Response Mechanism Of Drought Tolerance Of Spring Maize To Subsoiling Treatment

In Inner Mongolia,long-term unreasonable cultivation and tillage mode and drought are the main factors that lead to the shallow soil depth of effective tillage layer,thickening of plough bottom and difficulty of planting maize root system,thus affecting maize yield.As a protective tillage measure,subsoiling tillage can effectively alleviate its effects.In order to further promote the high and stable yield of maize in Inner Mongolia,this study carried out fixed-point experiments in three areas in two years under the condition of field,and set subsoiling season(spring subsoiling and autumn subsoiling)and subsoiling depth(30cm,40 cm,50cm)to explore the response mechanism of drought tolerance of spring maize to subsoiling regulation.The main achievements are as follows:(1)Compared with CK(farmers’ 15cm),different subsoiling treatments can effectively improve the physical structure of soil.Subsoiling tillage can reduce the soil bulk density by 0.40%-8.36%,and the deviation value of soil three ratio is 19.16%-38.24%.It can reasonably adjust the three ratio of soil and improve crop resistance.Soil water content was positively correlated with corn yield,while soil bulk density and soil three ratio deviation were negatively correlated with corn yield.(2)There was a positive correlation between root dry weight and root surface area and yield after different subsoding treatments,and there was a significant positive correlation between root surface area and yield under normal irrigation and drought stress.Through the root digging test of Tumd Right Banner,it was found that ASS50(autumn deep soiling 50cm)treatment had the greatest influence on maize root in 40-50 cm soil layer.Compared with CK,the growth rate of each treatment in the drought stress area was larger than that in the normal irrigation area,and the root growth could be better promoted by the subsoil tillage in the drought stress area than that in the normal irrigation area,that is,the improvement effect of the underground soil conditions under the subsoil tillage treatment on the traditional tillage treatment was better in the drought stress area than that in the normal irrigation area.(3)The grain filling rate and dry weight of grain were significantly increased by different subsoiling depth,and grain yield was significantly increased with the increase of subtillating depth.Under the conditions of the same submerging season,irrigation treatment and different submerging depth in each region,with the increase of submerging depth,the time to reach the maximum filling rate was advanced,the grain growth increased and the maximum filling rate increased when the grain filling rate was the highest.(4)Drought stress significantly reduced dry matter accumulation and grain yield of maize at maturity.Compared with CK,dry matter accumulation and grain yield of maize at maturity were significantly increased under different subsoiling treatments.Under the conditions of the same subsoil season,irrigation and different subsoil depths,dry matter accumulation and maize grain yield increased with the increase of subsoil depth,and the effect of ASS50 treatment was the most obvious.In 2020,the yield increased by 17.84%compared with CK in Wuyuan drought stress area(5)Comprehensive analysis of the test results in The three districts of Tumd Right Banner,Wuyuan and Jalaid Banner showed that THE response range of ASS50 was the largest,so 50 cm of subsoiling in autumn was recommended as the optimal subsoiling tillage regulation mode in the three districts of Inner Mongolia.