Aims Improvement of end-use quality in wheat (Triticum aestivum) depends on thorough understanding of grain quality and effects of environment (E), genotype (G) and their interaction (G×E). Our objectives were to assess the relative effect of G, E and G×E on main quality traits of wheat grains.
Methods Two experiments were carried out in 2000-2002. In the first experiment, six wheat cultivars representing a wide range of gluten strength (strong-, medium-, and weak-gluten wheat) were planted at five sites with different latitudes (Tangyin 36° N, Wuzhi 35° N, Xuchang 34° N, Zhunadian 33° N, Xinyang 32° N) in Henan Province. In the second experiment, nine wheat cultivars released from nine different provinces were planted in eight provincial locations (Hubei 30º37＇N, Sichuan 30º39＇N, Jiangsu 32º23＇N, Shaanxi 34º18＇N, Henan 34º48＇N, Shandong 36º29＇N, Shanxi 37º26＇N, and Hebei 38º02＇N), representing a wider range of environments.
Important findings Significant genotypic differences in all the quality traits were observed in both experiments, indicating that cultivar selection was most important for desirable end-use quality. Significant environmental variations were observed in all the quality traits in experiment 2, but only in content of protein and gluten, sedimentation value and water absorption in experiment 1, which indicated that location was the second important factor determining wheat quality. From the magnitude of F values we concluded that, for quality traits such as grain hardness, sedimentation value, water absorption, stable period, maximum resistance and extension, genotypic effects were greater than environment effects, while environmental influence on protein content was much greater than that of genotypes in both experiments. But for other quality traits such as flour yield, forming time, mixing tolerance and softness, they were inconsistent in the two experiments. In the first experiment, no genotype-by-environment variations were observed. In the second experiment, though significant influences of genotype-by-environment were observed for grain hardness, ash, water absorption, forming time, stable period and maximum resistance, they were smaller than the main effect of either G or E. Significant differences existed in most quality traits between the two years, mainly caused by weather factors such as precipitation, hours of sunshine and average day temperature in May. Close correlation existed between weather factors and quality traits, indicating that excessive precipitation, fewer hours of sunshine and lower day temperature in May would negative affect grain quality for strong-gluten wheat cultivars.