Effect Of Supplement Irrigation And Nitrogen Application On Carbon And Nitrogen Transport Mechanism Of Maize

The field experiment was conducted at Guangxi University(22°50?N,108°17?E)from March 2018 to December 2019.The varietiy was Wanchuan 1306 with planting density of 55555 plants/ha,and the row spacing was 60 cm and the plant spacing was 30 cm.A split-plot experimental design was used,and water condition was the main plot with two irrigation amounts: rainfed and supplement irrigation;nitrogen level was a split plot with 0 kg/ha(N0),150 kg/ha(N150),200 kg/ha(N200),250 kg/ha(N250),300 kg/ha(N300).This two-year field experiment aimed to determine the effects of different water and nitrogen application conditions on carbon and nitrogen transport in the maize,the main results are as follows: 1 Effects of different water conditions and nitrogen amounts on chlorophyll index,leaf area index and dry matter weightSupplement irrigation and increase of nitrogen application could improve chlorophyll content index and leaf area index,promote the accumulation of plant dry matter and the transfer of nutrients to the ear,and increased the yield and fertilizer utilization.The dry matter accumulation of organ in nitrogen application treatment was significantly higher than that in no nitrogen application treatment;in the early stage of plant growth,there was no significant difference between the dry matter weight of stem and leaf in supplement irrigation treatment and rainfed treatment;in the middle and late stage of plant growth,the stem,leaf and ear dry matter accumulation of supplement irrigation treatment was significantly higher than those of rainfed treatment.2 Effects of water conditions and nitrogen application amounts on the rate of carbon,nitrogen content,the carbon and nitrogen accumulation in organs of plantsThe nitrogen content of different organs increased with the increase of nitrogen application amounts;the nitrogen content of stem and leaf decreased and the nitrogen accumulation increased with growth stage development;the carbon content of stem first increased and then decreased with growth stage development,while the carbon content of leaf first increased and then decreased,and final phase increased.Nitrogen and carbon accumulation of nitrogen application treatment were significantly higher than that of no nitrogen application treatment.Supplement irrigation could significantly improve the nitrogen and carbon accumulation of all organs compared with rainfed condition.3 Effects of water conditions and nitrogen application amounts on grain yield and yield componentsSupplement irrigation had no significant effect on plant height,stem diameter and ear height,and the plant height,stem diameter and ear height of high nitrogen application level was higher than those of low nitrogen level.The results showed that the single panicle weight,1000 grains weight and yield of supplement irrigation treatment were higher than those of rainfed treatment;the single panicle weight,1000 grain weight,yield and harvest index could be increased by increasing the nitrogen application amount,but the nitrogen use efficiency decreased.The yield and nitrogen use efficiency of N200 treatment were the best in all treatments.4 Effects of water conditions and nitrogen application amounts on carbon and nitrogen of plant and soilNitrogen application was beneficial to the improvement of soil total nitrogen,ammonium nitrogen and nitrate nitrogen;but exceeded 250 kg/ha and began to decrease.Soil organic matter and soil microbial biomass carbon increased with the increase of nitrogen application.The results showed that supplement irrigation had no significant effect on soil organic matter and microbial biomass carbon;compared with rainfed treatment,supplement irrigation improved soil total nitrogen,ammonium nitrogen and nitrate nitrogen in the maize growth period with abundant rainfall.