The Weed Communities Characteristics And Control Effects Of Corn Fields With Shallow Buried Drip Irrigation In Xiliao River Plain

In view of the unclear composition of weed community under shallow buried drip irrigation in corn field in Tongliao area,as well as the chaotic use of herbicides and residual damage of herbicides in corn production.Taking maize as the research object,this study explored the effects of different irrigation methods and different tillage methods on weed community characteristics in corn field,and preliminarily defined the species and occurrence of weeds in Tongliao area.Through the study on the effect of herbicide application methods on weed control in corn field and the effect of herbicide on soil enzyme activity,in order to establish a set of comprehensive weed control measures under shallow buried drip irrigation in corn field in Tongliao area,so as to provide theoretical basis and technical reference for weed control in corn field.The main results were as follows:1.Use of shallow buried drip irrigation can effectively control the density of weeds and the frequency of dominant weeds.The total density of weeds in flood irrigation maize field was higher than that in shallow buried drip irrigation corn field,with an average increase of 36.38%in two years.The frequency of dominant weeds in flood irrigation was higher than that in shallow buried drip irrigation;The Shannon Wiener index,Simpson index and Pielou index of weeds under flood irrigation were higher than those under shallow buried drip irrigation,and species richness index was not significant;The grain yield of shallow buried drip irrigation was higher than that of flood irrigation,with an average increase of 6.91%in two years.2.Rotary tillage under shallow buried drip irrigation has a certain inhibitory effect on weeds in corn field.Rotary tillage with shallow buried drip irrigation can effectively reduce the density of weeds in corn field,with an average reduction of25.10%in two years.There is no significant difference in weed species.The dominant weeds in no tillage and rotary tillage were Amaranthus retroflexus L.and Echinochloa crusgalli(L.)Beauv.The Shannon Wiener index,Simpson index and Pielou index of weeds in no tillage field were higher than those in rotary tillage under shallow buried drip irrigation,and the species richness index was not significant.The grain yield of rotary tillage was higher than that of no tillage,with an average increase of 3.71%in two years.3.The results of herbicide screening test showed that 66%acetochlor·atrazine·2,4-D-ethylhexyl SE had good control effect on weeds in corn field at the doses of 3750 g a.i./hm~2,and the overall control effect on weeds reached 91.04%30 days after application;28%nicosulfuron·atrazine·mesot-rione OD had good control effect on weeds in corn field at the doses of 2 400 g a.i./hm~2,and the overall control effect on weeds reached 88.68%30 days after application.4.For pre-emergence herbicides in corn field under shallow buried drip irrigation,spraying on the 1st day or dropping on the 3rd day was the best application method and application time.Under the spray method,the control effect of spraying on the first day was the best after sowing,and the control effect reached more than88.09%.Under the dropping method,the control effect of dropping on the third day was the best,and the control effect reached more than 87.10%.5.The experimental results of the effect of herbicides on soil enzyme activity showed that the effects on soil urease activity and soil sucrase activity were inhibited from 10 d to 20 d after application and gradually recovered from 30 d.The effect on soil alkaline phosphatase activity was that it returned to the control level in the later stage of the experiment.The effect on soil protease activity was strong in the initial stage,and then the enzyme activity gradually recovered to the control level.