Abstract
An extraordinary amount of ammonium sulphate (7.56 kg. per are) was top-dressed under the field condition to the rice plant, which had been grown without nitrogenous fertilizer, at intervals of 5 days at successive growth stages during 3 seasons frorn 1957 to 1959. 1. The effects of the treatment on the yield, yield-components, morphological characters and so forth have been clarified and a part of the results is given in Fig. 1, as a result the top-dressings at various growth stages have come to be classified into the following 5 groups from the view point of their roles in determining yield: dreessing (I) transplanting stage and stage of just after transplanting, (II) at early tillering stage, (III) at late tillering stage, neck-node differentiating stage and primary branch differentiating stage, (lV) at spikelet differentiating stage and early stage of reduction division of P.M.C, (V) on and after late stage of reduction division of P.M.C. 2. The effects of the treatment (1) on the heading date and the lodging resistance (Tablel), (2) on the plant height, the length of each leaf-blade and-sheath, the length of the highest culm and that of each inter-node (Fig. 2 and 3) and (3) on the chemical composition of the plant (Fig. 4 and 5) have been brought to light. 3. The results above mentioned will also be effectively utilized in estimating or diagnosing the effectiveness of nitrogenous fertilizers applied or affected at various growth stages.
