灌浆期温度对两种类型小麦籽粒蛋白质组分及植株氨基酸含量的影响

以扬麦9号和徐州26两个蛋白质含量不同的小麦品种为材料，利用人工气候室模拟灌浆期高温环境，研究了高温对小麦籽粒蛋白质组分和植株游离氨基酸含量的影响。结果表明，高温处理显著提高了小麦籽粒蛋白质及清蛋白、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。与适温处理相比，高温提高了地上部营养器官中游离氨基酸含量，显著降低了灌浆后期籽粒游离氨基酸含量。表明高温下提高的营养器官游离氨基酸含量及籽粒对氨基酸的快速利用是籽粒蛋白质含量增加的生理原因。此外，发现籽粒中蛋白质及其组分形成所需的适宜昼夜温差随不同小麦品质类型而异。

Effects of Temperature during Grain Filling on the Contents of Grain Protein Components and Free Amino Acid in Two Different Wheat Cultivars

High temperature during grain filling is a key climatic factor affecting wheat grain quality in Huanghuaihai and lower reaches of the Yangtze River in China. High temperature during grain filling decreases the duration of grain filling and increases protein content in wheat, but its physiological mechanism is unclear. The experiments were carried out in growth chamber to investigate the effects of high temperature and day/night temperature difference during grain filling on protein components formation and free amino acid content. Two wheat cultivars including Yangmai9 with low grain protein content and Xuzhou 26 with high grain protein content were treated under different temperature conditions during grain filling. Four day/night temperature regimes of 34℃/22℃, 32℃/24℃, 26℃/14℃ and 24℃/16℃ from 7 days after anthesis until maturity were used to obtain two daily average temperatures of 28℃ and 20℃, and two day/night temperature difference treatments of 12℃ and 8℃. The results showed that contents of crude protein, albumin, globulin and gliadin in grains were significantly increased, but gluten content was decreased by high temperature (Fig.1, 2, 3). When the day temperature was 34℃, protein content of Yangmai9 was decreased, but that of Xuzhou26 was increased. Consequently, the ratio of glutenin to gliadin was decreased by high temperature. Compared with optimal temperature treatments, free amino acid content was also increased in vegetative organs during early period of grain filling but significantly reduced in grains by high temperature during later period of grain filling (Fig.4, 5, 6), which indicated that increment of grain protein content under high temperature was associated with increasing free amino acid content in vegetative organs, and accelerating utilization of amino acids in grain. In addition, the optimal temperature difference of day and night favoring the formations of grain protein and protein components differed with wheat genotypes.