Potencial de uso do silício na resistência a salinidade em alface hidropônico cultivado em ambiente semiárido

Abstract

The Brazilian semi-arid region is characterized by irregular rainfall and high evapotranspiration rates. Its edaphoclimatic characteristics make family farming in the region deficient, which can lead to episodes of abiotic stress in crops, making it necessary to take measures that can provide greater productivity and sustainability. Hydroponics is a soilless cultivation system that can be used on small properties, in reduced spaces, on poor soils, making it an excellent alternative for agricultural cultivation in the Semiarid region. However, the management of the nutrient solution used, which is responsible for the availability of important macro and micronutrients in the development of the crop, is extremely important for greater production optimization. The present study carried out an experiment with the objective of evaluating the performance of lettuce plants under conditions of saline stress, using an increase in silicon in the root through a hydroponic nutrient solution, aiming to mitigate the effects of abiotic stresses on lettuce grown in a semi-arid region. The experimental design used was completely randomized (DIC), with a 3x4 factorial scheme, with 3 doses of silicon (0; 0.4; 2.0 mol/L) and 4 doses of NaCl (1.5; 2.5; 3.5 and 4.5 dS/m) to analyze the effect of silicon on salt stress. The treatments were formulated based on the nutrient solution of Furlani (1999) with an increase in silicon and the control treatment was composed of the nutrient solution of Furlani (1999) without adaptations. In total, 12 treatments were formulated, with 6 replications each, totaling 72 experimental units. The morphological variables analyzed were: Fresh mass of the plant, total and commercial number of leaves per plant, Fresh mass of the aerial part, stem diameter, stem length, and head circumference. The biochemical analyzes analyzed were: Total soluble sugars, reducing and non-reducing sugars, silicon, pigments, membrane damage. An infrared gas analyzer - IRGA (Infra-Red Gas Analyzer, Lcpro) was used to analyze gas exchange. The results obtained from the response variables were subjected to analysis of variance using the F test with at least 95% confidence. For the isolated effect of silicon levels in the nutrient solution, the Tukey multiple comparison test was used (p < 0.05 ). The study found results under the negative effects of silicon associated with high doses of salinity, which generally affect plant growth, especially interfering with photosynthetic activity, culminating in the loss of metabolic efficiency of sugars and pigments.