The Role of Mycorrhiza in Drought Tolerance of Marigold (Calendula officinalis L.)

To study the effect of mycorrhizal symbiosis and drought stress on marigold¡ a factorial experiment in a completely randomized design with three replications was conducted at the Plant Research Laboratory of Islamic Azad University¡ Neyshabur branch in 2014. The first factor consisted of application and non-application of mycorrhiza (Glomus intraradices) and the second factor consisted of drought stress with three levels (irrigation based on 100%¡ 75% and 50% of field capacity). The results showed that growth parameters like plant height¡ leaf number¡ leaf area¡ root¡ shoot dry/fresh weight¡ Chla and Chlb content were significantly decreased by drought stress in both mycorrhizal and non-mycorrhizal plants. However¡ inoculation of plants by mycorrhizal fungus increased growth parameters and photosynthetic pigments as compared with non-mycorrhizal ones. Traits like RWC¡ potassium and phosphorus in response to drought stress were decreased. Inoculation of plant roots with Mycorrhizal fungi increased significantly RWC¡ potassium and phosphorus content of the plants under drought conditions as compared with non-inoculated plants. The results also showed the mycorrhizal symbiosis by Glomus intraradices improved drought tolerance of marigold through enhancing the absorption of water and mineral ions.