The Effects of Foliar Application of Urea, Calcium Nitrate and Boric Acid on Growth and Yield of Greenhouse Cucumber (cv. Khassib)

Cucumis sativus L. is one of the most eminent and consuming vegetables which is widely cultivated in the Middle East. Using the controlled and greenhouse cultivation is one of the most appropriate methods to increase production per unit area. In this method, controlling the effective factors of production such as plant nutrition is the important factor to achieve high performance. Besides the accuracy applied in nutritional regulation of plant roots (both in soil and hypothermic environments), in many cases, foliar nutrition is considered by breeder of greenhouse productions. Foliar nutrition is more effective on young leaves, and deficiency of macro and micro nutrients can be removed by this factor. Khassib is one of the most important cultivar of greenhouse cucumber which is widely cultivated in Iran. The present study was conducted to evaluate the effect of foliar application on greenhouse cucumber.
The experiment was performed on greenhouse cucumber (cv. Khassib) for five months (from March 2007 to July 2008) in Ziba Dasht Technical Instruction Center which is located near Karaj, Iran. For this reason the experiment was conducted based on split-split-plot design with three replications. Eight experimental treatments were applied for foliar application including U1C1B1: urea calcium nitrate 溊 acid, U1C1B0: urea calcium nitrate, U1C0B1: urea boric acid, U1C0B0: urea, U0C1B1: calcium nitrate boric acid, U0C1B0: calcium nitrate, U0C0B1: boric acid, U0C0B0: control. The effects of urea, calcium nitrate and boric acid in concentrations 3, 10 and 0.5 (gL-1) respectively on qualitative and quantitative characteristics of greenhouse cucumber, including fruit yield, yield of first class fruit, number of fruits, percentage of first class fruit, fruits T.S.S, plant length, percentage of leaf dry matter, and leaf weight ratio were studied.
The results showed that calcium nitrate had a significant effect on fruit yield at 5% probability level. Foliar application of calcium nitrate with concentration of 10 gL-1resulted in an increase of yield so that the average of fruit yield for sprayed plants was 3917.9 g per plant, while this value in control plants was 3576.5 g. Boric acid with concentration of 0.5 gL-1 had a remarkable effect on fruit yield at 5% probability level that enhanced the average of yield from 3591.6 to 3902.8 g per plant. The interaction of U×C×B treatment on fruit yield at 1% probability level was significant, while this value was not found among other treatments. Foliar application with calcium nitrate results in an increase of yield and production in young and growing fruits. The augmentation of yield in treatment U1C0B0 due to the facts that pure urea and calcium nitrate have 46% and 16% nitrogen, respectively, i.e., extra nitrogen causes toxicity and branching instead of fruiting. Among threeway interactions, U×C×B statistically had a remarkable impact on the yield of first class fruit at 1% probability level and also the maximum and minimum of this value belonged to U1C0B0 and control, respectively. Only U×C×B had a remarkable impact on plant length among all interactions. Generally, the growth of cucumber depends on genetic features, temperature and soil productivity. The highest level of leaf area index was for calcium nitrate that indicated the significant effect at 5 % probability level with the mean of 15.89. When we compare the foliar application treatments with fosamko, it can be found that the spraying treatments affected leaf dry matter significantly at 1% and 5% probability levels, while this value was not found for control treatments. However, there was no significant difference between using and not using nutrition compared to fosamko on yield.
According to the findings of the present study the following factors can be concluded: a) Among the main effects, calcium nitrate played the eminent role on most traits, after that boric acid and finally urea carried this role; b) Among two-way interaction, only U1B1, as foliar application, significantly affected the yield of grade 1 fruit; c) Among three-way interactions, only U1C0B0, as foliar application, significantly affected the yield of grade 1 fruit, total fruit and the number of fruit; d) There was no a significant change on qualitative features of cucumber using nutrition compared to fosamko. Therefore, cucumber production can be performed by cheaper methods with no change in qualitative characteristics. Finally, due to the fact that cucumber is one of the most important vegetables in Iran, it is suggested that various studies with different fertilizers will be conducted on cucumber.