Screening And Physiological Characterizations Of Seed Priming Agents On Rice Seedlings Under Temperature Stress

With the advent of global climate anomalies, early rice always meets with low temperature injuriy which affects normal growth in seedling period, even causes rotting seedlings and death, affecting the final product and qrality. seed priming can be a chemical-control method of increasing temperature adversity patience of rice. So Huaai21of cold-sensitive early rice was used as experiment materials, it was primed for36h with six different agents and its different concentration, and cultivated in water(6℃in rice seedling of single-leaf, or38℃/30℃in rice seedling of two-leaves). The article studied the effects of y-PGA and other chemical compound agents on rice, and explored the alleviation effects and physiological mechanism under chilling stress and heat stress. Detailed results as follows:1. The results of screening experiment of best priming concentrations of different agents showed that, under chilling stress, CaCl2, miscellaneous agents, PEG, trehalose, SA and JA were0.55g/L, low concentration,75g/L,0.796g/L,0.069g/L and2.1mg/L respectively, under heat stress they were1.1g/L, low concentration,150g/L,0.398g/L,0.069g/L and2.1mg/L respectively.2. Effects of compound agents of y-PGA and each agent of the best concentration on rice seedlings were studied under chilling stress. The results showed that, under chilling stress each compound priming all increased shoots fresh weight and root fresh weight of rice; they obviously increased soluble sugar content of0d, decreased MDA content of2d and recovery3d; APX, CAT and SOD activity of the rice seedlings firstly increased and then decreased along with time extension of chilling stress. Through morphological indexs and physiological indexes of comprehensive evaluation, miscellaneous agent’s compound priming treatment was the best, followed by PEG compound priming treatment.3. Effects of compound agents of y-PGA and each agent of the best concentration on rice seedlings were studied under heat stress. Each compound priming all increased shoots fresh weight of rice, comparing with heat control, shoots fresh weight of recovery 3d primed by SA compound priming increased15.15%; soluble sugar content of each compound priming treatment decreased and exceeded heat control; MDA content increased along with time extension of heat stress, MDA content of recovery3d primed by JA compound priming decreased44.07%significantly, others treatments was not significant. Through morphological indexs and physiological indexes of comprehensive evaluation, JA compound priming treatment was the best.4. Semi-quantitative RT-PCR experiment showed that, chilling response genes of rice seeding of0h,12h,24h and48which was primed for36h with miscellaneous agents compound, y-PGA and water and cultivated in water(6℃in rice seedling of single-leaf) existed obvious differences. Expression of OsDREB1B and OsCDPK7by induction of miscellaneous agents’ compound were much stronger than water priming. Expression of OsFAE2of and OsMYBS3were not significantly different. OsLIP19was induced by chilling, but suppressed by seed priming. OsICEl expression was not influenced under chilling stress.