.  (En. 10 ref. 3 tab) Department of Microbiology and Department of Botany, Delta State University, Abraka, P.M.B. 1. Abraka, Nigeria.

This preliminary work was undertaken to determine the extent of which the extractives of the sawdust of Camwood (Baphia nitida Lodd) a tropical timber species can control growth of sclerotium rolfsii, a major agent of yam rot.  Results showed that the growth of sclerotium rolfsii was retarded by the ethanolic extract of camwood, an indication that the ethanolic Camwood extract may control sclerotium rolfsii in yam tuber.

YR 149.  Ejechi,  B. O. and Souzey, J. A. (1999)

Inhibition of biodeterioration of yam, tuber (Dioscorea rotundata) poir in storage with phenolic extract of acalypha hispida Burm, F. leaves. – Journal of Stored products Research 35, 127-134 (En, 14 ref.  4 tab.)  Dept. of Microbiology, Delta State, University, Abraka Nigeria.

The effect of an aqueous crude leaf extract and an extract of leaf phenolic acids of acalypha hispida on biodeterioration of yam (Dioscorea rotundata) Inoculated with sporesa or sclerotia of sclerotuim rolfisii penicillium spp,. Fusarium sp., Rhizopus sp. and Aspergillus, niger was investigated.  The phenolic acids extracts was more inhibitory than the aqueous crude extract.  Biodeterioration of inoculated and uninoculated fleshly harvested yam tubers stored for 8 months was reduced by 52-66% following treatment with extracts.

YR 150. Ekefan E. J., Simons, S. A. and Nwankiti, A. O. (2000)

Cultural characteristics and pathogenicity of isolates of collectotrichum gloeosporioides on yam (Diosocrea alata). – Science forum: Journal of Pure and Applied Sciences.  109 – 118 (En, 23 ref. 4 tab). Dept of Agriculture University of Reading, Earley Gate, United Kingdom.  

The paper reported on a preliminary investigation on the cultural/morphological characteristics of 8 isolates of C. gloeosporioides and their pathogenic variation on a susceptible variety of D. alata.

YR 151.  Onyenobi, F. I. (2000)

Control of meloidogyne infestation of seed yams with Vydate L D.P. – African Journal of Root and Tuber Crops  4 (1) 4-7 (En. 20 ref. 3 tabs) College of Agriculture and Veterinary Medicine,  Abia State University, PMB 2000, Uturu, Abia State Nigeria.

The germination potentials of root-knot infested seed yams (100 – 150g) treated with Vydate L. by dipping for 2h  at 500 – 4,000 mg a.i. per ml were not significantly attacked but showed more vigorous growth of vines and canopy than the untreated plant though phytotoxicity was observed on plants treated at 4 000Ng,a,, per ml.  The total weight of yam tuber yield from seed yams treated at 500 Ng a.i per ml was highly significant. After harvest, the final soil population of meloidogyne incognita d2 and infectivity bioassay test results were both significantly lower.

YR 152.  Green, K. R. and Simons, S. A. (1994)

Dead skin on yams (Dioscorea alata) caused by colletotricthum gloeosporioides, - Plant Pathology  43 (6) 1062 – 1065 (En, 6 ref.) Department of Agriculture, University of Reading, Earley Gate, Reading RG6 2AT, UK Experiments were undertaken to identify the specific symptoms associated with dead skin on tuber of D. alata and to test the hypothesis that C.gloeosporioides is the causal organism of dead skin on yam tubers.

YR 153.  Mozie, O.   (1996)

Effect of Mechanical injury and regulated air flow on storage losses of white yam tubers – Tropical Science  36.  65-67  (En. 4 ref)  De Botanical Consultancy Service, P. O. Box 5914, Onitsha Nigeria.

In two-thirds of all rotted tubers examined in storage, the point of entry for the rot organisms was a mechanical injury of some kind.  In the other cases senescence of sound tubers might have caused decay with regulated air movement around the tubers, rotting of sound tubers was completely suppressed.  Slow air movement resulted in the lowest moisture losses but the greatest total storage loss.

YR 154.  Moura – Costa, P.H., Kandasamy, K. I. and Mantell, S. H. (1993)

Evaluation of in vitro screening methods for assessing anthracnose disease reactions in tropical yam (Dioscorea spp.) – Tropical Agriculture.  70 (2)  147-152 (En, 25 ref. 2 tab)  Department of Agric. Horticulture and Environ. Wye College (University of London). 

The aim of the study was to compare  anthracnose disease reactions of various yam genotypes known to produce different responses to the disease under field conditions and to determine whether the reactions obtained were sufficiently similar under both in vivo and in  vitro situations to enable the development of tissue culture-based techniques of rapid anthracnose disease screening for yams.

YR 155.  Nwankiti, A.O., Olatunde, G. O., Afolami, S.O.  (1997)

Survey of existing control measures for yam rot and sprouting during storage – Annual Report 1997 and Programme of Work for 1998: National Root Crops Research Institute Umudike, 49 (En.)

The research investigated farmers method of storing yams to prevent tuber rotting and sprouting.  Survey on this was carried out in Oyo, Osun and Benue State.  Results showed storage practices of use of plant extracts of Khaya senegatensis.  Mitrogyna inertia, palm fruit fibre wood ash to prevent rotting and delay sprouting.  Manual removal of sprouts was also being practised.

YR 156.  Nwankiti, A. O., Williams J. O., Olayemi, S.C., Nwangwu, S.C. and Okoye

   W.I.  (1998)

Evaluation of local herbs for control of rotting and sprouting of yams in storage.  Annual Report 1997 and Programme of Work for 1998.  National Root Crops Research Institute, Umudike  49-51 (En. 3 tab.)

The research aimed at assessing the effectiveness of local materials for control of rotting and sprouting in storage of yam.  Water extracts of neem seed and leaf. Back of  mahogany garlic, wood ash back of Kyana seneglensis, leaves of Mitragyna inermis and spent engine oil were used in treating freshly harvested yam tubers and observed for sprouting and rotting.  Results showed that the herbs controlled rottings; while spent engine oil suppressed sprouting of tubers.

YR 157.  Ogundana, S. K.  (1993)

Storage Rot of yam tubers in Nigeria. – Advances in yam Research Vol.2: Production and Post-harvest Technologies of the yam tuber  124-134  (En, 50 ref. 4 tab)  Dept. of Microbiology, Obafemi Awolowo University, Ile-Ife, Nigeria.

This paper described major storage disease of yam, causal agents and methods of control.  The paper recommends that in all storage operations, the material which enters the store should be of optimum quality since the extent of disease at the end of storage will be influenced by the degree of handling damage shown by the tubers at the start of storage.

YR 158.  Rompf, R. Terauchi, R., Gunter K.  (1997)

A fungal defence gene of Dioscorea bulbifera L. its sequence, promotor and transcriptional regulation – L’igname  plante s’eculaire et culture d’avenir.  Actes du s’eminaire international cirad – Inra – Orstom – Conf. Montpeller France.  225 – 256 (En. 214) Plant Molecular Biology Biocentre University of Frankfurt Main Germany.

The aim of this paper was to study the induction of defence related genes upon elicitation with a cell wall preparation of colletotrichum gloeosporioides.

YR 159.  Sweetmore, A. Simons, S. A. and Kenward M, (1994)

Comparison of disease progress curves for yam anthraconose (colletotrichum gloeosporiorides) – Plant Pathology.  43 (1)  206-215 (En. 24 ref. 7 tab.) Crop Protection Research Unit, Department of Agric., University of Reading, Earley Gate, Box 236, Reading RG6, 2 AT, U.K.

The aim of the study was to construct disease progress curves for yam anthracnose and to examine the effects of both site and leaf age, and their interactions on the development of the disease.

YR 160.  Winch, J. E., Jackson, G. V. H., Newhook, F. J. and Cole, J. S.   (1993)

Blackening on yam in response to Colletotrichum gloeosporioroides –

Plant Pathology   42(2)  187-194  (En.,34 ref 2 tab) Botany Department., University of Auckland, New Zealand.           

Paper presented evidence that C. gloeosporiodes causes the blackening on mature leaf surfaces with symptoms distinct from anthracnose lesions which the same pathogen induces on immature leaves where it where it penetrates to both surfaces.

PHYSIOLOGY

YR 161.  Agbo, F,M,O,  (1990)

Determination of dormancy in different cultivars of yam species – Annual Report: National Root Crops Research Institute (NRCRI) Umudike 31-33.   (En, 4 ref.  1 tab.)

Investigation was to determine the period of dormancy in the elite varieties of 6 widely cultivated yam species and to assess differences between and within species.  Results indicated that the classification of varieties into short, medium or long dormant types would be a realistic proposition of the breeder.

YR 162.  Aighewi, B. A., Asiedu, R² and Akoroada, M.O.³  (2002)

Patterns and locations of sprouts on intact taubers of a multiple sprouting Dioscorea rotundata poir. variety pepa. – African Journal of Root and tuber crops 5 (1) 18-19 (En.6 ref: 2 tab)  ¹Department of Crop Production University of DSchang, DSchang, Cameroun, ²IITA, Ibadan, Nigeria.

The location and pattern of sprout formation on intact tubers of a multiple sprout variety, pepa were studied .  Result showed only 0.4% of the tubers had a single sprout at the proximal apex of the tuber, while 85.5 produced a bunch of sprouts in that region. Up to 96.1% of tubers had sprouts only in the proximal region while a small proportion had sprouts all over the tuber (11.2%), only in the middle portion (0.3%), or only in the distal (tail) portion (0.8%).

YR 163.  Emehute, J.K.U., Orkwor G. C., Anioke, S,. C.  (1996)

Sourcing of local raw materials as substitute(s) for yam minisett dust. – National Agricultural Research Project (NARP), Priority Research and REFILLS Project Report: National Root Crops Research Institute, Umudike.  13-18 (En, 3ref. 4 tab) 

Six local raw materials-based dusts were selected for this trial. They were compared with the NRCRI yam minisett dust in a randomized complete clock design experiment replicated three times.  From the results, four of the dusts, i. iii, iv and vi, gave over 85.0% minisett establishment in at least one of the locations.   A result which is comparable to the figure obtained with NRCRI yam minisett dust formulated using solely propriety pesticides.

YR 164.  Rodriguez W. M. and Leihner, D.E. (1997)

Growth Rates and dry matter partitioning during different phenological growth stages of the greater yam(Dioscorea alata L) – L’igname Plante S’eculaire et culture d’avenir.  Actes du s’eminaire International Cirad – Inra – Orstom – Coraf.  Montpeller  France. 247- 249  (En, ) Universidad de costa Rica, escuela de Fitotecnia, Codigo Postol 2060, San Jase, Costa Rica.

The objectives of this study was to quantify yam D. M. production and partitioning according to phenological phases, and to determine absolute and relative growth rates for different plant parts during these phases and relate them to LAI development.

PLANT PROTECTION

YR. 165.  Manyong V. M and Oyewole B. (1997)

Spatial patterns of biological constraints to cassava and yam production in West and Central Africa: implications for technology development and transfer. – African Journal of Root and Tuber crops. (ISTRC-AB)   3 (1): 1-50, 15-21(En, 13 ref. 5 tab)

International Institute of Tropical Agriculture, PMB 5320, Ibadan Nigeria.

The objective of this paper was to identify both physical and socio economic factors that favor the build up and economic incidence of biotic constraints on cassava and yam, two of the most prominent root and tuber crops grown in west and central Africa.  Result showed that large proportion of both the cassava and yam growing areas in west and central Africa are at high risk from the build-up and severity of biotic stresses.

YR 166 Nwauzor, E. C.   (1998)

Evaluation of dust preparation from Neem and “Otiri” for seed dressing as alternative to yam minisett dust. – Annual  Report 1997 and Programme of Work for 1998.  National Root Crops Research Institute, Umudike.  42-43.   (En. 1 tab).

The research was aimed at developing alternative yam minisett dust.  Oven-dried and pulverised leaves of Neem and “otiri” were used to conduct the experiment. Results recommended mixture of Neem and “Otiri” leaf dust as substitute for conventional minisett dust.

PROCESSING /UTILIZATION

YR 167.  Agwunobi, L N., Osuagwu A, and Alozie, S. O.    (1990)

Development and utilization of yam varieties as Food and feeds – Annual Report: National Root Crops Research Institute,  (NRCRI)  Umudike 49 – 51 (En. )

Yam tubers stored in traditional barns have short shelf  lives due to the rapid loss of weight profused sprouting and infection by pest, and disease.

The aim of this study was to determine the optimum level at which D.alata replace maize without adverse effect on layers performance.  Result indicated that yam meal can replace maize completely in diets of layers without adverse effect on performance provided that the protein and energy contents of the diets are equally balanced.

YR 168  Okaka, J. C. and Okechukwu P. E.  (1993)

Yam Processing:  Problems and Prospects – Advances in Yam Research Vol.2: Production and Post  Harvest Technologies of the Yam Tuber    78-90 (En, 20 ref. 4 tab).  Dept of Food Technology, Institute of Management and Technology, Enugu.

This paper examined options for improved storage and use of tubers with focus on heat penetration and cooking kinetics during processing of yam tubers.  Result showed that yams suffer a single shift in thermal diffusivity while processing within the temperature range 45-95^oc.  Thus in blanching and high temperature processing the thermal diffusivity falls from about  0.84 x 10^-7  M²/₅ to 0.23 x 10-7 M²/₅.

YR 169.  Akoroda, M. O.  (1993)

Agro-industrial inclusion of tuber peels in white Yam Flour – Advances in yam Research Vol.2:   Production and Post-Harvest Technologies of the yam tuber. III – 123 (En, 13 ref. 1 tab)  Agronomy Dept. University of Ibadan, Nigeria.

This study proposed that many tubers lost or rejected because of poor shape or past-harvest spoilage could be agro-industrially transformed into unpeeled tuber flour.   Result  showed that yam tubers wastage can be minimised by mechanical conversion of whole unpeeled tubers into reconstitutable flour which is a traditional food of about 25 million people in the South West of Nigeria.  Evidence of the non-toxic and superior nutrient content of peels was presented.

YR 170.  Bogunjoko J.S.T.  (1993)

Research and Development into commercial yam processing in Nigeria: Cadbury’s Pound yam. – Product Development for Root and Tuber crops Volume III  - Africa       471 – 473  (En,)

The paper described efforts by Cadbury Nigeria to develop a processed product to serve as a convenient substitute for pounded yam.  Other reason for developing pounded yam was that processing reduced the level of post production loss and preserved the yam for a period of approximately one year or more.

YR 171.  Onwuka, C.F.I., Adetiloye, P. O. and Afololami, C.A.  (1997)

Use of household wastes and crop residues in small ruminant feeding in Nigeria – Small Ruminant Research  24(3)  233-237 (En.  14 ref.)  Dept. of Animal Nutrition, University of Agriculture Abeokuta PMB 2240, Ogun State, Nigeria. 

A survey of 252 households in five communities within Ogun State, Nigeria was carried out using a detailed structured pre-tested questionnaire which centred on household structure their economic activities and types and uses of farm and household wastes in livestock feeding.  Result showed that predominant household wastes and crops residues were cassava, yam, cocoyam, orange peel etc.  The most commonly fed were cassava and yam peels. etc.

PRODUCTION

 YR 172.  Chukwu, G.O. and Chukwu, K. E.  (2002)

Cosmovision and folk science in yam production. – Proc. 36^th Ann. Conf. Agric, Society of Nigeria, F.U.T. Owerri, Oct. 125 – 129  (En, 13 ref.)

The paper described the cosmological beliefs of the people, their folk science and traditional institutions that surround their advanced yam culture as well as their interactions with the outside world..

YR 173.  Chukwu, G. O. and Mejeha, R. O.  (2002)

Poverty Alleviation in Food-Prone Environment:  The case of yam farmers in Anam Anambra State. – Proc. 36^th ann. Conf. Agric. Society of Nigeria, F.U.T. Owerri, Oct. 134 –137 (En. 11 ref.  2 tab) National Root Crops Research Institute, Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

A survey was conducted at Anam,  a flood-prone major yam producing area in Anambra State, using rural appraisal method to document their rural technologies of sustaining yam production to improve their economic well being.  Results showed that 70% of the respondents had over 30 years of experience in yam production but 54% had non-formal education.  Flood fertilises the soil with alluvium annually.

YR 174.  NG, S.Y.C.  (1991)

Production and distribution of virus-free yam (Dioscorea rotundata poir). – Tropical Root Crops in a Developing Economy:  Proceedings of the Ninth Symposium of the International Society for Tropical Root Crop.   Held at Accra Ghana.  20-26 October 1991.  324 – 328  (En, 16 ref.)

This paper described the different production and distribution systems used by the IITA for the distribution of virus free white yam germplasm.

SOILS AND FERTILIZER

YR 175.  Ano, A. O., Chukwu, G. O., Orkwor, G. C. and Ikeorgu, J.E.G.  (2000)

Evaluation of the contribution of leguminous cover crops to the conservation of soil resources base and productivity of yam based systems – Annual Report: National Root Crops Research Institute, Umudike 7-8 (En, 2 tab)  

The trial was conducted at Umudike to determine the contribution of leguminous cover  crops to the conservation of soil resources base and the productivity of yam based-intercropping  systems.   Result showed that  fertilizer had no effect on seed yam yield while cropping system had.  Intercropping  yam minisett with legume depressed seed yam yield.  This was most pronounced with groundnut and least with pigeon pen.

YR 176.  Ano, A. O., Asiegbu, J. A. and Udealor, A.  (1999)

Effect of green mulch of multipurpose tree species applied to yam minisett on soil physico-chemical properties and seed yield. -  Annual Report: National Root Crops Research Institute  44-47 (En. 2 ref.  4 tab, Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

The objectives of the study were to determined the effect of green mulch from Dectyldenia barteri, Gliricidia Sepium, pentacletra, macrophylla and spondias mombin applied to yam minisett on seed yield and to determine the effect of green mulch on soil physical and chemical properties.  Result showed that effective production of seed yam through minisett technique requires adequate plant nutrient to be available in the soil.

YR 177.  Asadu, C.I.A., Dixon, A.C.O and Okechukwu, R.  (2002)

Comparative evaluation of the contributions of soil physicochemical properties to variations in the yields of four major staple food  crops in eastern Nigeria. – Soil and Tillage Research  65,  141-155 (En. 30 ref.  9 tab)  Dept.  of Soil Science, University of Nigeria Nsukka Nigeria.

The contributions of soil variables to the variations in the yields of cassava (Manihot esculenta), yam (Dioscorea, rotundata) maize (Zea Mays) and pigeon pea (cajanus Cajan) were evaluated over 2 years in this study.  The study showed that soil variable accounted for more than 70% of the variation in cassava root yields and harvest index.   

YR 178.  Chukwu, G. O., Ano, A.O. , Asadu C.L.A. and Orkwor G. C. (2000)

Response of Hybrid yams to combinations of N and K Fertilizers – Annual Report: National Root Crops Research Institute, Umudike 6-7 (En, 1 ref. 1 tab.)

The study aimed at establishing optimum combination of N and K fertilizer for sustainable production of hybrid yams on Acrisols.  Result showed that hybrid yams out-yielded DRN D10 by 139.6 – 144.0%, indicating the higher yielding potentials of the hybrids over popular landraces.

YR 179.  Chukwu, G. O. and Agugo, B.A.C.  (2000)

Fertilizer use and its effect on the quantity of yam tubers in Nigeria:  Farmers’ practice and perception. – Journal of Development Studies 4(2) 58-67  (En. 16 ref. 6 tab.)

A survey was carried out 1995 in the root crop belt of Nigeria using a participatory approach, to ascertain farmer’s fertilizer use practices and their assessment of the effects of fertilizers on the quality of yam tuber.  Result showed that 60-70% of the respondents had no formal education and there was variability in biophysical features across the yam belt. Farmers perceived fertilizer to be responsible for poor pounding quality and poor  storability of  yam tubers

YR 180.   Meyen, I. W., Basssey, A.D. E.U. and Ibedu, M. A.  (1995)

On-farm Determination of the optimum rate of NPK fertilizer application to yam minisett intercropped with maize followed by cowpea. – Proceedings of the 9^th annual Farming Systems Research and Extension Workshop in South Eastern Nigeria  57 – 58  (En. 1 ref. 1 tab).

The aim of the study were to confirmed the result obtained in 1991  O.F.R. trials, to test for the stability of the results in many other locations and to find out the net return from the treatment.  Result of an on-farm research trial on the rate and time of application of NPK 20-10-10 fertilizer to yam Mnisett/Maize fb. cowpea in two zones of the State  1991 showed that 600kg of 20-10-10 fertilizer applied at 6 weeks aftaer planting gave the highest yield.

YR 181.  Meyen, I. W., Ibedu, M.A. and Bassey, A.D.E.U.   (1996)

On-Farm determination of tahe optimum rate of Compound Fertilizer 20:10:10 for yam/maize/cassava intercrop in Akwa Ibom State – Proceedings of the 10^th Annual Farming Systems Research and Extension Workshop in South Eastern Nigeria)  108-109. (En, 1 tab) Akwa Ibom ADP, Uyo, Akwa Ibom.

Two rates, 400kg/ha and 600kg/ha of the compound Fertilizer NPK 20:10:10 were compared for their effects on yam/egusi/maize cassava  intercrop.  Results indicated that the difference in the yields of component  crops of the two treatments  were not statistically significant (P£0.05). The gross profit margin of N143, 126/ha was recorded for 400kg/ha while N213, 490, was recorded for 600kg/ha.

YR 182.  Obigbesan, G. O.     (1993)

Soil Nutrient Factors for Yam Production. – Advances in yam Research Vol.2  Production  and Post Harvest Technologies of the yam tuber, Department of Crop Production, Ogun State University, Ago-Iwoye, Nigeria.

Yams absorb about four times as much nitrogen and twice as much potassium and phosphorus as cassava.  Farmers plant yams in rich fertile upland soil and preferably in hydromorphic valley bottom lands because of their higher productivity.  Results of these investigations demonstrate that the yam cultivars presently grown seem to require only low fertilizer input for optimum yields even on soils of low fertility status.

YR 183.  Ohiri, A. C. and Chukwu G. (1991)

Evaluation of optimum levels of organic (cow dung) manure with and without mineral fertilizer for yam production – Annual Report: National Root Crops Research Institute, NRCRI, Umudike   32-36  (En, 9 ref. 2 tab)

Cow dung is quite common in most yam belt States and has been found to be an excellent source of organic matter.  Research results showed that complementary use of organic and inorganic fertilizer has proved very effective in long-term soil fertility maintenance.

YR 184.  Tsado, E. K. Oladiran, J. A, Gana, F. S., Kalo, M.G.M. (1998)

Survey of fertilizer use in Benue and Niger States – Annual Report 1997 and Programme of Work for 1998:  National Root Crops Research Institute, Umudike 57 (En.) 

The research was carried out to established different fertilizer types and rates used by farmers in Niger State.  Results showed that there was no standard recommendation on fertilizer in use; that fertilizer use for yam was not very common.  Recommendation in use was one from NAERLS farmers guide leaflet which is 60kg N + 60kg P₂0₅ + 60kg  K₂0  (400gk/ha of 15:15:15).

STORAGE

YR 185. Afolabi, J. F., Akano, D.A. and Atanda, O.O. (1997)

The use of termitaria in reducing looses in stored yams. – Tropical Science 37, 71-74 (En, 15 ref. 4 tab)  Faculty of Agriculture & Forestry, University of Melbourne, Parkville, Victoria 3052, Australia.

Two termitaria at three different concentrations were tested for their ability to reduce weight loss, sprouting and rotting in yam tubers during storage.  Result showed that coating yam tubers with termitaria soil reduces weight loss and rotting during storage.  The extend of the reduction seems to vary with different termitaria.

YR 186.  Alakali, J. S., Obetta, S.E. and Ijabo, O. (1995)

Heat of respiration of yam tubers and its effect on heat load. – African Journal of Root and tuber crops 1 (1)  31-15 (En, 12 ref. 1tab) University of Makurdi, Nigeria.

Parametric information was obtained for different initial storage temperatures which ranged from 15^oc to 35^oc.  Results showed that ambient temperature was independent of the period of storage and initial storage temperature, but rises with days and falls with night.  The heat of respiration accounts for 89% - 100% of the heat of the storage structure especially if the tubers for storage were uninfected by mold and other micro-organisms.

YR 187.  Chukwu, G, O, and Ifenkwe, G. E.  (2001)

Traditional systems of yam storage in Nigeria.  Rural Resources Development and Sustainability 117 – 120.  (En., 12 ref.  3 tab.)  National Root Crops Research Institute Umudike Abia State.

A survey undertaken in the yam belt of Nigeria to document traditional systems of yam storage revealed that traditional yam barn is the most popular storage method.

YR 188.  Daniel, I,O,  NG, N. Q. and Tayo, T. O.  (1995)

Potential of seed storage for long-term conservation of yam germplasm – Root Crops and Poverty Alleviation; Proceedings of the sixth Triennial symposium of the International Society for Tropical Root Crops – African Branch 409-411 (En, 8 ref.  2 tab.) Genetic Resources Unit, IITA, PMB 5320 Ibadan.

Some aspects of the storage physiology of botanical seeds of West African yams were studied in attempt to preserve yam germplasm resources on a long term basis.  The half – (P50) values derived by probit analysis of viability decline curves during accelerated ageing of seeds suggested that seed longevity could be prolonged with desiccation and cold storage.  Analysis of variance revealed no significant loss in the viability of seeds that were dried to 14.5%, 10% and 5% seed moisture content, and stored at 4 temperature regimes

(-20^oc, 5^oc, 15^oc, 25^oc) for 500 days.

YR 189.  Emehute, J.K.U. (1999)

Studies on the shelf life of local plant-based yam minisett dust. – Annual Report: National Root Crops Research Institute,  47-48  (En.  1 tab.) NRCRI, Umudike, PMB 7006, Umuahia, Abia State, Nigeria.

The objective of the study was to evaluate the shelf life of the newly developed yam minisett dust to be able to give a complete technology package to users.  Result showed that the shelf life of the dusts could extend beyond three years.   Farmers were advised to use dusts of 0-3 years old on setts cut from healthy seed yams following the recommended agronomic practices.

YR 190.  Ezeike, G.O.I.     (1993)

Effect of cold, ambient and modified environments on storage characteristics of yam (D.Spp) tuber- Advances in yam Research Vol. 2: production and Post-Harvest Technologies of the yam Tuber. 99 –110 (En, 11 ref. 5 tab.)  Dept. of Agricultural Engineering, University of  Nigeria, Nsukka, Nigerian.

A study was undertaken with D. rotundata tubers (two varieties) stored in five different environments, namely: the traditional yam barn,  the underground pit structure, the adiabatic box, the modified atmosphere environment and the refrigerated environment.  Results revealed that statistical analysis of weight loss data showed that environment was a significant factor.  The greatest significant weight loss occurred in the adiabatic box, followed by the barn and the pit with the least being the refrigerator and modified environment.

YR 191.  Ezeike, G.O.I.   (1993)

Current Technology For yam (D.ssp) Tuber Storage – Advances in Yam Research  Vol.2: Production and Post-Harvest Technologies of the yam Tuber 56-69  (En, 36 ref. 1 tab).  Agricultural Engineering Department, .University of Nigeria, Nsukka Nigeria.

This study was focussed on field assessment of storage losses and qualitative analysis on factors of tuber deterioration.  Results showed that contrary to popular opinion the yam tuber suffers substantial looses in storage in the range of 20 to 60 percent.

YR 192.  Nigerian Stored Products Research Institute.  (1991)

23^rd Annual Report  1-107  (En.) Nigeria Stored Products Research Institute, Lagos, Nigeria.

Research carried out under the Grain Storage Programme, the root and tuber storage programme, the fruit and vegetable storage programme and the Oil Seed Storage Programme is reported. Nine technical report were published on the following subjects: Storage of White yam (Dioscorea rotundata) tubers; long term storage of gari, construction and assessment of 2 evaporative coolers for storage of fruits and vegetables etc. and then economics of storage in ware houses in Nigeria..

YR 193.  Nnodu, E. C. and Alozie, S. O. (1991)

Using gibberellic acid to control sprouting of yam tubers – Tropical Agriculture Trinidad)  (1991) 69 (4)329 – 332 (En, 14 ref  3 tab).  National Root Crops Research Institute, Umudike, PMB 7006, Umuahia, Nigeria.

This study was undertaken to check whether shortening the immersion time of yam tubers in GA3 solution as well as repeated re-use of a tank mix of the solution, will still be effective in controlling sprouting during storage.  Results showed that GA3 (150 ppm) was effective in inhibiting sprouting in stored yams and that at least six hours of immersion of the tubers in GA3 solution was  required for effective inhibition.  Furthermore, the same tank mix GA3 can be used successively 4-6 times before losing its effectiveness.  The significance of this finding was that many tubers can be handled in a day at a cheaper cost than the method of dipping the tubers for 20 – 22h previously reported.

YR 194.  Olaifa, J. I.  (1994)

Gamma irradiation for sprout inhibition in yam, control of the yam scale, Aspidiella hartii  (HOMOPTERA: DIASPIDIDAE) and maize weevil, sitrophilus zeamais (COLEOPTERA; CURCULIONIDAE) – Proceedings of the National Workshop on Irradiation Technology and its Application in the Food and Pharmaceutical Industries.  75-85  (En, 11 ref.  10 tab).  Department of Agronomy, Ladoke Akintola University of Technology Ogbomoso,  Nigeria.

Yam tubers and maize grains were subjected to varying doses of gamma irradiation at the time they were due for storage.  Results showed that tubers exposed to 100Gy irradiation rotted two weeks after irradiation which suggested that 100Gy irradiation was too much for D. rotundata.  Tubers exposed to 50 Gy recorded the least weight loss of 22.0% after 9 months .  This was followed by 30 Gy irradiation.  The 70 and 10Gy treated tubers were rotten by the 9^th month.  All the irradiated tubers were better than unirradiated ones which  all sprouted by the 3^rd month, and lost 60% weight by the 5^th month finally rotted by the 7^th month.

YR 195.  Okwuowulu, P. A., Nnodu, C. C., Udensi, U. A., and  Opara,

   M. U.A.  (1995)

Some effects of time of fertiliser application and age at harvest on the storability of edible yams. – Tropical Science 35 (1)  58-63.

Dioscorea rotundata cv,. Obiaoturugo and Nwopoko cayenensis type D. rotundata (D.Cayenensis) cv. Abi, D. alata cv. Ominelu and Um680, and D.bulbifera cv. Adu-olode tubers were harvested 6-8 months after planting and stored in a traditional barn or a modified indoor store. Weight losses from yam tubers during storage differed significantly among the six cultivars.  Sprouting and rotting of tubers also differed significantly.  Neither fertilizer application (recommended level of NPK) nor its timing (6,8,or 10 weeks after planting) significantly affected the harvest or storage.

YR 196.  Osuji, G.O. (1993)

Manipulation  of carbohydrate metabolism of the yam tuber (Dioscorea spp) to prolonged yam storage and to induce uniformity of sprouting –Advances in yam Research Vol.2: Production and Post Harvest Technologies of the yam tuber.  70-77 (En, 25 ref).  Dept. of Applied Biochemistry, Anambra State University of Technology, Awka Campus , Awka.

This paper reported the coordination of the metabolism of carbohydrate in yam and there-after described the manipulation of the metabolic reactions in order to prolong the shelf life of the tubers.  Result showed that experimental tubers responded to the manipulation of their storage environment.  This provided a basis for a better storage of tubers than in traditional barns.

YR 197.  Ukpabi, U. J., Okoli, O. O. and  Ene, L.S.O.  (1994)

Preservation of Root and tubers in Nigeria: A case for irradiation – Proceedings of the National Workshop on Irradiation Technology and its application in the Food and Pharmaceutical Industries (1994)  58 – 62  (En. 13 ref.  1 tab).  National Root Crops Research Institute, Umudike PMB 7006, Umuahia, Abia State.

This paper presents the nature of the problems associated with the preservation of the various roots and tubers and the limitations to measures adopted to overcome them.  It also shows the relevance of further studies on the systematic application of irradiation in extending the storage life of these food and seed materials.

YR 198.  Wokoma, C. A., Hart A. D. and Iloka, A. W.    (1996)

Evaluation of the efficiency of three methods for storage of tubers of the leafed yam (D.Dumetrorum). – Proceedings of the 10^th Annual Farming Systems Research and Extension Workshop in South Eastern Nigeria 157 –159  (En, 2 tab.)  Rivers ADP, Port Harcourt, Rivers State.          

Trial was carried out in two zones of the State and replicated in four locations using women groups.  The yam tubers used for the experiment were harvested from the plots established at the zones.  Result showed that D. Dumetorum tubers stored by the pot-in-pot storage method could retain an acceptable sensory quality up to the 12^th week.

WEED CONTROL

YR 199.  Anuebunwa, F. O. (1991)

Weed control in yam/maize/cassava intercrop for resource limited farms – Nigerian Journal of Weed Science  4.63-69  (En. 11 ref. 5 tab).

A two year trial (1988 and 1989) was conducted on farmers fields in Ogoja Agricultural zone of Cross River State of Nigeria.  Different weed control measures using low growing crops of egusi (colocynthis citrullus (L) O.ktze cv. Abahi alone or in addition to cowpea (vigna unguiculata (L) walp cv. IT82E-60) plus one manual hand weeding were compared.  These were tested on yam intercropped with maize and cassava for their biological and economic productivity as well as acceptability or rejection.  The use of Egusi and cowpea as weed control measures compared favourably with farmers’ practice.  This had comparatively the best weed control and highest return on capital.

YR 200.  Melifonwu, A.A. and Ayeni, A.O. (1994)

Influence of ash from burning of vegetation on protection of protection of egusi melon from phytotoxicity of formulated mixture of atrazine and metolacher in yam/melon/egusi melon intercrop – The Nigerian Agricultural Journal  27(1) 49-60  (En, 14 ref. 5 tab.)  National Root Crops Research Institute, PMB. 7008, Umudike, Nigeria.

Trials were conducted to evaluate ash from burning of field vegetation for protecting egusi melon from injury due to pre-emergence herbicide application in yam/maize/egusi intercrop. Results showed that phytotoxicity to egusi melon were more reduced and melon seed weight less reduced by pre-emergent treatments of primextra when the herbicide was applied at 1.25 to 2.50kg a.i. ha^-1 in burned plots followed by conventional tillage.

YR 201.   Orkwor, G. C., Okereke, O. U., Ezedimma, F.O.C., Hahn,

                 S. K., Ezumah and Akobundu. I. O.  (1991)

The response of yam (Dioscorea rotundata Poir). to various periods of weed interference in an intercropping with maize (Zea Mays L.) Okra (Abelmoshus esculentus L. Moench), and sweet potato (Ipomoea batatas I. Lam) – Tropical Root Crops in a Developing Economy: Proceedings of the Ninth Symposium of the International Society for Tropical Root Crops.  349 –354 (En. 10 ref.  2tab).

Yam was intercropped with maize, okra and sweet potato and subjected to various periods of weed interference and weed-free regimes.  Weed interference in the mixture reduced yam tuber yield by 35%; Maize by 60%; Okra, 79% and sweet potato roots by 80%.  Timing appeared to be more crucial in weed removal than the frequency of weeding the mixture.

YR 202.  Unamma, R.P.A., Anuebunwa, F. O. and Oputa, C. O. (1990)

On-farm evaluation on different weed management alternatives in a yam- management alternatives in a yam – maize intercrop -  Nigerian Journal of Weed Science.  3, 59-66  (En. 7 ref. 3 tab) NRCRI Umudike PMB 7005, Umuahia  Abia State.

Trials were conducted in 1985 and 1986, on farmers’ fields in the Umuahia, ADP zone of Abia State of Nigeria.  Alternative weed Management strategies involving the use of 3 herbicides applied either singly or in combinations of these were tested on white yam (Dioscorea rotundata poir cv. Nwopoko).  All the weed control alternatives gave yields that were as good as, or significantly better.

YAM RESEARCH

YR 203.  Akroda, M. O. and Hahn, S. K. (1995)

Yams in Nigeria:  Status and trends. – African Journal of Root and tuber crops 1 (1) 38-41 (En. 4 ref.) International Institute of Tropical

Agriculture (IITA), PMB 5320, Ibadan, Nigeria..

The paper gave a recent overview of the status of yam, showed that the demand was high but its production was most adversely affected by the short supply of seed tubers as well as by difficulties associated with the storage of harvested tubers.  The challenges to researchers, farmers, marketers and industrialists.

YR 204,  Quin, F. M.  (1992)

An overview of yam research – In Food yams:  advances in research  (edited by Okwor, G. C. et al)  Ibadan, Nigeria IITA/NRCRI.  215-230 (En.  32 ref.)

The article gave a significant over view of yam research and development past and present.

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