National Engineering and Technology Center for Information Agriculture, MOE Engineering and Research Center for Smart Agriculture, Key Laboratory for Crop System Analysis and Decision Making, Ministry of Agriculture, Jiangsu Key Laboratory for Information Agriculture, Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Sensors (Basel). 2020 Mar 12;20(6):1577. doi: 10.3390/s20061577.
Critical nitrogen (N) dilution curves (CNDCs) have been developed to describe the dilution dynamic of N and to diagnose N status in plants. In this study, to develop a convenient alternative CNDC determination method, four field experiments involving different N rates (0-360 kg N ha) and six wheat varieties were performed at different eco-sites from 2014 to 2019. The normalised difference red-edge (NDRE) index extracted from the RapidSCAN CS-45 (Holland Scientific Inc., Lincoln, NE, USA) sensor was used as a driving factor instead of plant dry matter (PDM) to establish a new alternative winter wheat CNDC. The newly developed CNDC was described by the equation Nc = 0.90NDRE, when NDRE values were ≤ 0.19 and constant Nc = 3.81%, which was independent of the NDRE values. Compared to PDM-derived CNDC (R = 0.73) developed with the same dataset, a comparable precision was obtained using NDRE-derived CNDC (R = 0.76) and both CNDCs could accurately discriminate wheat N status. Moreover, the NDRE could be inexpensively and rapidly measured using the active sensor. The relationship between NDRE-derived CNDC and grain yield was also analysed to facilitate in-season N management, and the R value reached 0.79 and 0.87 at jointing and booting stages, respectively. The NDRE-based CNDC can be used to effectively diagnose wheat N status and as an alternative approach for non-destructive determination of crop N levels.
临界氮（N）稀释曲线（CNDCs）已被开发用于描述 N 的稀释动态，并诊断植物中的 N 状况。在这项研究中，为了开发一种方便的替代 CNDC 测定方法，我们在 2014 年至 2019 年期间，在不同的生态位进行了涉及不同 N 速率（0-360 kg N ha）和六个小麦品种的四项田间试验。从 RapidSCAN CS-45（美国内布拉斯加州林肯的 Holland Scientific Inc.）传感器中提取的归一化差异红边（NDRE）指数被用作驱动因素，而不是植物干物质（PDM），以建立新的替代冬小麦 CNDC。新开发的 CNDC 通过方程 Nc = 0.90NDRE 进行描述，当 NDRE 值≤0.19 且常数 Nc = 3.81%时，该方程与 NDRE 值无关。与使用相同数据集开发的基于 PDM 的 CNDC（R = 0.73）相比，使用 NDRE 衍生的 CNDC 获得了相当的精度（R = 0.76），并且这两种 CNDC 都可以准确区分小麦的 N 状况。此外，使用有源传感器可以廉价且快速地测量 NDRE。还分析了 NDRE 衍生的 CNDC 与籽粒产量之间的关系，以促进田间 N 管理，在拔节期和孕穗期的 R 值分别达到 0.79 和 0.87。基于 NDRE 的 CNDC 可用于有效诊断小麦 N 状况，以及替代非破坏性测定作物 N 水平的方法。
