Relationship between physiological and biochemical measurements with spectral reflectance for two Phaseolus vulgaris L. genotypes under multiple stress.

Hyperspectral reflectance is becoming an increasingly popular source of information for plants' physio-chemical status. In this study, net photosynthetic rate (A) and the activity of four antioxidant enzymes of Phaseolus vulgaris L., superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX), were compared with hyperspectral data using regression methods (principal component regression (PCR) and partial least squares regression (PLSR)) and vegetation indices (normalized difference vegetation index (NDVI), photochemical reflectance index (PRI), water index (WI) and the normalized reflectance (R) ratio R710/R750). The experiment was conducted on potted plants of two common bean genotypes ('Blue lake' and 'Terli'), receiving four treatments (control, drought, salinity and drought + salinity), in an unheated greenhouse. The results suggest that both types of abiotic stress have a significant impact on the photosynthetic operation and the function of the antioxidant mechanism. The two regression methods performed well in predicting photosynthetic rate (A), while a strong correlation between A with the two vegetation indices was also revealed. Antioxidant enzymes appeared to be correlated with the WI (GPX and SOD enzymes) and the normalized reflectance (R) ratio R710/R750 (APX and SOD enzymes). Hyperspectral data seem to be particularly useful for fast and non-destructive assessment method for photosynthesis and enzymes activity of common bean plant. [ABSTRACT FROM AUTHOR]