Assessment of Drought Tolerance in Rabi Sorghum Genotypes under Polyethylene Glycol-induced Osmotic Stress

Abstract

Sorghum is a vital cereal crop globally, especially in arid and semi-arid regions of India, where rabi sorghum is critical for food security. This study investigates the impact of polyethylene glycol (PEG 6000)-induced osmotic stress on the germination, seedling growth, and vigor of twenty rabi sorghum genotypes. PEG 6000, a non-toxic osmotic agent, was utilized to simulate drought conditions by reducing water potential. The genotypes were subjected to three osmotic stress regimes (0%, 0.5%, and 1% PEG) and evaluated for germination percentage, root and shoot length, seedling dry weight, and seedling vigor indices. Results demonstrated significant variations in germination and seedling performance across genotypes and osmotic stress levels. The highest germination percentage was observed in ICSV-15017 (86.67%) under control conditions, while the lowest was in Annigeri-1 (23.33%) under 1% PEG. Shoot and root lengths decreased with increasing PEG concentration, with ICSV-15017 and SVD-1419 consistently showing superior growth under stress. Seedling dry weight and vigor indices also varied significantly, with DSV-5 and SVD-1419 exhibiting higher values compared to others under osmotic stress. The study identifies ICSV-15017, Parbani Motti, and DSV-4 as the most drought-tolerant genotypes, based on minimal reductions in germination percentage, seedling length, and vigour index under PEG-induced stress. In contrast, Annigeri-1 and ICSV-16006 showed limited drought tolerance. These findings highlight the effectiveness of PEG-induced osmotic stress for screening drought-tolerant sorghum genotypes and provide valuable insights for developing drought-resistant varieties in water-scarce regions.