Water deficit and weed population density effects on rainfed lowland rice
1990
Bueno, F.D. | Janiya, J.D. | Ingram, K.T. | Pablico, P.P. | Moody, K. (International Rice Research Inst., Los Banos, Laguna (Philippines))
Field experiments were conducted to assess the effects of water deficit and weed competition on water relations, crop growth, and yield of rainfed lowland rice. Water deficit reduced rice plant height whereas, weed height was not significantly reduced by either water deficit or weed density. Tillers/hill and leaf area index (LAI) of both rice and weeds were inversely related to weed population density. Water deficit at 20-45 DT significantly reduced rice dry weight but it did not significantly affect weed dry weight. Weed density did not significantly reduce weed dry weight. Neither water deficit nor weed density significantly affected midday leaf water potential (LWP) of rice and weeds. However, weeds consistently and significantly maintained higher midday LWP than rice. Water deficit and increasing weed population density significantly reduced rice grain yield. Water deficit at 20-45 DT was more detrimental to yield than at 50-75 DT. Regardless of water treatment, increasing weed population density reduced grain yield as a consequence of marked reduction in number of panicles. Under water deficit conditions, weed control becomes imperative during the vegetative growth of rice.
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