水稻新株型与亚种间杂交稻物质运转率低的机理研究

The source-sink characteristics of new plant type (NPT) and japonica/indica hybrid (J/IH) rice were elucidated, and the mechanism of poor remobilization of assimilates from vegetative tissues to the grains were revealed in respects of hormonal balance and activities of enzymes. The results showed that both NPT and J/IH had large sink size (total number of spikelets) and strong productivity of dry matter (source), which was obviously exhibited during the grain filling period. However, poor grain filling limited their potential in the grain yield. The ratio of dry matter weight to spikelets (dry weight per spikelet, expressed as mg/spikelet) during the grain filling and whole growth periods for NPT and J/IH was greater than that for the intervarietal hybrid (IVH) with a better grain plumpness, indicating that source limitation was not the cause of poor grain filling of NPT and J/IH. But the ratio and the physiological activities (contents of hormones and activities of enzymes) of grains were much lower for NPT and J/IH than for INV. It was observed that the physiological activities of grains during early grain filling period played an important role in regulating the remobilization of assimilates and grain filling rate, which affected the whole grain filling period. The poor remobilization of assimilates in NPT and J/IH was mainly attributed to their low sink activity. The pre-stored usable sugars ( soluble sugars + starch) in the stem and sheath at heading was an important matter base for initiating grain filling. The amount of sugars per spikelet affected the sink activity, and therefore mediated the rate of remobilization of assimilates and grain filling. Sucrose synthase in the grains and α-amylase and sucrose-phosphate synthase in the stems were key enzymes in the determination of remobilization of assimilates. The remobilization of assimilates could be enhanced by an increase in the ratio of abscisic acid to gibberellins in the grains and activities of the enzymes. A controlled soil-drying (plants can rehydrate overnight) during mid and late grain filling periods could not only save the irrigating water, but also promote remobilization of assimilates, improve grain filling and increase grain weight in NPT and J/IH rice.

水稻新株型与亚种间杂交稻源叶与籽粒库光合同化物的输出输入动态；茎、鞘和穗枝梗输导组织形态解剖结构与韧皮部同化的装载与卸载；叶、茎、鞘、穗中激素含量及与糖代谢有关酶的活性变化及其与物质运转的关系；生态条件和化学调控物质对物质运转的影响。揭示水稻新株型和亚种间杂交稻物质运转率低的机理，为其遗传改良和栽培调控提供理论指导。