Using an Active Sensor to Develop New Critical Nitrogen Dilution Curve for Winter Wheat

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&#8722;360 kg N ha<sup...

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Bibliographic Details
Main Authors: Jie Jiang, Cuicun Wang, Yu Wang, Qiang Cao, Yongchao Tian, Yan Zhu, Weixing Cao, Xiaojun Liu
Format: Article
Language:English
Published: MDPI AG 2020-03-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/20/6/1577
Description
Summary: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&#8722;360 kg N ha<sup>-1</sup>) 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<sup>&#8722;0.88</sup>, when NDRE values were &#8804; 0.19 and constant Nc = 3.81%, which was independent of the NDRE values. Compared to PDM-derived CNDC (R<sup>2</sup> = 0.73) developed with the same dataset, a comparable precision was obtained using NDRE-derived CNDC (R<sup>2</sup> = 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<sup>2</sup> 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.
ISSN:1424-8220