Competitive relationship between Cyperus rotundus, Echinochloa colona, and Rottboellia cochinchinensis in upland rice [Philippines]
1988
Nyarko, K.A. | De Datta, S.K. (International Rice Research Inst., Los Banos, Laguna (Philippines))
A series of experiments conducted in 1987 at International Rice Research Inst. [Los Banos, Laguna, Philippines] sought to establish the competitive relationship between upland rice, Cyperus rotundus, Echinochloa colona, Rottboellia cochinchinensis and their adaption mechanism to changing light environment. The competitive relationship of rice with weeds depended on the mixture and density. Dominance was in the order R. cochinchinensis E. colona IR43 C. rotundus. Rice biomass was reduced by 28 to 79% and weed biomass by 48 to 86% through interspecific competition. R. cochinchinensis reduced rice yield by 100%, E. colona by 84%, and C. rotundus by 27%. Light transmission ratio (LTR) was 3% for R. cochinchinensis, 26% for E. colona, and 99% for C. rotundus at 50 cm within canopy. Nitrogen content in shoots was linearly correlated with LTR. Rice adapted to partial shading by having high leaf N content, which increased its photosynthetic rate at low light density.
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