Effect of Claroideoglomus etunicatum Fungus on the Growth and Nutrient Absorption of Maize plant under the combined stress of boron and salinity

Salt stress and boron toxicity in the soils of arid and semi-arid regions of the world limit plant growth. A factorial experiment in a completely randomized design with three replications was used to investigate the effect of arbuscular mycorrhizal fungus on the growth and nutrient uptake of maize under salinity stress and boron toxicity. Two levels of boron (control and 30 mg B kg-1), two salinity levels (control and 8 dS m-1) from the source of boric acid and sodium chloride and two fungal levels (without inoculation, inoculation with Claroideoglomus etunicatum fungus) were considered. The results showed that salinity stress and boron toxicity had no effect on root colonization percentage (P>0.05). At the level of 30 mg B kg-1 boron, the fungus significantly increased the chlorophyll index, shoot boron, potassium, and phosphorus uptake (7.09%, 15.83%, 31.62%, and 51.57% respectively) and significantly decreased root boron, iron, copper and manganese uptake, (35.15%, 28.72%, 39.62% and 42.12% respectively). At the level of 8 dSm-1, the fungus significantly increased the amount of chlorophyll, copper, and manganese uptake, (5.05%, 35.38%, 25.97% respectively) and significantly decreased sodium uptake (40.31%). Under combined stress conditions and in the presence of fungus, chlorophyll index, root boron, potassium, phosphorus, and iron uptake, (8.42%, 61.56%, 82.01%, and 23.63% respectively) were significantly  increased but shoot sodium, zinc, copper, and boron absorption, (20.98%, 40.07% 72.54% and 34.38% respectively) were significantly decreased. The results of this research indicated that inoculation of fungus could help to improve the growth and absorption of nutrients in conditions of boron toxicity and soil salinity stress.