Morfologia e produção de cultivares de tomate sob saturação luminosa e estresse salino.

Abstract

Morphology and yield of tomato cultivars under light saturation and salt stress. Using saline water has been increasing in agriculture in several countries, considering the need to increase the supply of food, by incorporating land and water of low quality to the productive sector. In this sense, it is essential to identify genotypes tolerant to salinity, evaluating their effects on physiological and production parameters. In this work, we evaluated the effects of salinity on growth and production, and the effects of light intensity variation on the gas exchange of two varieties of tomato, a cherry cultivar and a table one were studied. In greenhouse, we studied three levels of water electrical conductivity (ECa = 0.6, 3.0 and 6.0 dS m-1) and four light intensity levels, factorially combined (2x3x4), resulting in 24 treatments, with four replicates. Plants were grown in plastic pots (25 kg), constituting the plot of two pots, one plant per unit. The light intensity levels were adjusted using an external source in an Irga (LcPro +, ADC-England) apparatus, calibrated to the values of 0, 400, 800 and 1200 μmol of m-2 s-1 photons. We evaluated growth variables (plant height, leaf number and stem diameter), yield (fruit mass per plant, longitudinal and radial diameter of fruits) and physiological variables (stomatal conductance, transpiration, carbon in the substamatic chamber and photosynthesis) on plants. Data were analyzed by F-test, comparing the mean values of the salinity levels by the Tukey's test (p < 0.05), and regression analysis was done with the data referring to the levels of light intensity. We verified that the levels of light intensity significantly affected the gas exchanges of the two evaluated tomato cultivars. The light benefited the photosynthetic process up to a certain level, but with the excess of light energy, the photosynthesis was impaired. Of the two varieties studied, cherry tomatoes were more tolerant than table tomatoes.