| Under pot-cultivated conditions at an experimental farm of Henan agricultural university, during 2007-2009, and investicated the effects of post-anthesis high temperature stress (HTS) on grain yield and quality.During 2007-2008,15 wheat cultivars were chosen to investigate the effects of optime HTS on grain weight,grain yield and protein content.The HTS was carried out in walk-in chambers, in which temperature was controled around 38℃and wheat in pots was treated for 2 days (5 hours each day) at early grain filling and late grain filling stages;During 2008-2009,3 gluten wheat cultivars which wheat vatiety showed more resistant to HTS were chosen as test materials ,under optime temperature(38℃,2-4 days) and different day/night temperature regimes (35℃/25℃,25℃/15℃) to investigate the effects of post-anthesis HTS and drought stress (DS) and their interactions on grain yield and quality.The main results were as follows:1. The effects of post-anthesis high temperature stress on different wheat genotypes were different .The results indicated that HTS of different grain filling stages resulted in decrease of 1000-grain weight of the 15 wheat cultivars from 4.46% to 34. 78% and from 8.66% to 32.47%, respectively. And decrease of grain yield from 6.69% to 34.92% and from 13.04% to 37.86%, respectively. But the protein content in grains of 15 wheat cultivars increased from 1.03% to 8.72% and from 2.44% to 16.35%, respectively.The result suggested that a significant difference of sensitivity to HTS existed among different wheat cultivars. According to the cluster analysis based on decrease of grain weight and yield, 15 wheat varieties were divided into five categories. Luohan 6, indicating the effefts of HTS was the largest among all the cultivars, was in the first group. Yanzhan 4110, luohan 2 and Zhengmai 366 were in the fifth group, which showed more resistant to HTS. Based on increase of grain protein content, effeft of HTS on Yumai 50 was the smallest among all the cultivars, whereas Yunong 949 and Yunong 202 showed more sensitive to HTS. 2.The results indicated that post-anthesis high temperature increased total protein content,but decreased protein yield.The influence of HTS on protein content aggravation follow their stress deepend. Under different temperature regime,the protein and its components of three gluten wheat cultivars in 35℃/25℃were higher than in 25℃/15℃. Drought stress increased protein content,too.The results also showed that there was a significant interaction of high temperature and drought stress on protein quality with different gluten wheat cultivars.3.The results indicated that post-anthesis HTS reduced total starch and amylopectin content. Drought stress reduced total starch, amylase, amylopectin content and ratio of content of amylase to amylopectin.There had a significant interaction of high temperature and drought stress on amylopectin and ratio of content of amylase to amylopectin.The results also showed that total starch content of weak gluten Yumai50 and middle gluten Luohan2 reached significant differences under high temperature and drought stress. Under different day and night temperature regime,the total starch and amylopectin content of three wheat cultivars were higher in 25℃/15℃.4.Studies on effects of high temperature and drought stress and their interactions on flour color,15DAA HTS increased L* of weak gluten Yumai50,but decreased the others,but there had not a significant difference among treatments (middle gluten Luohan2 during 15-19 was except).Under different day and night temperature mode, L*of three wheat cultivars were higher in 25/15 mode,however,a*, b*and swelling power were higher in 35/25 mode.The results also showed significant interactions of high temperature and drought stress on a*and b* of weak gluten Yumai50 and middle gluten Luohan2..
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