Summer squash morphophysiology under salt stress and exogenous application of H2O2 in hydroponic cultivation

Abstract

Summer squash is a vegetable of significant acceptance in the market due to its economic and nutritional
importance, with the potential for expansion in the food industry. In this context, this study aimed to evaluate the gas exchange and growth of summer squash plants subjected to a saline nutrient solution and exogenous application of hydrogen peroxide. The study was conducted in a greenhouse in Pombal – PB. The cultivation system used was the Nutrient Film Technique (NFT) hydroponic system. The experimental design was completely randomized, in a 4 x 4 factorial arrangement, whose treatments consisted of four levels of electrical conductivityof the nutrient solution - ECns (2.1, 3.1, 4.1, and 5.1 dS m-1) and four concentrations of  hydrogen peroxide – H2O2 (0, 20, 40, and 60 μM), with three replications. The increase in the nutrient solution salinity from 2.1 dS m-1 reduced the leaf area and transpiration of the summer squash plants. Hydrogen peroxide at a concentration of 40 μM increased the root length, the instantaneous carboxylation efficiency, and the CO2 assimilation rate when the plants were subjected to the saline solution of 2.1 dS m-1. Also, the application of 60 μM H2O2 mitigated the effect of salt stress on the internal CO2 concentration and stomatal conductance of the summer squash plants.