Cultivo de girassol em sistema hidrop?nico sob diferentes níveis de salinidade

摘要

Hydroponic systems have constituted an alternative for combating the adverse natural factors of agricultural production in the semi-arid regions of Brazil, such as shallow rocky and infertile soils, and the scarcity of good quality water resources (high salt content). This work studied the yield of the sunflower (variety EMBRAPA 122/V-2000) destined for achene and fodder (phytomass) production, grown hydroponically, using coconut fiber as substrate and irrigated with brackish water of varying salinities. The experimental layout used was completely randomized into a 5 x 2 factorial design with three replications, five levels of water salinity and two planting density - with one or two plants per pot being studied. The irrigation water was composed of 50% standard nutrient solution and 50% municipal water supply, with added levels of NaCl, resulting in an eletrical conductivity (ECw) of 1.7; 4.3; 6.0; 9.0 and 11.5 dS m-1. The differential density of the sunflower plants positively affected the yield components of grain and biomass, showing greater viability when using two plants per pot.