Effect of application of mycorrhizal fungus and Azotobacter on physiological characteristics of Trigonella foenum-graecum L. under water stress conditions

In order to investigate the effect of biofertilizers on biochemical properties of fenugreek plant under stress conditions, a factorial experiment was conducted in a randomized complete block design with three replications. Different levels of irrigation were considered at three levels (irrigation after 50, 100 and 150 mm evaporation from evaporation pan) as the first factor and application of biological fertilizers in four levels included as mycorrhizal + Azotobacter, mycorrhizal fungi, Azotobacter and control (no biofertilizer) as the second factor. The results revealed that the hydrogen peroxide, malondialdehyde and glycine betaine in mycorrhiza + Azotobacter treatment decreased significantly in different levels of irrigation. The highest content of ascorbic acid (7.23 mgkg-1 fw) and glutathione (36.20 mgkg-1 Fw) were observed in combined mycorrhizal fungi and Azotobacter treatment in optimum irrigation conditions. Water deficit stress reduced significantly soluble sugars, so Mycorrhizal+Azotobacter treatment increased the amount of soluble sugars in Fenugreek. The maximum amount of proline was observed in control (without biofertilizer) and irrigation treatment with 150 mm evaporation from the pan. So that the activity of catalase, ascorbate peroxidase and glutathione reductase in the inoculated plants with microorganisms under drought stress conditions of 100 and 150 mm evaporation from pan compared to 50 mm evaporation from pan was decreased. On this basis, the increase of enzymatic antioxidants activity and the enhancement of non-enzymatic antioxidants production in combined treatment of mycorrhiza+bacteria, can reduce the activated oxygen vulnerability, and could increase the tolerance to water stress.