水稻器官形态和干物质积累对穗分化不同时期高温的响应

为明确水稻穗分化期高温对生长发育所造成的影响,以耐热籼稻黄华占和热敏感籼稻丰两优6号为材料,利用人工气候箱在穗分化期进行40℃(10:00-15:00)高温处理,以人工气候箱32℃适温处理为参考,室外环境温度为对照(CK),研究枝梗-颖花分化期(Ⅰ期)和花粉母细胞形成-减数分裂期(Ⅱ期)高温胁迫对水稻器官形态及干物质积累的影响。结果表明:1)Ⅰ期高温抑制幼穗分化,使穗分化期延长2.5~8.8 d;Ⅱ期高温阻碍水稻抽穗,导致穗分化期延长6.8~7.1 d,显著缩短上部茎节,降低抽穗度,其中热敏感品种降幅大于耐热品种;2)穗分化期高温处理显著降低每穗颖花数和颖花大小,颖花数下降原因在不同处理时期间存在差异,Ⅰ期高温减少颖花分化数;而Ⅱ期高温显著加速颖花退化,两个品种退化幅度均达50%以上,并显著降低了花药大小和颖花受精率,热敏感品种丰两优6号受高温影响要大于耐热品种;3)高温对叶片生长有促进作用,Ⅱ期高温处理表现尤为明显,两个时期高温处理对上3叶净光合速率和水稻单茎干物质积累没有显著影响。Ⅰ期高温不同部位间干物质积累无显著差异,而Ⅱ期高温显著降低茎鞘和穗部干物质积累,但高温导致高节位分枝发生,积累了一部分干物质,整体上单茎干物质积累量并没有显著下降。

Response of Rice Organ Morphology and Dry Matter Accumulation to High Temperature at Different Panicle Initiation Stages

A pot experiment in controlled-environment chambers was conducted to determine the effects of high temperature(40℃) on the rice organ morphology and dry matter accumulation during panicle initiation stage. Two mid-indica rice cultivars(Huanghuazhan,heat-tolerant;Fengliangyou 6,heat-sensitive) were planted and exposed to high temperature(40℃,10:00-15:00), and normal temperature(32℃,10:00-15:00) during branch-spikelet differentiation stage(I) and pollen mother cell formation-meiosis stage(Ⅱ), meanwhile rice was grown in ambient conditions as CK. The results indicated that, 1) at stage I high temperature inhibited panicle initiation, extending the panicle initiation stage by 2.5-8.8 d, while at stage Ⅱ,by 6.8-7.1d, which shortened the length of the top internode and reduced the heading degree,especially in Fengliangyou 6. 2)Heat stress at panicle initiation stage significantly decreased the number and the size of spikelets, which might be due to the significant difference in treatment period.High temperature at stage I inhibited spikelet differentiation, while at stageⅡ, heat stress mainly promoted spikelet degeneration,the degeneration rate of the two cultivars were up to 50%, with‘Fengliangyou6’ having a higher ratio. High temperature exposure at stage Ⅱ also significantly declined the size of anther, and the spikelet fertility. 3)High temperature promoted the growth of the top three leaves, especially at stage Ⅱ. Heat stress at the two stages had no significant effect on the leaf photosynthesis and dry matter accumulation of single main stem. Heat stress(40℃) exerted no significant influence on dry matter accumulation of culm, leaves and panicle at stage I, but significantly decreased the dry matter accumulation of culm and panicle at stage Ⅱ, leading to upper-internode tillering and resultant dry matter accumulation.