Solanum aethiopicum L. is indigenous to Africa and constitutes an important vegetable. Morpho-agronomic traits were used to study diversity among 44 accessions of S. aethiopicum groups to identify traits of high discriminatory ability and donor parents with specific or multiple traits for introgression and utilization in breeding programmes. Field experiments were conducted from 2008 to 2010. The principal component (PC) analysis of morpho-agronomic data indicated high discriminatory ability for fruit calyx length, fruit length and leaf length. On PC1, fruit length showed positive and significant correlation coefficients with leaf length, fruit calyx length and width. An independent association was recorded among fruit width, fruits per infructescence and seed yield (t/ha). Ordination (biplot) and grouping (dendrogram) revealed genetic variation and relatedness, phenotypic plasticity and geographical heterogeneity among the accessions within and among the clusters. Members of cluster 1 (group ‘c’) are a promising donor parent for multiple traits (earliness and fruit length), and members of group ‘b’ are superior for fruits per plant, fruits per infructescence and fruit infructescence per plant. Hybridization among distant clusters would provide an opportunity for bringing together gene constellations of diverse background. Earliness and fruit length were highly variable among the S. aethiopicum groups. The results are important for the breeding and selection of this crop.
Seven Solanum species (eggplants) were investigated for molecular diversity. Besides its widespread cultivation, nutritional and economic importance, its genome has not been extensively researched. 39 Solanum accessions, a landrace and tomato variety (LBR 48) were molecularly analyzed by simple sequence repeat (SSR) marker technique. A dendrogram was obtained based on the Jaccard's coefficient of similarity and unweighted pair group method with arithmetic mean (UPGMA) clustering. A total of 417 alleles were amplified with the number of alleles ranging from 5 (EM 141) to 38 (EM 120 b). Polymorphism was fairly high (0.05 to 0.92) among SSR markers with high number of repeats. Findings indicate that entries originating from different parts of the world did not form a distinct cluster, and there was no association between SSR marker pattern and geographical origin. SSR markers indicated a strong genetic affinity among S. viarum, S. melongena and S. aethiopicum Aculeatum group. Genetic relatedness between S. dasyphyllum and S. macrocarpon and between S. aethiopicum and S. macrocarpon are important for breeding. SSR markers assayed were informative for phylogenetic analysis; and have the potential to serve as perfect markers for studying variation. For plant breeders, close genetic relationships detected provide an avenue for introgression of high yielding and resistant genes into commercial and farmers' varieties.
The storage of bulbs of onion (Allium cepa L.) is very crucial to ensure its availability throughout the year. Experiments were conducted at Sokoine University of Agriculture to evaluate the growth and yield characteristics of some tropical short-day onion cultivars and the storability of their bulbs after harvest. The first experiment in 1994 involved 21 cultivars evaluated for their growth and yield variables. The second experiment, involving six cultivars, was carried out in 1996 and in addition to performance evaluation, the storability of bulbs was investigated. Results showed significant differences among the cultivars in yield, yield components and storability. Granex 429 had the highest yield among cultivars in both trials, but had very poor storability. Serrana and XPH 6074 had long storability and maintained more than 50% of their weight after 5 months of storage. These two cultivars are promising as good sources of genes to incorporate storage traits in other cultivars of onion.
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