Abstract
This study was undertaken to evaluate the effect of short period high water temperature (35°C) on the growth response of immature leaves in rice plants. The test plants was exposed to high water temperature during one phyllochron, from the time of emergence of a given leaf of the main stem to the time of emergence of the adjacent younger leaf. Control plants were kept continuously at 30°C water temperature. High water temperature at the time of emergence of the (n)th leaf ("n" indicates an optional ordinal number of leaves counted acropetally from the incomplete leaf in the main stem) decreased the blade width of (n+1)th to (n+3)th leaves, the blade length of (n+1)th to (n+3)th leaves, and the sheath length of (n)th to (n+1)th leaves, respectively. The restraint effect of high water temperature was most remarkable against the blade width of (n+2)th leaf, the blade length of (n+1)th leaf, and the sheath length of (n)th leaf. High water temperature also decreased the total leaf length(blade and sheath) of (n)th to (n+3)th leaves and the blade area of (n+1)th to (n+3)th leaves. The restraint ratio in each leaf length against the control plot was significantly lower (under 15.6% level) than in each blade area (31.6∼34.3% level). These notable blade restraints caused by high water temperature may impose a serious influence for the growth ability in rice plants.
