The environmental temperature occurring during the grain filling stage is an important factor affecting starch synthesis and accumulation in rice. We investigated starch accumulation, amylase activity and starch granule size distribution in two low-amylose japonica rice varieties, Nanjing 9108 and Fujing 1606, grown in the field at different filling temperatures by manipulating sowing date. The two rice varieties exhibited similar performances between two sowing dates. Total starch, amylose and amylopectin contents were lower at the early-filling stage of T1 treatment (Early-sowing) compared with those at the same stage in T2 treatment (Late-sowing). In contrast, at the late-filling stage, when field temperatures were generally decreasing, total starch and amylopectin contents in T1 were higher compared to those in T2. The ideal temperature for strong activity of ADP-glucose pyrophosphorylase and soluble starch synthase was about 22 °C. A higher temperature from the heading to maturity stages in T1 increased the activities of starch branching enzyme and suppressed the activities of granule bound starch synthetase and starch debranching enzyme. We found that rice produced larger-sized starch granules under the T1 treatment. These results suggested that due to the early-sowing date, the high temperature (30 °C) occurring at the early-filling stage hindered starch synthesis and accumulation, however, the lower temperatures (22 °C) at the late-filling stage allowed starch synthesis and accumulation to return to normal levels.

籽粒灌浆期发生的环境温度是影响稻米淀粉合成和积累的重要因素。我们调查了两种低直链淀粉粳稻的淀粉积累，淀粉酶活性和淀粉粒度分布通过操纵播种，在不同灌浆温度下在田间种植了南京9108和福建1606等水稻品种。两个水稻品种在两个播种日期之间表现出相似的表现。与T2处理（后期播种）同期相比，T1处理（早期播种）早期阶段的总淀粉，直链淀粉和支链淀粉含量较低。相反，在后期灌装阶段，当田间温度普遍下降时，T1中的总淀粉和支链淀粉含量高于T2。ADP-葡萄糖焦磷酸化酶和可溶性淀粉合酶具有较强活性的理想温度约为22 ℃。T1从抽穗期到成熟期的较高温度增加了淀粉支化酶的活性，并抑制了颗粒结合的淀粉合成酶和淀粉脱支酶的活性。我们发现大米在T1处理下会产生较大尺寸的淀粉颗粒。这些结果表明，由于播期早，在 灌浆初期出现的高温（30 °C）阻碍了淀粉的合成和积累，但是 在灌浆后期较低的温度（22 °C）允许淀粉的合成和积累恢复到正常水平。