Liu Weixing, Ma Geng, Wang Chenyang, Wang Jiarui, Lu Hongfang, Li Shasha, Feng Wei, 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 Feb 1;9:32. doi: 10.3389/fpls.2018.00032. eCollection 2018.
Unreasonably high irrigation levels and excessive nitrogen (N) supplementation are common occurrences in the North China Plain that affect winter wheat production. Therefore, a 6-yr-long stationary field experiment was conducted to investigate the effects of irrigation and N regimes on root development and their relationship with soil water and N use in different soil layers. Compared to the non-irrigated treatment (W0), a single irrigation at jointing (W1) significantly increased yield by 3.6-45.6%. With increases in water (W2, a second irrigation at flowering), grain yield was significantly improved by 14.1-45.3% compared to the W1 treatments during the drier growing seasons (2010-2011, 2012-2013, and 2015-2016). However, under sufficient pre-sowing soil moisture conditions, grain yield was not increased, and water use efficiency (WUE) decreased significantly in the W2 treatments during normal precipitation seasons (2011-2012, 2013-2014, and 2014-2015). Irrigating the soil twice inhibited root growth into the deeper soil depth profiles and thus weakened the utilization of soil water and NO-N from the deep soil layers. N applications increased yield by 19.1-64.5%, with a corresponding increase in WUE of 66.9-83.9% compared to the no-N treatment (N0). However, there was no further increase in grain yield and the WUE response when N rates exceeded 240 and 180 kg N ha, respectively. A N application rate of 240 kg ha facilitated root growth in the deep soil layers, which was conducive to utilization of soil water and NO-N and also in reducing the residual NO-N. Correlation analysis indicated that the grain yield was significantly positively correlated with soil water storage (SWS) and nitrate nitrogen accumulation (SNA) prior to sowing. Therefore, N rates of 180-240 kg ha with two irrigations can reduce the risk of yield loss that occurs due to reduced precipitation during the wheat growing seasons, while under better soil moisture conditions, a single irrigation at jointing was effective and more economical.
在中国华北平原，不合理的高灌溉量和过量施氮现象普遍，影响冬小麦生产。因此，开展了一项为期6年的定位田间试验，以研究灌溉和施氮制度对根系发育的影响，以及它们与不同土层土壤水分和氮素利用的关系。与不灌溉处理（W0）相比，拔节期单次灌溉（W1）显著提高了产量，增幅为3.6%至45.6%。随着灌水量增加（W2，开花期第二次灌溉），在较干旱生长季（2010 - 2011年、2012 - 2013年和2015 - 2016年），与W1处理相比，籽粒产量显著提高了14.1%至45.3%。然而，在播种前土壤水分充足的条件下，正常降水季节（2011 - 2012年、2013 - 2014年和2014 - 2015年），W2处理的籽粒产量并未增加，水分利用效率（WUE）显著降低。对土壤进行两次灌溉会抑制根系向更深土层生长，从而削弱对深层土壤水分和硝态氮的利用。施氮使产量提高了19.1%至64.5%，与不施氮处理（N0）相比，水分利用效率相应提高了66.9%至83.9%。然而，当施氮量分别超过240和180 kg N·ha时，籽粒产量和水分利用效率的响应并未进一步提高。240 kg·ha的施氮量促进了深层土壤根系生长，有利于土壤水分和硝态氮的利用，也有助于减少硝态氮残留。相关性分析表明，籽粒产量与播种前土壤储水量（SWS）和硝态氮积累量（SNA）显著正相关。因此，180 - 240 kg·ha的施氮量配合两次灌溉可以降低小麦生长季降水减少导致的产量损失风险，而在土壤水分条件较好时，拔节期单次灌溉有效且更经济。
