低温胁迫对水稻幼苗叶片生理生化特性的影响

目的]研究低温胁迫对水稻叶片生理生化特性的影响。方法]以水稻品种两优5916为试验材料,研究低温胁迫过程中水稻幼苗叶片的光合参数、叶绿素荧光参数、抗氧化系统酶活和丙二醛含量的变化。结果]低温胁迫下,水稻的净光合效率、气孔导度与蒸腾速率均明显下降,叶绿素荧光参数光合系统Ⅱ最大潜在光化学效率(F_v/F_m)与光化学转换的实际量子效率(ФPSⅡ)也显著降低,初始最小荧光(F_o)与光合系统Ⅱ非调控能量耗散系数(ФNO)升高。对抗氧化系统酶活的测定结果表明,在低温处理过程中水稻幼苗叶片的抗氧化系统SOD、POD、CAT酶活呈先升高后降低的趋势,丙二醛含量则逐步升高。结论]在低温胁迫下,水稻对光能的吸收转换效率降低,而蒸腾速率与气孔导度的降低导致叶片净光合速率的降低,由于叶片抗氧化系统酶活的降低以及MDA含量的增加,叶片光合系统Ⅱ受到了不可逆的损伤。

Effects of Low-temperature Stress on the Physiological and Biochemical Characteristics of Rice Seedling Leaves

Objective] To study the effects of low-temperature stress on the physiological and biochemical characteristics of rice seedling leaves.Method] Taking rice cultivar Hangyou 5916 as test materials,the changes of photosynthesis parameters,chlorophyll fluorescence parameters,enzyme activities of antioxidant system and MDA content in the process of low-temperature stress were studied.Result] Under lowtemperature stress,the net photosynthesis rate,stomatal conductance and transpiration rate obviously decreased,and chlorophyll fluorescence parameters Fv/Fm,φpsⅡ obviously decreased,but Fo and φNO increased.The determination results of the activities of SOD,POD and CAT enzymes firstly increased and then decreased,MDA content gradually increased.Conclusion] Under low-temperature stress,photochemical conversion efficiency decreased,the net photosynthesis rate decreased by the decrease of stomatal conductance and transpiration rate.PSⅡ was damaged because enzymes activities of antioxidant system decreased and MDA content increased.