EFEITO DE DIFERENTES LUMINÁRIAS LED NA FOTOSSÍNTESE DE ALFACE CULTIVADA EM AMBIENTE CONTROLADO.

Abstract

The prospects for population growth over the next 30 years show that more efficient production systems will be essential, such as indoor cultivation, in which production takes place within a fully controlled environment, including artificial lighting. LED lighting in agricultural systems allows you to modulate the spectrum in order to meet the needs of the plants. Red, blue and green lights are often used and are highly active for photosynthesis. However, little is known about the response of plants to this type of light. In this work, the response of lettuce plants (Lactuca sativa) under different light spectra was evaluated. Plants were grown under different combinations of blue, red and green LED lights for a period of 20 days in indoor cultivation. Biochemical parameters such as chlorophyll a, chlorophyll b, chlorophyll a/b ratio and physiological parameters such as chlorophyll “a” fluorescence and gas exchange were evaluated. After the final data collection, the results were submitted to analysis of variance (ANOVA) and to the Snott-Knott test at 5% of probability. In the results of the physiological parameters, there was an intense overlap of averages, making it impossible to point out a prominent treatment. At the end of acclimatization, treatment L1 (33.83% Blue, 22.29% Green, 44.05% Red) promoted an increase in the values of net photosynthesis rate (A), stomatal conductance (gs) and transpiration (E), while the values of internal carbon (Ci) decreased. The wavelengths of the L1 treatment in the 'delícia' and 'verdão' varieties induce higher values of Fv/Fm (0.75) in plants of the species. Considering the five varieties studied, at the end of the experiment, 100% survival was obtained for plants that showed adequate development of leaves and roots, regardless of the type of LED lamp used for each treatment. This study contributes for the understanding of lettuce metabolism and it helps the improvement of the indoor cultivation process of the species.