French marigold (Tagetes patula) flavonoid extract-based priming ameliorates initial drought stress on Oryza sativa var indica, cultivar Satabdi (IET4786): a sustainable approach to avoid initial drought stress.

Abstract

Drought stress remains a serious concern in Oryza sativa L. var indica, cultivar Satabdi (IET4786) production, particularly during the earliest growth phases, ultimately affecting yield due to the recent trend of delayed rain arrival in West Bengal, India. This study aimed to develop a cost-effective strategy to improve the drought tolerance capacity of rice seedlings by priming the seeds with flavonoid-enriched extract (FEE) of French marigold (Tagetes patula) petals to withstand the initial drought milieu. The morpho-physiological and biochemical responses of rice seedlings were evaluated to perceive the priming efficacy in alleviating water stress-induced untoward effects. The findings revealed that mechanical priming of the IET4786 seeds with FEE (50 mg/mL for 30 min) significantly improved seedling survival against initial drought stress for 14 days. After 24 h of recovery from drought stress, the primed seed-derived seedlings exhibited significantly improved morphological, physiological, biochemical, and redox parameters compared to the seedlings derived from unprimed seeds under net house conditions. In search of mechanistic insights, seed priming significantly increased proline content by endorsing Δ¹-pyrroline-5-carboxylate synthetase activities, endorsed methylglyoxal clearance homeostasis by improving glyoxalase I and II activities through restoring glutathione (GSH) level, and enhanced polyamine accumulation in the leaves of seedlings to endure drought stress.