Growth and essential oil content of peppermint (Menhta piperita var. officinalis) and lemon verbena (Lipia citriodora var. Verbena) were evaluated in response to salinity and nutrient solution concentrations, measured as electrical conductivity (EC , , , , and dS m–1). | Turk J Agric For 31 (2007) 245-253 © TÜB‹TAK Influence of Nutrient Concentrations and NaCl Salinity on the Growth, Photosynthesis, and Essential Oil Content of Peppermint and Lemon Verbena Seyed Jalal TABATABAIE*, Javad NAZARI University of Tabriz, Faculty of Agriculture, Post Code: 51664, Tabriz, IRAN Received: Abstract: Growth and essential oil content of peppermint (Menhta piperita var. officinalis) and lemon verbena (Lipia citriodora var. Verbena) were evaluated in response to salinity and nutrient solution concentrations, measured as electrical conductivity (EC , , , , and dS m–1). In peppermint, the highest fresh weight and dry weight were observed in the dS m–1 treatment. The increased EC with either NaCl or all nutrients at dS m–1 reduced the fresh weight of lemon verbena. The maximum fresh weight and dry weight in lemon verbena were obtained in both and dS m–1 treatments. Increasing EC level up to dS m–1 increased leaf area but the leaf area was reduced by dS m–1 treatment achieved by adding NaCl or all nutrients. The rate of photosynthesis (Pn) was higher in treatments with EC levels of and as compared to the other treatments. In both peppermint –1 and lemon verbena, the concentrations of N, P, and K increased as the EC of the solution increased from to dS m but in the treatment their concentrations fell. The total content of essential oil was reduced by increasing the EC of the solution because of the reduction in total fresh weight of the plants. In peppermint, the essential oil content in the dS m–1 treatment was and higher than those of both and treatments, respectively. The major constituents of the essential oil in peppermint were menthol and menthone and in lemon verbena they were geranial and neral in all treatments. The increased Pn and –1 leaf area in moderate EC level led to improved plant growth. Consequently, dS m could be an .
