| Based on the temperature controlled by artificial climate chamber , Wuyujing 3 (Japonica) and Yangdao 6 (Indica) were used in this study . and four treatments wee conducted : higher temperature in whole grain-filling stage (GFS); higher temperature in early GFS and optimum temperature in the later GFS; optimum temperature in early GFS and higher temperature in the later GFS; D, optimum temperature in whole GFS (CK). The results illustrated that effects of high temperature in grain filling stage on carbohydrate contents of plant stems, leaves and granules and yield , quality and mineral element absorption . The results showed:1. Starch degradation of the stems and leaves increased under high temperature in grain filling stage , which lowered starch content and increased soluble carbohydrate content. At the same time soluble protein content of flag leaves , total and remain nitrogen content of stem and leaves were all failed .2. Effects of high temperature in early grain filling stage on the decreasing soluble carbohydrate content of endosperm were consistent with the later . Reactions of starch and amylose content to high temperature were different among cultivars , eg. Starch and AC of Wuyujing 3 performed from high to low change under GFS and higher temperature in early stage and optimum temperature in later stage ,compared to CK , lowered starch and amylose content under high temperature in later stage . But Yangdao6 performed lower starch and amylose content under high temperature than optimum temperature.3. Soluble protein , insoluble protein and coarse protein contents of endosperm under high temperature in grain filling stage were clearly higher than optimum temperature.4. Effects of high temperature on rice industrial conditions were significant , which lowered the grain filling rate , accelerated the grain filling and shortened the filling time . Simultaneously , the over consumed of photosynthesis matter , which reduced the final dry matter and lowered the grain weight.5. High temperature improved the grain filling rate , reduced the time of dry matter accumulation, lowered dry matter accumulation , and decreased rice milling quality . Among effects of high temperature on milling quality indices , brown rice rate was the smallest, milled rice rate was middle and head rice rate was the biggest. Effects of high temperature in filling stage on AC were clearly different among cultivars , the AC value of Yangdao6 increased, while that of Wuyujing3 decreased. High temperature in grain filling stage improved rice nutrient level, and coarse protein content of head rice and its albumin ,globulin , prolamin and glutelin content were all increased differently . However , effects of high temperature on the lowered free amino acid content of head rice may due to it accelerated the synthesization of amino acid to protein .6. High temperature in grain filling stage accelerated the absorption of Mg , K , especially for K , accordingly , reduced the values of Mg/ K and Mg / (N·AC·K) ,which had positive effects on rice eating quality . Effects of temperature within 20 days after heading were the key stage on Mg , K content of starch .7. Under high temperature in grain filling stage , both cultivars performed higher RVA Gelatinization temperature, Final viscosity, Consistency and Setback, lower Peak viscosity, Hot viscosity, and Breakdown , which resulted in lower rice eating quality .8. Effects of the high temperature on carbohydrate metabolism of different organs and dynamic changes of grain filling were through influencing the expressions of rice yield and qualities . 20 days after heading were the key stage of grain filling , which were also the important formation stage of yield and qualities. During this stage , there were great differences among yield and qualities of different cultivars . Effects of high temperature in early stage ( within 20 days after heading ) were far higher than in later stage , so temperature controlling in early stage was the main measure in production.9. Reactions among ge... |
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