Evaluation of grain quality of winter wheat and its response to meteorological factors

Using field staging test method and the main winter wheat varieties as test materials, which are predominantly cultivated in the north and south wheat areas; variance analysis and principal component analysis methods to evaluate grain traits; and linear correlation, quadratic curve correlation, and stepwise regression to identify significant meteorological factors; a winter wheat quality prediction model was constructed in the form of meteorological factor-quality response curve to explore variations in the qualities of different wheat varieties in different areas and the meteorological factors that cause these variations. The varieties used in the experiment were 'Tanmai 98' and 'Shannong 18' planted in the northern wheat areas of Gucheng of Hebei Province and Tai'an of Shandong Province, respectively; and 'Xumai 33', 'Wanmai 52', and 'Zhengmai 9023' planted in the southern wheat areas of Xuzhou of Jiangsu Province, Suzhuo of Anhui Province, and Jingzhou of Hubei Province, respectively. Five wheat varieties were planted at different times (10 days in advance, suitable time, 10 days later, and 20 days later). The results showed that the tested wheat varieties were all medium protein varieties. Among the main quality traits, starch had the highest content and minimum variation, followed by protein regarding the content with medium variation, and fat with the lowest content but the maximum variation. The differences in protein and fat in the different areas was significant. The quality and its' stability of winter wheat were higher for winter sowing in the northern area and their quality traits were excellent. Each nutritional component was generally higher and stable in the north than in the south. The amino acid quality of the protein component was explained by three principal components. The content of the non-essential amino acid, glutamic acid, was the highest, whereas that of the essential amino acid, methionine, was the lowest; the amino acid quality of wheat was better in the northern than in the southern areas. The daily temperature difference in the northern area was more conducive to increasing the amino acid content. The fatty acids of the fat component were explained by four principal components. The content of the unsaturated fatty acid, linoleic acid, was the highest and that of the saturated fatty acid, pentadecene monoenoic acid, was the lowest. Temperature and humidity were the main meteorological factors affecting the grain quality of winter wheat. The protein or amino acid quality could be improved by adjusting the daily range of temperature in the flowering-mature period and reducing soil moisture; the fat or fatty acid quality could be improved by adjusting soil moisture and the minimum temperature in the flowering-mature period.