Eggplant (Solanum melongena L.) culture in hydroponics under greenhouse and shade net with saline stress

Plants are exposed to factors that limit their growth and yield, such as environmental conditions and salinity. The present research evaluated growth and ionic concentrations in eggplant plants in hydro- ponics under greenhouse and shade net with saline stress by NaCl. Doses of NaCl 0 mM, 15 mM, 30 mM and 45 mM were applied to eggplant grown in the two structures. The variables evaluated were: yield, dry biomass, foliar area, SPAD units, normalized difference vegetation index (NDVI) and ion concentration in NO3-, K+, Ca2+ and Na+ leaves. The results showed significant differences (p <= 0.05) in the protected structures, with increases in yield, foliar area, NDVI and NO3- concentration in leaves under the shade net. Under the NaCl doses applied, 15 mM NaCl decreased dry biomass and foliar area; with doses of 30 mM and 45 mM the yield decreased and the concentration of NO3- was lower with doses of 30 mM and 45 mM, however, the concentration of Ca2+ and Na in leaves increased. The applied dose of 15 mM of NaCl decreased dry biomass and leaf area; the yield and the concentration of NO3- was lower with doses of 30 mM and 45 mM, however, increased the concentration of Ca2+ and Na+ in leaves. The interaction between the factors under study showed that applying 15 mM and 30 mM of NaCl in greenhouse increases the biomass, the concentration of Ca2+ and Na+ in the leaves and in the shade net increased the concentration of NO3- and Ca2+ on the leaves. The 45 mM dose negatively affected the yield on both structures. In the cultivation of eggplant under the shade mesh structure with saline stress, the negative effects on plant growth were minimized.