Improving the Physiological, Biochemical and Caffeic acid Levels of Cymbopogon citratus Under Salt Stress by Inoculating with Arbuscular

Arbuscular mycorrhizal fungi can improve salinity tolerance and plant productivity in saline-alkaline soils using different strategies including nutrient uptake, osmotic regulation, soil shaping, etc. Therefore, the use of arbuscular mycorrhizal fungi has been considered to reduce the effects of salinity. This study aimed to investigate the effect of arbuscular mycorrhizal fungus on the physiological, biochemical and caffeic acid levels of lemongrass (Cymbopogon citratus) under salt stress.

The experiment was conducted as a factorial in the form of a completely randomized design in three replications. The experimental treatments included the first factor of arbuscular mycorrhizal fungi (inoculation and non-inoculation) and the second factor of salinity treatment at four levels (0, 50, 100 and 150 mM). The characteristics of photosynthetic pigments, ion leakage, proline, soluble carbohydrates, flavonoid, anthocyanin, protein, ascorbate peroxidase, the amount of sodium and potassium ions and changes in caffeic acid content of lemon grass were investigated.

Plant inoculation with arbuscular fungus at salinity levels (150 mM) reduced ion leakage by 34.14% compared to the control. Plant inoculation with arbuscular fungus improved chlorophyll a, chlorophyll b, total chlorophyll and carotenoids by 118.51, 82.35, 50.70 and 98.64 percent, respectively, compared to its absence at salinity levels (150 mM). The results show that lemongrass plants against salt stress (150 mM) maintain the state of proline, carbohydrate, flavonoid, anthocyanin, protein and ascorbate peroxidase enzyme activity in inoculation with arbuscular fungus at the rate of 20.48, 94.94, 27%, respectively. It increases by 27, 30 and 17.39% compared to the control (without inoculation). Also, the results showed that under the salinity stress of 150 mM and the presence of arbuscular fungus, the amount of potassium increased by 15.39% compared to the control; While the amount of sodium in the presence of this mushroom decreased by 8.46% compared to the control. Investigations showed that the percentage of caffeic acid in lemon grass inoculated with arbuscular mycorrhiza increased by 0.686% compared to control plants.

This study suggests the potential use of mycorrhizal technology as a practical biotechnological approach to increase the growth and increase production of bioactive compounds of Cymbopogon citratus in salt-affected soils.