Frequencies of application and dilution of nutrient solution in hydroponic cultivation of arugula

Nutrient solution formulation such as irrigation frequency is fundamental for the success of hydroponic cultivation, since the absorption of nutrients from the nutrient solution is a selective and dynamic process, in which the relative proportion between nutrients in the solution stands out. Thus, the present experiment was conducted to evaluate the production and development of arugula in hydroponic cultivation subjected to different dilutions and frequencies of application of the nutrient solution. The experiments were carried out in a randomized blocks design, with four replicates. A split-plot scheme in a 5 x 2 factorial arrangement was used, which consisted of five dilutions based on the electrical conductivity of the nutrient solution (ECsol: 2.00 (control), 1.81, 1.62, 1.40, and 1.30 dS m-1, corresponding to 100, 90, 80, 70, and 65% concentrations, respectively)  and two application frequencies (variable and fixed), totaling 40 experimental plots, in three production cycles. Shoot fresh mass, shoot dry mass, leaf area, leaf area index, number of leaves, plant height, relative chlorophyll index and macronutrients were analyzed. Regarding shoot fresh mass, there was an increase with the concentration of the nutrient solution, reaching a maximum of 15.52 and 8.40 g plant-1, with nutrient solution was of 1.77 dS m-1 (first cycle) and 1.88 dS m-1 (second cycle). Using only 90% of the recommended nutrient solution is the most appropriate from the commercial point of view, as it led to maximum potential in relation to production, using a smaller number of inputs.