Study On The Application Of Tirlfoxysulfuron Controlling Weeds In Cotton Field

Cotton is one of the most important economic crops in our country, the broad-leavedweeds in cotton field of our country is mainly controlled by soil treatment method, and it isurgent need to explore one kind of efficient postemergence herbicide to control broad-leavedweeds in cotton field. Trifloxysulfuron is one of the newest efficiency and low toxicityherbicide used in cotton field. In order to investigate the application of this new herbicide inChina, we took series methods such as enzyme assay, pot-culture in greenhouse and fieldexpriment to research the spectrum of weeds control, herbicidal activity, safety to commonvarious cotton varieties, the difference and mechanism of tolerance of various cotton varietiesto trifloxysulfuron. The results could be summarized as follows:1. The results of bioassay by pot-culture in greenhouse method indicated thattrifloxysulfuron had a wonderful herbicidal activity to common broadleaf weeds andsome gramineous weeds in cotton field, the treatment of trifloxysulfuron used at11.25ga.i.ha-1showed the greatest fresh weight control efficacy among the tested weeds of Cyperusrotundus, Setaira viridis, Eclipta prostrate, Herba Conyzae, Leptochloa chinensis, Bidenspilosa, Chenopodium serotinum and Xanthium sibiricum with the number of over90%. It wasmore efficient against Cyperus rotundus, Portulaca oleracea, Abutilon theophrasti,Amaranthus retroflexus and Setaira viridis by applying trifloxysulfuron thanpyrithiobac-soidum with the activity ratio of171.01,3.82,13.55,10.50and12.60oftrifloxysulfuron contrasted with pyrithiobac-soidum.2. The research of safety to various cotton varieties by pot-culture in greenhouse methodshowed that the plant length and fresh weight were inhibited notablely as the cotton wastreated with trifloxysulfuron at45g a.i.ha-1at the leaf stage of3-4, further more the inhibitionto various cotton varieties was significantly different. The Lumianyan40, K638, Delinong5,Chuanglu21had a stronger resistence to trifloxysulfuron while Lu H498, Lumianyan36,Lumianyan39, Lumianyan28were more sensitive.3. The selectivity index data showed that both trifloxysulfuron and pyrithiobac-sodiumhad advantages and disadvantages on the selectivity between Huamian5, Shannongmian8and weeds. Trifloxysulfuron had a higher selectivity between C. rotundus, Abutilon theophrastiPortulaca oleracea, Setaira viridis and the two cotton varities. However, theselectivity of pyrithiobac-sodium was a little better between Portulaca oleracea, Amaranthusretroflexus and Huamian5and Shannongmian8.4. The tolerant variety Lumianyan40and sensitive variety Lu H498were chosen forenzyme assay to research the different cotton varities resistance mechanisms totrifloxysulfuron, the result showed that the IC50of ALS of the vatiety of Lumianyan40was alittle higher than Lu H498; meanwhile, the ALS activity of the two cotton varieties wereinhibited firstly then recovered from inhibition of trifloxysulfuron rapidly in vivo analysis, thetolerant variety Lumianyan40had a less repression and a quicker recovery than sensitivevariety Lu H498. The GSTs activity presented rising firstly then falling tendency andLumianyan40showed a stronger response to trifloxysulfuron than Lu H498, Lumianyan40reached the point of1.454after treatment of3days, while Lu H498got the uppermost of1.454after treatment of5days, the GSTs activity of two cotton varities fall to the controlgroup level at the9days after processing.5. The experiment on effect of applying trifloxysulfuron results showed that the joint oftrifloxysulfuron, pyrithiobac-sodium and quizalofop-p-ethyl expand weeds controllingspectrum efficiently and had a good efficency on the broadleaf and gramineous weeds,espessically were efficient to Cyperus rotundus. The total stump efficiency and total freshefficiency of the match of trifloxysulfuron, pyrithiobac-sodium and quizalofop-p-ethylapplied at16.875g a.i.ha-1,75g a.i.ha-1,45g a.i.ha-1in cotton field by directional sprayingwere91.4%,94.6%respectively with the yield increasing rate reached19.16%.In short, trifloxysulfuron had a excellent efficiency to the common broad-leaved weedssuch as Eclipta prostrata, Xanthium sibiricum, Portulaca oleracea, Chenopodium album andgrass weeds such as Setaira viridis, Leptochloa chinensis in our country; and it had a goodsafety to cotton crops after4leaves, there exist a good application prospect in our country.