花后不同时期弱光和高温胁迫对小麦旗叶荧光特性及籽粒灌浆进程的影响

在田间试验条件下研究了花后不同时期弱光和高温胁迫对小麦旗叶荧光特性及籽粒灌浆进程的影响.结果表明，弱光处理3 d后，旗叶PSⅡ最大光化学效率（Fv/Fm）和光合速率（Pn）显著降低，但PSⅡ实际光化学效率（ΦPSⅡ）、荧光光化学猝灭系数（qP）和非光化学猝灭（NPQ）与对照相比差异较小；高温处理3 d后，Fv/Fm、Pn、ΦPSⅡ和qP均极显著降低, NPQ升高幅度较小.胁迫解除后，灌浆前期（花后8～10 d）弱光和高温处理后的旗叶荧光参数和光合速率略有恢复，但灌浆中期（花后15～17 d）处理后的各参数始终呈下降趋势, 说明前期处理效应是可逆的，而中期处理加速其衰老进程.用Logistic方程对各处理的籽粒灌浆过程模拟明，弱光和高温处理后籽粒粒重的降低主要是平均灌浆速率、最大灌浆速率和渐增期灌浆速率显著降低所致.灌浆持续期、最大灌浆速率出现时间、缓增持续期和缓增期灌浆速率受弱光和高温影响较小.

Effects of weak light and high temperature stress after anthesis on flag leaf chlorophyll fluorescence and grain fill of wheat

A field experiment with wheat showed that after anthesis, the photosystem II (PS II), photochemical efficiency (Fv/Fm) and photosynthetic rate (Pn) of flag leaf decreased substantially, its actual quantum yield of PS II electron transport (phiPS II) and photochemical quenching co-efficient (qP) declined slightly, while its non-photochemical quenching (NPQ) increased slightly three days after shading, compared with the control. Three days after high temperature treatment, the Fv/Fm, Pn, phiPS II and qP decreased significantly, while the NPQ increased slightly. During the course of recovery after the stresses, the parameters fluorescence and Pn which were stressed by shading and high temperature at prophase recovered slightly, while those stressed at metaphase decreased all along, indicating that the damage at prophase was reversible, but the stress at metaphase accelerated the caducity of flag leaves. The grain-filling processes of different treatments were modeled with Logistic equation, which showed that the decline of per kernel weight was mainly caused by the decrease of mean filling rate, maximal filling rate, and slow-increase period filling rate. Filling duration, occurrence time of maximal filling rate, duration of slight-increase period, and slight-increase period filling rate were less affected by weak light and high temperature.