利用人工气候箱设置高温(日均温度32℃)和适温(日均温度22℃)2个处理，对籽粒灌浆过程中4种主要内源激素（IAA、ZR、GA3和ABA）含量差异及其动态变化作了比较分析。结果表明，高温对籽粒灌浆的影响主要表现为加速早期灌浆和缩短持续时间。在水稻灌浆初期，高温处理下籽粒IAA、ZR、GA3含量明显低于适温处理，而灌浆中、后期的处理间差异较小；温度处理对籽粒ABA含量的影响尤为显著，整个灌浆期均呈高温处理明显高于适温处理的基本趋势；2个供试品种在不同温度处理下的4种内源激素含量变化存在着一定差异，其变化与品种的灌浆动态有关。高温下灌浆前期籽粒中IAA、ZR、GA3含量的降低，尤其是ABA含量的剧增，可能是其早期灌浆加速及灌浆持续时间缩短的主要原因。
Temperature at grain filling stage has great impact on grain development. It has been well known that high percentage of chalky grains, poor cooking and eating quality may be caused by high temperature during the filling period, which is probably attributed to the shortened duration of grain filling, the low photosynthesis rate and activity changes of some enzymes relevant to grain filling. However, little information has been known about the effect of temperature on main endogenous hormones in developing grains at filling stage, which commonly play an important role in grain development as a growth signal. In this paper, two temperature treatments, i.e. daily average temperature 32℃(High) and 22℃(Optimum), were established to compare the difference in the endogenous hormone levels between two temperature treatments with two early indica rice cultivars applied, aiming to recognize the relationship between the effect of temperature on grain development and the response of endogenous hormone in grains to temperature. The results showed that by higher temperature, grain development was accelerated at early grain-filling stage, and the grain filling duration was shortened (Fig.1). The contents of IAA, ZR, and GA3 in developing rice grains were dramatically reduced at early grain filling stage when the plants were exposed to higher temperature, while a little difference was found in their contents between two temperature treatments at later stage (Fig.2–4). Compared with optimum temperature treatment, there was much higher ABA content in developing grains throughout the whole filling stage in high temperature treatment in spite of remarkable difference between cultivars (Fig.5). Considering effect of temperature on grain filling process and its relation with hormones levels in developing grain, it could be deduced that the acceleration of grain development and the shortening of grain filling duration should be ascribed to the reduction in IAA, ZR, GA3 contents and the increase in ABA content in developing grains at early grain-filling stage when rice plants exposed to high temperature.
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