Silicon Application Contributes to Efficient Gas Exchange in Tomato Plants

The study aimed to analyze the effect of silicon application on tomato crops subjected to different water management conditions. The experiment was conducted in a completely randomized design with two water replacement conditions (60 and 100% of crop evapotranspiration - ETc), four forms of silicon application (no application, full-dose soil application, split soil application and foliar application) with four replicates. When the plants were in the reproductive stage, gas exchange analysis was performed in two periods (critical period before water replacement and after water replacement). The photosynthesis rates, internal CO2, stomatal conductance, transpiration, and instantaneous water use efficiency were determined. The data were subjected to analysis of variance and the means compared by the Tukey test with 5% significance. The application of silicon caused significant variation in gas exchange in tomato leaves, with an increase in rates and an increase in instantaneous water use efficiency. The application of silicon promotes an increase in gas exchange in tomato plants, whether in adequate water conditions or with a deficit in the crop. The application of the element, via soil and foliar, showed a significant increase in gas exchange in tomato plants. The best results were obtained for application via soil, regardless of the water condition or time of evaluation.