Evaluation of the impact of drought stress and mycorrhizal fungus on the morphological characteristics of mint species

Drought stress is among the most important stresses limiting the growth and production of crops and medicinal plants. The co-existence of plants with mycorrhizal fungus reduces drought stress impacts. The present experiments were conducted seeking to investigate the influence of drought stress and mycorrhizal fungus on the morphological characteristics of mint (Mentha pulegium L) species in Namin County over 2020-2021 as a split-factorial study in the form of randomized complete blocks with three iterations. The evaluated treatments varied in the three factors of drought (a) (a1: no stress (normal) and a2: 50% field capacity), factor b (b1: no inoculation and b2: mycorrhizal fungus inoculation), and factor c (c1: Marivan, c2: Salmas, and C3: Miandoab). Results of variance analysis indicated significant differences between the levels of individual impacts of a (drought stress level), b (mycorrhizal fungus levels), and c (cultivars) in terms of all the studied traits. Moreover, significant differences at 1% and 5% levels were observed between the levels of the ABC interaction effect (drought stress with mycorrhizal fungus inoculation in various cultivars) in terms of the traits of dry and wet weight, the number of branches, essential oil content, essential oil performance, and root colonization. The 50% field capacity treatment resulted in a 31.1%, 19.1%, 6.4%, 4.9%, and 36.9% decline in the traits of wet and dry plant weight, number of branches, number of flowers, and root colonization, while causing a 7%, 21.6%, 31.9%, and 53.1% increase in the traits of plant height, root length, essential oil performance, and essential oil content, respectively. Inoculation with mycorrhizal fungus increased all the traits investigated in the present study. The growth traits revealed to increase in the plant through proper water resource management and the use of mycorrhizal fungus seeking optimal use of water resources and nutrients. Results revealed that Inoculation with mycorrhizal fungus increased the resistance of mint against the stress through the improvement of the studied traits.