氮素穗肥运筹对两个杂交中籼稻叶片形态、光合生产及产量的影响

【目的】为探究氮素穗肥不同促花肥和保花肥比例对水稻光合生产和产量的影响,并为水稻氮素穗肥管理提供依据,【方法】以株型和产量均存在较大差异的2个杂交中稻品种(德香4103和宜香3724)为材料,在常规施氮量(180 kg/hm2)下,研究了占总氮40%的穗肥不同促花肥和保花肥运筹比例(1∶3,2∶2,3∶1,4∶0)对水稻叶片生长、形态、光合生产及产量的影响。【结果】2个水稻品种均在低促花肥、高保花肥时(1∶3)表现出叶片直立、受光形态好,净光合速率高和群体干物质积累量大的特点,并最终获得较高产量;而在高促花肥、低保花肥下,2个水稻品种的剑叶、倒2叶叶面积和叶角增大,披垂度增加,群体质量变差,结实率和粒重下降,产量降低。德香4103因其颖花量较大,上3叶叶面积和总叶面积相对适宜,粒叶比高,且在不同穗肥运筹下叶面积和叶角变幅较小,因而受光姿态和群体质量更优,干物质积累量更大,产量更高。【结论】水稻氮素穗肥运筹应塑造良好叶片形态和群体质量,并增加花后物质积累量才能有助于产量提高;并对水稻株叶型选育进行了探讨。

Effects of Nitrogen Topdressing for Panicle Initiation on Leaf Morphology,Photosynthetic Production and Grain Yield of Two Middle-season Hybrid Rice

【Objective】Nitrogen fertilization has a great influence on rice leaf growth, morphology, photosynthetic production and grain yield, especially the management of spikelet-promoting and spikelet-developing nitrogen. The objectives of this study are to elucidate the effect of spikelet-promoting and spikelet-developing nitrogen application ratios on middle-season hybrid rice.【Method】Two middle-season rice combinations (Dexiang 4103 and Yixiang 3724, which differ greatly in leaf morphology and grain yield) were used. The total nitrogen application rate is 180 kg/hm2, 40% of which is topdressed for panicle initiation. Four kinds of spikelet-promoting and spikelet-developing nitrogen ratios(1∶3, 2∶2, 3∶1, 4∶0) were designed. Leaf morphology (including leaf length, width, angle, leaf area index, and group light transmittance), net photosynthetic rate, dry matter accumulation and grain yield were measured at full heading and harvest stage. 【Result】Lower ratio(1:3) of spikelet-promoting nitrogen fertilizer can achieve a higher grain yield both in the two combinations, and erect leaf morphology, good leaf posture for light, high net photosynthetic rate and large dry matter accumulation were observed simultaneously. On the contrary, relatively low grain yields of both rice combinations were observed under the treatment of high ratio of spikelet-promoting and nitrogen fertilizer. This might be mainly attributed to the much increased leaf area, angle and dropping degree under the higher ratio, which further caused a poor population quality and a decline in seed-setting rate and 1000-grain weight. As for the two different rice combinations, Dexiang 4103 had a higher grain yield. In fact, Dexiang 4103 possessed a larger total number of spikelets, while a smaller leaf area and angle variation for all fresh leaves under different nitrogen application ratios, which allowed Dexiang 4103 to maintain a good population quality and good posture to capture more light. As a result, Dexiang 4103 produced a higher dry matter accumulation and yield.【Conclusion】Based on these results, in order to increase the dry matter accumulation after heading and yield, we suggest that the application of panicle nitrogen fertilizer should shape a good leaf morphology and high quality population. Finally, the leaf breeding of hybrid rice was discussed.