Effects of Water and N Fertilizer on the Yield and Fruit Quality of Tomatoes under Drip (Tape) Irrigation System

Being vulnerable to food shortage, tomatoes are dependent on nitrogen fertilizer  for their growth and crop yields (Zomorrodi, 2006). In effect, there is a close relationship between the amount of nitrogen fertilizer consumed and the accumulation of nitrate, which poses a threat to consumer health (Mousavi Fazl, 2005). The accumulation of nitrate in tomatoes has a considerable negative effect on its quality and increase the amount of toxic substances in tomatoes (Malakuti et al., 2005). The results of many studies show that the appropriate combination of nitrogen fertilizer treatments and the irrigation regime in such a way that the plant encounters a certain level of water stress during a particular period or throughout the growing season may lead to the maximum efficiency of water usage in the plant (Bagheri et al., 2016). Zomorrodi (2006) examined the effect of deficit irrigation on the quantitative and qualitative characteristics of tomatoes. The results showed that the effects of irrigation water on vitamin C, acidity and soluble solids were significant. Khorramian (2015) also studied different levels of drip irrigation with the supply of 40, 70 and 100% water requirement on the yield and water use efficiency in tomatos. The findings of this study showed that maximum yield was obtained from drip irrigation with 100% water level, while 40% water level treatment had the highest water use efficiency.