ROCKET PRODUCTION IN A LOW COST HYDROPONIC SYSTEM USING BRACKISH WATER

ABSTRACT The production of vegetables in communities of family farmers in semiarid regions is limited due to rudimentary cultivation practices and systems, water scarcity, and excess salts in the water and soil. Thus, the objective of this work was to evaluate the production of rocket (Eruca sativa L. cv. Folha Larga) in a low cost hydroponic system, considering strategies for the use of brackish water in the nutrient solution. The experiments were conducted in complete randomized designs, in 6×2 factorial arrangements, with five replications, using rocket plants grown in different nutrient solutions, consisting of six salinity levels (1.5, 3.0, 4.5, 6.0, 7.5, and 9.0 dS m -1) and two circulation frequencies of the nutrient solution (twice a day, at 8:00h, and 16:00h; and three times a day, at 8:00h, 12:00h, and 16:00h). In Experiment I, the nutrient solution lost by evapotranspiration was replenished with the respective brackish water used in its preparation; and in Experiment II it was replenished with public water (0.12 dS m -1). The shoot and root fresh and dry biomass of the plants and their respective dry weight proportions, and biometric variables were evaluated. Replenishing of the nutrient solution with public water resulted in lower losses in biomass and plant growth. The increases in circulation frequency of the nutrient solution did not affect the biometric variables, however, the plants prioritized shoot biomass development to the detriment of the root when using high circulation frequencies. RESUMO A produção de hortaliças em comunidades de agricultores familiares, residentes em condições semiáridas, são limitadas por práticas e sistemas rudimentares de cultivo, escassez hídrica e problemas de salinidade. Neste sentido, o objetivo do presente trabalho foi analisar a produção de rúcula, cv. Folha larga, em sistema de hidroponia de baixo custo, adotando-se estratégias de uso da água salina no preparo e reposição da solução nutritiva evapotranspirada. Em dois experimentos, plantas de rúcula foram expostas a seis níveis de salinidade da solução nutritiva (1,5; 3,0; 4,5; 6,0; 7,5 e 9,0 dS m -1) aplicadas em duas frequências de circulação (duas vezes ao dia - às 8 e 16 horas; três vezes ao dia - às 8, 12 e 16 horas). O delineamento experimental adotado foi inteiramente casualizado, em esquema fatorial 6 x 2, com cinco repetições, sendo que, no Experimento I a reposição da solução nutritiva foi efetuada com a respectiva água salina utilizada no prep