Drought Tolerance Assessment in Grain Sorghum (Sorghum bicolor [L.] Moench) Genotypes Using Agro-morphological Traits and DNA Markers

Abstract

Background: The traditional crop varieties and modern cultivars grown by farmers are important source for food security and support the livelihoods of the majority in Africa. Sorghum improvement can be achieved by the utilization of the wide range of diversity existing in sorghum, which can lead to improvement of people’s sustainable livelihoods, agricultural productivity and economic development. Methodology: The performance of 19 grain sorghum (Sorghum bicolor L.) genotypes was assessed under water stress conditions using agro morphological and Inter Simple Sequence Repeats (ISSRs) markers. Two field experiments were executed during the summers of 2012 and 2013 at Shambat Experimental Farm, Sudan. A split-plot design with three replications were used to layout the field experiment. The sorghum genotypes were evaluated in the field under normal irrigation and water stress conditions. Data was collected to determine genotypic variability among the grain sorghum genotypes and to estimate the phenotypic correlation coefficients between different traits. In addition, the genetic diversity of the genotypes was determined by ISSRs. Results: The results showed that, drought stress caused significant reduction in most of the studied characters. Significant differences among the genotypes were found for all characters studied. The sorghum genotypes showed differential yield response to drought stress. High grain yield (t haG1) was exhibited by genotypes HSD7511 and HSD8849 which gave 2.3 and 3.7 t haG1, respectively. Grain yield (t haG1) was significantly and positively correlated with grain yield per plant and other yield components. However, it had no significance and negative association with plant height and days to maturity. Based on DNA markers analysis (ISSR), high level of polymorphism was detected among the 19 sorghum genotypes. Conclusion: From the 19 grain sorghum, accessions HSD7511 and HSD8849 gave the highest yield under drought stress. Drought stress affected significantly yield and yield components than the vegetative growth. The ISSR technique was efficient in determining the genetic diversity among the 19 sorghum genotypes and thus can be exploited further to establish consistent heterotic group between sorghum genotypes.