Effect Of Temperature On Yield And Cadmium Accumulation Of Early-season Rice At Different Growth Stage

Temperature has a serious impaction on growth and yield of rice. In this study, we conducted temperature-control assay on three rice growth stage, tillering stage, booting stage and filling stage, by using phytotron. After seven-day-long low (daily mean temperature 17.5?), middle (daily mean temperature 25?) and high temperature (daily mean temperature 32.5?) treated, the photosynthetic, growth speed, yield and Cd (cadmium) accumulation of rice plant was assessed, with the aim to get a better understanding of the rice response to harsh temperature stress. Our study can provide a scientific foundation for the establishment of meteorological index and grain production safety. The main results are as fellow:1. The experiment indicates high temperature has a significant impaction on yiled of early-season rice, booting stage is the most sensitive period for yield of early-season rice among these three stage. lowest yield appears at booting stage with the high temperature, 30.02%?42.46% less than low temperature treatment at the booting stage, and 25.62%?6.22% less than middle temperature treatment at the booting stage.2. Cd content of aboveground part (stem, leaf, panical) of earlier growing stage is higher than middle and later growing stage. The impaction of temperature on Cd content of aerial part appears high and middle temperature treatment> low temperature treatment, the impaction of temperature at maturity stage is relatively decreased compare to other three stage.3. Cd accumulation of gross aboveground part (stem, leaf, panical) of later growing stage is higher than earlier growing stage. Low temperature inhibit Cd accumulation of gross aboveground part from the treatment stage to maturity; Cd transfer from stem to leaf and panicle is increases initially and decreases afterwards under the high treatment at booting and filling stage.4. The rice Cd accumalation and content are differnent when treated with different temperature in different rice stage respectively. Cd content and accumulation of brown rice has no distinct difference among different temperature treatment at tillering stge; Cd content increased under high temperature and decreased under low temperature at booting and filling stage; Cd accumulation increased under high temperature at booting stage; temperature changes at filling stage has limited effects on Cd accumulation.5. The rice cultivars tested differentiated in Cd content and accumulation, but the differentiated appears under soil culture with a high Cd content, limited difference appears under soil culture with a low Cd content. A very significant difference among Cd content and accumulation of different rice cultivars (F=21.23**,32.42**) under the high Cd content soil cultivation; and there is no significant difference under the low Cd content soil cultivation (F=0.52,0.955).6. Different rice cultivar has the different response to temperature of Cd content and accumulation. Under soil culture with a high Cd content,1.26-2.53 times between the maximum and minimum of Cd content of V3 meanwhile 1.21?1.39 times for V5; 1.08?2.14 times between the maximum and minimum of Cd accumulation of V1 meanwhile 1.09?1.36 times for V5.