EFFECT OF NITROGEN FORM ON YIELD, FRUIT NUMBER AND LEAF NUTRIENT CONTENT OF TWO GREENHOUSE CUCUMBER CULTIVARS IN SOILLESS CULTURE

Two experiments in two different seasons were conducted to study the effect of nitrogen form in nutrient solution on two greenhouse cucumber cultivars. Five nutrient solutions with different ratios of NH₄/NH₄+NO₃, two cucumber cultivars (‘Soltan’, ‘Pardis’), three replications and three plants in each plot were used in a split plot design. At the end of each experiment the characteristics of fruit yield and number and amount of nitrogen, phosphorus, potassium and calcium in leaves were measured. With compound analysis of two experiments the following results were obtained: Increasing NH₄-N in nutrient solution caused reduction in fruit yield and number, decreased fruit dry matter and increased total nitrogen and amount of phosphorus, but decreased potassium and calcium. This showed antagonistic effect of elements. Yield of ‘Pardis’ cultivar was more than ‘Sultan’ and also other characteristics were different between cultivars. According to the results of this research, we concluded that cucumber cultivars prefer NO₃-N to NH₄-N.