灌水量对小麦籽粒粉含量和相关酶活性及水分利用效率的影响

在2004-2005年和2005-2006年小麦生长季，设置不同的灌水时期和灌水量处理，研究了小麦籽粒产量、籽粒淀粉含量、淀粉合成相关酶活性和水分利用效率。结果表明，全生育期不灌水条件下，籽粒中的可溶性淀粉合酶(SSS)和淀粉粒结合态淀粉合酶(GBSS)活性在灌浆初期显著升高，在灌浆中后期显著降低，同时灌浆后期支链淀粉、直链淀粉和总淀粉含量亦显著降低。拔节期和开花期每次灌水60 mm有利于小麦在灌浆中后期保持较高的SSS和GBSS活性，提高灌浆后期籽粒中的支链淀粉、直链淀粉和总淀粉含量；灌水量进一步增加时，灌浆中后期的SSS活性显著降低，GBSS活性升高，灌浆后期的支链淀粉含量降低，直链淀粉含量升高。在两个生长季中拔节期和开花期每次灌水60 mm处理的土壤贮水消耗量较高，水分利用效率最高和籽粒产量较高。在此基础上增加灌水量时，开花至成熟阶段0~60 cm土层的土壤含水量显著升高，土壤贮水消耗量降低，籽粒产量无显著变化，水分利用效率和灌溉水利用效率降低。

Effects of Irrigation Amount on Grain Starch Content, Starch Synthase Activity, and Water Use Efficiency in Wheat

Water deficiency is one of the main factors limiting wheat (Triticum aestivum L.) production. Grain starch, which comprises 65–70% of the dry weight in grains, is influenced by some eco-environmental factors, such as temperature and water content in soils. To study the effects of irrigation stage and amount on grain yield and water use efficiency (WUE), field experiments were carried out in Tai’an and Yanzhou, Shandong Province in 2004–2006 growing seasons with a high-yielding wheat cultivar Jimai 20. The water contents of soil layers within 0–140 cm (2004–2005) or 0–200 cm (2005–2006) were monitored under different irrigation regimes. The treatments of irrigation were at jointing and anthesis stages (W1), and at jointing, anthesis and grain filling stages (W2) with 60 mm water each time in 2004–2005 growing season as well as at jointing and anthesis stages in 2005–2006 growing season with 30 mm (deficient irrigation), 60 mm (moderate irrigation), or 90 mm (luxury irrigation) water per irrigation. No irrigation was taken as the control. The grain starch content and the relative enzyme activity were measured at every 7 d interval after anthesis.The soluble starch synthase (SSS) activity and granule bound starch synthase (GBSS) activity significantly increased at early filling stage and reduced from middle to late filling stage, and the contents of amylopectin, amylose, and starch significantly reduced at late filling stage in the control. Moderate irrigation at jointing and anthesis with 60 mm water each time was in favor of keeping high activities of SSS and GBSS from middle to late grain filling stages. The moderate irrigation had higher levels on the contents of amylopectin, amylose, and starch at late filling stage than the control. However over irrigation significantly reduced the SSS activity and significantly increased the GBSS activity at middle and late filling stages, while over irrigation significantly reduced the amylopectin content and significantly increased the amylose content at late filling stage. Moderate irrigation at jointing and anthesis with 60 mm water each time obtained the highest WUE in the both growing seasons. Over irrigation significantly increased the soil moisture content in 0–60 cm soil layers, significantly reduced the soil water consumption amount, WUE and irrigation water use efficiency, and not significantly increased grain yield.