Mitigating Chromium Stress in Bitter Gourd (Momordica charantia L.) through Seed Priming with Soybean and Pumpkin Seed Extracts
Abstract
Chromium (Cr) is a highly toxic heavy metal that severely restricts plant growth, physiology, and yield by generating oxidative stress and disturbing nutrient balance. This study evaluated the potential of soybean and pumpkin seed extracts as natural priming agents to mitigate Cr stress in bitter gourd (Momordica charantia L.). A pot experiment was conducted under a completely randomized design (CRD) with three chromium levels (0, 20, and 40 mg kg⁻¹) and three priming concentrations (0, 0.1, and 1 g L⁻¹) of methanolic and aqueous soybean and pumpkin seed extracts. Morphological, physiological, and biochemical attributes were assessed, including shoot and root length, biomass accumulation, chlorophyll and carotenoid contents, antioxidant enzyme activities (CAT, POD, SOD), and non-enzymatic antioxidants (phenolics, flavonoids, ascorbic acid). Chromium stress markedly reduced growth, pigment contents, and protein concentration, while increasing lipid peroxidation and hydrogen peroxide accumulation. However, seed priming with soybean and pumpkin extracts significantly alleviated these toxic effects by improving photosynthetic pigments, maintaining relative water content, and enhancing both enzymatic and non-enzymatic antioxidant activities. Among treatments, soybean extract priming at 1 g L⁻¹ (aqueous) was most effective in restoring growth and physiological balance under chromium toxicity. Overall, the findings demonstrate that seed priming with plant-based extracts provides a simple, eco-friendly, and cost-effective strategy to enhance chromium tolerance and improve productivity of bitter gourd under heavy-metal stress conditions.
Keywords: Bitter gourd, chromium stress, seed priming, soybean extract, pumpkin extract, antioxidant enzymes.
