Environmental stress evaluation of Coffea arabica L. leaves from spectrophotometric fingerprints by PCA and OSC–PLS–DA

Abstract

The effects of hydric stress and sunlight access conditions on metabolic compounds in coffee leaves were investigated utilizing statistical mixture design extractor solvents. PCA and OSC–PLS–DA chemometric methods were used to analyze UV–visible spectra of irrigated and non-irrigated Coffea arabica L. leaves from low (80 cm, light exposed) strata. The first latent variable of the OSC–PLS–DA score plot perfectly discriminated extracts of 34 calibration and 14 validation samples of irrigated and non-irrigated leaves. Higher spectral signals observed at the 410, 505, 535, 607 and 665 nm wavelengths are attributed to conjugate double bond pigments, mainly pheophytin a, indicating that non-irrigated conditions are more stressful than irrigated ones for this species. No significant difference was found for leaf sample extracts with varying light access conditions. Keywords: Coffea arabica L. leaves, Hydric stress, Mixture design, PCA, OSC–PLS–DA