Search For New Stay-Green Sources In Sorghum Bicolor (L.) Moench

Growth of biomass sorghum (Sorghum bicolor (L.) Moench) under semi-arid conditions in Mediterranean region is mainly hindered by water deficit. This study aimed at physiologically and genetically evaluating sorghum genotypes for biomass performance under different water regimes. Of the seventy-seven varieties studied, tropical landraces were more promising at large, in terms of aboveground biomass yields under irrigation and rain-fed experiments. Performance under drought-stressed conditions was dependent upon green leaf area retention (r: -0.47; P: 0.001), plant height (r: 0.50; P: 0.001), and maturity (r: 0.61; P: 0.001). A stay-green source (SDS 1948-3) along with a senescent type (IS 33350) was identified. In the segregating progeny from their cross, stay-green inheritance appeared polygenic with a dominant major gene that determine a reduced rate of senescence. Stay-green genotypes displayed high leaf relative water content (r = -0,22; P <= 0,01), and high leaf nitrogen content (r = -0,26; P <= 0,01). Nine linkage groups were constructed using 40 SSRs loci purposefully selected from known map positions that could span 439 cM (Kosambi's function), with a mean distance of 15 cM between any two adjacent loci. Three chromosomal regions possibly related with delayed senescence were perliminarly located. SDS 1948-3, a population supplied by ICRISAT, coming from Kenya, could be of interest contributing to drought tolerance in breeding for sorghum with high and stable biomass yield.