摘要
Chilling is one of the major abiotic stresses for plants,especially for rice cultivation.Many essential metabolic processes for growth and development are temperature-dependent.In that case,reducing the negative effects of cold stress using exogenous chemicals is a possible option.Therefore,the current study examined the effects of pre-sowing seed treatment with different chemicals,viz.hydrogen peroxide(H_(2)O_(2)),salicylic acid(SA),calcium chloride(CaCl_(2)),thiourea(TU),and citric acid(CA)on the germination of rice seeds(cv.BRRI dhan28)under chilling environments.Rice seeds were soaked in distilled water(control),10 mM CA,2 mM SA,10 mM CaCl_(2),10 mM H_(2)O_(2),and 10 mM TU solutions for 24 h.After that,seeds were exposed to chilling stress by incubating at 4±1℃ for 8 h,followed by at 25±2℃ for 16 h for 7 days.Exposure to chilling stress significantly reduced thefinal germination percent(13.6%),germination rate index(36.0%),coefficient of the velocity(25.0%),shoot fresh weight(44.4%),and root fresh weight(60.5%).Moreover,chilling induced oxidative damage and reduced the activity of antioxidant enzymes(catalase and ascorbate peroxidase).In contrast,treatments with H_(2)O_(2),SA,CaCl_(2),TU,and CA considerably enhanced germination indices and seedling growth compared to chilling stress condi-tions.The study showed that priming with H_(2)O_(2),SA,CaCl_(2),TU,and CA significantly boosted antioxidant enzyme activities and reduced MDA and H_(2)O_(2) contents in chilling-stressed rice plants,indicating less oxidative stress and improved tolerance.Principal component analysis showed that among these priming agents,H_(2)O_(2),SA,and CA are most effective in chilling stress mitigation.Therefore,using seed-treating chemicals to combat the effect of chilling stress can help rice seedlings grow better in the winter season.
