| To improve field weed management efficiency in maize and soybean intercropping and reduce the cultivation cost.We filtered out post-emengence herbicides suiting for maize and soybean intercropping.Field study,which conducted at Huangyang town test site in Wuwei of Gansu Academy of Agricultural Sciences,was adopted a single factor experimental design in 2016.Effect of five post-emengence herbicides on weed control effect and crop safety were investigated.However,it was an important practical significance that the study containing the effect of thifensulfuron under different soil miosture on efficacy,injury,recovery of maize and soybean intercropping was carried out because of drought and water shortage in the northwest district of china.Field study,which conducted at Ganzhou qu,Zhangye,Gansu province in 2017 and 2018,was adopted a split plot experimental design,Effect of thifensulfuron under different soil moisture on field weeds control effect,fresh weeds weight inhibition rate at 15,20,30 days after spraying were investigated,as well the soybean agronomic traits,photosynthesis,physiologic trait and yield were measured.Finally we screened out a factor which mainly affected soybean yield thereby building a stepwise regression,path analysis between soybean agronomic characters and per-soybean yield at 7,15,25 days after spraying herbicide.Research results as follows:1.Screening post-herbicide for maize and soybean intercropping.Maize was safe to thifensulfuron,but soybean was relatively safe to thifensulfuron.A better control effect on broad-leaf weeds was over 80%at 30 days after spraying thifensulfuron.maize yield was increased significantly after spraying thifensulfuron,Meanwhile the system yield of maize-soybean intercropping was also 3.7%higher than CK after spraying thifensulfuron.2.Effect of thifensulfuron under different soil miosture on weed control effect.Both increasing the dose of thifensulfuron and increasing soil moisture also improved weed control effect.The weed control effect and fresh weed weight inhibition rate were 84%,87%respectively after spraying 27 g/hm~2 thifensulfuron under 25±5%,it was 14.7%,17%higher than that after spraying 9 g/hm~2 thifensulfuron under same soil miosture.3.Effect of thifensulfuron under different soil miosture on the soybean injury and soybean growth recovery.Soybean injury was improved visablly as increasing thifensulfuron dosage.Soybean injury was aggravated when soil moisture was 25±5%,but soybean injury was in favour of growth recovery under 25±5%.In fact,the injury of soybean leaf under 25±5%was beyond itself growth recovery,and then soybean leaves injury was up to 65%at 15 days after spraying 27 g/hm~2 thifensulfuron under 25±5%where soybean leaves injury was 10%higher than that under 15±5%.Per-soybean leaf area recovery rate was 61%at 28 days after spraying 27 g/hm~2 thifensulfuron under 25±5%where per-soybean leaf area recovery rate was 11%higher than that under 15±5%.The recovery rate of soybean leaf injury rate was 53%at 25 days after spraying 27 g/hm~2thifensulfuron under 25±5%where the recovery of soybean leaf injury rate was 12%higher than that under 15±5%.However,soybean leaf injury rate was 45%at 15 days after spraying 18 g/hm~2 thifensulfuron under 15±5%where soybean leaf injury rate was 10%lower than that under 25±5%.Soybean SOD,MDA,Pn recovered to the CK level until 28days after spraying 18 g/hm~2 thifensulfuron under 15±5%,while soybean SOD,MDA did not restore to the CK level until 28 days after spraying 18 g/hm~2 thifensulfuron under25±5%.4.Effect of thifensulfuron under different soil miosture on soybean yield.No significant soybean yield increase after spraying 9 g/hm~2 thifensulfuron because of low weed control effect.Although weed control effect was improved availably after spraying 27g/hm~2 thifensulfuron,soybean yield had no significant increase because of its dramatic injury.However,a good performance of weed control effect after spraying 18 g/hm~2thifensulfuron under 15±5%,meanwhile a significant increase of per-soybean pods,per-soybean seeds,and the highest soybean yield was obtained,the yield value were 1.32,1.34 t/hm~2 respectively,whereas yield value were 2.3%,3.7%higher than that under25±5%.5.Screening a key factor which affected per-soybean yield.Through stepwise regression,path analysis between soybean agronomic traits and per-soybean yield at 7,15,25 days after spraying herbicide,the date indicates that the soybean plant height was only a factor which contributed to soybean yield.The correlation coefficient between soybean height inhibition rate and per-soybean yield was also over 0.7,and direct action at 15 days after spraying herbicide had a maximum,the value was 0.987.So it was illustrated that a relation between soybean yield increase and soybean fast-growing regulated by thifensulfuron?... |
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