Response And Simulating Of Growth And Water Productivity Of Maize For Seed Production Under Water And Nitrogen Stress In Arid Area Of Northwest China

Aiming at the problems of shortage of water resources and low fertilizer use efficiency in maize for seed production in arid Northwest China,the methods of combining field experiment and model simulation were adopted.Field experiment about water and nitrogen stress was conducted in Shiyanghe Experimental Station for Water-saving in Agriculture and Ecology in Gansu province in 2018-2019.The responses of growth,yield,harvest index,water productivity and nitrogen utilization efficiency to water and nitrogen stress were investigated.The effects of water and nitrogen stress on dry matter and nitrogen partitioning in maize for seed production were analyzed.The model of water productivity based on Logistic formula was established?The water and nitrogen stress function based on Jensen and Blank formula was constructed,respectively,and the parameters of the water nitrogen stress function to the water productivity based on biomass model and the harvest index were determined.In addition,a model of dry matter and nitrogen partitioning for maize for seed production was constructed.A total of four aspects of the research results are outlined as follows:?1?The effects of water and nitrogen stress on evapotranspiration,biomass,yield,kernel number,harvest index,nitrogen uptake,partitioning index,and nitrogen partitioning index for maize for seed production in arid Northwest China were analyzed.With the aggravation of water and nitrogen stress,evapotranspiration,biomass,yield,kernel number and nitrogen uptake was decreased.Nitrogen application can alleviate the reduction of yield caused by water stress in a certain range.However,nitrogen stress had no significant effect on evapotranspiration and dry matter and nitrogen partitioning.?2?The differences in water nitrogen stress between water productivity based final biomass(WP_B-ET)and water productivity based yield(WP_Y-ET)were were further revealed.WP_B-ETwas relatively insensitive to ET while WP_Y-ETsignificantly reduced with the decrease of ET,and the reason of this difference was related to the HI and kernel number.In this area,higher and yield were obtained when more than 75%of the field water capacity of the soil under the plastic mulch was maintained in combination with nitrogen application at 75?150 kg N hm^-2.?3?A model of dry matter and nitrogen partitioning in the maize for seed production was established based on growing degree day,and the characteristics of dry matter and nitrogen partitioning in different periods were simulated.The simulation results were generally good,and the simulation effect of the distribution model on the partitioning index is better than that on the nitrogen partitioning index.?4?The model of water and nitrogen stress function based on Jensen formula and Blank formula was constructed,and the model of water productivity function based on Logistic formula and harvest index were modified.The relative errors between the simulated value and the measured values on biomass,harvest index,and yield of the newly constructed water nitrogen function model are all about 20%.The error between the simulated value and the measured value of water productivity and nitrogen uptake are about 30%.The simulation accuracy of the phased water and nitrogen stress function model based on Jensen formula and Blank formula was compared.The water and nitrogen stress function based on Jensen formula can better reflect the influence of water and nitrogen stress on the growth of maize for seed production.