水稻抽穗期高温胁迫对不同品种受粉和受精作用的影响

Effects of High Temperature Stress at Heading Stage on Pollination and Fertilization of Different Types of Rice Variety

水稻抽穗期高温障碍导致结实性降低已经成为长江中下游水稻的重要自然灾害之一。以现代常规粳稻、三系杂交籼稻和两系杂交籼稻为试料,研究了抽穗期高温处理对现代水稻品种和组合受精率的影响。现代粳型品种表现出较好的抽穗期高温耐性;杂交稻特别是两系杂交稻抽穗期高温耐性相对较弱,抽穗期39℃的高温胁迫下,受精率接近于零;在杂交稻中,汕优63在较轻高温胁迫下表现较好耐性,但在较强的高温胁迫下高温耐性迅速下降。相同处理下抽穗期高温耐性在品种间有较大差异。2个两系超级杂交稻的单药花粉数均在1750粒以上,数量最多,宁粳1号数量最少,为每花药979.8粒。总体趋势为杂交稻多于常规稻,籼型品种多于粳型品种,分析表明单药花粉数与高温耐性不相关。高温胁迫导致花药开裂系数显著下降,宁粳1号在较强的高温胁迫条件下还能维持一定程度的纵裂率,开花后柱头上花粉数量相对较多。可见水稻抽穗期高温耐性与花粉生产能力无关,与花药开裂和柱头捕获的花粉量关系较大。

High temperature stress at heading stage is one of the important natural disasters causing the reduction of the seed set- ting rate of rice in the middle-lower reaches of Yangtze River. This study investigated the effects of high temperature stress at heading stage on fertilization rate of modem rice varieties and combinations, including modern inbred japonica, three-line hybrid indica rice and two-line hybrid indica rice cultivars under the field condition. The modem inbred japonica cultivar showed better high temperature tolerance at heading stage, while the hybrid rice, especially the two-line hybrid indica rice cultivar, was suscep- tible to high temperature at heading stage, and their fertilization rate was close to zero under 39℃ at heading stage. Shanyou 63 showed well tolerance to moderate high temperature stress, which was decreased rapidly under the severely high temperature. The high temperature tolerance showed the great differences among cultivars under the same treatment. The pollen numbers per anther in the two tested super two-line hybrid rice was the highest, which was more than 1750. Ningjing 1 had the lowest pollen number, which was only 979.8 per anther. In general, the pollen number per anther in hybrid rice was higher than that in inbred rice, and that in indica higher than that in japonica. The correlation of pollen number per anther was not significant with high temperature tolerance. High temperature stress decreased the anther dehiscence coefficient significantly. Ningjing 1 could maintain certain extent of longitudinal fracture rate under the severely high temperature stress, and more pollen quantity on stigma after anthesis. The results indicated that high temperature tolerance at heading stage is not related with pollen production, but has close relation- ship with anther dehiscence and pollen quantity on stigma.