论文信息 - Rice Yield Loss and Economic Threshold Levels by Densities of Scirpus planiculmis and Lindernia dubia in Wet-Seeded Rice Paddy Fields

Rice Yield Loss and Economic Threshold Levels by Densities of Scirpus planiculmis and Lindernia dubia in Wet-Seeded Rice Paddy Fields

This study was conducted to find the levels of reduction in rice yield and to determine economic threshold levels as affected by densities of Scirpus planiculmis and Lindernia dubia in wet seeding rice cultivation. In wet seeding rice cultivation, yield of rice in densities of S. planiculmis (192 per m2 ) and L. dubia (384 per m 2 ) was reduced by 43 and 22%, respectively. Relationship between rice yield and densities of weeds were predicted with these equations of Y=531.3kg/(1+0.003931x), r 2 =0.964 for S. planiculmis and Y=547.0kg/(1+0.000792x), r 2 =0.922 for L. dubia. According to Cousens' method, economic threshold densities of S. planiculmis and L. dubia were calculated by 7.2 and 34.9 per m 2 , respectively. This result indicat ed that yield of rice in wet seeding rice cultivation could be reduced by over economic threshold densities of S. planiculmis and L. dubia.

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