Study On Irrigation Strategy And Root Distribution Prediction Model Of Winter Wheat Under Deep Irrigation

Deep irrigation of winter wheat can directly instil water into the deep soil,which couldboost root system,promote winter wheat growth and development,improve yield and water use efficiency.Deep irrigation is an efficient water-saving irrigation method.In order to further explore the optimal irrigation strategy under deep irrigation and improve the deep irrigation theory system,this experiment uses the plastic pipe to plant winter wheat in the Shanxi Water Conservancy Vocational and Technical Collegetraining base,and set 5 treatments with irrigation depth as the control factor.T1 irrigation depth is 60% of the root maximum distribution depth,T2 is 60% in returning green stage + 60% in elongation stage + 90% in heading stage + 90% in filling stage,T3 irrigation depth is 90% of the root maximum distribution depth,T4 is 90% in returning green stage + 90% in elongation stage + 60% in heading stage + 60% in filling stage,CK is ground irrigation.By comparing and analyzing the water consumption characteristics,plant growth status,yield and water use efficiency of winter wheat under different treatment conditions,the optimal irrigation strategy under deep irrigation conditions was obtained.BP neural network was used to establish the winter wheat root distribution prediction model under deep irrigation condition,and good prediction results were achieved,which could provide a theoretical basis for the implementation of deep irrigation.The main findings are as follows:(1)The difference in soil water distribution between different treatments is significant.In the soil layer of 0-40 cm,the soil moisture varies greatly with time,and the relationship between average water content of each treatment is: CK>T1>T4>T2>T3;in the soil layer of 40-90 cm,the change of soil moisture is relatively reduced,and the relationship between the average water content of each treatment is: T3>T2>T1>T4>CK;in the soil layer below 90 cm,the soil moisture changes little with time,showing a slow downward trend.The relationship between the average water content of each treatment is roughly as follows: T3>T2>T4>T1>CK.(2)Under the condition of deep irrigation,the soil temperature of each layer showed a trend of decreasing first and then increasing,and the surface soil temperature was significantly higher than that of the lower layer.The effect of irrigation depth on the soil temperature of different soil layers is different.In the surface soil,the soil temperature increases with the increase of irrigation depth.In the middle soil,the soil temperature increases first and then decreases with the increase of irrigation depth.in the lower soil,the difference in soil temperature between treatments is small.(3)Under different irrigation depths,the changes of water consumption and daily water consumption in winter wheat stage were basically the same,which showed that it first increased and then decreased,and reached the maximum at heading stage.The water consumption of different soil layers in each growth period showed a trend of decreasing from top to bottom,and the water consumption in the surface layer was much larger than that in the lower layer.Comparison of total water consumption during the whole growth period: CK>T4>T1>T2>T3,the proportion of irrigation water to total water consumption: T3>T2>T1>T4>CK,indicating that deep irrigation treatment can reduce the total winter wheat Water consumption,more effective use of irrigation water,has a certain water saving effect.(4)Deep irrigation can significantly increase the total root length of winter wheat and increase the root length density in the lower soil.Properly increase the depth of irrigation in the early stage of fertility,it can induce the root system to plow into the deep soil,increase the root coefficient,and the depth of irrigation should not be too large in the late growth stage,and must take into account the water content of the surface soil,otherwise it will cause the water shortage of the shallow root system.,affecting the overall development of the root system.The total root length of treatment 4 was at a high level in each growth period,which was most beneficial to the growth and development of winter wheat roots.(5)Under the condition of deep irrigation,the BP artificial neural network model was used to predict the root length density of winter wheat: the average relative error between the predicted and measured values of the training samples was 5.92%;the predicted values and measured values of the test samples.The average relative error between values is 7.30%.Both the training sample and the test sample have achieved high simulation accuracy,indicating that the soil depth,development time,average daily water consumption of each soil layer,daily average temperature of each soil layer,dry weight of the aboveground part,plant height,etc.It is feasible to predict the distribution of winter wheat root system,which can provide a new method for winter wheat root research under deep irrigation conditions.(6)The depth of irrigation in different growth stages has an effect on the growth of winter wheat plants.At the jointing stage and heading stage,with the deepening of irrigation depth,the plant height,leaf area and dry matter weight of winter wheat showed an increasing trend;at the filling and maturity stages,the depth of irrigation was too deep,which led to plant height,leaf area and dry matter.The reduction of various indicators is not conducive to the growth of winter wheat plants.The increase of winter wheat yield under deep irrigation conditions was mainly caused by the increase of single ear number and 1000-grain weight.Treatment 4 was most beneficial to the growth of winter wheat grain,which could promote the increase of winter wheat yield and improve the water use efficiency of winter wheat.(7)Combining the water consumption characteristics,plant growth status,yield and water use efficiency of winter wheat,it can be concluded that treatment 4 is an optimal irrigation strategy under deep irrigation conditions,that is,the depth of re-greening water and water-drawing water are 90% of the depth root distribution,the depth of heading water and grouting water are 60% of the depth of root distribution.