Many laboratory studies investigating chlorophyll fluorescence (F) of plants have provided sufficient evidence of the functional link between dynamic changes in photosynthetic activity and F emissions. Far fewer studies, however, have been devoted to detailed analysis of F emission under steady-state conditions, which may be amenable to measurement by passive spectroradiometers onboard airborne or satellite missions. Here, we provide a random-effects meta-analysis of studies using both passively (sun-induced) and actively (e.g. laser-induced) measured steady-state F for detecting stress reactions in terrestrial vegetation. Specifically, we review behaviour of F in red and far-red wavelengths, and also the red to far-red F ratio, for plants physiologically stressed by water deficit, temperature extremes, and nitrogen insufficiency. Results suggest that water stress is, in general, associated with a decline in red and far-red F signal intensity measured at both leaf and canopy levels, whereas the red to far-red F ratio displays an inconsistent behaviour. Chilling, for which only studies with active measurements at the leaf level are available, significantly increased red and far-red F, whereas heat stress produced a less convincing decrease in both F emissions, notably in canopies measured passively. The clearest indicator of temperature stress was the F ratio, which declined significantly and consistently. The F ratio was also the strongest indicator of nitrogen deficiency, revealing a nearly uniformly increasing pattern driven by predominantly declining far-red F. Although significant knowledge gaps were encountered for certain scales and F measurement techniques, the analyses indicate that future airborne or space-borne acquisitions of both red and far-red F signals would be beneficial for timely detection of plant stress events.

Item Type:	Refereed Article
Keywords:	steady-state chlorophyll fluorescence, passive sun-induced fluorescence, active laser-induced fluorescence, photosynthesis, stress, water, temperature, nitrogen, random-effects meta-analysis, FLEX satellite mission
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Environment
Objective Group:	Ecosystem Assessment and Management
Objective Field:	Ecosystem Assessment and Management not elsewhere classified
Author:	Malenovsky, Z (Dr Zbynek Malenovsky)
ID Code:	105626
Year Published:	2015
Web of Science® Times Cited:	17
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2016-01-11
Last Modified:	2016-05-10
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