Studies on Growth Regulation of Rice Plants by Soil Treatment with Pentachlorophenol (PCP) : I. Effect of PCP on controlling over-growth and lodging of rice plants in ill-drained paddy field

摘要

With the aim of controlling the over-growth of rice plants in ill-drained paddy field, a series of experiments has been carried out by using Pentachlorophenol (PCP). The results are summarized as follows: 1) Soil treatment with PCP at the end of effective tillering stage resulted in control of plant height and ineffective tillering. There was a tendency that the more the dosage of PCP, the greater the control of plant growth and ineffective tillering. 2) PCP controlled effectively the growth of such leaves and internodes which were just developing at the time of soil treatment with PCP, and the control was becoming gradually ineffective at the later growing stage. 3) Soil treatment with PCP at the end of effective tillering stage was very effective in controlling the excessive vegetative growth and strengthened the rice plant resistance to lodging, because PCP controlled the elongation of basal internodes and increased breaking resistance of culms. 4) Nitrogen content in rice plant decreased temporarily by soil treatment with PCP, but after the recovery of plant growth it maintained the higher concentration than that in the control.