Effects of High Temperature and Drought Stress on Grain Filling Characteristics in Wheat during Grain Filling Period

Under pot conditions in the artificial weather room,two wheat cultivars with different gluten-strengths(Yumai 34,a strong-gluten cultivar,and Yumai 50,a weak-gluten cultivar) were used to investigate the effects of post-anthesis high temperature and drought stress on grain filling characteristics.The results indicated that high temperature stress decreased both grain filling rate and period,and caused early appearance of the maximal grain filling rate,thus reduced grain dry matter accumulation.However,the response of the two cultivars to high temperature at different grain filling stages were different: when suffered from high temperature in early and middle grain filling stage,the reduction in grain weight of Yumai 34 and Yumai 50 was relatively the greatest,respectively.While in the late grain filling stage,grain weight was less influenced by high temperature and drought in both wheat cultivars.The dry matter accumulation of the two cultivars was reduced by drought in early and middle grain filling stages.The reduction in grain weight in middle and early grain filling stage of Yumai 34 and Yumai 50 was relatively the greatest under drought stress,respectively.But grain weight was slightly increased in late grain filling stage under drought stress.The results also showed that significant interactions of high temperature and drought on grain filling characteristics existed in both wheat cultivars.The decrease of grain weight was mainly due to the suppression of grain filling rate during slow-increase stage,and duration of rapid-increase and slight-increase stage.