Keeping the yam 'a part of man'

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Yam Genetic Improvement: Planting materials,Labour,Germplasm,Soil fertility,Diseases and pests(including weeds),Post-harvest handling and processing

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Keeping the yam 'a part of man'

  1. 1. Keeping the yam ‘a part of man’ - a breeder’s contribution Robert Asiedu International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  2. 2. Benin Institut National des Recherches Agricoles du Benin (INRAB) CameroonA breeder Institute of Agricultural Research for Development (IRAD) Cote d’Ivoireneeds many Centre National de Recherche Agronomique (CNRA) Centre Suisse de Recherches Scientifiques en Côte d’Ivoire (CSRS)friends University of Abobo Adjame Ghana Crops Research Institute (CRI) Savanna Agric. Research Institute (SARI) Kwame Nkrumah University of Science and Technology (KNUST) Nigeria National Root Crops Research Institute (NRCRI) University of Ibadan Ahmadu Bello University, Zaria Togo Institut Togolais des Recherches Agronomiques (ITRA) CIRAD, France Virginia State University, USA International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  3. 3. Yam and man Food, Income and Culture Ethnobotany of yams – Ayensu & Coursey Interactions of yam and man - Coursey Sense of identity – Perrot Yams in society - Degras Co-speciation of yam and man Yam festivals A man’s crop? Status The future of yams - Manyong and Nokoe (2003) Urbanization, Competition, Environmental degradation International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  4. 4. Domestication Stakeholder analysis: - 27 villages, Zou Province, Benin - practised by experienced male yam growers - in search of more productive varieties (60% of 80 respondents) - selection based on similarity of leaves to known cultivars (58% of respondents)Mignouna and Dansi. (2003) Genetic Resources and Crop Evolution 50: 519–528Scarcelli et al. (2006) Molecular Ecology 15, 2421–2431 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  5. 5. YamProduction 60 Production (million tons) 50 World 40 Togo Nigeria 30 Ghana Côte dIvoire 20 Benin 10 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  6. 6. Yam Area 5 4.5 4 3.5 World Area (million ha) 3 Togo Nigeria 2.5 Ghana 2 Côte dIvoire 1.5 Benin 1 0.5 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  7. 7. Yam Yields inWest Africa 16 14 12 World Yield (tons/ha) 10 Togo Nigeria 8 Ghana 6 Côte dIvoire 4 Benin 2 0 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Year International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  8. 8. Yam supply (g)per capita perday 2005 900.00 800.00 Yam supply (g) per capita per day 700.00 600.00 500.00 400.00 300.00 200.00 100.00 0.00 Togo Nigeria Ghana Côte dIvoire Benin Consumption (kcal/cap/day) 2003: Togo (233), Nigeria (203), Ghana (314), CI (331), Benin (395) International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  9. 9. Yam Genetic Key challengesImprovement • Planting materials • Labour • Germplasm • Soil fertility • Diseases and pests (including weeds) • Post-harvest handling and processing International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  10. 10. High and stable yield of marketable tubersGenetic (per unit of area, labour and time)Improvement Pest and disease resistanceObjectives (nematodes, viruses, anthracnose, tuber rots) Tuber characteristics (size, shape, branching, food quality, storability) Suitability to cropping systems and tolerance to abiotic stresses (shoot morphology, nutrient responsiveness and use efficiency, tolerance to mid- to late season drought) International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  11. 11. Focus on Dioscorea rotundataSelected Food D. alataYams D. cayenensis D. dumetorum D. burkilliana D. bulbifera D. esculenta D. opposita D. japonica D. trifida D. nummularia D. abyssinica D. praehensilis International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  12. 12. Planting Materials•Whole tuber•Tuber fragment•Milking (double harvest)•Multiple tuberisation•Bulbil formation International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  13. 13. Labour Saving Good performance under no/limited staking Early maturity and/or multiple tuber production Suitability to short fallow systems -Nutrient uptake, responsiveness & use efficiency -Pest resistance Tuber morphology for easy harvesting Long tuber dormancy International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  14. 14. Characterization Molecular characterization (genotyping of core collection) (reference collection) Ploidy studies using DNA flow cytometry of Dioscorea alata and D. rotundata AFLP marker diversity of Dioscorea alata Development of genomic tools for improvement of yam International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  15. 15. Characterizationof the corecollection D. alata (red) D. bulbifera (purple) D. cayenensis (yellow) D. dumetorum (ash) D. esculenta (blue) D. rotundata (green) Figure 1. Genetic diversity tree of 342 yam accessions base on SSR data using unweighted neighbour- joining analysis International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  16. 16. Creating additional variation:Interspecific crosses Parents No. flowers poll. Fruit Set Seed SetFemale Male Number % Number %D. rotundata D. rotundata 2491 965 38.74 3313 22.16D. rotundata D. cayenensis 1581 154 9.74 9 0.1D. rotundata D. alata 1663 6 0.36 9 0.09D. alata D. alata 8120 1445 17.8 2577 5.28D. alata D. cayenensis 89 0 0 0 0D. alata D. rotundata 730 0 0 0 0 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  17. 17. a b TDr 95/19158 F1 TDc 98-136 TDr 95/18544 F1 TDc 98-136 C d + TDr 85/18555 TDc 95-165 TDr 89/02475 TDc 98-136 F1 F1Examination of progenies generated from inter-specific crosses using an isozyme marker confirmed true hybrids International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  18. 18. D. alata for reaction to yam anthracnose and virus diseasesEvaluation: and their effect on yieldHost plantresistance Anthracnose and virus diseases of D. alata: effects of yam genotype and planting date Screening of Dioscorea alata for reactions to viruses Reaction of Dioscorea rotundata to virus diseases in four agroecological zones Impact of Yam mosaic virus genus Potyvirus on field performance of white yam Pathogenic and genetic variability among Colletotrichum gloeosporioides isolates from different yam hosts in the agroecological zones in Nigeria International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  19. 19. Anthracnose disease Sources of resistance identified to selected isolates and used but variability of pathogen is a continuing challenge Abang et al. 2006. Journal of Phytopathology 154: 51-61 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  20. 20. Viruses Sources of resistance identified and hybridized Odu et al. 2006. Journal of Phytopathology 154: 716-724 Odu et al. 2006. Journal of Phytopathology 154: 688-693 Odu et al. 2004. Field Crops Research 89: 97-105. Odu et al. 2004. Plant Pathology 53: 141-147 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  21. 21. Recipient No. of Genotypes D. rotundata D. alata 2008 Germplasm AGIP NaOC, Nigeria 24 26 delivery to DDS, Nigeria 4 14 PNDRT, Cameroon 21 16 partners NRCRI, Nigeria 11 2007 CARI, Liberia 57 AARC, Awassa, Ethiopia 30 INRAB, Benin 46 20 ITRA, Togo 16 2006 NRCRI, Nigeria 84 7 INRAB, Benin 12 52 CNRA/CSRS 36 44 CRI, Ghana 17Tubercules de TDa 98/01176 préconditionnés SARI, Ghana 17en plein champ pour le stockage dans levillage de Kprakro(Dimbokro) 6 déc.2007 ITRA, Togo 26 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  22. 22. Varietal National Root Crops Research Institute, Nigeria: Three new varieties of D. rotundata in 2001releases Four new varieties of D. rotundata in 2003 Crops Research Institute, Ghana: Three new varieties of D. rotundata in 2005 Need for advocacy for yam variety release protocols International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  23. 23. NematodesResistanceidentified inDioscoreadumetorumbut not in Cracks & flaking of skin Necrotic spots Dry rotthe two Damage caused by Scutellonema bradysdominantspecies –D. alataand D.rotundata Galls Galls & crazy roots Galls and rot Damage caused by Meloidogyne spp. International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  24. 24. Insect pests of yam tubers Mealybugs Scale insects Yam beetles Tuber moth damage International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  25. 25. The challenge:Sustainability Pest build-up(sedentarization) of Soil fertility and structureyam production Vesicular arbuscular mycorrhiza in the nutrition of yams • Effects of arbuscular mycorrhizal inoculation and phosphorus application on yield and nutrient uptake of yams • Effect of NPK fertilizer on the tuber yield, leaf nutrient concentrations and mycorrhizal colonization of white yam (Dioscorea rotundata) Breeding for nutrient responsiveness International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  26. 26. Colonization (%) of roots of Dioscorea alata by VAM fungi at 4 sitesin NigeriaClone Site Abuja Ibadan Onne Ubiaja MeanTDa 85/00250 68.00 84.72 39.94 88.32 70.25TDa 00/00064 78.23 45.09 61.06 88.84 68.31TDa 00/00104 75.55 55.58 51.98 89.23 68.09TDa 92-2 72.90 20.91 34.65 75.77 51.06TDa 99/00395 44.49 45.69 34.78 77.29 50.56TDa 02/00193 58.97 35.78 48.64 54.64 49.51TDa 93-36 50.54 28.47 32.48 82.38 48.47Mean (36 clones) 68.64 45.15 44.31 78.20 59.08S.e.d: clone = 6.3, location = 2.1, clone x location = 12.6CV% = 26.1 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  27. 27. Colonization (%) of roots of Dioscorea rotundata at 4 sites in NigeriaClone Site Abuja Ibadan Onne Ubiaja MeanTDr 97/00588 85.42 78.89 58.38 81.23 75.98TDr 89/02665 79.38 44.53 78.01 71.50 68.36TDr 96/01799 79.03 47.67 77.33 69.00 68.26TDr 96/00528 53.73 49.57 52.90 31.25 46.86TDr 97/00903 62.38 47.53 1.12 69.78 45.20TDr 97/00632 56.73 31.45 51.37 40.47 45.01EHOBIA 33.18 30.53 28.83 44.25 34.20Mean (for 34 clones) 67.99 43.04 57.11 59.73 56.97S.e.d: clones = 6.54; Location = 2.24; Clone x location = 13.07CV (%) = 28.1 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  28. 28. 200AM Fungi 180 mycorrhiza no mycorrhiza 160 140 Tuber weight (kg) 120 100 80 60 40 20 0 0 0.05 0.5 5 P concentrations (mg P kg-1soil) Tuber yield of TDr 97/00903 as affected by AM fungal inoculation and P application. International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  29. 29. 16.00 14.00Tuber yields of 12.00eleven genotypesof Dioscorea 10.00 Tuber yield (t/ha) 0rotundata at 200 8.00different 400 600application rates 6.00of NPK 15-15-15 4.00 2.00 0.00 93-31 93-32 01/00504 96/00629 97/00205 97/00609 97/00632 97/00777 97/00793 97/00903 97/01818 Dioscorea rotundata genotypes International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  30. 30. Food quality and Food and nutritional qualityend-use suitability Description (target attributes for fresh tuber and flour markets) Intrinsic and exogenous influences Effect of tuber harvest time and storage period on the pasting properties of yam starch Influence of time of harvest on the yield and sensory attributes of white yam Influence of environment and processing on tuber micronutrient content International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  31. 31. Tuber Density of Screening for tuber contents of total carotenoids, iron, zinc, ascorbic acid, and phytic acidMicronutrients Variation in retention of total carotenoids, Fe and Zn in Dioscorea cayenensis food products Influence of environment and genotype x environment interactions on tuber contents of iron and zinc Total carotenoids (in µg/g fwb) Dioscorea cayenensis (82 accessions) Range: 1.25 – 5.12 Mean: 2.72 + 0.80 D. dumetorum Two accessions with values of 22.29 and 26.60 µg/g International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  32. 32. Tuber Density of Tuber content of ascorbic acid (in mg/100g fwb) :Micronutrients D. rotundata (325 accessions) Range: 3.56 – 16.87 Mean: 8.3 + 2.26 D. cayenensis (79 accessions) Range: 4.19 – 11.34 Mean: 7.85 + 1.29 D. dumetorum (31 accessions) Range: 15.42 – 39.43 Mean: 25.83 + 6.29 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  33. 33. Tuber nutrient contents of 31 genotypes of D. rotundata evaluatedat 4 sites over two years in Nigeria Iron Zinc Ascorbic acidSOV DF MS % SS MS % SS MS % SSTotal 371 4.90 3.94 2.46TRT 123 9.74*** 65.8 9.02*** 75.8 4.76*** 64.2GEN 30 13.76*** 34.4 23.08***62.4 5.68*** 29.2ENV 3 115.94***29.0 45.60***12.3 61.40*** 31.5GxE 90 4.86*** 36.5 3.10*** 25.2 2.56*** 39.4 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  34. 34. Micronutrients Retention (%) of micronutrients in products from 15 genotypes of Dioscorea cayenensis Boiled yam Pounded yam Flour Carot. 31-97 9-97 11-75 (69.6) (48.6) (43.2) Iron 56-99 66-99 18-44 (77.2) (80.3) (29.4) Zinc 70-96 62-97 13-32 (85.4) (83.6) (22.6) International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  35. 35. Descriptive statistics for functional (pasting) characteristics of 33 genotypesof D. rotundata grown at Abuja, Nigeria Peak Breakdown Final Setback Peak time Pasting viscosity viscosity viscosity viscosity (Min.) temp.( C)Mean 209 38 247 76 6 84SE 11.7 6.6 12.86 7.66 0.11 0.17Min. 69 4 97 29 5 82Max. 338 147 397 209 7 86Pr. > F ** ** ** * ** ns * *, *Significant at P<=0.01, and at P=0.05 respectively; ns=not significant P>=0.05 International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  36. 36. Evaluation of Dioscorea alata varieties for making pounded yamMean pasting 350.00properties of D. 300.00alata and control 250.00 200.00 D. alata 150.00 D. rotundata 100.00 50.00 0.00 gh n . k p. . e is c ow isc ac t im m ou lv tb V kd te Tr ng Se na ak ea ng sti Fi Pe Br sti Pa Pa International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  37. 37. Mean scores for pounded yam from D. alata Variety Color Smoo. Cons. Elast. Stick. Hard. Mean 4.66 4.22 3.97 3.56 4.22 4.66 SE 0.27 0.11 0.14 0.14 0.14 0.12 P level *** *** *** ** ** ***Scale of 1 to 9, where 1= extremely inferior, 2= much inferior, 3= moderatelyinferior, 4 = slightly inferior, 5= no difference, 6= slightly better, 7=moderatelybetter, 8=much better, 9= extremely better International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  38. 38. Keeping yam apart of man • Is it possible? – yes • Is it important? – yes! International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
  39. 39. Thankyouverymuch!! International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

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