Effects of nitrogen fertilizer and intercropping patterns on crop root growth, nitrogen uptake, and yieldOA

In the arid regions of northern Xinjiang Uygur Autonomous Region(hereafter referred to as northern Xinjiang),China developing intensive and sustainable cropping patterns is crucial for ensuring food security and promoting green agricultural development.As a typical cereal and legume intercropping system,maize and peanut intercropping demonstrates significant potential to enhance yield and resource use efficiency.However,the effects of nitrogen management and row configuration on crop productivity and inter-specific interactions under the unique ecological conditions of in northern Xinjiang remain unclear.This study employed a field experiment with four planting patterns(maize monoculture(MM),peanut monoculture(MP),four rows of maize intercropped with four rows of peanuts(4M4P),and six rows of maize intercropped with six rows of peanuts(6M6P))and five nitrogen application levels(0(N_(0)),100(N_(100)),200(N_(200)),300(N_(300)),and 400(N_(400))kg/hm^(2)).The results showed that under the 6M6P intercropping pattern combined with the N_(200) application level,maize morphological parameters were significantly improved,with plant height increasing by 10.48%,stem base circumference by 13.64%,and root length density(RLD)by 47.63%.Additionally,adaptive root morphological responses of maize were promoted in deeper soil depths,with RLD increasing by 15.48%-54.76%in the 0-60 cm soil depth.Intercropping significantly inhibited peanut growth and root development,as reflected by reductions of 12.37%in main stem height,27.01%in dry matter weight,and 15.73%-25.23%in RLD in the 0-20 cm soil dept.However,nitrogen application at the N_(200) level effectively alleviated this inhibition,increasing peanut aboveground nitrogen accumulation by 80.12%-92.93%compared with the N_(0) level.Although the peanut nitrogen harvest index(NHI)decreased by 6.21%-7.06%relative to MM,it remained at a relatively high level.This planting configuration also significantly enhanced maize dry matter accumulation(increased by 28.50%)and nitrogen uptake(increased by 38.65%-55.21%)compared with MM.The nitrogen use efficiency(NUE)of both crops was the highest at the N_(100) and N_(200) levels,whereas N_(300) and N_(400) levels suppressed the aforementioned indicators.A positive correlation was observed between dry matter accumulation and nitrogen accumulation.Nitrogen translocation was enhanced in maize and allocation to grains was improved through improved morphological plasticity and root system adaptation,as reflected by its NHI,remaining at a high level of 79.54%-83.00%.This configuration achieved the highest land equivalent ratio(1.30)and maize grain yield under the experimental conditions.Together,these findings elucidate how nitrogen management and row configuration regulate crop growth and competitive dynamics in intercropping systems,providing a scientific basis for optimizing cereal and legume intercropping management in arid regions.