TOLERANCE TO WATER DEFICIT STRESS IN TOMATO INOCULATED WITH ARBUSCULAR MYCORRHIZAL FUNGI

Drought and low rainfall are arising problems in recent years in many countries that limit agricultural production. An appropriate solution to overcome water deficit stress in sustainable agriculture is establishment of mycorrhizal symbiosis in plants. Mycorrhizal fungi affect plant growth by widespread activity in roots and soil. A greenhouse experiment was carried out using tomato (Lycopersicon esculentum L. cv. Behta) plants inoculated with two species of mycorrhizal fungi Glomus intraradices (Gi) and Glomus etunicatum (Ge) in a sterile soil. The experiment was factorial based on a completely randomized design with three replications. After plants establishment, three ranges of soil moisture: (0.9FC-FC) (D0) and (0.7FC-0.8FC) (D1) and (0.55FC-0.65FC) (D2) were applied to the pots. In both fungal species root mycorrhizal colonization decreased by decreasing soil moisture. Inoculation of plants with Gi and Ge increased shoot dry weight by 14.5% and 16.2%, respectively, compared to non-mycorrhizal plants but shoot dry weight declined by decreasing soil moisture. Mycorrhizal fungi significantly (P<0.01) increased leaf relative water content (RWC), leaf water potential (LWP) and stomatal conductance (gs) but these parameters were decreased by decreasing soil moisture. Mycorrhizal plants at all levels of soil moisture had more shoot P concentration than the control plants, but Ge significantly increased shoot K concentration. Thus, both P and K contents decreased by decreasing soil moisture. Based on the results, it can be concluded that the arbuscular mycorrhizal fungi can increase tomato growth and nutrient uptake under water deficit stress.