GENETIC VARIABILITY OF ETHIOPIAN SORGHUM [Sorghum bicolor (L.) MOENCH] GENOTYPES FOR WATER USE EFFICIENCY, DROUGHT TOLERANCE AND GRAIN YIELD

Abstract

Sorghum is one of the most important cereal crops grown in the world for human consumption, animal feed and bio-energy. Biotic and abiotic stresses are the most dominant constraints for the production and productivity of the crop. The study was conducted with the objectives of estimating water use efficiency, drought tolerance and grain yield of sorghum genotypes under stress condition. The trials were conducted using 64 sorghum genotypes using Latin square design with two replications at Werer. Days to fifty percent flowering, Days to maturity, plant height, and stand count at harvest, grain yield, thousand seed weight and water use efficiency data were recorded. The data were subjected to analysis of variance using generalized linear model and means were separated using Duncan Multiple Range Test. Analysis of variance for yield revealed highly significant difference between genotypes under non-stress and stress condition. The traits measured were showed highly significant differences among tested genotypes under the two experimental regimes. Grain yield showed positive and high significant phenotypic and genotypic correlations with DTF, DTM, SB, SDB, HFW, DHW, and TSW. Although grain yield of stress regime showed highly significant positive correlation to SB, SDB, HFW, DHW, TSW), and WUE. In addition, path analysis together with correlation coefficient showed that head fresh weight exhibited a highly significant positive correlation and positive direct effect on grain yield followed by thousand seed weight, and stem dry biomass. A high GCV and PCV were noted for stem biomass, stem dry biomass, dry head biomass, thousand seed weight and grain yield; suggesting that these traits are influenced by genetic control. Hence, selection can be relied upon these traits for further improvement. The first three principal components and four principal components (PCs), with eigenvalues greater than 1, explained about 73% and 77% of the total variation among genotypes for all traits under stress and non-stress conditions respectively. Highest heritability estimates were found in PH and DTM. Values of genetic advance as percent of mean showed very high value for PL, DTF, PE, PH, DTM and GY which is greater than 20%. Greater magnitude of broad sense heritability coupled with higher genetic advance in traits studied provided the evidence that these were under the control of additive genetic effects indicating that selection in the genotypes should lead to a fast improvement of the traits. Water use efficiency has shown a highly significant positive genotypic correlation to DTM, SB, SDB, HFW, HDW, and GY. Phenotypic correlation also found that a highly significant positive correlation to SB, HFW, DHW, TSW and GY for the stress regime. Genotypes ETSC300253, Acc9830 and Acc36524 showed a consistent character through the two evaluation experimental regimes as well as evaluated by drought tolerance selection indices including their water use efficiency. The study also graved that Breeders can evaluate genotypes by using STI, GMP, MP, TOL, and STI drought tolerance selection indices.