Optimal Nitrogen Fertilization Rates and form for Cucumber in Plastic House

A field experiment was carried out during 1999/2000 growing season to determine the relationship between nitrogen and cucumber yield, as well as to optimize the nitrogen quantity and form for cucumber growth under green house conditions. The research included two experiments. In the first experiment, two-cucumber cultivars were planted (Anas and Super) and subjected to three different combinations of four fertilizers (Ammonium sulfate, 20-20-20, .KNO3, Urea). In the second experiment different nitrogen levels (0, 16.43, 30.87, 46.58, and 62.30 Kg N/ dunum) were applied to summer cucumber cultivar IV36. The results of the first experiment indicated that there were no significant differences in yield among different treatments for the first cultivar (Anas), compared to other cultivar (Super) which had significant differences in yield among treatments. The results indicated that the maximum yield (5528 Kg /du) in the second cultivar (Super) was obtained when (KNO}, Urea, 20-20-20) were used. For plant length there were no significant differences among treatments for the two cultivars. Maximum leaf numbers (69.5) were obtained when (Ammonium sulfate, KNO3, 20-20-20) were applied. For the second experiment the highest total yield was 9721 Kg/dunum (du), which was obtained when 30.87 Kg N/du were added. Maximum marketable yield was found when 27.2 Kg N/du was added. The yield at this amount was 7665 Kg/du. Maximum profit was obtained when 22.34 Kg/du of pure N fertilization were added. The nitrogen analysis for both fruits and leaves indicated that the nitrogen content in the fruits was significantly different among treatments, while in leaves there were no significant differences among treatments.