Drought-induced Plant Pigment Dynamics and Light Use Efficiency of Photosynthesis: the Role of Remote Sensing in Early Stress Detection

Authors: Phuong D. Dao*, Department of Geography, University of Toronto Mississauga, Yuhong He, Department of Geography, University of Toronto Mississauga
Topics: Remote Sensing, Spatial Analysis & Modeling
Keywords: chlorophyll fluorescence, plant photosynthesis, light use efficiency, grassland drought, hyperspectral remote sensing
Session Type: Paper
Day: 4/3/2019
Start / End Time: 8:00 AM / 9:40 AM
Room: Stones Throw 2 - Slate, Marriott, Lobby Level
Presentation File: No File Uploaded

This study aims to explore the impact of drought stress on the light use efficiency of photosynthesis, and how close-range hyperspectral spectral reflectance and imagery can be used as the indicators of these changes. Two growth-chamber drought experiments were conducted on the natural Bromus inermis and Bromus inermis seedling grown from seeds, which was collected from Jokers Hills, King City, Ontario, Canada. Accordingly, eight natural grass samples and six seedling samples were grown under chamber-controlled environments and applied with four water treatments including 100%, 75%, 50%, and 25% of field precipitation to generate different drought intensities. For drought impact examination, the changes in light use efficiency (LUE) parameters (the maximum quantum yield of photosystem II (PSII) (Fv/Fm), the quantum yield of PSII (–§PSII), non-photochemical quenching (NPQ)) and gas exchange parameters (photosynthetic rate and stomatal conductance) were analyzed. The utility of spectral indices including photochemical reflectance index (PRI) derived from leaf-level spectral reflectance and close-range canopy hyperspectral imagery in detecting and monitoring the drought-induced changes on grasses was evaluated. Leaf chlorophyll and carotenoid contents retrieved from remote sensing were also evaluated to explore how the light was absorbed and used in the photochemical processes. The results show that LUE parameters Fv/Fm, –§PSII, and NPQ are well correlated with PRI at both leaf and canopy levels. The results suggest the use of non-destructive close-range PRI-based examination of plant photosynthetic performance under drought stress conditions. The study provides useful information to assist with early stress detection, stress evolution monitoring, and early recovery.

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