EARLY-STAGE SCREENING OF BRASSICA FOR DROUGHT TOLERANCE UNDER PEG-INDUCED STRESS

Abstract

Background: Drought is one of the most limiting environmental stresses affecting both early seedling establishment and later developmental stages of agricultural crops. Its frequent occurrence, intensified by irregular rainfall and rapid climate shifts, severely disrupts the productivity of oilseed crops and contributes to substantial yield reductions. These challenges highlight the urgent need to identify drought-resilient and locally adapted Brassica germplasm that can withstand water-deficit conditions and support sustainable crop improvement programs.

Objective: This study aimed to evaluate the performance of ten Brassica genotypes under varying levels of polyethylene glycol (PEG-6000)–induced drought stress and identify drought-tolerant candidates suitable for future breeding initiatives.

Methods: A controlled-environment Petri dish experiment was conducted using a Completely Randomized Design with three replications. Four treatments were applied: a non-stressed control and PEG-6000 concentrations of 5%, 10%, and 20% to simulate mild, moderate, and severe drought stress. Ten genotypes were assessed for germination percentage, shoot length, root length, root-to-shoot ratio, shoot and root fresh weight, shoot and root dry weight, seedling fresh weight, and seedling dry weight. Data were recorded eight days after sowing and analyzed using analysis of variance to determine significance across genotypes, treatments, and genotype-by-treatment interactions.

Results: Highly significant differences (p < 0.001) were observed among genotypes, treatments, and their interactions. Values ranged widely across traits, including germination percentage (40–100%), shoot length (0.33–8.30 cm), root length (0.20–5.37 cm), and root-to-shoot ratio (0.28–0.93). Biomass parameters also showed considerable variation, with shoot fresh weight (0.002–0.54 mg), root fresh weight (0.01–0.04 mg), shoot dry weight (0.0005–0.0134 mg), and root dry weight (0.0003–0.010 mg). The 5% PEG-6000 treatment consistently enhanced seedling performance compared to higher stress levels. Among genotypes, RBN-08003 showed superior performance across multiple traits, whereas UAF-11 ranked lowest under most treatments.

Conclusion: Mild drought simulated through 5% PEG-6000 proved most favorable for seedling growth in the evaluated Brassica genotypes. The genotype RBN-08003 demonstrated strong drought tolerance and appears promising for incorporation into future breeding programs focused on water-limited environments.