Effects Of Arbuscular Mycorrhizal Fungi On Root Structure Of Strawberry Under Compound Salt Stress

Strawberry cultivar‘Sweet Charlie'was selected as tested material,and salt stress was simulated by NaCl and Na2SO4 with mole ratio of 1:1 within 28 days.Six treatments,including inoculate and not inoculate arbuscular mycorrhizal fungi(AMF)and three salt concentrations of 0,50 and 100mmol/L were set.The effects of AMF on strawberry root topology structure,microstructure and ultrastructure were evaluated under different salt concentration.The mechanism of AMF alleviation of strawberry under compound salt stress was analyzed from the perspective of root structure change.The results could provide theoretical basis for the sustainable development of strawberry production.The results were as follows:1.The compound salt stress adversely affected the growth of strawberry.The AMF infection rate was reduced,while the salt injury index was increased.The root activity was not significantly affected by salt stress.The inoculation of AMF improved the root activity,alleviated the salt toxicity,and gradually reduced the salt injury index of strawberry.2.The topological structure indexes including root length,root area,root volume,forks and projective root area of strawberry were reduced under the composite salt stress.However,the root length,root area,projective root area,root volume and the forks were increased by AMF inoculation.3.The microstructural indexes of strawberry roots,including root diameter,cortical thickness,stele diameter and vessel number,were decreased under composite salt stress.AMF inoculation improved the microstructures indexes of strawberry roots such as root diameter,cortical thickness,stele diameter and vessel number.4.Under the stress of salt,the cytoplasmic degree of the cortex cells of strawberry root system was enhanced,and the starch grains were increased.AMF inoculation changed the ultrastructure of strawberry,and the cell wall of the root cortex was less corklike,and starch grain increment were less,which alleviated the inhibition effect of salt stress on strawberry.In summary,this study concluded that strawberry was extremely sensitive to the saline soil environment,and the growth of strawberry root system was seriously affected by the compound salt stress,and its topological structure,microstructure and ultrastructure were all changed.AMF inoculation alleviated the inhibition of the compound salt stress on the growth of strawberry root system.