Respostas fisiológicas da rúcula ao cultivo sob telas fotoconversoras no inverno e verão

Abstract

Despite producing best in mild temperatures, the rocket has been cultivated throughout the year in various regions. In tropical areas, the use of photoconversor screens of different shading levels modify the intensity of solar radiation and the spectrum of light on the crops , also changing the temperature of the environment . The aim of this study was to evaluate the physiological responses of the rocket under photoconversor screens during the winter and summer in tropical climate region in São Paulo state. The impact of this technology on productivity and anatomy was evaluated. The field experiment was conducted in randomized block design with four replications. The rocket was grown in beds covered on the top and sides with the screens red, blue, black and thermo-reflective. Additionally the treatment in full sun was evaluated. The response curve to light, chlorophyll fluorescence, chlorophyll content, adaxial and abaxial epidermis, palisade and spongy, stomatal density and venation were evaluated. The evaluation of fresh and dry biomass and productivity was performed when the rocket reached 450 degree day. The results showed that photoconversor screens distinctly modify the environment during the winter and summer, but do not cause significant changes in the photosynthetic process of plants in different screens colors and seasons studied, as well as the density of epidermal cells. In all treatments the spongy parenchyma was higher than palisade parenchyma in the summer, the reverse occurred in winter. Changes in the intensity and spectrum of light as well as the temperature provided superior performance of red screens, with higher values of height and leaf area in the winter and of the thermo-reflective screens in the summer.