Abstract
The effect of fluorine(HF)added to the irrigation water at 0, 5, 10, 20, 30, 50 and 100 ppm under the soil culture on the growth of Oryza sativa L.(cv. Koshihikari)was investigated. The effects of leaf-emergence rate, plant length and number of stems per hill were not observed by 5-30 ppm concentrations of fluorine added to the irrigation water. The number of stems per hill and photosynthetic activity of the leaves were obviously decreased by 50 and 100 ppm concentradons of HF. The chlorophyll contents in the leaves were not affected even by a low concentration of fluorine. The number of ears and grains per hill were decreased by the concentrations of 50 and 100 ppm in the irrigation water. It was clarified that the dry weights of unhulled rice, leaves and stems were markedly decreased by the concernrations of 50 and 100 ppm HF added to the irrigation water.
