Genetic Diversity And Breeding Of Solanum Aethiopicum Shum Group For Drought Tolerance

ABSTRACT

Solanum aethiopicum is one of the most important Solanum species, with four morphological groups. Two of the groups, Gilo and Shum, are mainly cultivated because of their nutritional value and income generating potential for farmers in developing countries. Of focus for this study was the Shum, a leafy morphological group whose productivity and quality is directly affected by drought. Global limitations on water resource availability call for the need to develop productive varieties that are drought tolerant. This research was aimed at: (i) determining the genetic distinctiveness between Shum and its progenitor, S. anguivi (SAN); (ii) evaluating genetic diversity within Shum germplasm; (iii) identifying parental material for development of drought tolerant S. aethiopicum Shum varieties; and (iv) determining the combining ability of selected Shum group germplasm for drought tolerance. Twenty-five accessions, five of which were wild progenitors, were evaluated for morphological attributes. Similarly, clustering was used to identify structure within 20 accessions of Shum based on 61 morphological variables. Further, Shum germplasm were evaluated to discover accessions (G) which excelled across water deficit regimes (WLs) where a split-plot arrangement was used. In order to determine the mode of gene action and combining ability for drought resistance among accessions, 24 F1 hybrids from a North Carolina II mating design were evaluated at five moisture regimes premised on crop growth stage and applied moisture as a percentage of field capacity of potting substrate. Five distinct clusters were identified; the progenitor accessions for Shum were grouped in their own cluster; and days to germination and emergence provided the best separation between Shum and SAN. Four distinct clusters were obtained within Shum where it was established that genotype discrimination is possible at seedling (seedling vigor), vegetative (leaves per plant, harvest index and plant growth habit) and reproductive (for instance basing on petal length and seed color) stages. From drought