Morphological, physiological, and enzymatic responses of Caucasian alder (Alnus subcordata C. A. Mey) seedlings to water deficit conditions by inoculation of Rhizophagus irregularis

This study was conducted in greenhouse condition to investigate the growth, morphological and physiological changes and some antioxidant enzyme activities of one-year-old seedlings of Alnus subcordata C. A. Mey. inoculated with Rhizophagus irregularis mycorrhizal fungi under water deficit stress in a period of 70 days. The experiment was carried out at two inoculation levels (control or non-inoculated seedlings and inoculated with R. irregularismycorrhizal fungi) and with two levels of irrigation including irrigation at field capacity (control treatment) and irrigation at 30% of field capacity (water deficit treatment) in a completely randomized design with four treatments and 10 replications. Results revealed that morphological and physiological characteristics of A. subcordata seedlings significantly decreased under water deficit stress at 99% level while all enzymatic activities significantly increased. Although the morphological characteristics such as height and diameter growth, root length, leaf area, and leaf, stem, root, and total biomass significantly increased by 20-30% in R. irregularis mycorrhiza treatment of the irrigation control plants, these features increased by 55, 40, 46, 47, 37, 35, 50 and 37%, respectively when the plants under water deficit treatment were added R. irregularis mycorrhiza compared to non-mycorrhiza water deficit treatment. The meancomparisonresults indicated that the photosynthesis rate, stomatal conductance, transpiration, and leaf water potential reduced by 57, 54, 53, and 65%, respectively under water deficit regime whereas addition of R. irregularis mycorrhizal fungi in soil alleviated the effects of water deficit. Also, under water deficit condition, activities of catalase, peroxidase, superoxide dismutase, and ascorbate peroxidase significantly increased in comparison with field capacity irrigated seedlings while treatment of soil with mycorrhiza mitigated the destructive effects of water deficit. In general, the present study showed that inoculation of R. irregularis mycorrhizal fungi can alleviate physiological indexes and antioxidant enzyme and consequently leading to an increased tolerance of A. subcordata seedlings during the first year.