Effects Of Water And Nitrogen Management On Carbon And Nitrogen Metabolism And Water And Nitrogen Utilization Efficiency Of Maize Population Under Shallow Buried Drip Irrigation

In order to explore the effects of water and nitrogen management on carbon and nitrogen metabolism and water and nitrogen utilization efficiency in maize after anthesis under shallow buried drip irrigation,the experiment was carried out in the Agricultural High-tech Demonstration Park of Horqin District in Tongliao City from2019 to 2020.The conventional border irrigation(4000 m~3·ha)and constant nitrogen application(300 kg·ha)were used as control with drip irrigation quota as the main treatment and nitrogen application rate as side treatment,and the three drip irrigation levels of 40%,50%and 60%of conventional border irrigation and three nitrogen application rates of 50%,70%and 100%of conventional nitrogen application rates were respectively set in main treatment and side treatment to study the effects of water and nitrogen reduction on post-flowering leaf source characteristics,photosynthetic characteristics,carbon and nitrogen metabolism enzyme activities,dry matter accumulation and transportation and yield and water and nitrogen use efficiency of maize under shallow buried drip irrigation.The main results were as follows:1.Under the same nitrogen application level,the leaf resources of W3 was much better than that of W1 under the N3 levels,in which the leaf area increased by 24.19%compared with those of W1 from 30 days to 60 days after anthesis,and the photosynthetic nitrogen use efficiency of W3 was significant higher than that of W1from 40 days to 60 days after anthesis and there was no significant differences in photosynthetic nitrogen use efficiency between the W3 and W2 under the N2 and N3levels;under the same irrigation amount,the leaf resources of N3 was much better than that of N1 after anthesis,in which the leaf area and chlorophyll content of N3increased by 9.51%,63.47%and 15.55%,49.59%.compared with those of N2 and N1 at each period after anthesis.2.Under the same nitrogen application level,the differences of net photosynthetic rate,instantaneous light energy use efficiency and instantaneous water use efficiency of W3 and W2 were not significant under the N3 levels,which were significantly higher than those of W1 after anthesis and the instantaneous light energy use efficiency and instantaneous water use efficiency of W3 and W2 increased by13.32%,16.38%and 17.41%,21.67%;under the same irrigation amount,the instantaneous light energy use efficiency and instantaneous carboxylation rate of N3were significantly higher than those of N1 at each period after anthesis,in which ofW2 increased by 18.37%,28.33%and 15.41%,23.22%.3.Under the same nitrogen application level,activities of carbon and nitrogen metabolism enzyme of W3 were all significantly higher than those of W1 from 40days to 60 days after anthesis,and activities of carbon and nitrogen metabolism enzyme of W3 and W2 were both significantly higher than those of W1 from 50 days to 60 days after anthesis under the N3 levels,in which activities of malic enzyme,malate dehydrogenase and phosphoenolpyruvate carboxylase of W2 and W3increased by 7.90%,11.62%,13.84%and 16.39%,23.80%,21.56%respectively;under the same irrigation amount,activities of carbon and nitrogen metabolizing enzymes and non structural carbohydrate enzymes of N3 under the W2 and W3 were significantly higher than those of N1 at each period after anthesis.Compared with CK,activities of carbon and nitrogen metabolizing enzymes in W2N3 and W3N3 at maturity were significantly higher than CK,in which the activities of malate dehydrogenase and nitrate reductase of W2N3 and W3N3 increased by 7.09%,20.83%and 12.10%,18.55%respectively.4.Under the same nitrogen application level,the transport amount of non-structural carbohydrate and nitrogen of W3 were both significantly higher than those of W1;under the same irrigation amount,the dry matter accumulation amount and nitrogen accumulation and transport amount of N3 were all significantly higher than those of N1 at each stage after anthesis,and the nitrogen accumulation and transport amount of N2 and N3 were significantly higher than those of N1 under the W2 and W3,which were increased by 32.63%,45.01%and 45.48%,76.77%respectively compared with N1.Compared with CK,there was no significant difference in the accumulation and transport amount of dry matter,nitrogen and non-structural carbohydrate in W2N3 after anthesis,in which the transport amount of starch was 11.03%higher than that of CK.5.Under the same nitrogen application level,the agronomic utilization efficiency and nitrogen absorption efficiency of nitrogen fertilizer of W3 were both significantly higher than those of W1,and t yields of W2 and W3 were also significantly higher than those of W1 under N2 and N3,which increased by 10.63%,11.99%and 6.19%,8.87%respectively compared with W1;under the same irrigation amount,the yield and irrigation water use efficiency of N2 and N3 were significantly higher than those of N1 under the W2 and W3,in which yields of W2 and W3increased by 12.36%,14.86%and 11.25%,15.19%respectively compared with N1.6.Compared with CK,the yield and nitrogen use efficiency of W2N3 were not significantly different,and the irrigation water use efficiency and water use efficiency increased by 93.68%,14.72%and65.41%,11.10%on average.Based on the photosynthetic carbon and nitrogen metabolism and water and nitrogen use efficiency,the suitable drip irrigation amount for high yield and high efficiency of shallow-buried drip irrigation was 2 000(m~3·ha)and the nitrogen application amount was 300(kg·ha)under the normal precipitation year in the West Liaohe Plain.The amount of water and nitrogen used as a reference index for high yield and high efficiency of maize.