Studies on Weed Control by Submergence in Rice Cultivation : I. Effect of submergence on the structure of weed communities and the quantity of weeds : II. Effect of submergenec on the growth and yield of rice plant

Abstract

The effects of submerging paddy fields continuously for one month after transplanting under irrigation water of various depth (and afterwards withdrawing water to keep a shallow irrigation until the end of the season) on the emergence of weeds and the growth and yield of rice plant were experimentally investigated during 1952 to '54 at Konosu Experiment Farm. (1) Weeds - Under 10 or 15 cm. deep submergence, absolute weed quantity, especially relative quantity of weeds resistant to 2, 4-D were found small as compared with those under 3 cm. deep submergence. (2) Rice plant - With 10 or 15 cm. deep water, growth of rice plant was suppressed at the early stage of tillering period, but afterwards it was recovered and became better than that under 3 cm. submergence, showing no decrease in yield. (3) It should be possible to control weeds more effectively by combining deep submergence with spray of herbcides such as 2, 4-D.