Effect of deficit irrigation and different levels of nitrogen fertilizer on some quantitative and qualitative properties of lemon balm (Melissa officinalis)

To investigate the effects of deficit irrigation and different levels of nitrogen fertilizer on some quantitative and qualitative properties of Melissa، a pot experiment was conducted for one year (2011) in Mazandaran province. Experiment was carried out as a factorial based on randomized complete block design with three replications. Irrigation treatments (25، 52 and 75 percent field capacity، FC) and nitrogen fertilizer (0 and 2. 5 percent ammonium nitrate) were allocated to main and sub plots، respectively. The results showed that the effect of different levels of deficit irrigation were significant on quantitative and qualitative properties of Melissa. Fertilizer treatments were significant on dry weight، leaf area، shoot number and fresh weight، percent citronellal، caryophyllene oxide percent، geranial and neral percent. Interaction of treatments was significant only on leaf number، dry weight of shoot، fresh weight of plant and geranial percent. Results showed that maximum plant height، leaf area، number of stems، number of leaves and dry and fresh weight was obtained in 75 percent FC treatment. Percent of citronellal، caryophyllene oxide، geranial and neral with 6. 14 percent، 11. 61 percent، 20. 09 percent and 17. 38 percent، respectively، had a maximum amounts in 75 percent FC treatment. Also، application of nitrogen fertilizer caused 5. 33 and 9. 15 percent reduction of citronellal and caryophyllene oxide respectively and increased geranial and neral percent by 17. 64 and 15. 56، respectively.