Wang Mingxia, Zhao Ben, Niu Xiaoli, Chu Wanqiang, Lv Guijun
School of Hydraulic Engineering, Yellow River Conservancy Technical University, Kaifeng, Henan, China.
College of Tobacco Science, Henan Agricultural University, Zhengzhou, Henan, China.
Front Plant Sci. 2025 Jul 1;16:1609847. doi: 10.3389/fpls.2025.1609847. eCollection 2025.
The nitrogen nutrition index (NNI) of winter wheat decreased under water deficit conditions, primarily due to an increase in the critical nitrogen concentration (%N) associated with a reduction in shoot biomass (SB). However, the effect of plant nitrogen concentration (PNC) on NNI under water deficit conditions remains unclear. This study aimed to: (1) determine whether significant differences in PNC and leaf nitrogen concentration (LNC) of winter wheat exist among different water treatments under controlled conditions; (2) analyze the reasons for changes in PNC and LNC under water deficit conditions; and (3) assess the stability of relationships between PNC and LNC, as well as between plant nitrogen accumulation (NAp) and leaf area index (LAI), across different water treatments.
To address the above mentioned objectives, a series of rainout shelter experiments were conducted during the winter wheat growing seasons from 2018 to 2021.
The results indicated that water deficit treatments limited PNC and LNC values at specific growth stages of winter wheat under controlled conditions. However, such severe water deficits are unlikely to occur in typical field conditions; thus, PNC was not identified as the primary factor affecting NNI in field environments experiencing water deficit. Component analysis clarified the causes behind the decline in PNC and LNC. The decline in specific leaf area (SLA) and leaf biomass fraction (LBF) contributed to the decrease in PNC, with SLA accounting for more variation than LBF. Similarly, declines in both SLA and specific leaf nitrogen (SLN) led to reduced LNC, with SLN explaining more variation in LNC than SLA across different water treatments. LNC was jointly controlled by both PNC and the ratio of SLN to LBF. Furthermore, water deficit did not alter the proportional linear relationship between NAp and LAI, suggesting that the impact of water deficit on PNC and LNC is limited, which helps a better understanding of the factors contributing to the declination of NNI.
在水分亏缺条件下，冬小麦的氮营养指数（NNI）会下降，这主要是由于与地上部生物量（SB）减少相关的临界氮浓度（%N）增加所致。然而，水分亏缺条件下植物氮浓度（PNC）对NNI的影响仍不清楚。本研究旨在：（1）确定在可控条件下，不同水分处理的冬小麦PNC和叶片氮浓度（LNC）是否存在显著差异；（2）分析水分亏缺条件下PNC和LNC变化的原因；（3）评估不同水分处理下PNC与LNC之间以及植物氮积累（NAp）与叶面积指数（LAI）之间关系的稳定性。
为实现上述目标，在2018年至2021年冬小麦生长季进行了一系列防雨棚试验。
结果表明，水分亏缺处理在可控条件下限制了冬小麦特定生长阶段的PNC和LNC值。然而，这种严重的水分亏缺在典型田间条件下不太可能发生；因此，在经历水分亏缺的田间环境中，PNC未被确定为影响NNI的主要因素。成分分析阐明了PNC和LNC下降的原因。比叶面积（SLA）和叶片生物量分数（LBF）的下降导致了PNC的降低，其中SLA比LBF解释了更多的变异。同样，SLA和比叶氮（SLN）的下降均导致LNC降低，在不同水分处理下，SLN比SLA解释了更多LNC的变异。LNC由PNC以及SLN与LBF的比值共同控制。此外，水分亏缺并未改变NAp与LAI之间的比例线性关系,这表明水分亏缺对PNC和LNC的影响有限，这有助于更好地理解导致NNI下降的因素。
