Effects Of Deep Plowing And Straw Returning On Root Lodging Resistance Of Different Density Tolerant Maize Varieties

In Inner Mongolia,the soil layer is shallow and the plow layer is thick,and the root lodging is serious after increasing planting density,which restricts the increase of maize density and yield and the direct harvest of mechanized grain.In order to solve this problem,this study selected four different density tolerant maize varieties as materials,compared with farmers’shallow rotary tillage,set up deep plowing and straw deep plowing tillage,planting density of 82500 plants/hm~2and 112500 plants/hm~2,and investigated the morphological characteristics of underground roots,Aerial root morphology and mechanical indicators,root dry weight and yield of maize at the root lodging rate,big bell mouth stage,silking stage and milk ripening stage,Analyze the changes in root lodging resistance of different density tolerant maize varieties,as well as the effects of deep plowing and straw returning to field to increase density on the root lodging resistance traits of each variety.The main results are as follows:1.Compared with shallow rotation,deep tillage and straw returning reduced the lodging rate of corn roots by 2.86%-5.6%,and the effect was more obvious under high density condition.The lodging rate of density-tolerant varieties(Xianyu 696,Simon No.6)was significantly lower than that of the low-density varieties(Jingke 968,Zhengdan 958)under the deep-turning straw returning treatment.2.Root width,root length,root surface area,root volume,root mean diameter,root dry weight,root morphology and mechanical properties of maize under deep turning and straw returning increased compared with shallow rotation,and densification decreased the above index values.Root character values of densification tolerant varieties were greater than those of intolerant varieties.After densification,the root index of all varieties with deep turning and straw returning reduced compared with shallow rotation,and the root index of intolerant varieties decreased significantly.With the development of the growth process,the effect of deep-turning straw returning under high density on the increase of root length,average root diameter and rooting pull of intolerant varieties gradually appeared,and the effect on the increase of root width and root surface area of tolerant varieties was more obvious.3.Compared with shallow rotation tillage,deep turning and straw returning increased maize yield by 8.97%-14.09%.The yield of density-tolerant varieties was higher than that of non-density-tolerant varieties.With the increase of density,the yield of density-tolerant varieties continued to increase,while that of non-density-tolerant varieties decreased.Under deep turning and straw returning,the yield of dense varieties increased by 9%-14%compared with shallow turning and low turning,and the yield of non-dense varieties increased by 6%-11%.It can be seen that deep turning and straw returning to the field also have a good regulation effect on non-dense varieties.4.Root lodging rate was negatively correlated with root characteristic width,root length,root surface area,root volume,mean root diameter,rooting Angle,rooting diameter,rooting tension and root dry weight.Among them,the correlation coefficients of root surface area(-0.62),rooting Angle(-0.74),rooting diameter(-0.74),rooting diameter(-0.75)at spinning stage,rooting surface area(-0.58)at milk maturity stage and rooting Angle(-0.74)were larger.In conclusion,deep turning of straw back to field can effectively control root morphological and mechanical indexes of different densification tolerance varieties,and lodging resistance in root systems of densification tolerance varieties was even more obvious.