Influence of nutrient solution composition on yield and quality of spinach grown in floating system.

In soilless cultivation, nutrient solution composition affects directly quality-quantitative traits of vegetables. The aim of the current research was to investigate the effect of four nutrient solutions having different nutrient proportions (SN = 0.46 NO3/ 0.02H2PO4/ 0.02SO4/ 0.18K/ 0.20Ca/ 0.12Mg; SS = 0.02NO3/ 0.02H2PO4/ 0.46 SO4/ 0.18K/ 0.20Ca/ 0.12Mg; SK = 0.38NO3/ 0.04H2PO4/ 0.08 SO4/ 0.46K/ 0.02Ca/ 0.02Mg; SCa = 0.38NO3/ 0.04H2PO4/ 0.08SO4/ 0.02K/ 0.46Ca/ 0.02Mg) and three concentrations (20, 40 and 80 meq L-1) of total macronutrients (N-NO3, S-SO4, P-H2PO4, K, Ca, Mg) in the nutrient solution on yield and quality of spinach grown in floating system. After 40 days from sowing, leaf fresh weight, total carbohydrate concentration, vitamin C and nitrate were recorded. High proportion of NO3- (TN) and K+ (TK) in the nutrient solution at the highest macronutrient concentration (80 meq L-1) gave plants with high fresh weight and nitrate, while treatments with high proportion of SO42- (TS) produced plants with low concentration of nitrate and high concentration of carbohydrates. High proportion of Ca2+ (TCa) in nutrient solution increased the concentration of vitamin C in leaves.