Abstract
Experiments were conducted to know the infuluence of water-percolation on the ripening of rice, using paddy-field and some pots, during three consecutive years, 1957∼1959. The results were as follows. 1) Water-percolation was effective to promote the absorption of nutrients, carbon-assimilation and the ripening, resulting in the increased yield of rice kernel. This effect of percolating water was observed similarly in the plot where percolation treatment was initiated at 10 days aftr heading as well as in the plot where the treatment was initiated at booting stage. Thus, water percolation in an ill-drained paddy field is necessary and important for the middle stage of ripening and after wards. 2) The effect of water percolation on increasing yield varies according to the status of plant growth, environmental factors for ripening, etc, and this effect is considerally remarkable in the case where the ripening percentage is low.
