A water culture experiment was made to ascertain the relation between the effects of silica and nitrogen, silica and phosphorus, in the nutrition of rice plant. The result of the experiment can be summarized as follows; (A) In the case of nitrogen and silica. 1. Addition of silica in the culture solution produced great increase in the growth, in the production of grain and straw, in the silica content in the plant. 2. The above effects of silica were observed in all cases of various amount of nitrogen supply, ranging 4 to 70 mg per liter in the nutrient solution, and the greater the amount of nitrogen-supply, the larger were these effects of silica. 3. On the surface of grains grawn in silica-unsupplied plots, numerous brown spots (perhaps a kind of disease) were always observed, and these were greater especially when nitrogen-supply was large, while on the grain in silica-supplied plots the spots were scarcely observed. (B) In the case of phosphorus and silica. 1. The effects of silica described in 1 above were observed in all of cases of various amount of phosphorus-supply, ranging 0 to 50mg per liter, in the nutrient solution, but dislike the case of nitrogen, the increments of yield of grain and straw, decreased with phosphorus supply increased. 2. As to the brown spots, no effect of the amount of phosphorus-supply was observed, 3. In this experiment, it was ascertained that silica plaied the role of phosphorus, even in a very small degree, in the nutrition of rice plant.
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