Abstract
The effect of fluorine (HF) added to the culture solution on the growth of Oryza sativa L.cv.Koshihikari was investigated. HF was added to the culture solution at 50 ppm for 10 days at the active-tillering and panicle formation stages. The number of stems per hill was decreased by fluorine added, either at the tillering or panicle formation stages, especially by the fluorine treatments at the panicle formation stage. The dry weights of unhulled rice, leaves, leaf sheath (culm included), and roots were markedly decreased by the fluorine treatment. The number of ears per hill and the grains per hill were also decreased by fluorine. Thus, the dry weight of all organs, the number of ears per hill, and the number of grains per hill were decreased by the fluorine treatment at the panicle formation stage more severely than that at the active-tillering stage. A significant correlation was recognized between the number of ears per hill, the number of grains per hill and weight of unhulled rice. It was found that the effect of fluorine on the growth and yield of rice plants when given at the vegetative stage were different from that given at the reproductive stage.