Relationships between the photochemical reflectance index (PRI) and chlorophyll fluorescence parameters and plant pigment indices at different leaf growth stages.
This study aimed to evaluate the photochemical reflectance index (PRI) for assessing plant photosynthetic performance throughout the plant life cycle. The relationships between PRI, chlorophyll fluorescence parameters, and leaf pigment indices in Solanum melongena L. (aubergine; eggplant) were studied using photosynthetic induction curves both in short-term (diurnal) and long-term (seasonal) periods under different light intensities. We found good correlations between PRI/non-photochemical quenching (NPQ) and PRI/electron transport rate (ETR) in the short term at the same site of a single leaf but these relationships did not hold throughout the life of the plant. In general, changes in PRI owing to NPQ or ETR variations in the short term were <20 % of those that occurred with leaf aging. Results also showed that PRI was highly correlated to plant pigments, especially chlorophyll indices measured by spectral reflectance. Moreover, relationships of steady-state PRI/ETR and steady-state PRI/photochemical yield of photosystem II (Φ(PSII)) measured at uniform light intensity at different life stages proved that overall photosynthesis capacity and steady-state PRI were better correlated through chlorophyll content than NPQ and xanthophylls. The calibrated PRI index  accommodated these pigments effects and gave better correlation with NPQ and ETR than PRI. Further studies of PRI indices based on pigments other than xanthophylls, and studies on PRI mechanisms in different species are recommended.
Department of Biological and Environmental Engineering, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
Parinaz
P
Rahimzadeh-Bajgiran
Masashi
M
Munehiro
Kenji
K
Omasa
D002138:Calibration; D002734:Chlorophyll / Q000378:metabolism*; D004579:Electron Transport / Q000528:radiation effects; D005453:Fluorescence; D055668:Photochemical Processes / Q000528:radiation effects; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism* / Q000528:radiation effects; D012044:Regression Analysis; D032322:Solanum / Q000254:growth & development* / Q000502:physiology* / Q000528:radiation effects; D013997:Time Factors
D002734:Chlorophyll