The Effects of Marginal Land Conditions and Planting Time on the Yield and Quality of Mentha x piperita

In this research, the effects of 2 different planting times (autumn and spring) on the yield and quality of peppermint (Mentha x piperita L. var. Mitcham) were investigated under marginal land conditions. The test was conducted in cukurova region located in the Eastern Mediterranean by using a randomized complete block design with three replications. Based on the results, the highest plant height (43 cm), fresh herb yield (12763 kg ha-1), dry herb yield (3407 kg ha-1), dry leaf yield (1976 kg ha-1) and essential oil yield (56.3 Lt ha-1) was determined in spring planting. The maximum ratio of essential oil was found in the first cuttings (3.18%). The yield values were higher in the first cuttings on year basis. With increasing the number of cuttings, a gradual decrease was observed in yield components. As a result of the gas chromatography analysis, oxygenated monoterpenes constituted the major chemical component group of M. x piperita essential oil (74.21-80.86%). The highest oxygenated monoterpenes were specified in the 1st cuttings of both planting seasons. Menthol (23.2-37.46 %) and menthone (22.82-31.56 %) were identified as the major components. Menthol percentage was higher in spring planting, and this rate has decreased every year compared to the previous one. As the number of cuttings increased, menthone rate also enhanced. On the other hand, as the rates of menthone increased, there was a decrease in menthol rates. alpha-Pinene (2.33-5.61%), limonene (0.63-4.13%), 1,8-cineole (5.22-9.98%), menthofuran (1.47-4.72%), isomenthone (1.145.95%), menthyl acetate (2.14-5.2%) and neomenthol (1.09-2.5%) were determined as other important components. Although the agronomic yield obtained from marginal land conditions was relatively lower, it was found superior in terms of quality and has adapted to standards values. As a result, the cultivation of the M. x piperita is economically viable in marginal lands without irrigation problems.