Influence of Water Stress on Agro-Morphological Traits and Essential Oil Content Among Iranian Genotypes of Mentha longifolia

In this research, agro-morphological variation among twenty genotypes of Mentha longifolia L. was assessed in 2 years based on agricultural production under water stress condition. The experiment was arranged in split–split-plot design with water stress treatment in two irrigation levels of 100% (as control) and 60% field capacity in three replications. The result of variance analysis indicated that there was a significant variation (P ≤ 0.01) in traits among the genotypes and in response to the water deficit condition. Different traits were measured such as plant height, yield, date of flowering, inflorescence length, stem diameter, fresh and dry weight of leaf, essential oil content, and essential oil yield. Results showed that traits such as yield and essential oil yield had considerable variation, varying from 374.17 to 899.33 g m−2 and 17.7–391.6 kg ha−1 on the analysis in response to water stress condition, respectively. Cluster analysis using the unweighted pair group method with arithmetic means grouped the studied twenty genotypes into two major clusters based on agro-morphological traits which all the studied genotypes were known as yield ecotype. Five genotypes including Hormozagan, Khuzestan, Kerman-1, West Azarbaijan, and Ghazvin had the most significant biomass and essential oil performance and resistance under water stress condition that can be introduced for domestication breeding programs and cultivation.