K.D. Joshi

How narrowly adapted are the products of decentralised breeding? The spread of rice varieties from a participatory plant breeding programme in Nepal

Acceptable rice varieties for high-altitude areas of Nepal were bred by participatory plant breeding (PPB). One of the most adopted varieties, Machhapuchhre-3 (M-3), performed much better in the formal trials system than the products from centralised breeding and was released in 1996. From 1996 to 1999, the spread of M-3 was monitored in high-altitude villages along with unreleased variety Machhapuchhre-9 (M-9), derived from the same cross. The study was done by interviewing individual households, groups, and field verification. Both M-3 and M-9 spread from farmer-to-farmer and through interventions by Non-Government Organisations (NGOs) and Government Organisations (GOs). Their adoption had steadily increased and their spread commenced five to six years earlier than would have been the case in a conventional system. The PPB programme was decentralised – all selection was in only two villages in the same valley – but this did not result in specific adaptation. The varieties were adopted in distant villages situated at much lower altitudes to the original PPB sites and the greatest yield advantage of the varieties over the local landraces was also at these lower altitudes.

Participatory varietal selection in rice in Nepal in favourable agricultural environments - A comparison of two methods assessed by varietal adoption

AbstractTwo participatory approaches to varietal selection were compared in February-sown (Chaite) rice and main-season rice in high potential production systems in Nepal. One method, called farmer managed participatory research (FAMPAR), was researcher intensive, while the other, called informal research and development (IRD), demanded fewer resources. The trials were conducted in 18 villages in high potential production systems in Chitwan and Nawalparasi districts of Nepal. Six new varieties of Chaite rice and 16 of main-season rice were tested in over 300 trials of Chaite rice and nearly 1100 trials of main-season rice over two years in 1997 and 1998. Surveys were done in 1997, 1998 and 1999 to record the extent of adoption and spread of the new rice varieties in the study villages. In many cases, farmers tested varieties for two years before deciding whether to adopt or drop them. Varieties were quite widely accepted, adopted for niches in a few villages, or rejected. The two participatory approaches identified the same varieties, but FAMPAR, which used formal survey methods, was more useful for diagnosing reasons for adoption or rejection. However, IRD used much cheaper anecdotal methods of evaluation, so it was more cost-effective. Moreover,farmer-to-farmer seed dissemination was higher in IRD villages, probably because farmers in FAMPAR villages felt that the project would re-supply seed if needed. The benefits from both approaches are considerable, but to adopt them substantial policy changes in varietal testing, release and extension systems will be required.

The impact of participatory plant breeding (PPB) on landrace diversity: A case study for high-altitude rice in Nepal

AbstractParticipatory plant breeding (PPB) methods were used to develop two farmer-accepted, cold-tolerant rice varieties in Nepal — Machhapuchhre-3 (M-3) and Machhapuchhre-9 (M-9). Both were derived from the cross Fuji 102/Chhomrong Dhan. Following the introduction of these varieties, the changes in the rice landraces and varieties that farmers grew were studied in ten villages. In seven of them for which data were analysed for both 1996 and 1999, adopting farmers grew 18 landraces and four modern varieties of which three, M-3, M-9 and Lumle-2, were the products of PPB. These three varieties covered 10% of the total rice area and 33% of the rice area of the adopting farmers in the seven study villages in the 1999 survey. The adoption of the PPB varieties impacted most on the more commonly grown landraces. With the exception of two villages, the varietal richness among adopting farmers was either static or increased, and there was an overall increase in allelic diversity. However, in future, the increasing adoption of M-3 and M-9 could result in significant reductions in varietal richness, although, allelic diversity may not be greatly reduced.

Plant breeding can be made more efficient by having fewer, better crosses.

BackgroundCrop yields have to increase to provide food security for the world’s growing population. To achieve these yield increases there will have to be a significant contribution from genetic gains made by conventional plant breeding. However, the breeding process is not efficient because crosses made between parental combinations that fail to produce useful varieties consume over 99% of the resources.ResultsWe tested in a rice-breeding programme if its efficiency could be improved by using many fewer, but more judiciously chosen crosses than usual. In a 15-year programme in Nepal, with varietal testing also in India and Bangladesh, we made only six crosses that were stringently chosen on complementary parental performance. We evaluated their success by the adoption and official release of the varieties they produced. We then modelled optimum cross number using assumptions based on our experimental results.Four of the six crosses succeeded. This was a fifty-fold improvement over breeding programmes that employ many crosses where only about one, or fewer, crosses in 200 succeed. Based on these results, we modelled the optimum number of crosses by assuming there would be a decline in the reliability of the breeder’s prediction of the value of each cross as more crosses were made (because there is progressively less information on the traits of the parents). Fewer-cross programmes were more likely to succeed and did so using fewer resources. Making more crosses reduced the overall probability of success of the breeding programme.ConclusionsThe efficiency of national and international breeding programmes would be increased by making fewer crosses among more carefully chosen parents. This would increase the number of higher yielding varieties that are delivered to farmers and hence help to improve food security.