采用远红外增温设施在水稻开花第1 d分别对4个水稻品种（南粳41、武香粳14、扬粳6号和汕优559）进行5 h（10:00~15:00）高温处理（40℃），然后转入常温，观测当天及其后4 d开花颖花的花粉活力及同期开花颖花成熟期的结实对高温的响应特征。结果表明，高温处理后，处理后各天颖花的花粉活力均显著下降（P< 0.05），但随开花日序的后移其下降幅度逐步减小。其中，下降最大为处理当天或其后1 d，花粉在柱头和培养基上的萌发率以及花粉I-KI溶液的可染率分别平均降低了16.00、25.85和11.74个百分点，而处理后4 d的降幅仅为8.49、6.63和6.02个百分点。相同的趋势也表现在同期开花颖花的结实特征上，高温处理的当天和其后4 d开花颖花的结实率分别平均下降了14.04和5.95个百分点；而高温处理当天的空粒率和秕粒率平均分别提高了10.06和3.98个百分点，处理后4 d分别提高了3.98和1.97个百分点。另外还发现，高温处理下品种间存在一定差异，其中，汕优559的花粉活力和籽粒结实受高温的影响最小。相关分析发现结实率、空粒率和秕粒率与柱头花粉的萌发率、花粉在培养基上的萌发率均呈显著直线相关，而花粉I-KI溶液的可染率仅与空粒率存在显著相关（P< 0.05）。可见，水稻遭遇短期高温后，随着开花日序的后移高温对颖花形成的潜在热害逐渐降低，在生产实践中花粉在柱头和培养基上的萌发率可作为品种选育和高温热害发生的几率、热害程度预测的可靠指标。
The field experiment was conducted using four rice cultivars (Nanjing 41, Wuxiangjing 14, Yangdao 6, and Shanyou 559) with the treatment of the temperature (40±0.2)℃ for five hours (10:00–15:00) at the 1st day of rice heading. The results showed that rice pollen activity decreased with the delaying flowering time under normal temperature, and significantly reduced by high temperature (P<0.05). The difference of pollen activity between under high and under normal temperatures decreased with the delaying of flowering time, with in the highest decrement in the day of treatment or the first day after treatment. Pollen germination rate on stigmas, pollen germination rate on culture medium and stainable pollen grain rate by I-KI of the four cultivars on average under high temperature were 16.00, 25.85, and 11.74 percentage points lower than those under normal temperature at that time, and 8.49, 6.63 and 6.02 percentage points lower than those under normal temperature at 4 days after treatment. The seed setting rate of four cultivars on average under high temperature were 14.04 percentage points lower than that under normal temperature at the day of treatment, and 5.95 percentage points lower than that under normal temperature at 4 days after treatment, but empty grain and unfilled grain rates of four cultivars on average under high temperature were 10.06 and 3.98 percentage points higher than those under normal temperature at the day of treatment, and 3.98 and 1.97 percentage points higher than those under normal temperature at four days after treatment, respectively. In addition, significant difference of temperature effects on pollen activity and seed setting existed among the four cultivars with the least impact in Shanyou 559. According to the regression analysis, the rates of seed setting, empty grain and unfilled grain showed a significantly linear correlation with the rates of pollen germination on stigmas and on culture medium (P< 0.05), respectively. The above results suggest that the potential heat injury of short-term high temperature to rice pollen activity and seed setting is decreased with the delaying of flowering time and that the rates of pollen germination on stigmas and an culture medium may be the suitable indicators for selective breeding of heat resistance and the prediction of heat injury probability and degree.
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