Improving rice seedling physiological and biochemical processes under low temperature by seed priming with salicylic acid.

Abstract

Temperature is one of the major environmental limiting factors that affect rice (Oryza sativa L.) production. This study was carried out to induce chilling tolerance in rice (cv. Hashemi) by seed priming with salicylic acid and to unravel the physiological and biochemical processes at early growth stage. Seeds were soaked in 0, 20, 50 and 100 mg.l-1 salicylic acid solutions for 24 hours and then dried back to the original moisture content and were sown in three temperatures (28°C as normal, 12°C and 8°C as chilling stress). Sharp decrease in photosynthesis pigments was observed under low temperature in rice seedling leaves in compared to control though chilling stress effects on photosynthetic pigments was mitigated by seed priming with salicylic acid. Maximum decrease in protein contents (35%) was observed in 8°C though it was 4% for 12°C. seed priming with salicylic acid improved protein contents in all concentrations. Soluble sugars content increased with decreasing in temperature as it was 33% and 41% in 12 and 8°C, respectively. Maximum soluble sugars accumulation (34.41 mg.g-1 fw) was recorded in seedling raised from primed seeds with 100 mg.l-1 SA at 12°C. Indeed, seed priming with salicylic acid via increasing in photosynthesis pigments, proline, soluble sugars and protein content could decrease low temperature harmful effects and therefore increase rice seedling root and shoot growth.