Application of Trichoderma viride and Bacillus subtilis Modulates Antioxidant System in Mustard (Brassica juncea) under Water-deficit Stress

Water-deficit stress is an important concern worldwide that reduces crop yield and quality. Mustard is an important oilseed crop of India which is adversely affected by water-deficit stress in terms of growth and yield. Tolerance to water-deficit stress is correlated with the redox regulatory and antioxidant system. To mitigate negative effect of water-deficit stress, field experiment was conducted at Dholi (Muzaffarpur), Bihar during 2019-20 with an aim to study the effect of microbes on antioxidant systems in mustard grown under water-deficit stress vis-à-vis normal irrigated conditions. Pre-screened contrasting genotypes (tolerant ‘NPJ 214’ and sensitive ‘TM 179’) were sown in the experimental farm using factorial experiment in randomized block design with three replications. The treatments (12) comprised of two factors viz., genotypes (2) and microbial inoculants along with control (3) sown under normal ‘irrigated’ and ‘water-deficit stress’ conditions. Soil inoculation microbes Bacillus subtilis and Trichoderma viride was done 35 days after sowing and was compared with non-inoculated control. Results revealed that the activity of antioxidative enzymes viz., catalase and peroxidase increased under water-deficit stress; the increase was reduced by the application of B. subtilis and T. viride in both tolerant and sensitive genotypes, and more pronounced in the sensitive genotypes. Similar results were recorded with respect to lipid peroxidation and proline content. Increase in concentration of stress-induced metabolites was less in colonized plants of mustard indicating modulation of antioxidant system. The maximum ameliorating effect was observed with application of T. viride which could be an important tool in alleviating the adverse effects of water-deficit stress in mustard.