Effect Of Post-Anthesis Heat Stress On Grain Quality In Wheat (Triticum Aestivum L.)

Wheat grain quality is largely depended on environmental conditions. Temperature is a major climatic factor for grain filling in wheat. With the intensifying of climate change, the post-anthesis high temperature has greatly affected the formation of grain quality in wheat. To investigate the impacts of post-anthesis heat stress on the dynamic accumulation of grain protein/starch and protein/starch composition in wheat, two-year experiments were carried out in phytotron with two different varieties, Yangmai 16 (YM16, heat sensitive) and Xumai 30 (XM30, heat tolerant) under different high temperature levels and high temperature durations during anthesis and grain filling stages. The results showed that:1. The contents of grain protein and its components increased significantly with the rising temperature levels and durations. The contents of albumin in YM16 was more sensitive to high temperature stress than XM30, while the contents of gliadin, gluten and the ratio of gliadin to gluten (Gli/Glu) in YM16 were less sensitive than XM30. The similar sensitivities were observed in the contents of globulin and total protein in two varieties under different temperature levels after anthesis. In addition, the contents of albumin, globulin and gliadin in the two varieties were all sensitive to temperature levels and temperature durations. However the contents of glutelin and total protein were only sensitive to temperature levels under the different temperature treatments during anthesis.During grain-filling stage, the contents of albumin and glutelin in YM16 were both more sensitive than that in XM30, while the contents of globulin was less sensitive than XM30 under the different temperature levels. In addition, the contents of gliadin and total protein of two varieties had similar sensitive trend for temperatures. The contents of albumin and total protein in two varieties were all sensitive to temperature levels and temperature durations, while the contents of globulin, gliadin and glutelin in two varieties were only sensitive to temperature levels under different temperature treatments at grain-filling stage.In general, the effects of heat stress on the contents of Gli/Glu, albumin, gliadin and glutelin at anthesis stage were more obvious than those at grain filling stage, but the effects of heat stress on the contents of globulin and total protein at anthesis stage were the same as those at grain filling stage.2. The contents of amylose and the ratio of amylose to amylopectin (Am/Ap) also increased significantly with the rising temperature levels and durations under different high temperature treatments at anthesis. However, the grain starch and amylopectin contents decreased significantly with the increasing of temperature levels and durations. The grain starch and amylopectin contents in YM16 were more sensitive than those in XM30, while the Am/Ap and amylose content in YM16 were less sensitive than those in XM30 under the different temperature levels at anthesis. The contents of grain starch and its components in two varieties were all sensitive to temperature levels and temperature durations under the different temperature treatments during anthesis.During grain filling stage, the contents of grain starch and its components in two varieties had the same sensitive trend under different high temperature levels. Moreover, the contents of amylose and total starch of two varieties were both sensitive to temperature levels and temperature durations. However, the Am/Ap and amylopectin in two varieties were only sensitive to temperature levels under different high temperature treatments.Overall, grain starch and its components contents were more sensitive to heat stress at anthesis stage than those at grain filling stage.