【作者】 张文虎；

【导师】 杨建昌； 朱庆森；

【作者基本信息】 扬州大学 ， 作物栽培学与耕作学， 2003， 硕士

【摘要】 籽粒充实不良是新株型（NPT）稻和粳/籼亚种间杂交稻（J/IH）产量提高的主要限制因素。本研究以具有代表性的新株型品系和亚种间杂交稻组合为材料，观察了其源库特征和物质运转特征，以揭示其籽粒充实不良的原因。获得的主要结果如下： 1．与籼型杂交稻汕优63（对照）相比，新株型稻和粳/籼亚种间杂交稻库容量（总颖花量）大，抽穗前干物质累积量较低，抽穗时干重/颖花比（mg/颖花）低。但抽穗至成熟期的物质生产能力强，干物质累积量高，干重/颖花比高。结实率高的品系或组合，产量亦高。结实率低限制了NPT和J/IH产量的潜力。 2．NPT和J/IH抽穗至成熟茎鞘中非结构性碳水化合物（NSC）输出率、同化物运输率、标记剑叶的¹⁴C分配到籽粒的比例和收获指数均显著低于对照。物质运转率高的品系或组合，结实率和籽粒充实度也高。表明光合同化物向籽粒的转运率低是NPT和J/IH结实率低和籽粒充实不良的重要原因。 3．NPT和J/IH抽穗期的糖花比（抽穗时茎与鞘中NSC量与颖花数之比，用mg/颖花表示）和灌浆初期（花后3～12d）籽粒的生理活性（籽粒中IAA含量、ATP酶和淀粉合成酶活性）较低。灌浆初期籽粒的生理活性与NSC的表观输出率、同化物运转率、结实率和谷粒充实率呈显著或极显著正相关(r=0.775^*～0.954^**)。抽穗期的糖花比与灌浆初期籽粒生理活性呈极显著正相关r=0.951^*～0.961^**)。表明NPT和J/JH抽穗期低的糖花比影响灌浆初期籽粒生理活性，低的库活性减弱了同化物向籽粒的调运，导致籽粒充实不良。 4．灌浆期适度的土壤干旱处理（土壤水势-25kPa）明显提高了茎中α-淀粉酶和蔗糖磷酸合成酶（SPS）活性，促进了茎中储存NSC向籽粒运转，增加了NPT和J/IH的结实率和粒重。在结实期喷施低浓度(25×10^-6M)脱落酸（ABA），籽粒中ABA扬州大学硕士学位论文含量增加，赤霉素（GAs，GAI+G抽）含量减少，物质运转率提高，籽粒灌浆加快，粒重增加。表明调节茎中淀粉水解酶和SPS活性，或改变籽粒中激素间的平衡，特别是ABA含量的增加和GAs含量的减少，可以促进NPT和1八H光合同化物向籽粒的运转，进而促进籽粒充实。更多还原

【Abstract】 Poor grain filling is a major constraint in the increase in grain yield of new plant type (NPT) and japonica/indica hybrid (J/IH) rice (Oryza stativa L.). The objective of this study was to investigate potential causes of poor grain filling of NPT and J/IH rice by examining source-sink relations and translocation of assimilates in typical NPT lines and J/IH combinations. The main results are as follows:1 . Compared with indica hybrid Shanyou 63 (CK), NPT and J/IH had greater sink size ((total number of spikelets per square meter) and less dry matter accumulation before heading with a smaller ratio of dry matter weight to spikelet number (mg/spikelet). However, both NPT and J/IH had greater productivity and more accumulation of dry matter with a greater value of dry matter (mg) per spikelet from heading to maturity. A line or combination with greater ripened-grain percentage showed higher grain yield. Poor grain filling as a result of low ripened-grain percentage limited the yield potential in NPT and J/IH rice.2. Both NPT and J/IH exhibited poorer remobilization of nonstructural carbohydrate (NSC) reserves from the stem (culm + sheath), a smaller transfer ratio of assimilates, less partitioning of I4C to grains from labeled flag leaves, and lower harvest indices, relative to CK. A line or combination with a greater transfer ratio of assimilates showed a greater ripened-grain percentage, indicating that poor remobilization of assimilates from vegetable tissues to grains results in poor grain filling of NPT and J/IH rice.3. NPT and J/IH rice showed a low sugar-spikelet ratio at heading (the ratio of amount of NSC in the stem at heading to spikelet number, expressed as mg/spikelet) and low physiological activities (indole-3 -acetic content and activities of adenosine triphosphate enzyme and starch synthase) in the grains at early grain filling stage (3-12d after anthesis). The physiological activities of grains at early filling stage were significantly correlated with the transfer ratio of assimilates, ripened-grain percentage, and grain plumpness(r = 0.775 to 0.954). The sugar-spikelet ratio at heading was positively correlated with physiological activities of grains during the early grain filling period (r = 0.951 to 0.961). It is suggested that low physiological activities of grains at early filling stage is attributed to low source-sink ratio at heading, and the low sink activity weakens the ability to remobilize assimilates into grains, and leads to poor grain filling in NPT and J/IH rice.4. A moderate soil drying (soil water potential at -25 kPa) imposed during grain filling period significantly enhanced a-amylase and sucrose-phosphate synthase (SPS) activities in the stem, facilitated remobilization of assimilates from stems to grains, and increased ripened-grain percentage and grain weight of NPT and J/IH rice. Exogenously applied abscisic acid (ABA) with low concentration (25 X 10-6 M) during grain filling increased ABA whereas reduced gibberellins (GAs, GA1 + GA4) contents in grains, enhanced remobilization of assimilates, increased grain filling rate and grain weight. These results suggest that either an enhancement of activities of starch hydraulic enzymes and SPS in the stem or an altered hormonal balance in the grain, especially a decrease in GAs and an increase in ABA, increases translocation of assimilates from vegetative tissues to grains, and therefore improves grain filling of NPT and J/IH rice.更多还原