Arbuscular Mycorrhiza Interaction with Medicago sativa Plants: Study of Abiotic Stress Tolerance in Sustainable Agriculture.

Objetive: This study investigated the effects of inoculation with Rhizofagus intraradices on physiological parameters and antioxidant defense in Medicago sativa plants under salt, drought and cold stress. Material y methods: M. sativa seeds, var. Dekalb (DK166), were disinfected and seeded in sterilized mixture of soil/sand. 10 g of R. intraradices was added to half of the pots and all plants received 5 ml of a culture of Shinorhizobium meliloti. They were grown in a greenhouse at 25/20°C (day/night), with 16 light, 50-60% relative humidity and regular watered during 45 days. After this time, were place the treatment of control, drought, salinity and cold. R. intraradices colonization was calculated in all treatments. Stomatal conductance was measured using a porometer and the efficiency of photosystem II (PE) was measured with Fluor Pen FP100. The shoot and root dry weight (DW), proline content, the oxidative damage to lipids and the enzyme activities of SOD, CAT, APX, were determined in all treatments after stress. Results: All physiological and enzymatic measurements were significative (t-Student) better in inoculated plants, showing a positive interaction mycorrhization-physiological status. Stomatal conductance, in inoculated plants, increased under drought and salinity, showing protection to these abiotic stresses. Photosynthetic efficiency in non-mycorrhizal plants decreased under all stresses, but in mycorrhizal plants, it remained similar in all stress treatment, showing their mitigation. The aerial and roots dry weights were similar under different abiotic stress in non-mycorrhizal plants, but in mycorrhizal plants, were higher and showed different from each stress. Lipids peroxidation in non-inoculated plants increased under drought and salinity conditions, while in inoculated plants remained constant showing mitigation. Inoculated plants increased activities of superoxide dismutase and ascorbate peroxidase in shoots and roots under all stresses showing antioxidant defense. Catalase had a variable performance. Conclusion: The mycorrhization have a positive interaction with different physiological parameters and antioxidant defense in M. sativa and promoted mitigation under abiotic stresses. [ABSTRACT FROM AUTHOR]