ASD--Temporal and Spatial Variation Analysis of Maize Canopy Chlorophyll and Leaf Chlorophyll Based on Leaf Spectrum

Based on this, in this study, a research team from the Institute of Crop Science of the Chinese Academy of Agricultural Sciences and the College of Agriculture of Ningxia University took maize as the research object and conducted research in 2019 and 2020 in the Chinese Agricultural The Xinxiang Experimental Station of the Academy of Sciences established various canopy structures through five nitrogen treatment gradients (0, 100, 200, 300 and 400 kg/hm2 (denoted as N0–N400)), collected canopy leaves of crops in different growing seasons, and measured the Its LCC and leaf spectral reflectance (ASD FieldSpec 4 spectrometer + plant probe + leaf clip, spectral range 350-2500 nm)

The main goals are:

(1) Understand the effect of nitrogen application on the vertical distribution of chlorophyll in the canopy of maize and the dynamic changes of chlorophyll distribution in the growing season;

(2) Explore the difference in spectral reflectance characteristics of canopy leaves under different spatiotemporal conditions and verify whether the VI model based on leaf spectral reflectance can accurately invert LCC;

(3) Determine sensitive leaf positions (which can be used to characterize the relationship between LCC and CCC) and evaluate the robustness and accuracy of the leaf spectrum-based VI model to assess canopy chlorophyll status

Top view (a) of the study area on September 2, 2020

【result】

Vertical section of the corn canopy LCC during the 2020 growing season

(a, c, e) Spectral reflectance curves of leaves at different positions

rRMSE (%) of 6 LCC-VI models: (a) mRER, (b) VOG2, (c) CIred-edge, (d) NDRE, (e) MTCI and (f) DD

The mid-term model (a), the late model (b) and the reproductive model (c) are compared between the predicted CCC values ​​and the measured values ​​in 2019

【in conclusion】

Five nitrogen application levels were used to construct different maize canopy structures, revealing the vertical heterogeneity of maize canopy leaf chlorophyll content (LCC) and leaf spectral reflectance characteristics

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