Unique contributions of chlorophyll and nitrogen to predict crop photosynthetic capacity from leaf spectroscopy. (16th September 2020)

• Record Type: Journal Article
• Authors: Wang, Sheng; Guan, Kaiyu; Wang, Zhihui; Ainsworth, Elizabeth A; Zheng, Ting; Townsend, Philip A; Li, Kaiyuan; Moller, Christopher; Wu, Genghong; Jiang, Chongya
• Editors: Lawson, Tracy
• Is Part Of: Journal of experimental botany. Volume 72:Number 2(2021)
• Page Start: 341
• Page End: 354
• Publication Date: 2020-09-16
• Subjects: Bioenergy crop -- chlorophyll -- CO2-saturated photosynthetic rate -- hyperspectral leaf reflectance -- maize -- nitrogen -- partial least squares regression -- radiative transfer model; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/eraa432
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : Leaf chlorophyll content and nitrogen concentration have unique contributions to predict maize photosynthetic capacity. Radiative transfer model accurately predicts chlorophyll, while generalized data-driven partial least squares regression estimates nitrogen better. Abstract: The photosynthetic capacity or the CO2 -saturated photosynthetic rate ( V max ), chlorophyll, and nitrogen are closely linked leaf traits that determine C4 crop photosynthesis and yield. Accurate, timely, rapid, and non-destructive approaches to predict leaf photosynthetic traits from hyperspectral reflectance are urgently needed for high-throughput crop monitoring to ensure food and bioenergy security. Therefore, this study thoroughly evaluated the state-of-the-art physically based radiative transfer models (RTMs), data-driven partial least squares regression (PLSR), and generalized PLSR (gPLSR) models to estimate leaf traits from leaf-clip hyperspectral reflectance, which was collected from maize ( Zea mays L.) bioenergy plots with diverse genotypes, growth stages, treatments with nitrogen fertilizers, and ozone stresses in three growing seasons. The results show that leaf RTMs considering bidirectional effects can give accurate estimates of chlorophyll content (Pearson correlation r =0.95), while gPLSR enabled retrieval of leaf nitrogen concentration ( r =0.85). Using PLSR with field measurements for training, the cross-validation indicates that V max can be well predicted from spectra ( r =0.81). The integration of chlorophyll content (strongly related to visible spectra) and nitrogen concentration (linked to shortwave infrared signals) can provide better predictions of V max ( r =0.71) than only using either chlorophyll or nitrogen individually. This study highlights that leaf chlorophyll content and nitrogen concentration have key and unique contributions to V max prediction.