Phenotyping sorghum [Sorghum bicolor (L.) Moench] for drought tolerance with special emphasis to root angle

Abstract

The study was conducted to characterize early maturing sorghum genotypes under moisture stress and non-stress environments based on root angle. Phenotyping of 23 early maturing sorghum genotypes was carried out under post-flowering moisture stress and non-stressed environment using randomized complete block design (RCBD) in two replications at Werer Agricultural Research Center in 2018 off season. The genotypes were selected based on root angle data that varied from 13.0 to 26.75°. The analysis of variance revealed significant variation among genotypes for most of the traits. Post-flowering drought reduced grain yield by 21% and all the traits showed a reduction in value except flag leaf area. Grain yield showed positive correlations with seedling vigor, grain filling rate, thousand grain weight and panicle weight while negative correlations with number of fertile tiller and panicle exertion for both environments. Root angle revealed positive correlation with grain yield, grain filling rate and thousand grain weight while there was negative phenotypic correlation with panicle exertion in the stressed environment. Therefore, selection for high correlated traits could aid breeding program to develop genotypes with superior yield under both environments flag leaf area, chlorophyll content, harvest index and root angle traits could be used as morphological marker for drought tolerance screening in sorghum since there was positive correlation with yield observed for stressed environment only. The result revealed the importance of intermediate to slightly wider root angle for drought tolerance of early maturing sorghum genotypes by enhancing lateral water absorption of the roots under silty clay soil. Key words: Correlation, early maturing sorghum, morphological marker, post-flowering drought, root architecture, root traits.