茉莉酸甲酯对武运粳24和宁粳3号灌浆早期高温胁迫生理特性的影响

摘要

Methyl jasmonate (MeJA) was used on the conventional japonica rice varieties Wuyunjing 24 and Ningjing 3 to study its effects on rice physiological characteristics under high temperature stress during early grain filling stage . The results indicated that MeJA could increase the accumulation of soluble sugar in rice leaf and keep the osmotic balances .Furthermore ,MeJA increased the stomatal conductance (Gs ) and transpiration rate (Tr ) ,which accordingly reduced the temperature of leaf and panicle and further effectively alleviated the high temperature damages .Exogenous MeJA reduced the heat damages to the photosynthetic system , thereby leading to the increased PS Ⅱ maximum quantum yield (Fv/Fm ) ,photochemical efficiency (ΦPSⅡ ) ,photosynthetic electron transport rate (ETR) ,energy ratio ofphotochemicalreactions(Pr)andnetphotosyntheticrate(Pn).Increasedgrainweightandseedsettingratewere found in those MeJA treated rice plants and antioxidant enzyme activity analysis showed that when exposed to high temperature for 12 days , superoxide dismutase (SOD ) and peroxidase (POD ) antioxidant enzyme activities of Wuyunjing 24 were decreased ,while SOD and POD activities of Ningjing 3 in late stage of high‐temperature treatment were greatly increased compared to the CK .The results indicated that MeJA enhanced the activities of SOD and POD and reduced the accumulation of malonaldehyde(MDA) ,which ultimately increased the membrane stability .In conclu‐sion ,exogenous MeJA could reduce the rice canopy temperature and effectively relieve heat stress injury to plant physi‐ological characteristics .Furthermore ,exogenous MeJA could promote recovery function during recovery stage and fi‐nally mitigate yield losses .%以武运粳24和宁粳3号两个常规粳稻品种为材料，采用桶栽方式，研究高温条件下外源茉莉酸甲酯（M eJA ）在灌浆早期对水稻生理特性及产量的影响。结果显示，喷施外源M eJA可以提高植株体内可溶性糖的积累量，维持膜的渗透平衡；外源 MeJA通过增加叶片的气孔导度（Gs ）和蒸腾速率（Tr ），降低水稻的叶温及穗温；MeJA 通过减轻高温对光合系统的损害，进而提高 PSⅡ的最大光量子产量（Fv／Fm ）、实际光化学效率（ΦPSⅡ）、光合电子传递速率（ETR）及分配给光化学反应的光能（Pr ）比例，并最终提高净光合速率（Pn ）。高温条件下，武运粳24中超氧化物歧化酶（SOD）、过氧化物酶（POD）的活性降低，而宁粳3号中的SOD、POD酶活性在高温后期则高于常温处理，而喷施MeJA能提高两品种SOD和 POD两种酶在高温处理后期的活性，并降低丙二醛（MDA）的后期积累量，维持膜稳定性。综上所述，在高温条件下，MeJA 可以有效降低水稻植株温度，有效缓解高温胁迫对植株生理生化过程的伤害，并通过提高千粒重和结实率减轻高温导致的产量损失。