Abstract
Investigations were carried out to examine the effect of high electric conductivity (EC) on the growth of spinach under artificial light conditions, by either raising the concentration of nutrients, or by addition of NaCl to the hydroponic culture solution.
Increasing the strength of the nutrient solution by raising the concentration of nutrients to the range of 5.0 dS/m, significantly increased the leaf fresh weight. However, increasing the concentration of individual macronutrients ; nitrate, phosphate and potassium, or even micronutrients, had no effect on plant growth.
Addition of NaCl to the standard Strength (2.3 dS/m) nutrient solution, promoted plant growth depending on the level of the relative humidity (RH). The highest plant growth rate was realized with 2 g/liter NaCl at 75±5% RH, and with lg/liter NaCl at 60±5% RH, respectively.
Water loss in leaves after harvesting, was higher in the control plants than in the treatment plants grown with additional NaCl. However, NaCl treatment did not affect the nitrate and oxalate contents in the leaves.
