Physiological and analytical studies on reaction to low temperature at seedling stage in rice (Oryza sativa L.)., 1; the physiological responses of rice seedling to low temperature, under different air and water temperature
1989
Oh, Y.B. (Rural Development Administration, Suwon (Korea R.). Crops Experiment Station) | Kim, Y.J. (Chonnam National Univ., Kwangju (Korea R.). Coll. of Agriculture)
To understand the physiological response of rice seedling to low temperature and to search an efficient parameter for cold tolerance, a series of experiments was conducted under the different air and water temperature combinations in phytotron of Crop Experiment Station during 1987-'88. The materials were two japonica cultivars, Odaebyeo and Kwanakbyeo, and two Tongil-type cultivars, Suwon 339 and Chilseongbyeo showing big difference in cold tolerance at seedling stage. Cold tolerance of rice at seedling stage was stronger in the order of Odatebyeo, Kwanakbyeo, Suwon 339, and Chilseongbyeo to the physiological responses such as degree of discoloration, dead leaf area, brown spot, relative water uptake and relative transpiration at cool condition compared with favorable temperature. The more susceptible variety to low temperature showed the less amounts of root, the lower root activity and relative water uptake. Also, the cold susceptible Tongil-type varieties exhibited earlier physical disorder than tolerant japonica ones by rapid loss of water content of shoot resulted from both fast decline of root function and continuous considerable transpiration from leaf surface under the low temperature since the former showed wider stomatal aperture than the latter. Accordingly, the cold susceptible variety decreased in chlorophyll content and relative photosynthetic rate in seedling leaves under the cold condition. The low temperature increased the amine, carbohydrates including total sugar and starch content in rice plants but decreased all amino acid content except histidine compared with the favorable condition. The cold tolerant variety increased the starch and carbohydrates and decreased glutamate dehydrogenase activity, while the susceptible one showed higher in amine content and decreased glycolate oxidase activity
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