مشخصات پژوهش

The effect of various Mg concentrations (0, 1, 2, 3 and 4 mM) in the nutrient solution on plant growth, fruit quality and sugars content in hydroponicallygrown cucumber (Cucumis sativuscv. Nagen 792) under optimum(100%)and low (50%) light intensities was evaluated.The results showed that the decreases in the dry matter, SPAD index and soluble protein and accumulation of soluble sugar and starch content in the leaves Mg deficiency (0 mM Mg)are suggestive of decreased growth, and the decrease induced by Mg deficiency was bigger under low light intensity than under optimum light intensity. Plant growth was improved at 3 mM Mg, but it was reduced when the Mg concentration increased (4 mM Mg). Concentration of Mg in the leaf and fruit increased drastically with increasing Mg in the nutrient solution. This became steadily more pronounced under low light intensity. Mg deficiency plants (0 mM Mg) developed visible symptoms- interveinal necrosis in middle leaves, especially optimum light intensity.Fruit quality traits such as fruit dry matter percentage and total soluble solid (TSS) and fruit Fv/Fm were increased at higher concentration of Mg (3 mM) in the solution, especially under optimum light intensity. But, fruit firmness was improved at lower concentration of Mg (1 mM) in the solution especially in optimum light intensity In conclusion, Mg requirement of cucumber plants likely increases with light intensity. Thus, higher concentration of Mg (3 mM) in thenutrient solution was the most favorable for cucumber plant growth and fruit quality grown in hydroponics.