花后干旱和渍水下氮素供应对小麦籽粒蛋白质和淀粉积聚关键调控酶活性的影响

 防雨池栽条件下，设置渍水、干旱和对照3个水分处理，每个水分处理下再设置2个施氮水平，研究了花后渍水和干旱逆境下氮素对两个籽粒蛋白质含量不同的小麦（Triticum aestivum L.）品种籽粒蛋白质和淀粉积聚关键调控酶活性的影响。研究结果表明，与对照相比，花后干旱和渍水均降低旗叶谷氨酰胺合成酶（GS）和谷丙转氨酶（GPT）活性，但水分逆境下增施氮肥可以提高旗叶磷酸蔗糖合成酶（SPS）、GS和GPT活性。灌浆期籽粒-蔗糖合成酶（SS）、可溶性淀粉合成酶（SSS）、结合态淀粉合成酶（GBSS）、GS和GPT活性均呈下降趋势，水分逆境下小麦籽粒SS和GS活性降低，干旱提高GPT活性，而渍水使其降低。土壤水分适宜或亏缺条件下增施氮肥可以提高籽粒SS活性，而渍水下增施氮肥降低SS活性。干旱和渍水下增施氮肥可以提高籽粒SSS、GBSS、GS和GPT活性。干旱处理提高直链淀粉积累速率和蛋白质含量，而渍水使其降低。土壤干旱和渍水下增施氮肥降低直链淀粉和支链淀粉积累速率，提高了蛋白质含量，且适宜水分或亏缺条件下增施氮肥可以提高蛋白质积累量，而渍水下增施氮肥不利于蛋白质积累。

Effects of Nitrogen Rates on Activities of Key Regulatory Enzymes for Grain Starch and Protein Accumulation in Wheat Grown Under Drought and Waterlogging from Anthesis to Maturity

Effects of nitrogen rates on activities of key regulatory enzymes for grain starch and protein accumulation in two wheat varieties (Triticum aestivum L.) under drought and waterlogging from anthesis to maturity were studied in a cement pool culture experiment. Total three water treatments were established from anthesis to maturity, i.e. waterlogging, drought and moderate water supply (CK). Under each water treatment, two nitrogen levels of 120 and 240 kg·ha-1 were implemented. Both drought and waterlogging significantly reduced glutamine synthetase (GS) and glutamate pyruvic aminotransferase (GPT) activities in flag leaf, compared with CK. Nitrogen increased sucrose phosphate synthase (SPS), GS and GPT activities in flag leaf under drought and waterlogging. Sucrose synthase (SS), soluble starch synthase (SSS), granule-bounded starch synthase (GBSS), GS and GPT activities in grains decreased with the progress of grain filling. Drought and waterlogging reduced SS and GS activities while drought increased GPT activity in grain, and waterlogging reduced GPT activity. Nitrogen increased SS activity in grain under CK and drought, while reduced it under waterlogging. Nitrogen increased SSS, GBSS, GS and GPT activities under both drought and waterlogging. Drought increased amylose accumulating rate and protein content while waterlogging reduced them. Under drought and waterlogging nitrogen reduced amylose and amylopectin accumulating rate, while increased protein content in grain. Nitrogen increased protein accumulation under CK and drought while reduced protein accumulation under waterlogging.