中文摘要：

【目的】水稻籽粒灌浆是光合同化产物向籽粒运输并合成淀粉的生理过程,决定水稻结实率、粒重高低及品质优劣。籽粒灌浆过程不仅受遗传因素的影响,而且受到温度和水分等环境因子的调节。灌溉是水稻生产上一项重要的技术,对水稻产量的形成有重要调控作用。但有关花后灌溉方式对水稻籽粒淀粉合成相关基因表达的影响,缺乏研究。本研究旨在探讨花后干湿交替灌溉对水稻籽粒灌浆的影响并阐明其分子机理。【方法】2012—2013年以两优培九（两系杂交籼稻）和扬粳4038（杂交粳稻）为材料种植于土培池,自抽穗（50%穗伸出剑叶叶鞘）至成熟设置3种灌溉方式处理：（1）常规灌溉（conventional irrigation,CI）,保持浅水层,收获前一周断水;（2）轻干-湿交替灌溉（alternate wetting and moderate soil drying,WMD）,自浅水层自然落干至土壤水势达-20 kPa时,灌水1—2 cm,再自然落干至土壤水势为-20 kPa,再上浅层水,如此循环;（3）重干-湿交替灌溉（alternate wettingand severe soil drying,WSD）,自浅水层自然落干至土壤水势达-40 kPa时,灌水1—2 cm,再自然落干至土壤水势为-40 kPa,再上浅层水,如此循环。观察花后干湿交替灌溉对水稻强、弱势粒灌浆速率、粒重和淀粉合成相关酶活性的影响,并应用实时荧光定量PCR技术测定编码这些酶基因的相对表达量。【结果】强势粒的平均灌浆速率、粒重、淀粉合成有关的蔗糖合酶（SuS）、腺苷二磷酸葡萄糖焦磷酸化酶（AGP）、淀粉合酶（StS）和淀粉分支酶（SBE）等相关酶活性以及蔗糖合酶基因SuS2、SuS4,腺苷二磷酸葡萄糖焦磷酸化酶基因AGPL1、AGPL2、AGPL3、AGPS2,淀粉合酶基因SSI、SSIIa、SSIIc、SSIIIa和淀粉分支酶基因SBEI、SBEIIb的相对表达量在3种灌溉方式处理间没有显著差异。与常规灌溉相比,轻干-湿交替灌溉处理显著增加了弱势粒的平均灌浆速?

英文摘要：

[Objective]Grain filling in rice is a physiological process of transportation and conversion of photosynthetic assimilates into starch which determines the percentage of filled grains, grain weight, and rice quality. The process of grain filling could not only be affected by genetic factors, but also be regulated by environmental conditions such as temperature and moisture. Irrigation is an important technique in rice production and plays a vital role in regulating the formation of grain yield. However, little work has been done in the effect of postanthesis irrigation patterns on the expressions of genes encoding starch biosynthesis in rice grains. This study aims to investigate the effect of post-anthesis alternate wetting and drying irrigation on grain filling of rice and to understand its molecular mechanism.[Method]Two cultivars Liangyoupeijiu （two-line indica hybrids） and Yangjing 4038 （japonica hybrids） were used and grown in the cement tanks that were filled with soil. Three irrigation regimes were imposed from heading （50% of the panicles were protrudent the flag leaf sheath） to maturity： （1） conventional irrigation （CI）, plots were kept a continuous shallow water layer until one week before harvest; （2） alternate wetting and moderate soil drying irrigation （WMD）, the field was not irrigated until the soil water potential reached the threshold at -20 kPa, and then was flooded with 1-2 cm water depth, and was repeated this process again; （3） alternate wetting and severe soil drying irrigation （WSD）, water in the plots was withheld until the soil water potential reached the threshold at -40 kPa, and then was flooded with 1-2 cm water depth, and this process was repeated again. The effect of irrigation regimes on grain filling rate, grain weight, activities of the enzymes involved in starch synthesis in superior and inferior spikelets, and expressions of the genes encoding these enzymes were determined using real-time quantitative PCR.[Result]The results showed that the