| Organophosphorus insecticide that cancontrol pests is an organic compound with phosphorus,which plays an important role on agricultural production.Organic phosphorus insecticides that have advantages including broad insecticidal spectrum,good curative effect,no accumulation in mammals and low price when compared with other insecticides are widely used in agricultural cultivation.Corn and soybean cultivated widely in the world not only provide food but also are important industria l raw materials,which plays an important role in human life.In the production practice,it was found that some organophosphorus insecticides could promoted the crops growth when they were used to kill pests.But is the phenomenon different between crops?What is the mechanism of crop growth promoted by organophosphorus insecticides?There are no reports on these issues at present.Six kinds of organophosphate insecticides?acephate,dimethoate,phoxim,chlorpyrifos,trichlorfon,terbutidine?and 2,4-D were chosen to treat corn and soybeans seedlingsat recommended dose in filed.Three apparent indicators?chlorophyll content,plant biomass,plant root configuration?were used to judge whether the organophosphorus insecticides could promote the growth of tested plants and whether there was difference between two crops.It was studied on the mechanism of root growth promoted by phosphorothioate insecticides by detecting the expression of Gm Pht1 gene family in soybean root tips.The results were shown as followings:1.The chlorophyll contents in new leaves and functional leaves of soybean and corn were measured with SPAD?Soil and plant analyzer development?after treated for 10 days under the condition of hydroponics.The chlorophyll content declined in functional leaves of soybean after treatment with 2,4-D(50 mg·L-1 F),terbufos(5mg·L-1 and 50mg·L-1,R)and dimethoate(50 mg·L-1,R).The SPAD values were 31.4,31.64,30.27,30.62respectively.And SPAD value was 33.03 in control.The chlorophyll content in the new leaf of soybean was higher than that in control after treatment with dimethoate(50 mg·L-1,R),and the SPAD value in treatment and control were 30.14,23.45 respectively.The chlorophyll content improved in functional leaves of corn after treatment with2,4-D(50 mg·L-1,F),terbufos(0.5 mg·L-1,R),terbufos(5 mg·L-1,R),terbufos(50 mg·L-1,R),acephate(50 mg·L-1,R),acephate(50 mg·L-1,F),dimethoate(50 mg·L-1,R),dimethoate(50 mg·L-1,F),phoxim(50 mg·L-1,F).The SPAD values were 31.4,31.64,30.27,30.62 respectively.And SPAD value was 33.03 in control.The chlorophyll content improved in new leaves of corn after treatment with 2,4-D(50 mg·L-1,F),terbufos(0.5mg·L-1,R),terbufos(5 mg·L-1,R),terbufos(50 mg·L-1,R),phoxim(50 mg·L-1,F).The results shown that chlorophyll content in the leaves of soybean and corn could improve with organophosphate insecticides.And the effect of pesticides on chlorophyll content in the two crops was different.2.The dry weight and fresh weight of soybean seedlings improved compared with that in the control after treated with 2,4-D(50 mg·L-1,F)and dimethoate(50 mg·L-1,R)for 10days.The dry weight and fresh weight of corn seedlings also improved after treated with2,4-D(50 mg·L-1,F),acephate(50 mg·L-1,F)and dimethoate(50 mg·L-1,F)for 10 days.Biomass of soybean root improved after treated with terbufos(0.5 mg·L-1,5 mg·L-1,50mg·L-1,R),and acephate(50 mg·L-1,R).Biomass of corn root also increased after treatment with terbufos(5 mg·L-1,50 mg·L-1,R)for 10 days.But biomass of corn root didn't improve after treatment with tested insecticides for 7 days.And only the biomass of soybean root improved after treatment with acephate(50mg·L-1,R and F).The results shown that organophosphorus pesticides could promote the accumulation of organic matter in crops.And the effect of pesticides on accumulation of organic matter in soybean and corn was different.3.The root length,root surface area and projection area of soybean improvedsignificantly after treatment with terbufos(5 mg·L-1,R)and acephate(50 mg·L-1,R)for 7 days,and the maize architecture didn't improve significantly under the same treatment.Ten days treated after by tested insecticides:The root surface area and projection area of soybean improved after treatment with terbufos(5 mg·L-1,R),acephate(50 mg·L-1,R)and phoxim(50 mg·L-1,F).And the root growth of soybean improved after treatment with phoxim(50 mg·L-1,F).The root surface area and projection area of corn improved after treatment with 2,4-D(50 mg·L-1,F),terbufos(5 mg·L-1,50 mg·L-1,R)and acephate(50 mg·L-1,R).And the root growth of corn improved after treatment with acephate(50mg·L-1,R and F).The results shown that the root growth of soybean was promoted after treatment with terbufos and acephate for 7 days.But the root growth of corn would be promoted significantly after treatment with selected pesticides for 10 days.4.The expression of Gm PT4 in lateral root tip of soybean increased significantly after treatment with acephate(50 mg·L-1,R)for 12 hours.But the other phosphorus transporter didn't change significantly under the same treatment.Phosphorus transporter gene had no significant change after treatment with terbufos(5 mg·L-1,R)for 12 hours.The expression of Gm PT4 and Gm PT7 increased significantly in the lateral root tip of soybean after treated with terbufos for 5 days.The expression of Gm PT7,Gm PT12 and Gm PT13 in the lateral root tips and the expression of Gm PT14 in all root tips improved significantly.The results shown that the expression of phosphorus transporter gene in soybean improved under normal treatment with terbufos and acephate. |
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