Residual Effect of Herbicides on the Succeeding Crop of Rice

Abstract

The residual effects of herbicides applied in the second crop of 1971 on the infestation of weeds and the growth performance of rice in the first crop of 1972 are summarized. The treatments of 2,4-D IPE, Benthiocarb, and C-288+2,4-D IPE were infested with smaller number of weeds while those of CP 53619, Benthiocarb +2,4-D IPE, and C-290+2,4-D IPE were more heavily infested. However, the correlation between average weed control rating in the second crop of 1971 and average number of weeds per m2 in the first crop of 1972 gave r value of -0.0389 which was too small to attain significance. This indicates that application of herbicides does not affect appreciably the infestation of weeds in the succeeding crop of rice. Plant height and number of tillers per hill at 60 days after transplanting, plant height and number of panicles per hill at maturity stage, days to heading, and grain yield per ha did not differ significantly among treatments. Thus, residues from the application of herbicides in the second crop of 1971 may not persist in amounts toxic to the growth of rice in the following first crop of 1972.

本文係報告民國60年第2期作使用之稻田除草劑對民國61年第1期作水稻之發育及雜草發生之影響。 2, 4-D IPE, Benthiocarb與C-288+2, 4-D IPE處理之雜草數目較少，而CP 53619，Benthiocarb+2, 4-D IPE與C-290+2, 4-D IPE處理之雜草則較多，惟60年第2期作之平均治草效果級數與61年第1期作之平均雜草數目問之相關係數只有-0.0789，未達顯著水準。由此設論，稻田除草劑之施用並不顯著影響其後期作稻田雜草之發生。 插秧後60日水稻株高與每株分棻數，成熟期之水稻株高與每株穗數、抽穗期及每公頃稻谷產量之處理問差異均不顯著。由此可知60年第2期作施用之稻田除草劑，其在稻田土壤中之遺留量顯然不足影響其後期作水稻之正常發育。