Journal
PLANT AND SOIL
Volume 354, Issue 1-2, Pages 45-55Publisher
SPRINGER
DOI: 10.1007/s11104-011-0955-z
Keywords
Chlorophyll fluorescence; Chlorophyll pigments; Gas exchange; Photosystem II photochemistry; PRI; Remote sensing; Salinity treatment
Categories
Funding
- U.S. Army Corps of Engineers/Engineer Research and Development Center (ERDC)
- U.S. Army RDECOM ARL Army Research Office [W911NF-06-1-0074]
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The photochemical reflectance index (PRI) is correlated to photosynthetic efficiency and has been successfully applied at multiple scales for remote estimation of physiological functioning. However, interpretation of the PRI signal can be confounded by many different variables including declines in photochemical pigments. Our study was aimed at investigating PRI in response to salinity stress, and evaluating physiological and pigment responses of two co-occurring shrubs, Baccharis halimifolia and Myrica cerifera in laboratory studies. Photosynthesis, water relations, chlorophyll fluorescence, hyperspectral reflectance and leaf pigment contents were measured following salinity treatment. Physiological measurements indicated that both species exhibit adaptations which protect PSII during periods of stress. Chlorophyll fluorescence parameters were affected in both species, but indicated that other photochemical reactions (e.g. photorespiration) were important for energy dissipation in absence of chlorophyll changes. After many days of reduced photosynthesis, photochemical changes were detectable using PRI indicating chronic stress. Variations in PRI were not related to changes in pigments but strongly related to tissue chlorides indicating salinity effects on the PRI signal. Thus, PRI is an indicator of salinity stress in these coastal species and may be as an early signal for increasing salt exposure associated with rising sea-level and climate change.
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