高温胁迫对水稻灌浆结实期叶绿素荧光、抗活性氧活力和稻米品质的影响

选用西农优30和富优1号两个水稻品种, 在灌浆结实期利用人工气候室进行高温处理, 测定叶绿素含量、叶绿素荧光参数、抗活性氧活力的动态及成熟稻米的营养品质。结果表明, 高温胁迫下水稻叶片叶绿素含量降低, 叶绿素荧光参数初始荧光(F_o)明显上升, PS II的潜在活性(F_v/F_o)和PS II的最大光能转化效率(F_v/F_m)均低于对照, 呈下降趋势; 灌浆结实后期F_v/F_o和F_v/F_m的下降速率最快; 灌浆结实后期抗氧化活力低于对照。同时, 高温胁迫下的成熟稻米总淀粉及直链淀粉含量降低, 蛋白质含量升高, 垩白度上升而千粒重下降。高温胁迫下光合作用的原初反应被抑制, 抗活性氧活力降低, 水稻叶片功能期缩短, 可能是稻米品质降低的重要原因。

Effects of High Temperature on Chlorophyll Fluorescence, Active Oxygen Resistance Activity, and Grain Quality in Grain-Filling Periods in Rice Plants

The synthesis of assimilate such as starch, protein and lipid depends on the photosynthesis. Under stresses, the pigments, primary reaction and electronic transport chain which have relations with photosynthesis are hurt or inhibited. The effect of high temperature caused by “Greenhouse Effects” becomes more and more frequent. To elucidate the injury mechanism under high temperature in rice plants, the dynamic changes of chlorophyll content, chlorophyll fluorescence parameters and active oxygen resistance activity were measured and the grain quality indices including starch, protein, and chalkiness were also analyzed in rice plants of cultivars Xinongyou 30 and Fuyou 1 during grain-filling period under high temperature treatment in climatic cabinets. The results showed that under high temperature (33℃), chlorophyll content of leaves decreased, initial fluorescence (F_o) increased obviously, maximal photochemical efficiency of PS II (F_v/F_m) and the potential photochemical efficiency of PS II (F_v/F_o) decreased, F_v/F_o and F_v/F_m declined faster during the whole grain-filling period, especially in late period. Meanwhile, active oxygen resistance activity (AORA) lowered by 45.16 and 35.99% as compared with the control in the late grain-filling period; under high temperature condition, the total starch and amylose contents of grains were lower than those of control, the protein contents increased to a different degree, and chalkiness and 1000-grain weight changed significantly in two cultivars. The main reason of degeneration of grain quality under high temperature stress is related to the inhibition of primary reaction of photosynthesis, drop of active oxygen resistance activity and contraction of functional period in leaves of rice plants.