Antioxidant Defense System Mediating Water Stress Tolerance through Improving Growth Attributes in Fodder Sorghum (Sorghum bicolor L. Moench)

Drought is one of the major constrain, which alters vital plant functions and impacts plant performance at various growth phases. Under water stress, the purpose of this study was to assess sorghum (Sorghum bicolor L. Moench) genotypes for germination, seedling establishment, growth characteristics, biochemical content, and antioxidant enzymatic activity. Twelve sorghum genotypes were sown under water stress conditions of 60% (D1) and 40% (D2) field capacity (FC) in a pot experiment with control (100% FC). Growth characteristics such as plant height (PH), tiller number (TN), leaf length (LL), leaf width (LW), and leaf number (LN) were measured at 30, 45, 60, 75, and 90 DAS (days after sowing). The findings demonstrated that under D2 treatment, the membrane stability index (MSI), relative water content (RWC), and SPAD values decreased. On the other hand, D2 treatment increased the levels of proline (PRO), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), and malondialdehyde (MDA). Whereas, SOD, MSI, SPAD, PH, and PRO were primary contributors to the 41.1% of total variances found in the principal component analysis. The LW and POD, MDA and APX, and PH and PRO also showed significant positive correlations (r = 0.72, 0.71, and 0.63, respectively), according to the correlation matrix. According to genotypic ranking, genotypes IC-0409422, IG-02-382, EC-512407, and IC-0285900 had demonstrated improved growth under high drought stress because of high MSI, water relation, and reducing oxidative stress by bolstering antioxidant defense. These genotypes may be suitable for drought-prone areas and can be employed in future drought tolerance research.