PHOTOSYNTHETIC LIMITATIONS IN LEAVES OF TOMATO PLANTS SUBJECTED TO INCREASING SALT CONCENTRATIONS - DOI: 10.13083/1414-3984.v22n02a05

Abstract

The aim of this study was to evaluate gas exchange, fluorescence parameters of chlorophyll a, photosynthetic pigment concentration, and osmotic potential in tomato plants subjected to increasing salt concentrations. For this purpose tomato plants, cultivar Santa Clara, were grown in 5dm-3 pots containing Hoagland nutrient solution and subjected to treatments of 0, 50, 100 and 150 mM NaCl. The experiment was conducted in a greenhouse of the University Federal de Viçosa in a completely randomized design with four replications. Each experimental unit consisted of one pot containing two plants. The results showed that the osmotic potential in leaves and roots decreased significantly as the NaCl concentration in the nutrient solution increased by detecting the elevation of stress on the plants. The use of energy for the photosynthetic processes and dissipation of excess energy in photosynthetic machinery was compromised by increasing salt concentrations imposed by the treatments, reducing photosynthesis and photochemical efficiency demonstrated by gas exchange and the fluorescence parameters of chlorophyll a, indicating that there was damage to the photosynthetic apparatus in the biochemical phase. The photosynthetic pigments decreased significantly with increasing salt concentration, limiting the absorption of photosynthetically active radiation.