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Title: Dynamic response of plant chlorophyll fluorescence to light, water and nutrient availability

Author
item CENDRERO-MATEO, M.P. - University Of Arizona
item Carmo Silva, Ana
item NEARING, G.S. - University Of Arizona
item PORCAR-CASTELL, A. - University Of Helsinki
item Hamerlynck, Erik
item PAPUGA, S.A. - University Of Arizona
item Moran, Mary

Submitted to: Functional Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2015
Publication Date: 6/1/2015
Citation: Cendrero-Mateo, M., Carmo Silva, A.E., Nearing, G., Porcar-Castell, A., Hamerlynck, E.P., Papuga, S., Moran, M.S. 2015. Dynamic response of plant chlorophyll fluorescence to light, water and nutrient availability. Functional Plant Biology. 42:746-757. doi: 10.1071/FP15002.

Interpretive Summary: Water deficit limits plant photosynthesis and decreases crop yield. An important challenge is to establish a rigorous landscape-scale indicator of plant photosynthesis. The emission of fluorescence from plant chlorophylls provides direct measure of plant photosynthesis. Chlorophyll fluorescence can be measured at both field and landscape-scale using satellite-based sensors. However, the relationship between plant photosynthesis and chlorophyll fluorescence changes with water availability and light intensity. In this study, we determined that at ambient growth light conditions chlorophyll fluorescence is directly correlated with photosynthesis and it can be use as a water-deficit indicator. The results from this study provides quantitative support for the proposed observation time (09:30-10:00 AM) of the upcoming European Fluorescence Explorer (FLEX) satellite mission for monitoring plant responses to water deficit, as well as a promising starting point for interpretation of seasonal changes in crops growth using satellite-based sensors.

Technical Abstract: Water deficit limits net photosynthesis (Anet) and decreases crop yields. An important challenge for basic and applied research is to establish a rigorous landscape-scale indicator of Anet. Chlorophyll fluorescence (ChF) can be used at the field scale as an indirect measure of Anet in both healthy and physiologically-perturbed vegetation, and has the potential to assess Anet over large areas using satellite-based sensors. The objectives of this study were to determine the relationship between Anet, ChF and non-photochemical quenching (NPQ) with changes in light intensity, and to define the optimum photosynthetic active radiation (PAR) range for assessing physiological plant status with ChF. Gas exchange and ChF light-response curves were measured with a portable photosynthesis system in Camelina sativa plants grown under controlled conditions that were either well-watered or subjected to water deficit. A new analytical model was derived to explain the change in ChF due to varying light intensity, which demonstrated that NPQ has a direct control over ChF. Modeling results showed that at irradiance levels close to those used for plant growth (300-500 'mol m-2 s-1) ChF was directly correlated with Anet, inversely correlated with NPQ, and differed significantly between the well-watered and water-deficit treatments. The optimum PAR range for using ChF as a water deficit index corresponded to the range in which NPQ was most strongly associated with the PAR energy de-excitation pathway. This new information provides a promising starting point for interpretation of seasonal changes in crops growth using satellite-based sensors.