Research On Lodging Resistance Of Summer Maize Stem By Water And Nitrogen Treatment With Water And Fertilizer Integration By Micro-Spraying

For a long time,the utilization efficiency of water and fertilizer is not high,and the loss of water and fertilizer is easy to cause maize lodging or even yield reduction.The application of water and fertilizer integration technology can improve the utilization rate of water and fertilizer in agricultural production,and is of great significance to promote the growth of maize plants and solve the problem of maize lodging.In this paper,the experiment of irrigation and nitrogen application of summer maize under the integration of water and fertilizer was carried out,and two treatments were set up,namely,supplement irrigation/nitrogen application(W)and nitrogen application(N).According to the nitrogen absorption curve of summer maize,the treatments of supplementary irrigation/nitrogen application were conducted four times at the beginning of Sowing,Jointing stage,Trumpet stage and Heading stages(W1),and two times at the beginning of sowing and big bell stage(W2).According to the amount of nitrogen applied,the treatments were divided into two levels:210kg/hm~2(N2)and 150kg/hm~2(N4).The stem and leaf morphology,stem mechanical parameters,lodging resistance and yield of Summer Maize at different growth stages were studied,and the water and nitrogen treatment methods for comprehensive optimization of lodging resistance and yield of summer maize were explored.The results were as follows:(1)Under the condition of sprinkler irrigation and fertilizer integration,N2 treatment significantly reduced the plant height at Heading stage and Dough stage,significantly reduced the height of gravity center at Heading stage and Filling stage,and W2 treatment significantly reduced the height of gravity center at Heading stage and Filling stage.W1N2 and W2N2treatments could significantly increased the average area and orientation of five leaves near ear at grain Filling stage,effectively regulated the plant canopy structure,and avoided excessive growth or low growth of maize plants.There was no significant effect on dry matter quality of the third internode at the base of summer maize under different supplemental irrigation/nitrogen application and nitrogen application rates.The length of the third internode at the base of Summer Maize at the Filling stage was significantly shortened,and the stem diameter and cross-sectional area of the third internode at the base of Summer Maize at the Filling and Dough stages were significantly increased.(2)At the same times of supplementary irrigation and nitrogen application,N2 treatment significantly improved the bending strength,puncture strength and compressive strength of the third internode at the base of maize stalk at the Filling stage and Dough stage,but the change of times of supplementary irrigation and nitrogen application had no significant effect on the mechanical parameters of maize stalk.Under the same nitrogen application rate,W1 treatment can significantly improve the bending resistance and compressive strength of the third internode at the base of maize stem at Dough stage,and improve the lodging resistance of maize stem.At the Filling stage and Dough stage,the bending resistance,puncture strength and stalk compression strength of the third internode at the base of the maize stalks of W1N2 and W2N2are significantly higher than other two treatments.At heading stage,W1N2 treatment had the highest bending strength and compressive strength in the third internode of stem base.(3)The lodging resistance index of W1N2 and W2N2 treatments was significantly higher than that of the other two treatments at Filling and Dough stages,and the lodging resistance index of W1N2 treatment was significantly higher than that of other treatments in the male pumping stage.Lodging resistance index was significantly positively correlated with the bending strength,puncture strength and radial compressive strength of the third internode at the base of summer maize stem in each growth period,and positively correlated with the cross-sectional area of the third internode at the base of summer maize stem in Filling and Dough stages,and negatively correlated with plant height,height of gravity center and length of the third internode at the base of summer maize stem in Filling stage.(4)The lodging resistance of W1N2 and W2N2 treatments was significantly higher than other treatments when the inclination angle of corn stalk was more than 35°to failure in each growth period;During the transitional period from grouting to wax maturity,the lodging resistance of each treatment gradually increases,the lodging resistance of W1N2 treatment was significantly higher than that of other treatments.According to the four formulas of lodging wind speed derived from different theories,it was found that the critical lodging wind speed of W1N2 and W2N2 treatments were significantly higher than that of the other two treatments during the growth period,and there was a significant positive correlation between the critical wind speed and lodging resistance index,which could effectively evaluate the lodging resistance of summer maize stems.(5)When the summer maize yield,critical wind speed,and voltage resistance index were separately analyzed by the normalized weighted treatment,the W1N2 and W2N2 treatments were significantly better than the other treatments for their voltage resistance,and the W2N2treatment also showed superior voltage resistance when achieving high yields.Under comprehensive consideration,it is suggested that the scheme of water and nitrogen treatment under the condition of micro sprinkler irrigation in the experimental area is as follows:when the rainfall is abundant in the early growth stage of summer maize,the supplementary irrigation/nitrogen application can be carried out at sowing and big bell stage,and the nitrogen application amount can be increased to 210kg/hm~2 without multiple supplementary irrigation.