Desempenho produtivo e fisiológico da alface em sistema hidropônico sob temperatura elevada

Abstract

Lettuce is the most cultivated and consumed leafy vegetable in the world. Originate in areas with mild climate, its plants are very sensitive to conditions of high temperature and light, and therefore very difficult to grow it in areas with these climatic characteristics.Obviously, several breeding programs of the species around the world, They have enabled the development of cultivars adapted to different climatic conditions, even the typical low altitude and latitude regions where high light intensity and temperature are prevalent. Based on the above objective of this study was to evaluate the productive and physiological performance of lettuce cultivars hydroponically under high temperature and luminosity. The experiment was conducted in Caucaia-CE between April and June 2016. We used a completely randomized design with four cultivars (Isabela, Vanda, Elba and Crespa for summer) and four replications. The system used for cultivation was the NFT (Film Technical Nutrient). They evaluated the height and diameter of the plant (AP and PA), fresh weight and total dry (MFT and MST) and marketable fresh (MFC), the concentration of CO2 in substomatal chamber, stomatal conductance, photosynthetic rate, the reason between the concentration of CO2 in substomatal chamber and the ambient CO2 concentration, perspiration and the instantaneous efficiency of carboxylation. The means were compared by the Scott-Knott test. differences were observed among cultivars for the evaluated characteristics. The 'Elba' and 'Crespa for Summer' were the first to show signs of bolting and also greater height. The 'Isabela ' and 'Vanda' showed the highest values of MFC and MFT. As for the physiological performance of 'Isabella' and 'Crespa for Summer' had higher photosynthetic rate. Cultivar Isabela was the one with the best productive and physiological performance hydroponically under conditions of high temperature and luminosity, being more suitable for cultivation in these conditions.