灌浆期高温和水分逆境对冬小麦籽粒蛋白质和淀粉含量的影响

Effects of high temperature and water stress during grain filling on grain protein and starch formation in winter wheat

灌浆期高温和水分逆境是影响小麦籽粒产量和品质的关键气候因子。以扬麦9号、徐州26和豫麦34三个小麦品种为材料,利用人工气候室模拟灌浆期高温和水分胁迫环境,研究了花后高温及温度和水分互作对小麦籽粒蛋白质和淀粉形成的影响。结果表明,高温显著提高了小麦籽粒蛋白质含量及清蛋白、球蛋白和醇溶蛋白含量,但降低了谷蛋白含量,导致麦谷蛋白/醇溶蛋白比值降低。高温显著降低了籽粒总淀粉和支链淀粉含量及支/直比。籽粒蛋白质和淀粉及其组分形成所需的适宜昼夜温差随小麦品质类型而异,但温度水平对籽粒蛋白质和淀粉的影响较温差大。在高温和水分逆境下,温度对籽粒蛋白质和淀粉含量的影响较水分逆境大,且存在显著的互作效应。小麦籽粒蛋白质含量均表现为干旱>对照>渍水,以高温干旱最高,适温渍水最低;淀粉含量为对照>干旱>渍水,以适温对照最高,而高温渍水最低。高温和水分逆境显著提高了籽粒醇溶蛋白含量而降低了谷蛋白含量及支链淀粉含量,使蛋白质谷/醇比和淀粉支/直比降低,以高温渍水对籽粒蛋白质和淀粉组分的影响最为显著。不同品种之间,高蛋白小麦籽粒蛋白质和组分的形成受高温和水分逆境的影响更大,而低蛋白品种籽粒淀粉形成显著受温度和水分逆境的调节。分析表明,在高温和水分逆境下籽粒蛋白质含量与清蛋白和醇溶蛋白显著正相关,籽粒淀粉含量与谷蛋白、支链淀粉含量及支/直比显著正相关。

High temperature and water stress occur simultaneously during grain filling in the primary wheat production regions of Huanghuaihai and the lower reaches of the Yangtze River. These stresses significantly reduce wheat grain yield and quality. This research was conducted to determine the effects of high temperature, drought and waterlogging on protein and starch formation in different wheat cultivars. The results will help elucidate regulatory mechanisms of temperature and water stresses and lead to improved cultivation strategies for wheat production. Two experiments were conducted in growth chambers in 2002 ～ 2003 and 2004 ～ 2005. In the first experiment, two wheat cultivars （Yangmai 9 and Xuzhou 26 with low and high grain protein content, respectively） were planted under four day/night temperature regimes （34/22, 32/24, 26/14 and 24/16℃） from 7 days after anthesis until maturity. These treatments resulted in two average daily temperatures of 28 and 20℃, and two diurnal temperature difference treatments of 12 and 8℃ . In the second experiment, two wheat cultivars （Yangmai 9 and Yumai 34 with low and high grain protein content, respectively） were subjected to two day/night temperature regimes （32/24 and 24/16℃ ） and three soil water treatments ： （ 1 ） moderate water status [ soil relative water content （SRWC） of 75 % ～ 80 % ], （2） drought （ SRWC = 45 % ～ 50 % ）, and （3） waterlogged conditions （ 1 cm water layer above the soil surface）. Results indicated that grain crude protein, albumin, globulin, and gliadin were significantly increased by high temperature but glutenin content was reduced. This reduced the glutenin：gliadin ratio, desirable for low protein wheat but undesirable for high protein grain wheat. Total starch, amylose, and amylopectin were reduced by high temperature. Amylopectin was reduced more than amylose, resulting in a reduced amylopeetin： amylose ratio, In addition, the optimum diurnal temperature difference favoring the formation of grain protein and starch differed with wheat genotypes, but the effects of temperature extremes were more important than temperature fluctuations, The second experiment showed that grain protein and starch content were affected more by high temperature than water stress. The interaction of these two stresses also was important. Under high temperature or optimum temperature, grain protein content was highest under drought and lowest with waterlogging. Grain starch content was highest with no stress （ the control）, followed by drought and waterlogging, Grain gliadin was increased under high temperature and water stress, while glutenin and amylopectin were reduced, resulting in decreased ratios of glutenin：gliadin and amylopectin：amylose. High temperature combined with waterlogging reduced starch components more than individual stresses; since photosynthesis was inhibited and plant senescence was accelerated leading to reduced carbohydrate synthesis and allocation to grain. This also increased the relative protein content （as a percentage of total grain weight）. For Yumai 34, reductions in grain protein formation due to high temperature and water stresses were greater than for starch, but in Yangmai 9, starch formation was more sensitive to high temperature and water stresses. Correlation analysis revealed that protein content was positively correlated to albumin and gliadin content, but slightly negatively correlated to glutenin content. Starch content was positively correlated with glutenin and amylopectin content and the amylopectin： amylose ratio under high temperature and water stresses, The results indicate that optimum temperature with moderate drought is beneficial for high protein wheat to enhance both grain yield and quality, whereas optimum temperature and water conditions were most favorable for low protein wheat.