The effect of nitrogen nutrition and ethephon spray on flowering and some photosynthetic characteristics cucumber Victor

Fruits and vegetables are important part of the human diet and among these products cucumber has a particular importance. Field cucumbers usually produce more male flowers than female flowers.The importance of the production of female flower in the formation of fruit and its direct relation to the yield of the product is the reason for the study of the factors affecting the stimulation and production of female flower. Therefore, the aim of this study was to investigate the role of nitrogen and ethephon hormone and their interaction on flower arrangement and the gender of the cucumber flowers. Also, the effect of ethephon and nitrogen nutrition on photosynthetic parameters was investigated to clarify the physiological mechanisms of these two treatments on flowering.

This experiment performed as split plot format in a completely randomized design and Potted in a greenhouse with three replications and six treatments in Sari Agricultural sciences and Natural Recourses University (SANRU) during 2017-2018. The main plot was consisted 0 and 0.5 mM ethephon and the subplot consisted urea at 0, 2 and 4 g.L concentrations. The first spray started with urea and then three days later it was sprayed with ethephon. The second stage of urea spraying was carried out five days after the first spraying and again, three days after the urea second stage, the ethephon was repeated and this process was carried out for the third stage. In this research, the effect of ethephon and urea fertilizer studied and some parameters including the number of male and female flowers, the flower morphology characteristics such ovary diameter, corolla length and pistil length and certain gas exchange parameters such as transpiration rate, co2 assimilation rate and stomatal conductance evaluated.

The highest number of male flower observed in the control (44.3) and urea 2 per thousand without the use of ethephon (44). In addition, the highest number of female flowers belonged to the urea 4 per thousand without the use of ethephon (24) and 0.5 mM ethephon without application urea (17.6) contain treatment. Moreover, the maximum pistil length belonged to urea 4 per thousand without application ethephon spray with a mean of 4.6 mm, which did not have a significant difference with urea 2 per thousand with the use of 0.5 mM ethephon (4.2 mm). The highest transpiration rate observed in urea 2 per thousand without ethephon (3.54 mmol. m-2. s-1) and 0.5 mM ethephon without application urea (3.66 mmol. m-2. s-1) treatments that were superior to control. Treatment of Contain 0.5 mM ethephon without application urea (241.5 mmol. m-2. s-1) also showed highest stomatal conductance, which did not show any significant difference with other ethephon treatments and average nitrogen concentration without ethephon. The highest amount of carbon dioxide absorption recorded in ethephon treatment with urea 4 per thousand (8.6 µmol m-2 s-1), which was significantly more than control.

In general, it can be concluded that nitrogen and ethephon treatments interaction in most of the measured reproductive and vegetative factors, improved the parameters studied. Since one of the research aim is to increase the number of female flower, two treatments of urea 4 g.L without ethephon and 0.5 mM ethephon without application urea can have a positive effect on the number of female flower in cucumber.