Cultivo de pimentão hidropônico utilizando água com diferentes qualidades: salobra, residuária e de chuva.

Abstract

The quantitative and qualitative water scarcity, coupled with the high saline levels of the semi-arid reservoirs, make sustainable farming in many cases unfeasible. In addition, harnessing the water and nutritional potential of domestic wastewater is a viable alternative for these regions. In this sense, the use of management strategies that enable the combined use of brackish water, rainwater and domestic effluent in the preparation of nutrient solution can be an effective strategy in hydroponic cultivation. From this perspective, the objective was to study the viability of growing cv. All Big in a hydroponic module, taking advantage of available brackish water, domestic effluent and rainwater. Two experiments were carried out in a protected environment belonging to CTRN / UFCG in hydroponic module. The first experiment consisted of the mixture between saline water (SW) and domestic effluent (DE), resulting in six proportions: P1 = 50% SW + 50% DE; P2 = 40% SW + 60% DE; P3 = 30% SW + 70% DE; P4 = 20% SW + 80% DE; P5 = 10% SW + 90% DE; P6 = 100% DE) and two nutritional concentrations of the nutrient solution (S1 = 80% and S2 = 100%) of the recommended amount for hydroponics, resulting in 12 treatments and 60 experimental units, conducted under a completely randomized experimental design in a factorial scheme. 6 x 2, with 5 repetitions and 3 useful plants per repetition. In the second experiment, the treatments consisted of the mixture between saline (SW) and rainwater (RW), resulting in 4 proportions: P1 = 10% SW + 90% RW; P2 = 20% SW + 80% RW; P3 = 30% SW + 70% RW; P4 = 40% SW + 60% RW) and three concentrations of hydrogen peroxide (H2O2) [C1 = 0.0 (Control); C2 = 7.5 μM; C3 = 15 μM], resulting in 12 treatments and 60 experimental units, under a completely randomized experimental design, in a 4 x 3 factorial scheme, with 5 repetitions and 3 useful plants per repetition. The obtained data were subjected to analysis of variance by the 'F' test, at a level of 0.05 and 0.01 probability and in case of significance, the interaction between the factors or the main factors alone, Tukey test was performed. In general terms, it was found that the application of nutrient solution in the proportion of 30% brackish water (SW) + 70% domestic effluent (DE) and 80% nutritional concentration promotes higher fruit mass production per sweet pepper plant. The proportions between brackish water and domestic effluent do not promote photoinhibitory damage to FSII reaction centers. The application of H2O2 promotes the acclimatization of pepper plants to the salinity of the nutrient solution, however in salinity higher than 3.32 dS m-1 the application of 15 μM intensified the deleterious effects of salinity of the solution. The highest fruit yield was obtained with 30% brackish water + 70% rainwater nutrient solution, with the application of 7.5 μM H2O2.