Water yield and consumption of cauliflower plants grown in a hydroponic system using brackish waters and different flow rates

Studies related to the use of natural brackish waters, water consumption, and flow rates of nutrient solutions applied to cauliflower plants are incipient in Brazil. The objective of this study was to evaluate the water yield and consumption by cauliflower plants grown under the use of brackish waters based on chemical characteristics of waters from wells of the Brazilian semiarid, grown in nutrient film technique (NFT) hydroponic system. A completely randomized design with four replicates was used, in a 6 × 2 factorial arrangement, consisted of six different waters to prepare the nutrient solution and two flow rates. The waters were formulated based on a simulation of brackish waters from wells of different communities of the municipality of Ibimirim, state of Pernambuco, Brazil, which presented electrical conductivities of 1.67, 3.30, 4.71, 5.88, and 13.84 dS m-1, and municipal public water. The flow rates of the nutrient solution used were 1.5 and 2.5 L min-1. The use of brackish waters to prepare the nutrient solutions and refilling the solutions lost by evapotranspiration decreased the water consumption and cauliflower yields, with higher magnitude for the flow rate of 2.5 L min-1. The highest water yield values of the shoot fresh and dry biomasses were found for the calcium chloride water. The best water for the cauliflower production was the calcium sulphate water, and the worse was the S2 magnesium chloride water. The use of all waters is viable for cauliflower production, except the S2 magnesium chloride water; however, the use of the flow rate of 2.5 dS m-1 results in higher decrease in crop yield.