Influence of different levels of irrigation and nitrogen application on the root growth and yield of spring wheat under permanent raised bed
CHEN Juan;MA Zhong-ming;LYU Xiao-dong;LIU Ting-ting;College of Agronomy, Gansu Agricultural University;Qingyang Academy of Agricultural Sciences;Gansu Academy of Agricultural Sciences;
To establish an optimum combination of water and nitrogen for spring under permanent raised bed( PRB) tillage,a field investigation was carried out to assess effects of irrigation and N application on root growth,yield,irrigation water productivity and N efficiency. The experiment followed a completely randomized split-plot design,taking furrow irrigation 1200 m~3·hm~(-2)(W_1),2400 m~3·hm~(-2)( W_2),3600 m~3·hm~(-2)(W_3) as main plot treatments,and N rates( 0,90,180,270 kg·hm~(-2)) the sub-plot treatments. Our results showed that the root mass density( RWD) was significantly affected by irrigation and N application,the RWD of spring wheat reached a maximum at the filling stage,followed by a slow decline until maturity,while the effect of N on RWD depended on soil water conditions. The application of N_2 produced the maximum RWD under W_2 irrigation,the application of N_1 produced the maximum RWD under W_1 irrigation,and the application of N_3 produced the maximum RWD under W_3 irrigation. The order of irrigation regime effect on RWD of spring wheat was W_2W_3W_1. The order of irrigation regime and N rate effect on RWD of spring wheat was irrigation N irrigation and N interaction. W_2N_2 treatment produced the highest RWD value. The root-to-shoot ratio( R / S) descended with the rising of irrigation water and nitrogen amount,and the combined treatment( W_1N_0) produced the maximum R/S. The root system was mainly distributed in the 0-40 cm soil layer,in which the RWD accounted for 85% of the total RWD in 0- 80 cm soil depth. There was a significantly positive relationship between RWD in the 0-40 cm and the yield of spring wheat,RWD in the 40-60 cm had higher linear dependence on the yield of spring wheat. W_2 increased the proportion of RWD in the deep soil layer( 40-60 cm). The irrigation and N rate had a significant impact on biomass and grain yield of spring wheat,the biomass increased as the N rate and water amount increased,W_2N_2 treatment produced the highest grain yield,irrigation water productivity descended with increasing the irrigation amount,and the nitrogen agronomic efficiency descended with increasing N rate. It was concluded that the irrigation level W_2( 2400 m~3·hm~(-2)) and nitrogen level N_2( 180 kg·hm~(-2)) could be recommended as the best combination of water and N,which promoted the root growth,improved grain yield,water and nitrogen use efficiencies of spring wheat production under PRB tillage in the experimental area.
【Fund】： 公益性行业(农业)科研专项(201503125-02);; 中澳国际合作项目(SMCN/2002/094);; 甘肃省农业科技创新项目(GNCX-2014-35)资助~~
【CateGory Index】： S512.12
【CateGory Index】： S512.12