Root architecture and rhizobial inoculation in relation to drought stress response in common bean (Phaseolus vulgaris l.)

Abstract

The present study was aimed at assessing the root traits and rhizobial inoculation in relation to drought in common bean, Phaseolus vulgaris. Drought caused the largest decrease in shoot biomass followed by plant height, while an increase was recorded inroot/shoot ratio. Rhizobial inoculation caused largest increase in shoot biomass followed by root volume and root biomass and smallest increase in rooting depth. WB-216 and WB-185 had better rooting depth in all treatments. However, WB-83 (92.67) had highest rooting depth under irrigated conditions and SR-1 had highest rooting depth under irrigated conditions treated with rhizobium (108.50). Similarly, WB-216 had highest root/shoot ratio under drought (2.693) followed by WB-185 (1.285) while lowest value was recorded for Arka Anoop (0.373). In rhizobium treated drought condition, WB-216 recorded highest root/shoot ratio (5.540) followed by SFB-1 (1.967). Under irrigated conditions (both with and without rhizobium), WB-185 recorded highest root/shoot ratio while lowest was recorded for SR-1 (0.166). The mean squares due to root depth, root biomass and root volume were significant whereas the mean squares due to water and rhizobium were non-significant. Among interactions the genotype x water regime was significant for rooting depth (5 % level), genotype x rhizobia was significant for rooting depth and root volume (1 % level) and the interaction of genotype x water regime x rhizobium was significant for rooting depth, root biomass and root volume (1 % level). The results reinforce the need to further analyse the potential of other soil microbes in common bean rhizosphere in amelioration of the effects of water stress.