EFFECT OF WEED COMPETITION ON GROWTH AND YIELD OF DIRECT-SEEDED KDML 105 RICE UNDER DROUGHT CONDITION

摘要

Weeds, kinds and density, and their effect on growth and yield of direct seeded (dibbled) KDML 105 rice were investigated under drought condition in upland paddy field at Ubonratchatani Rice Research Center. Growth and yield of rice were compared among 3 weed conditions; Weed-free, Unweeded, and Hand weeding (once at 1 month after rice emergence). The major weeds found in this area were Digitaria adscendens, Lindernia anagallis, Ludwigia hyssopifolia, Mitracarpus villosus, Fimbristylis miliacea and Cyperus haspan. Comparing on weed density at 1 month after rice emergence and at harvesting, number of weeds in unweeded treatment were 1,519.4 and 1,415.9 plants/m2, respectively, and 1,267.2 and 514.7 plants/m2, respectively, in hand weeding treatment. Hand weeding reduced weeds density to about 36% of those in unweeded control, and grassy weeds were most affected. Rice plant in unweeded treatment died due to drought and weeds competition. Hand weeding, in this study, increased rice yield to about 38% of that in weed-free treatment. However, the rice yields were very low in both weed-free and hand weeding conditions because of the drought