Effects of farmers' seed management on performance and adaptation of pearl millet in Rajasthan, India

Pearl millet (Pennisetum glaucum [L.]R.Br.) is the staple food and fodder crop of farmers in the semi-arid areas of north-west India. The majority of farmer sin western Rajasthan depend on their own seed production and employ different seed production strategies that involve different levels of modern-variety introgression into landraces as well as different selection methods. This study quantifies the effects of three seed management strategies on environmental adaptation and trait performance. Forty-eight entries representing farmers’ grain stocks — pure landraces or landraces with introgressed germ plasm from modern varieties — as well as 33 modern varieties, multiplied by breeders or farmers, were evaluated in field trials at three different locations over two years under varying drought-stress conditions. Results indicate that the plant characteristics employed by farmers in describing adaptive value and productivity is an effective approach in discriminating the type of millet adapted to stress and non-stress conditions. It was also found that introgression of modern varieties(MVs) leads to populations with a broader adaptation ability in comparison to pure landraces or MVs alone – but only if MV introgression is practised regularly and is combined with mass panicle selection. Under high-rainfall conditions, farmer grain stocks with MV introgression show similar productivity levels as modern varieties. Under lessening rainfall, pure landraces show, in tendency, higher grain yields. In conclusion, farmers’ seed management could form an integral part of participatory breeding programs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Feasibility of breeding male-sterile populations for use in developing interpopulation hybrids of pearl millet

Inter‐population hybrids of pearl millet, Pennisetum glaucum (L.) R. Br., have a substantial grain yield advantage over open‐pollinated varieties that makes them an appropriate and economically viable proposition for many African agricultural situations, provided that stable male‐sterile populations can be developed for use as seed parents. The objective of this research was to examine the feasibility of breeding stable male‐sterile populations, using the d₂ dwarf version of Nigerian Composite NCD₂ and the A₄ cytoplasmic‐nuclear male sterility system as a test case. Results showed that two cycles of recurrent selection for sterility maintenance ability led to the development of a fully effective maintainer version of NCD₂. There was no significant difference between the original C₀ cycle bulk and the C₃ cycle bulk (developed from the third and final cycle of recurrent selection) for grain yield and other agronomic traits. The male‐sterile population at the third backcross stage, developed from the maintainer version of NCD₂, had as high a level of stable male sterility as the A¹ system commercial inbred male‐sterile line 841A₁. Thus, it is concluded that with the use of the A₄ cytoplasmic male‐sterile system, it would be possible rapidly to develop a maintainer version of any population without detrimental effects on grain yield and agronomic traits. Male sterility of populations developed from these maintainers will be highly stable, paving the way for their effective utilization as seed parents in breeding inter‐population hybrids.     

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

Participatory 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. This revised version was published online in July 2006 with corrections to the Cover Date.     

Farmers' seed selection practices and traditional maize varieties in Cuzalapa, Mexico

Experimental results and farmer surveys from a Mexican community located in the buffer zone of a biosphere reserve indicate that farmers' seed selection practices protect the phenological integrity of their traditional maize varieties as they define them, despite numerous factors contributing to genetic instability. Analysis of morphological and genetic data suggests that when subjected to significant gene flow through cross-pollination, ear characteristics are maintained through farmers' selection even though other characteristics may continue to evolve. Because the effects of farmers' selection practices are confined largely to ear characteristics, their practices appear to offer only limited scope for variety improvement. Farmers' expectations of what they can achieve through seed selection are similarly limited. These findings suggest complementary roles for professional breeders and Mexican farmers in enhancing mass selection methods to improve maize landraces on farms – if farmers themselves perceive benefits from the collaboration. This revised version was published online in August 2006 with corrections to the Cover Date.     

Utility of pearl millet landraces in breeding dual-purpose hybrids for arid zone environments of India

In pearl millet (Pennisetum glaucum (L.) R. Br.), single cross hybrids based largely on exotic germplasm, have found very limited adoption in drought-prone arid regions mainly due to their inadequate adaptation to prevalent extremely harsh agro-climatic conditions. This study tested the hypothesis that the use of restorer parents derived from adapted landrace germplasm could be an alternative strategy in developing suitable hybrids for arid regions. Forty inbred restorer lines developed from two phenotypically diverse landraces were used to develop hybrids evaluated in this study for their performance in five typical arid zone environments between 2003 and 2007. Inbred lines from both landrace populations differed significantly in their combining ability for biomass, harvest index and grain and stover yields. A larger proportion of experimental hybrids, based on selected inbred lines, significantly outperformed the commercial checks for grain and stover yields. Increase in grain and stover yields was achieved primarily due to their higher biomass productivity, with no decline in harvest index. Choice of landrace determined the relative grain and stover productivity of their hybrids. Phenotypic differences observed in parental landraces in tillering and panicle length were also visible in their respective hybrids, indicating that characteristics of landrace parental populations were transmitted in their hybrids.     

Collaborative and consultative participatory plant breeding of rice for the rainfed uplands of eastern India

We describe a participatory plant breeding (PPB) programme in rice for the rainfed uplands of eastern India. Collaborative participation (farmers grew and selected in segregating materials in their fields) and consultative participation (farmers selected among progenies in researchers' plots) were used. The PPB was started with only two crosses and, of these, Kalinga III/IR64 was the most successful and produced two released varieties: Ashoka 200F from collaborative breeding and Ashoka 228 from consultative breeding. Both yielded significantly more than control varieties, including Kalinga III, in research trials and in participatory trials in farmers' fields. Qualitative data from participatory trials was highly informative, statistically analysable, and cheaper to obtain than quantitative data. In low-yielding research-station and on-farm trials the two new upland varieties showed no significant genotype × environment interaction with the check varieties. However, in higher-yielding All India Coordinated Rice Improvement Project trials, both varieties were more adapted to low yielding environments than the national check variety. Farmers liked the varieties for their early maturity, improved lodging resistance, higher fodder and grain yield, long-slender grains and excellent cooking quality. Before certified seed production, farmer groups have produced large quantities of seed that have spread widely through informal channels. The returns from PPB, compared to conventional breeding, were higher because it cost less, the genetic gains per year were higher, and the benefits to farmers were realised earlier. This revised version was published online in August 2006 with corrections to the Cover Date.     

Cisgenesis and genome editing: combining concepts and efforts for a smarter use of genetic resources in crop breeding

Plant genetic resources (PGR) represent valuable sources of genetic variability for crop breeding. The development of novel biotechnologies is necessary for increasing the efficiency of their use in pre‐breeding and breeding work. The genome sequencing of hundreds of genotypes and the mining of allele diversity in major crops and populations of landraces and wild relatives allow the isolation of genes underlying characters of interest and their precise modification or transfer into targeted varieties. The technological developments and applications of new plant breeding techniques (NPBT) that maximize the similarity with gene transfer by crossing (cisgenesis/intragenesis) or the accuracy of biotechnological approaches (genome editing) are reviewed. Their potentialities and current limitations as well as the possible advantages of using them separately or combined for the exploitation of PGR in crop breeding are also discussed. Above‐mentioned NPBT tackle some objections to the application of biotechnologies in agriculture and are under review worldwide to assess the possible exclusion from the current regulation systems for genetically modified plants.