A MANIPULAÇÃO DA QUALIDADE DA LUZ ASSOCIADA À UV-B MELHORA A FOTOSSÍNTESE E OS TEORES DE RUTINA EM MICROTOMATEIRO CULTIVADO EM AGRICULTURA VERTICAL

Abstract

Urban vertical agriculture with lighting system can be a green infrastructure alternative to increase local food production regardless of environmental and soil conditions. In this system, light quality control can improve the plant physiological performance, in addition to being associated with the induction of metabolic pathways that contribute to the phenolic compound production important to human health. Therefore, this study aimed to evaluate the influence of white and monochromatic (red and blue) wavelengths associated with UV-B on photosynthetic performance and production on phenolic compounds in microtomato fruits cultivated in vertical agriculture. The experimental design adopted was completely randomized, with six light qualities (white, white + UV, blue, blue + UV, red, and red + UV), light intensity of 300 µmol.m-2s-1, a photoperiod of 12 h, and application of UV-B radiation for 1 h daily, and an average intensity of 3.7 W.m-2, being adopted six replicates per treatment for the physiological evaluations. Twenty-six days after the treatment installation, evaluations of gas exchange, chlorophyll a fluorescence, nocturnal breathing, and photorespiration were carried out. Fruits in the ripening stages (green, orange, and red) were collected for identification and quantification of the phenolic compounds (chlorogenic acid and rutin) to improve the physiological and metabolic performance of microtomato plants with different light qualities. This study identified that plants under blue light + UV showed higher photosynthetic rates (A=11.57 µmol.m-2.s-1) and a higher amount of rutin in fruits at all maturation stages, both in plants under blue light and under blue + UV. Meanwhile, photosynthetic efficiency [reduction in photosynthetic rate (A), stomatal conductance (gs), effective quantum yield of photosystem II (YII), and Electron Transport Rate (ETR) variables] was affected under red light condition, requiring the activation of suppressive mechanisms as found, in reason of the highest values of nocturnal respiration and unregulated quantum yield of the non-photochemical dissipation of the photosystem II (YNO). These results highlight the importance to select light spectral bands in the vegetable cultivation to produce fruits with a greater amount of secondary metabolites and that can act as compounds of color, flavor, and health promotion, special interest fact to producers in sustainable cropping systems.