Study On The Difference In Sensitivity Of Echinochloa Spp. To Quinclorac

Echinochloa spp. are worldwide troublesome weeds, which grow together with rice(Oryza sativa L.), and compete for water, nutrients and sunlight. As a result the yield and quality of rice decreased. In this paper, the sensitivity difference of Echinochloa spp. to four herbicides were studied. There were15samples that collected in part of rice area Jiangsu Province, including Echinochloa crusgalli (L.) var. mitis (Pursh) Peterm, Echinochloa crusgalli (L.) Beauv var. zelayensis (H.B.K.) Hitche, Echinochloa crusgalli (L.) Beauv and Echinochloa colonum (L.)Link. The cell membrane damage, chlorophyll content, protective enzymes and detoxification enzymes activities were measured after application of quinclorac. The results were as follows:1. The sensitivities of15samples to quinclorac, cyhalofop-butyl and butachlor were assayed by method of Petri dish respectively.The results showed that various populations of barnyard-grass which collected from the same region have different sensitivities. E. crusgalli (L.) Beauv var. zelayensis (H.B.K.) Hitche SXY sample was the most sensitive to quinclorac, the IC50was0.6297mg(a.i.)/L. E. crusgalli (L.) Beauv SXY sample was the most insensitive, its IC50was8.9052mg(a.i.)/L. The sensitivity of E. crusgalli (L.) var. mitis (Pursh) Peterm SXY sample was between them, its IC50was1.0909mg(a.i.)/L. The IC50of E. colonum (L.) Link YHJ sample was3.6388mg(a.i.)/L, but E. crusgalli (L.) Beauv YHJ sample was1.4984mg(a.i.)/L. The sensitivities of the same population collected from different areas were also different. The IC50of E. crusgalli (L.) Beauv YLD sample was1.6962mg(a.i.)/L, E. crusgalli (L.) Beauv SXY sample’s resistance ratio was its5.25times. E. crusgalli (L.) var. mitis (Pursh) Peterm SXY sample was the most sensitive to cyhalofop-butyl, its IC50was0.0943mg(a.i.)/L. E. crusgalli (L.) Beauv var. zelayensis (H.B.K.) Hitche YST sample was the most insensitive to cyhalofop-butyl, the IC50was0.6025mg(a.i.)/L. For the same population from different regions, E. crusgalli (L.) Beauv and E. crusgalli (L.) var. mitis (Pursh) Peterm had little difference in sensitivity, but E. crusgalli (L.) Beauv var. zelayensis (H.B.K.) Hitche and E. colonum (L.) Link had significant differences. The sensitivities of the same population to butachlor were obviously different. The SXY sample of E. crusgalli (L.) var. mitis (Pursh) Peterm was the most sensitive, and its IC50was0.0844mg(a.i.)/L, the XHH sample had the highest resistance to butachlor,and its IC50was17.0221mg(a.i.)/L, the resistance ratio was201.68times as much as the former. Different populations that collected from the same region had different sensitivities to butachlor too. The IC50of E. colonum (L.) Link YGZ sample was1.7461mg(a.i.)/L, but E. crusgalli (L.) Beauv YGZ sample was9.1533mg(a.i.)/L. The sensitivities of8samples to three herbicides with foliage application were determined in greenhouse. The results showed that sensitivities to quinclorac and cyhalofop-butyl were mainly in accordance with the results of bioassay method in Petri dish respectively, the sensitivities of eight samples to penoxsulam were similar. Therefore, various populations of barnyard-grass had different sensitivities to quinclorac, cyhalofop-butyl and butachlor respectively, the same populations from various regions were different too.2. Sensitivities of five samples to quinclorac were distinctly different. The3-leaf-old seedlings were treated by spray with quinclorac at dose of1.25and5g(a.i.)/667m2respectively. The results showed that the ranges of chlorophyll content decreased and MDA content increased of insensitive samples were less than that of sensitive sample compared with the control. However, the ranges of SOD activity increased were greater than that of higher sensitive sample. The ranges of PPO activity increased were positively correlated with their sensitivities after application of quinclorac. The PPO activity increasing extend in E. crusgalli (L.) Beauv SXY sample which was the most insensitive was less than that of in the most sensitive one, E. crusgalli (L.) Beauv var. zelayensis (H.B.K.) Hitche SXY sample. There was no clear trend on PPO activity after treatment. The fresh leaf fragment of barnyard-grass was soaked in deioned water containing dose of15.625、31.25、62.5、125and250mg(a.i.)/L of quinclorac respectively, and tissue leaching solution conductivities was measured. The results showed that the ratio of relative harm of more sensitive samples were higher than that of insensitive ones. Therefore, cell membrane damage, chlorophyll and MDA content, SOD and PPO activities showed a good correlation with sensitivity of barnyard-grass.3. The changes of GSH content, GSTs activity and protein content were measured after application of quinclorac. The results showed that GSTs activity, GSH content in E. crusgalli (L.) Beauv SXY sample and E. colonum (L.)Link YHJ sample were significantly higher than that of the control respectively. Protein content of the former was similar to the control, and that of the latter increased obviously. E. crusgalli (L.) Beauv SXY sample, the most insensitive one, was treated by5.0g(a.i.)/667m2concentration of quinclorac. The GSTs activity was obviously higher than that of the control, so do GSH content, and protein content was similar to the control at6days after treatment. However, the GSTs activity and GSH content were no significantly different compared with the control in E. crusgalli (L.) Beauv var. zelayensis (H.B.K.) Hitche SXY sample, the most sensitive sample, the protein content decreased obviously compared with the control. E. crusgalli (L.) var. mitis (Pursh) Peterm SXY was treated by5.0g(a.i.)/667m2concentration of quinclorac, its GSTs activity, GSH and protein content were lower than that of the control at2days after treatment. As time passing by, GSH content increased, it was higher than that of the control obviously during4to10days, but GSTs activity increased to a level higher than that of the control obviously until10days after treatment. Protein content increased rapidly at once, then decreased, it was the highest at4days after treatment, and higher than that of the control too, protein content drastically reduced and was lower than that of the control obviously at10days after treatment.