Liu Weixing, Wang Jiarui, Wang Chenyang, Ma Geng, Wei Qiongru, Lu Hongfang, Xie Yingxin, Ma Dongyun, Kang Guozhang
College of Agronomy, Henan Agricultural University, Zhengzhou, China.
State Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, China.
Front Plant Sci. 2018 Dec 5;9:1798. doi: 10.3389/fpls.2018.01798. eCollection 2018.
Excessive nitrogen (N) application combined with water shortage has a negative effect on crop production, particularly wheat ( L.) production in the North China Plain. This study examined root growth and water and nitrogen use efficiencies in wheat grown on loam soil in the North China Plain, from 2012 to 2014 using a fixed-position experiment initiated in 2010. The experiment followed a completely randomized split-plot design with four replications, taking irrigation [no irrigation (W0) versus irrigation at jointing plus flowering (W2)] as the main plot and N treatment (0, 180, 240, and 300 kg N ha) as the subplot. Compared with W0, W2 increased grain yield and root weight density (RWD) by up to 91.3 and 57.7% in 2012-2013, and 15.5 and 43.0% in 2013-2014, respectively, across all N application rates. Irrigation had no effect on grain water use efficiency (WUE), but caused a decrease in biomass WUE at vegetative growth stage (WUE) and at grain-filling stage (WUE). Significant improvements in grain yield and biomass WUE during vegetative growth stage, and reductions in nitrogen-use efficiency (NUE) and RWD, were observed with increasing N application. Compared with non-N treatment, N treatment increased yield by up to 98.9 and 93.7% in 2012-2013 and 2013-2014, respectively, decreasing RWD by 12.0 and 16.9%. Correlation analysis further revealed that RWD was positively correlated with grain yield, evapotranspiration (ET) and NUE. NUE was also positively correlated with nitrogen uptake efficiency (UPE). Overall, the findings suggest that optimal N application improves NUE by increasing above-ground nitrogen uptake as a result of optimized RWD and a synchronous increase in WUE, thus increasing yield. Under the experimental conditions, an N application rate of 240 kg N ha plus irrigation at jointing and flowering is recommended.
过量施氮与缺水相结合会对作物产量产生负面影响，对华北平原的小麦（L.）生产影响尤为明显。本研究利用2010年启动的定位试验，于2012年至2014年对华北平原壤土上种植的小麦根系生长及水分和氮素利用效率进行了研究。试验采用完全随机裂区设计，重复4次，以灌溉方式[不灌溉（W0）与拔节期加开花期灌溉（W2）]为主区，氮处理（0、180、240和300 kg N·ha）为副区。与W0相比，在所有施氮量水平下，W2在2012 - 2013年使籽粒产量和根重密度（RWD）分别提高了91.3%和57.7%，在2013 - 2014年分别提高了15.5%和43.0%。灌溉对籽粒水分利用效率（WUE）没有影响，但导致营养生长阶段生物量水分利用效率（WUE）和灌浆期生物量水分利用效率（WUE）降低。随着施氮量增加，营养生长阶段籽粒产量和生物量WUE显著提高，而氮素利用效率（NUE）和RWD降低。与不施氮处理相比，施氮处理在2012 - 2013年和2013 - 2014年分别使产量提高了98.9%和93.7%，RWD分别降低了12.0%和16.9%。相关性分析进一步表明，RWD与籽粒产量、蒸散量（ET）和NUE呈正相关。NUE与氮素吸收效率（UPE）也呈正相关。总体而言，研究结果表明，最佳施氮量通过优化RWD和同步提高WUE来增加地上部氮素吸收，从而提高NUE，进而提高产量。在试验条件下，建议施氮量为240 kg N·ha，并在拔节期和开花期进行灌溉。
