Effects Of Temperature And Light On Grain Yield And Quality Formation In Rice And Their Mechanisms

Effects of temperature and light on grain yield and quality formation, characteristic of grain filling and activity of Q-enzyme in rice were studied by the experiments of the artificial climate chamber, shading treatments and different sowing dates during the grain filling period with using Xieyou 9308(indica hybrids) and xiushui 110(mid-maturity Japonica) as materials. Based on these, change rules of the comprehensive qualities with changing of temperature and sunshine conditions in rice were expatiated. The results showed as follows:1. Grain yield decreased significantly under the treatments of high temperature and shading during the grain filling period and the effects on grain yield and its components during the grain filling period were greater than those during different periods. The effect of high temperature on grain yield of xieyou 9308 during the 0-15d after flowering was greater than that of xiushui 110. The effect of high temperature on grain yield of two varieties under high temperature during the 16-30d after flowering appeared in opposite direction. Grain yield of Xiushui 110 is greatly affected by shading treatments.2. The effects of high temperature on setting rate and filled grain number per panicle during the 0-15d after flowering were greater than those during the 16-30d after flowering. Differences in the seed setting percentage of grains in different parts of the panicle were analyzed. The result showed that the effects of high temperature on setting rate of seed at middle and lower parts were higher than those at upper part. Therefore, favorable temperature condition is helpful to improve setting rate and filled grain number per panicle and decrease the empty and unfilled grain rate.Setting rate was decreased significantly with the increment of shading degree, and its effect on seed at middle and lower parts of the panicle was higher than those at upper part. The effect of shading treatment on setting rate was smaller than that of temperature treatment in different time sections. Setting rate was not changed significantly as long asthe light intensity was not too low and short duration of low light intensity.3. Under the conditions of high temperature and low light, head milled rice rate and gel consistency of grain quality trait and breakdown decreased, chalkiness rate and chalkiness degree increased, rice comprehensive qualities became worse, and the effects of temperature treatments on qualities were greater than shading treatment. Among them, chalkiness rate and chalkiness degree were most sensitive. Under different sowing dates conditions, the mean daily temperature decreased with the sowing dates lated, the head milled rice rate was significantly negative correlated to the day mean temperature, chalkiness degree was significantly positive correlated to the day mean temperature, alkali value was negative correlated to the day mean temperature, and rice comprehensive qualities were higher. Rice qualities had no significant correlation with hours of sunshine.Under the conditions of high temperature during the 0-15d after flowering, breakdown, cool viscosity, setback and consistence decreased. There were differences in peak viscosity and hot viscosity between two cultivars. Under the conditions of the shading, setback increased gradually with the increment of shading degree, and other characters were decreased gradually. Therefore, favorable temperature condition is helpful to improve eating quality in some degree.4. High temperature can accelerate the grain-filling rate of rice in terms of grain-filling characteristics respectively, and the grain-filling duration was shorter; grain-filling characteristics were reversed under low light condition. The grain weight-increasing process changed smoothly under natural light intensity condition. Sowing date of rice had effects not only on the grain filling parameters, but also on the contributions of filling matter in different time sections. Generally, the middle contributions were high and the late contributions were low relatively.5. Q-Enzyme ac...