Yunnan Rice Chilling Injury Index Research Author(Subject) Directed By Wuyongbin

This paper was supported by the project named Research on Early Warning and Prevention Technology of Emergent Major Natural Disaster(Project No. 2012BAD20B00). Two kinds of rice(indica and japonica) were selected in the experiment of this study. Pot experiment was carried out at 4 different altitudes in Yunnan Province. 4 automatic weather stations were established to conduct parallel observation which mainly focused on physiological observation in main rice growth and development stages and rice growth dynamic observation, and to collect observation data related to rice growth, physiology, and production in order to conduct a comprehensive analysis on rice chilling damage index. To sum up the main contents of this paper is: in our rice pot experiment, based on physiological habits, growth simulation models and different weather conditions in different growth stages, analyze the effect of altitude variation on photosynthesis of rice and rice growth, study transportation impact on rice growth, rice physiology, and rice yield with altitude gradient changes. Combined with meteorological observation data, clarify the occurrence conditions of hazardous factors and its relevant index, and study rice chilling damage index.Analysis results illustrated that japonica rice was more easily affected by low temperature, which reduces the dry culm weight, leaf dry weight, leaf areas, effective panicles, and effective seeds. For the indica, the main weather factor was low temperature, however, considering the relevance between temperature and yield component factors, the effect to japonica is more significant than indica. For indica, the critical altitude is between 1500 m to 1800 m which could determine whether indica rice growth was affected significantly. For japonica rice, the critical altitude is between 1800 m to 2100 m which could determine whether japonica rice growth was affected significantly. As the altitude increases, the maximum net photosynthesis rate of rice leaf and the photosynthetic capacity goes down, and the apparent quantum efficiency is reduced as well. Still the light saturation point and CO2 saturation point increases gradually, but on the contrary, the light compensation point and CO2 compensation point decreases. Carboxylation rate is relatively low at low altitude. The same cultivar in different growth stages and different altitudes indicates different photosynthetic characteristics. And in the short term there were significant differences in photosynthetic characteristics caused by transportation. From lower altitude to higher altitude, the adverse effect for japonica is more significant than indica. Definition of Yunnan indica rice in jointing stage effects of chilling damage index was 19.6℃,chilling damage index,blossom and bear fruit period is 20.5℃,chilling damage index milk ripe stage was 19.1℃;definition of Yunnan japonica rice in jointing stage effects of chilling damage index was 17.2℃,chilling damage index,blossom and bear fruit period is 18.1℃,chilling damage index of milk maturity is 16.7℃.