Effect Of Water Regulation On Soil Nitrogen And Root Crown Growth Of Spring Maize And Root Crown Growth In Spring Maize

To investigate the effect of irrigation quota and distribution on the spatial and temporal distribution of soil nitrogen,root distribution and yield of spring maize,this study was conducted in Wangtuan Township,Concentric County,Ningxia,China in 2021 using ’Xiangyu 698’ as the test material in a split-zone experimental design,with the main zone being different irrigation quotas M:M1(3300m3/hm2)and M2(3750m3/hm2),and the split zone was the distribution of irrigation quotas in different fertility periods:D1(seedling-nodulation-loud trumpet-flowering-filling and harvesting:5%-10%-20%-35%-30%)and D2(seedling-nodulation-loud trumpet-flowering-filling and harvesting:10%-15%-25%-20%-30%),with a total of 4 treatments.We measured soil water and nitrogen,maize dry matter and nitrogen accumulation,maize root distribution and yield,analyzed the effects of different treatments on soil water and nitrogen,root morphological characteristics,nitrogen uptake and utilization and seed yield in the root layer of maize,and found out the optimal irrigation quotas and distribution ratios to provide a theoretical basis for water management and sustainable agricultural development of maize under film drip irrigation in the Yang Huang irrigation area of Ningxia.The main research results are as follows:1.High irrigation quotas and higher allocation ratios at the seedling-large trumpet stage of maize significantly improved soil water use efficiency.In the 0-40 cm soil layer,the water use efficiency of M2 treatment was 12.76%higher than M1 treatment,and the water use efficiency of D2 treatment was 4.67%higher than D1 treatment.The average soil water content of M2D1 treatment was 5.59%,1.21%and 1.32%,8.90%,11.69%and 8.83%higher than that of M1D1,M1D2 and M2D2 treatments in the 0-20 cm and 20-40 cm soil layers,respectively,throughout the reproductive period.2.The spatial and temporal changes of soil total nitrogen,nitrate nitrogen and ammonium nitrogen were significantly affected by irrigation quota and distribution method.Soil total nitrogen was highest in the M1D2 treatment with 2.41 g-kg-1 at harvest,and soil nitrate and ammonium nitrogen were highest in the M2D1 treatment in the 0-80 cm soil layer throughout the reproductive period.3.There was a negative correlation between irrigation quota and root distribution,and higher irrigation quota combined with irrigation allocation ratio toward flowering stage could prolong root life cycle and enhance root vigor.In the 0-40 cm soil layer of maize,all root system indicators showed higher irrigation rate in M1 treatment than in M2 treatment and higher allocation method in D2 treatment than in D1 treatment.The effects of irrigation quota and allocation method on the average root vigor of each treatment throughout the reproductive period were not significantly different,but the M2D2 treatment had higher root vigor in the late reproductive period(mid-irrigation).4.Higher irrigation quotas with appropriately lowered irrigation allocations in the early stage and elevated irrigation allocations in the flowering stage could maintain higher efficient leaf area in the later stage,which had positive effects on plant dry matter accumulation and nitrogen accumulation.Post-flowering dry matter accumulation under irrigation quota and allocation conditions was higher in M2D1 treatment by 18.35%,77%and 50.29%compared to M1D1,M1D2 1 and M2D2 treatments,respectively,and nitrogen accumulation in the spike was higher in M2D1 treatment by 15.73%,10%and 9.88%compared to each treatment at harvest.5.Higher irrigation rates combined with higher allocation ratios at the seedling-large trumpet stage were more favorable for maize cob trait formation and yield improvement.13.98 t/hm2 was the highest yield in the M2D2 treatment,and among the treatments,the average maize yield in the M2 irrigation treatment was 20.13%higher than that in the M1 irrigation treatment,and 7.60%higher in the D2 treatment than that in the D1 treatment.Maize yield was significantly or highly significantly positively correlated with its constituent factors,and soil water content was correlated with soil nitrate nitrogen content and spring maize root characteristics.Soil moisture,nitrogen and maize roots were significantly correlated with yield formation under different irrigation quotas and allocation methods,with the best performance of M2D2 treatment,i.e.,irrigation quotas of 3750 m3/hm2 and irrigation allocation ratios of seedling-pulling-loud trumpeting-flowering-filling and harvesting:10%-15%-25%-20%-30%,for maize yield and water The efficiency of maize yield and water use was the highest.Therefore,an irrigation quota of 3750 m3/hm2 combined with a moisture management model that appropriately increases the allocation ratio of the tubercle and plucking stages is recommended for spring maize production in the Yang Huang irrigation area of Ningxia to obtain a higher maize yield.