Study On Weed Management Of Summer-sowing Soybean After Winter Wheat In Huang-Huai-Hai Region Of China

Summer soybeans in Huang-Huai-Hai region of China usually are sowed immediately afterwinter wheat. Thus the continuous use of chemical herbicides and no-tillage (reducedtillage) kept the dominant weeds remain in the field year by year. In this thesis, weedspecies and community composition were investigated in summer soybean filed inXuchang Municipality, Henan Province. On basis of which, effects of different herbicideson weed control in glyphosate-resistant soybean fields were studied. The results weresummarized as follows:1. Weed species and their community constitutes in summer soybean filedSeventy-two weed species belonging to20families were occurred in summer soybean fieldin in Huang-Huai-Hai region. The main weeds, with the volunteering wheat as thedominant, include redroot pigweed, copperleaf herb, purslane horse bubble melon, goosegrass, nut grass, setaria viridis, calystegia hederacea, crabgrass, cockscomb and prostratespurge.2Effects of the commonly-used herbicides on weed community in summer soybeanfieldFive kinds of herbicides (glyphosate, quizalofop-p-ethyl, haloxyfop-r-methyl,fluoroglycofen-ethyl and fomesafen) were respectively used in the two-year experiments.The results showed that: the control effect of glyphosate performed the best with few weedsurvival. Quizalofop-p-ethyl had a good effect on controlling volunteering wheat andgoose grass, which would completely die after8-12days, meanwhile, haloxyfop-r-methylhad a good effect on controlling volunteering wheat and barnyard grass, but both of thetwo herbicides showed poor control of crabgrass. Fluoroglycofen-ethyl and fomesafen alsohad their resistant weeds, which were copperleaf herb and calystegia hederacea for theformer, and calystegia hederacea for the latter.Redroot pigweed and copperleaf herb occurred as dominant weed species after usingmixed quizalofop-p-ethyl with fluoroglycofen-ethyl, while no dominant weeds occurred inthe glyphosate-using field.3Cost analyses of different treatmentsCost analyses was completed by comparing the herbicide expenses and labor cost underdifferent treatments. The sequence was proved to be, from low to high, the glyphosatetreatment, mixture herbicide of quizalofop-p-ethyl and fluoroglycofen-ethyl, mixtureherbicide of haloxyfop-r-methyl and fomesafen, manual weeding.4Comparison of comprehensive benefit of different weed control systemsWith cost and yield considered together, conclusion can be given that using glyphosatewould be the best choice for future weed management of summer soybeans withglyphosate resistance, for the good control effect, high yield and low cost.