Abstract
This study was carried out to examine the effects of the mixed herbicide of cyclosulfamuron and dithiopyr on the weed controls, plant growth responses, and yield of rice. The mixture of cyclosulfamuron and dithiopyr(MCD) showed very high control value around 96% in both annual and perennial weeds. The effectiveness was continued until 50 days after transplanting. The plant height was slightly damaged in 20 days after treatment, but it was recovered quickly afterward. Unlike plant height, the tillers was not damaged with the mixture treatment. The leaf colour, chlorophyll content, and photosynthetic ability of rice were higher in the mixture treatment than those in the untreated control. Dry weight of rice was also 3 times higher in the mixture treatment than that in the untreated control. Rice yield was increased to about 2 to 3 times in the mixture treatment compared to the untreated control. The newly produced root numbers of rice seedlings after the treatment were not significantly damaged but the growth of newly produced roots was inhibited in the early rooting stage by the mixture treatment. However, those damages were recovered at 20 days after the treatment