The Application Research Of Halosulfuron-methyl In Corn

In this paper, the herbicide named halosulfuron-methyl was selected as theresearch object. In order to ascertain its application potential to control weeds incorn field, provide theoretical and practical basis for its development andapplication, we tested the safety to various corn varieties, herbicidal bioactivity,spectrum of weed controlling, conductibility among the tubers of purplenutsedge, the appropriate time and quantity to spray, the selectivity coefficientof halosulfuron-methyl between maize and sensitive weeds, Synergismevaluation of herbicide mixtures(halosulfuron-methyl and nicosulfuron), fieldefficacy trial and so on, in addition, researched corns，tolerance mechanism tohalosulfuron-methyl in accidence. The results could be summarized as follows:bioactivity determination and acting characteristic research ofhalosulfuron-methylResults of bioassay of halosulfuron-methyl to the seedling phase variouscorn varieties by pot-culture method shown that The security of23maizevarieties to halosulfuron-methyl was studied, and the following results was that with the doubling dosage140g/hm2(effective constituent), thehalosulfuron-methyl to5maize varieties(Siyu7, Wuyue18, et al.) were insecureand plant height inhibiting rates were beyond9.64%, to12maizevarieties(Jinhai5, Ludan981, et al.)were safer and plant height inhibiting rateswere between4.14%and7.78%, to6maize varieties(Zhengdan958, Taibao1, etal.) were safest and inhibiting effect were unconspicuous. In the meanwhile, theIC10also reveals different maize varieties had different tolerance tohalosulfuron-methyl, Tianyumi had the lowest tolerance with IC10value94.8703g a.i./hm2, the second lowest is Nongda0638, the tolerance ratio is only1.25, The tolerance ratio of Huanuo1, Ludan981Wuyue97-1and et al, isbetween1.51and1.97, and Wuyue21, Nongda108, Zhengdan958, Taibao1and Qiangsheng16shown the higher tolerance with the tolerance ratio2.05~2.43. The results coming from140g a.i./hm2and IC10were similar.Sandy culture result revealed the inhibition ratio of the halosulfuron-methylto taproot of seedling existed some difference, based on IC50, the sensitivityorder is Taibao1＞Qiangsheng16＞Zhengdan958＞Nongda108＞Wuyue21＞Ludan981＞Zhongyu9＞Jinhai5＞Xixingxuezhongmo＞Nongda0638＞ Tianyumi.Spectrum of weed controlling was carried by pot bioassay in greenhouse.Result shown that halosulfuron-methyl had good control effect to mostlyfamiliar weeds such as Xanthium sibiricum, Commelina communis, Bidenspilosa, Amaranthus retroflexus, Juncellus serotinus, Cyperus rotundus and et al.In contrast, almost halosulfuron-methyl was null to grasses, thus it could be seenthe weed control spectrum of halosulfuron-methyl and nicosulfuron wascomplementary.The leaf of broad-leaved weeds became yellowed, dwarf andinteriorleaf wilting after four days with halosulfuron-methyl treatment. and theplant became dry rot and dead after eight days. Gramineous weeds wereimpregnability with halosulfuron-methyl treatment. And the leaf of sedge weedsbecame yellowed and behaved stunted after four days, then became perishedafter eight days.The result of herbicidal bioactivity with pot-culture method shown that theactivity of halosulfuron-methyl was high to some common broadleaf weeds andsedges and the fresh weight inhibiting rates of Commelina communis,Amaranthus retroflexus, Cyperus rotundus and etal. were all above90%at35g/ hm2(effective constituent), and the IC50of Amaranthus retroflexus and Cyperusrotundus were4.81g a.i./hm2,6.98g a.i./hm2.The result of conductibility among the tubers of purple nutsedge shown thehalosulfuron-methyl not only blighted aboveground parts of purple nutsedge butalso made the tubers of purple nutsedge become black brown. thehalosulfuron-methyl had well conductibility, and also made the second levelbecome black brown.By pot bioassay method in greenhouse, it was found that the sensitivity ofmaterial had difference at different leaf-stage. The application timing was from1to3-leaf stage of weeds. And the control effect was more than90%at35ga.i./hm2. the control effect to Abutilon theophrasti was decreased with the growof weeds, so the best treament time was before3-leaf stage of weeds.Comparing the selectivity coefficient of halosulfuron-methyl andnicosulfuron between maize and sensitive weeds, the former was higher (Purplenutsedge (Cyperus rotundus)16.11, Redroot amaranth (Amaranthus retroflexus)13.18), and the latter was lower(Purple nutsedge (Cyperus rotundus)1.09,Redroot amaranth (Amaranthus retroflexus)2.06). Synergism evaluations of herbicide mixtures(halosulfuron-methyl andnicosulfuron) to Amaranthus retroflexus and Cyperus rotundus were all additiveeffect.The field efficacy trial shown halosulfuron-methyl and nicosulfuronmixtures, effects on common common broadleaf weeds and sedges in corn werewell. The doses in this trial were halosulfuron-methyl15,17.5,20,22.5,25g.ai/hm~2and nicosulfuron45,52.5g.ai/hm~2. All mixtures were better than onlyhalosulfuron-methyl or nicosulfuron. The effects of mixtures to purple nutsedgewere all above96.8%, to Chenopodium album above95.2%, to Acalyphaaustralis above94.5%, to Digitaria sanguinalis above95.2%, to Abutilontheophrasti above90.2%, the totle effect was above95.6%.study initially of the tolerance mechanism of cornIn vitro, study the effect on ALS of maize, the result shown when theconcentration of halosulfuron-methyl was enhanced, the inhibition rate on ALSwas increased. And in different concentration grads, the ALS relative activity ofthe tolerable variety Qiangsheng16, the medium tolerable variety Ludan981and the sensitive variety Tianyumi revealed similar trend, the sensitivity of ALS was not significantly different.In vivo, halosulfuron-methyl maize ALS activity could renew the inhibitionof halosulfuron-methyl rapidly, while the tolerable variety had a strongerrecovery capability. After2to2.5days, ALS activity could recovered to thenormal level.the significantly different of GSTs activity of the maize that did not treatedwith halosulfuron-methyl did not exist although being little fluctuation. Ather1.5days when maize was treated with halosulfuron-methyl, the GSTs relativeactivity increase obviously, and relative activity of ALS raised when the reactiontime was prolonged，reached the peak value after3or4days, then declined, atlast, fell back to control group level.