Differences In Canopy Temperature Depression Among Different Early-season Indica Rice Varieties And Its Relationship With Yield And Physiological Characteristics

The experiment was carried out in Jiangxi Agricultural University Science Park in 2013-2014. 36 different rice varieties were chosen to study canopy temperature, ear temperature, and their relationships with yield at different growth stages in 2013. In 2014, by analyzing rice quality, photosynthetic characteristics, group characteristics, leaf anatomical characters and related stress resistance of three low-temperature type and three high-temperature rice varieties selected from the 36 rice varieties, we investigated reasons of differences in CTD among different Early Hsien Rice varieties and then provide a theoretical basis for the strong stress resistance rice variety selection.(1) Under irrigation, rice canopy temperature was always lower than the temperature, the day CTD of different genotypes rice was associated with temperature difference between gas and spike at heading; the day CTD and night CTD at heading and milk stage were also closely related.(2) Lower day canopy temperature at booting and heading and lower ear temperature at heading were beneficial to increase production. On the premise of not high night temperature, the higher night canopy temperature at booting and heading stage were conducive to the accumulation of production. The relation between yield factors and canopy temperature was more complex, there was no clear link in the absence of high temperature stress.(3) According to cluster analysis on CTD of tested varieties at three growth stages, medium and low-temperature type rice varieties.(4) On the whole, CTD of low-temperature rice at booting and heading stage were greater than the high-temperature rice, yield of low- temperature type early rice was greater than the high-temperature type varieties. Milling quality of low-temperature type varieties was better than that of high- temperature type varieties; the greater CTD, the higher brown rice rate and milled rice rate.(5) Net photosynthetic rate, stomatal conductance, transpiration rate, intercellular CO2 concentration and chlorophyll content of low-temperature rice varieties were to varying extent superior to the high-temperature varieties at heading.(6) Canopy light transmittance rate and leaf area index of low-temperature rice were better than high- temperature varieties, plant type indices of two types had no significant differences, low-temperature varieties had relatively better group characteristics.(7) The characteristics of flag stomata and vascular bundle of low-temperature varieties were better than that of high- temperature varieties, which closely contact with the leaf photosynthesis and transpiration, had strong correlations with the CTD.(8) The stress resistance of low-temperature varieties at booting and heading stage were better than that of high- temperature varieties in general, conducive to form higher physiological activity and anti-aging.