Effects Of Water-fertilizer Coupling Under Mulched Drip Irrigation On Maize Yield And Water Use Efficiency

Water scarcity is a great challenge for sustainable agricultural development,and also is an important factor leading to reduced soil productivity and ecological degradation in arid regions.Therefore,improving water resource use efficiency was an essential way to develop economic and regional stability.With the advance of science and technology,water-saving irrigation technologies such as drip irrigation combined with mulching film cultivation technology and had been largely applied.Maize is a major field cultivation crop in Hexi region,and the application of film mulched drip irrigation water-fertilizer coupling technology and its optimal water-fertilizer management was significant to increase maize yield and improve water use efficiency.In our study,different irrigation quotas and fertilizer application levels on growth index,water consumption,yield,root characteristics of soil profile and water use efficiency of maize under mulched drip irrigation were carried out in the arid areas,and a water-fertilizer coupled regression model was established to determine the optimal irrigation quotas and fertilizer application.The main research findings are as follows:(1)The different water and nitrogen treatments affected maize plant height,diameter thickness,leaf area index and aboveground dry matter mass,and the overall trend of each index increased with increasing water and nitrogen fertilization from the whole reproductive period,with the maximum values occurring in the T3F2 treatment under high water fertilization conditions.In addition,the above-ground dry matter mass of maize with the number of days after sowing could be better fitted by logistic function.(2)The root system was the main organ for water and nutrient uptake by plants,and the root weight density showed an overall increasing trend with the increase of irrigation and fertilization.The root weight density of each treatment gradually decreased with the increase of soil layer in each reproductive period.From the whole soil layer,90%of the root system of maize was in the 0-60 cm soil layer from the jointing stage to the flowering stage.The exponential function could better fit the relationship between the root weight density of maize and the depth of soil layer in each fertility period.The root to shoot ratio tended to increase and then decrease as the fertility period progressed.(3)Irrigation water is an important factor affecting soil moisture,and the soil water content tends to increase relatively with the increase of irrigation water.With the increase of irrigation water,the water consumption of maize also increased accordingly.The maximum water consumption occurred at high levels of irrigation,but for the same level of irrigation,the effect of different fertilizer applications on corn water consumption was not significant.For maize yield,irrigation had a greater effect than fertilizer application on maize yield.With increasing irrigation,yield increased by 20.93%and 15.50%on average.For water use efficiency,T2F1 was the smallest and T3F2 was the largest.In addition,both irrigation and fertilizer application had highly significant effects on maize ears grain weight,ears grain number and yield,but not on 100 grain weight.However,for the interaction of irrigation and fertilizer application,there was no significant effect on yield and water use efficiency.It was also found that as the water consumption ET increased,the yield increased gradually and leveled off,and the relationship between water consumption ET and yield could be expressed as a quadratic function.Finally,based on the least squares principle,a regression model between maize yield and irrigation and fertilizer application was developed(R~2was 0.966).The theoretical optimal irrigation and fertilizer application combination was determined based on the nature of the regression model.The T3F2 treatment was not only optimal in growth index and above-ground dry matter quality,but also obtained the highest yield and water use efficiency.The research also established a water-fertilizer coupling regression model for maize,and established the theoretical optimal water and fertilizer amounts,which could provide theoretical basis and practical experience for the water and fertilizer management of maize in the region.