Effect of different densities of Echinochloa colona (L.) Link on the growth and yield of rice cv. PSBR C16 under dry-seeded rainfed lowland conditions
1995
Roldan, G.V.
The study was conducted in Victoria, Tarlac, Philippines to determine the effect of different densities of Echinochloa colona (L.) Link on the growth and yield of rice cv. PSBR C16 under dry-seeded rainfed lowland conditions. There was a high labor requirement in hand weeding the weed-free treatment. No significant differences were observed in the rice stand count. The natural population of E. colona was not evenly distributed in each plot with an average of 49.6 plants/sq.m. Competition for light increased with increase in the number of E. colona plants/sq.m. The height of rice cv. PSBR C16 was affected by different weed densities only at harvest and tillering of rice was affected only until 43 days after emergence (DAE). The height and tiller count of E. colona was not affected by competition with rice. Weed weights at 30 and 43 DAE significantly increased as the corresponding weed numbers increased. However, weed weight was not affected by the different weed densities at 60 DAE due to the early maturity of E. colona. LAI was not affected by the different weed densities. Rice biomass, straw weight and yield parameters were not significantly affected by competition in this experiment. Significant yield reduction was observed at densities equal to and greater than 10 E. colona plants/sq.m. The greatest yield reduction was observed when there was competition from the natural weed population
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