Seed systems and crop genetic diversity in agroecosystems T Hodgkin, R Rana, J Tuxill, D Balma, A Subedi, I Mar, D Karamura, R Valdivia, L Colledo, L Latournerie, M Sadiki, M Sawadogo, AHD Brown and D Jarvis International Plant Genetic Resources Institute, Rome, Italy This poster is dedicated to the memory of Alfredo Riesco, valued collaborator and friend, who died on 23 August, 2005 in an aeroplane crash near Pucallpa, Peru 1. Introduction Most rural farming communities in developing countries continue to use traditional or informal sources of seed and vegetative planting materials to meet their seed needs. Either they save their own seed or they obtain seed from sources such as relatives, neighbours and local markets, independently of the formal certified seed sector. The numbers and proportions of different crop varieties depend significantly on the patterns of exchange within an area and the forms that it takes. The operation of informal seed systems is clearly important to the maintenance of crop genetic diversity on farm. 2. Objectives The operation of informal systems of exchange of seed and other planting materials has been identified as a key element in the maintenance of crop genetic diversity on farm. As part of a multi- country project on in situ conservation of crop diversity on farm, IPGRI, together with partners in Burkina Faso, Hungary, Mexico, Morocco, Nepal, Peru and Vietnam, has investigated the characteristics and operation of seed systems of a selection of major field crops and vegetables, including barley, beans, cassava, cowpea, maize, pearl millet and sorghum. The studies aimed to identify how different seed system properties affect the extent and distribution of crop genetic diversity. 3. Results and Discussion Most seed in traditional farmer systems is maintained and exchanged through the informal system as studies of the percent of farmers using particular methods of obtaining seeds have shown. Country and crop Percent of farmers Self saved Exchange with relative or neighbour Other informal source (e.g. local market Formal sector Nepal mid hills – rice 44 54 0 2 Mexico, Yucatan – maize 39 44 not determined 17 Morocco – local durum wheat 76 6 18 0 Seed source, seed availability, patterns and amounts of seed exchange, on farm selection practices, and seed storage procedures can all have a significant effect on the amount and distribution of diversity present in traditional production systems. Through their effect on population size, gene flow, migration, selection and other evolutionary forces, these features of the seed system partly shape the genetic structure of crop variety populations. Population size Prior to 2002, 70% of farmers in central Yucatan State grew their own local varieties of common bean. Much of this material was lost as a result of a hurricane in 2002 and in 2003 the proportion of farmers growing beans was reduced to 20%, most using material from new off-farm sources. Thus, a dramatic reduction in the population size of most local bean varieties occurred over these 2 years. Migration Seed exchange between relatives and neighbours and seed purchase from markets are major sources of gene migration in traditional farming systems. Complex networks of exchange can build up involving many farmers. In this case, in Nepal, over 50 rice varieties are grown by local farmers and many exchanges occur in any year. Some farmers seem to act as nodal farmers for distribution of several varieties. Selection Selection of planting materials is important for banana growers in Uganda and Tanzania. Farmers may grow 20–30 varieties in a single area as complex mixtures. Farmers deliberately select and collect material from friends, neighbours and relatives according to specific preferred criteria. Criterion % farmers using criterion to select material Tanzania * Uganda * Bunch size 32 29 Palatability/taste 20 16.5 Maturity period 14 16.5 Resistance to disease 8.5 18 Other bunch or use characteristics 2.5 3 Other agronomic traits 6 1 * two villages from each country In Burkina Faso both men and women play an important part in selecting seed for crops such as pearl millet, sorghum and cowpea. However, selecting frafra potato seed is done by men and okra only by women. Over the 5 years of the project, seed quantity of pearl millet conserved by farmers from year to year increased significantly in villages such as Ouahigouya as a result of improved seed systems Change in pearl millet seed quantity produced by 12 farmers in Ouahigouya, Burkina Faso 4. Conclusions Farmers’ livelihoods in many poor rural communities around the world depend on maintaining effective local seed supply systems. Variation in production, market fluctuations and events such as floods or hurricanes have a substantial effect on the availability of seed locally and the diversity of the materials maintained in production. Maintaining crop diversity may depend as much on the maintenance of effective seed supply and exchange systems as on the conservation of specific varieties or types. References D Jarvis, R Sevilla and T Hodgkin (Eds.). 2005. Seed systems and crop genetic diversity. IPGRI, Rome. (in press) T Hodgkin, R Rana, J Tuxill, B Didier, A Subedi, I Mar, D Karamura, R Valdivia, L Colledo, L Latournerie, M Sadiki, M Sawadogo, AHD Brown and D Jarvis. 2005. Seed systems and crop genetic diversity in agroecosystems. In: Jarvis, DI, C Padoch and D Cooper (eds.), Managing Biodiversity in Agricultural Ecosystems. Columbia University Press, NY, USA. (in press). 137 25 Ind 65 50 119 121 34 11 120 130 129 OS 70 Ind 81 2 97 75 197 196 195 Ind 41 OS 145 146 144 126 6 183 182 Ind 184 OS Ind 31 37 OS OS OS 136 OS 71 Ind 89 127 OS 5 88 90 Ind 91 16 OS 64 180 181 OS 60 179 56 174 173 3 OS OS 84 83 82 OS 54 160 100 159 17 101 OS OS 102 45 RS 116 OS RS OS 24 114 115 113 68 Ind 118 119 120 121 188 77 Ind Ind 49 58 OS OS RS OS 154 171 170 169 168 OS 172 Ind S. mansuli Exchange S. mansuli Exchange S. mansuli Gift S. mansuli Exchange Sona mansuli Exchange S. mansuli Exchange Mutmur Exchange China 4 Exchange Masula Gift Kanchhi mansuli Gift Masula Exchange Masula Exchange Masula Exchange BG 1442 Gift Masula Gift Sona mansula , masula Exchange Sabitri Exchange Sona mansuli Exchange Nat masula Exchange Nat masula Exchange Sabitri Exchange Mas ula Excha nge Nat masula Exchange China 4, Phillips Gift China 4 Exchange Masula Purchase Masula Exchange Jaya Purchase Masula Exchange Jaya Exchange N. masula Exchange Jaya Exchange Jaya Exchange Masula Gift Sabitri Exchange Masula Exchange China 4 Exchange China 4 Gift Mansuli Purchase China 4 Exchange China 4 Exchange China 4 Exchange China 4 Exchange China 4 Gift K. mansuli Exchange Rani pankaj Gift K. mansuli Exchange China 4 Gift China 4 Gift Pokhreli masino Exchange China 4 Gift China 4 Gift China 4 Gift China 4 Gift Hybrid Purchase Jaya Exchange Nat masula Exchange China 4 Exchange Sabitri Exchange Television Exchange China 4 Exchange Nat masula Gift Sabitri Borrow China 4 Borrow Sabitri Borrow Lajhi Purchase China 4 Exchange Faram Exchange Rampur mansuli Gift Sabitri Exchange Chandina Exchange Phillips Purchase Masula Exchange Masula Exchange Masula Exchange Sona mansuli Exchange Sabitri Exchange Sabitri Exchange Sona mansuli PurchaseSabitri Exchange Sona mansuli Exchange BG 1442 Purchase Radha 32 Purchase S. mansuli Gift S. mansuli Gift Mansuli Exchange Phillips Exchange Lalsar Exchange China 4 Exchange Basmati Exchange Masula Exchange B 44 Gift Pusa basmati Purchase Sona mansuli Gift B 44 Exchange China 4 Exchange S. mansuli Gift S. mansuli Exchange S. mansuli Exchange S. mansuli Exchange S. mansuli Exchange Rampur mansuli Trial Sona mansuli Exchange K. mansuli Gift Basmati Exchange K. mansuli Exchange Kanchhi mansuli Borrow Jiri Borrow China 4 Borrow Sabitri Exchange China 4 Exchange K. mansuli Exchange Sabitri Purchase S. mansuli Purchase Farmers network analysis in Kachorwa ecosite 0 10 20 30 40 50 60 70 80 Seed (kg) 1997 1998 1999 2000 2001 2002 A farmer in Burkina Faso selecting sorghum. Flows of rice seed in a village in Nepal. Nodal farmers shown in red.