Physiological features of Potato (Solanum tuberosum L. Var. Diacol Capiro) canopy reflectance changes under different levels of water stress

The analysis of the plant's spectral signature makes it possible to identify specific metabolic responses through variations in reflectivity, measured from high-resolution spectral images, at both canopy and vegetation levels. In potato, reflectance variations and their relationship with photosynthetic behavior under water stress have been scarcely studied, particularly regarding stress assessments based on xylem water potential. In this study, the relationships between xylem water potential, changes in net photosynthesis, stomatal conductance, and transpiration, as well as variations in spectral response in the visible region considering specific bands and vegetation indices, were analyzed. Spectral measurements of light reflectance in the VIS region at canopy level, water potential, and leaf gas exchange parameters were performed at tuber differentiation and maximum tuberization phenological stages under three intensities of water stress (light, moderate and severe). Under moderate and severe water stresses, increases in canopy reflectance were observed from 530 to 570 nm, 660 – 670 nm and around 700 nm. The 400R/690R and 450R/550R ratios showed the strongest association and dependence with gas exchange variables under different water stress levels, in both growth stages. These results contribute to the monitoring of photosynthetic performance and the detection of water stress events in potato plants.