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This article describes village-based seed enterprises (VBSEs) for less favorable and remote areas where the formal sector (public and private) fails to meet farmers' seed requirements. The review covers national seed sectors and outlines the concepts and organization of a participatory approach to establishing and managing local seed enterprises

Analysis of spatial diversity, temporal diversity and coefficient of parentage (COP) were carried out along with measurements of agronomic and morphological traits to explain on-farm diversity of modern varieties or landraces of wheat (Triticum aestivum L. and Triticum durum L.) grown by farmers in Ethiopia. Farm level surveys showed low spatial diversity of wheat where only a few dominant varieties appeared to occupy a large proportion of wheat area. The five top wheat varieties were grown by 56% of the sample farmers and these varieties were planted on 80% of the total wheat area. The weighted average age of wheat varieties was high with an average of 13.8 years for bread wheat showing low temporal diversity or varietal replacement by farmers. The COP analysis showed that average and weighted diversity of bread wheat was 0.76 and 0.66, respectively variance component analysis showed significant variations for agronomic characters such as plant height, grain yield, and yield components (kernels spike-1 , thousand seed weight) among modern varieties and/or landraces. The principal component analysis explained better the variation among varieties and landraces. Cluster analysis based on agro-morphological traits grouped modern varieties and landraces into separate clusters. The present study describes the diversity of wheat crop available on the farm using different indicators. The variation among modern varieties and landraces offered opportunities for using genotypes with desired agronomic characters in plant breeding to develop varieties suitable for different agro-ecological zones in the country.

SUMMARYPollen mother cells of J'Iicotiana alata were exposed to acute doses of X-rays or fast neutrons and, at anthesis, the pollen produced was used to pollinate unirradiated plants of the same clone. The results indicate that fast neutrons are slightly more effective than X-rays for inducing self-compatible pollenpart mutations but that neither fast neutrons nor X-rays have the capacity to generate new self-incompatibility alleles. An unexpectedly high fraction of the self-compatibility mutations induced does not display the centric fragment which usually characterises such mutations. The ratio of fragment to non-fragment self-compatibility mutations of fast neutrons is identical to that of X-rays. The possible use of permanent self-compatibility mutations for production of F1 hybrid seed is discussed.