油菜素甾醇(BRs)对杂交粳稻灌浆期光合物质、群体氮素积累和利用的影响

以常规杂交粳稻常优3号和籼粳杂交超级稻甬优12为材料，通过叶面施肥分析了油菜素甾醇(BRs)对2个杂交粳稻灌浆期剑叶光合特性、群体干物质积累、氮素吸收利用、非结构性碳水化合物(NSC)积累和植株不同器官NSC/N的影响。结果表明，BRs对2个水稻叶片光合生理指标的影响表现为G_s>T_r>P_n>C_i。喷施2,4-表油菜素内酯(eBL)后能够增强灌浆期叶片净光合速率和蒸腾速率，维持叶绿素含量和胞间CO₂浓度，从而提升叶片光合能力；以及增加群体干物质、氮素和NSC积累量以及干物质积累比例和积累速率、氮素吸收比例和吸收速率、NSC转运比例和转运速率，但降低了氮素干物质生产效率；喷施油菜素吡咯(Brz)后的上述生理效应相反。eBL提升了2个水稻品种花后干物质、NSC和氮素的转移量及氮素对籽粒贡献率，降低了干物质和NSC对籽粒贡献率；Brz则降低了干物质、NSC及氮素的转移量和转移率，提升了干物质和NSC对籽粒贡献率。2个杂交粳稻整个灌浆期地上部不同器官NSC、氮素转运量均表现为eBL>CK>Brz，籽粒灌浆前期>籽粒灌浆后期。2个水稻品种地上部不同器官NSC/N随着籽粒的不断充实呈现上升趋势，其中茎鞘、穗部NSC/N变化最为显著；eBL减小了叶片和茎鞘中的NSC/N，Brz则反之，但喷施BRs后穗部变化规律不明显。籼粳杂交超级稻甬优12比常规杂交粳稻常优3号具有更强的剑叶光合速率，更高的干物质和氮素及NSC积累量，更大的灌浆前期NSC和氮素转运量，最终籽粒实际产量较常优3号增加5.03%~9.32%；eBL对2个水稻品种干物质和氮素积累及NSC转运作用规律不一，Brz对甬优12干物质、氮素积累及NSC转运抑制效应大于常优3号。

Effects of Brassinosteroids (BRs) on Photosynthetic Matter,Nitrogen Accumulation and Use Efficiency during Grain Filling Stage of Hybrid Japonica

Taking the conventional japonica hybrid rice Changyou 3 and indica-japonica super hybrid rice Yongyou 12 as materials, the experiment analyzed the effects of Brassinosteroids (BRs) on photosynthetic characteristics, dry matter accumulation, nitrogen absorption and utilization, non-structural carbohydrates (NSC) accumulation and the NSC/N ratio of different plant organs during grain filling stage. Results showed that the effect of BRs on photosynthetic indexes presented as G_s>T_r>P_n>C_i. Spraying 2,4-epibrassinolide (eBL) could enhance net photosynthetic rate (P_n) and transpiration rate (T_r), maintain chlorophyll content and intercellular CO₂ concentration (C_i), and eventually improve the leaves’ photosynthetic capacity during grain filling stage. It could also increase the amounts of dry matter, nitrogen and NSC accumulation, the proportions and rates of dry matter accumulation, nitrogen absorption and NSC transportation, but reduce the dry matter production efficiency of nitrogen nutrition. The effect of Brz was on the contrary. Spraying eBL improved amounts of the dry matter, NSC, nitrogen and the contribution rate to grains made by nitrogen of the two rice varieties, reduced the contribution rate to grains made by dry matters and NSC after flowering. However, Brassinazole (Brz) decreased transfer amounts and rates of the dry matter, NSC and nitrogen, promoted the contribution rate to grains made by dry matters and NSC. The transfer amounts of NSC and nitrogen of different organs in shoot of the two hybrid rice varieties were shown as eBL>CK>Brz, and early stage of grain filling (EGF) > late stage of grain filling (LGF). The NSC/N of different organs in shoot of the two rice varieties showed an increasing tendency with filling, among which the changes in stem-sheath and panicle were the most significant. Spraying eBL decreased the NSC/N of stem-sheath and leaf, Spraying Brz promoted it, while the effects of BRs on panicle was not clear. Yongyou 12 had a stronger net photosynthetic rate in flag leaves, greater accumulations of dry matter, NSC and nitrogen, larger transfer amounts of NSC and nitrogen in early stage of grain filling, and finally its actual yield was 5.03%-9.32% higher than that of Changyou 3. Spraying eBL showed a diverse rule on the accumulations of dry matter, nitrogen and NSC transportation of the two rice varieties. The inhibiting effect of Brz on dry matter and nitrogen accumulations and NSC transferring was stronger in Yongyou 12 than that of Changyou 3.