Studies on Water Management in the Ill-drained Paddy Field : V. The effect of surface drainage on the rice plant lodging

Abstract

We Studied the relation between the lodging and the water management in the field. We designed several plots, by varying the amount of inorganic nitrogen fertilizer and some organic matters, as well as the draining stage. Koraku-plot (drained from the floral initiation stage till the heading stage) lodged most (lodging grade II∼IV), but Zenraku-plot (drained chiefly during the vegetative growth stage) did least (I∼II), in general. But by heavy application of nitrogen, mid-summer draining plot lodged (III) ; and by the application of gene grass, flooding irrigated plot considerably lodged (IV). The characters of the rice plant connected with lodging were culm length, maximum number of tillers per hill, weight of 10 cm basal culm, length of internode (No.4), and they had a close relation to the absorption of nutrients, especially nitrogen. Though it had been said that mid-summer draining could prevent the rice plant from lodging, we found from our results that it could not always do, and the effect of draining upon the lodging differed by the draining stage and the conditions of soil and manure.