Inoculation with Arbuscular Mycorrhizal Fungi Promotes Microbial and Enzymatic Activity in the Rhizosphere of Strawberry under Salinity Stress

Abstract

【Background】 The climate in Inner Mongolia of China is suitable for growing strawberry but the shallow root system of the crop makes it prone to soil salinity. How to alleviate soil salinity and improve the resistance of strawberry against soil salinity is hence essential to safeguarding strawberry production in both fields and greenhouses that endured secondary soil salination. 【Objective】 The objective of this paper is to study the feasibility of using arbuscular mycorrhizal fungi (AMF) inoculation to improve physical and biogeochemical conditions of the rhizosphere of strawberry to improve its resistance against salinity stress. 【Method】 We used the cultivar of ‘Charlie sweet’ as the model plant and inoculated its roots with AMF. They were then grown in soils with a salinity gradient created by adding 0 to 100 mmol/L of solution of NaCl and Na2SO4 mixed at 1:1 ratio. In each treatment, we measured the number of microbes and the activity of urease, catalase, sucrase and amylase in the rhizosphere. 【Result】 With the salt concentration increasing, the salinity index of the crop increased, while the rate of mycorrhizal infection, the number of soil microorganisms and the enzymatic activity all decreased. Compared with control without inoculation, 28 days after instigating the salt stress inoculation reduced the salt damage index of the strawberry by 10.91% to 23.93%, depending on salt concentration, 28 days after instigating the salt stress. Inoculation also increased the activity of all enzymes and the number of microorganisms at significant level (P<0.05). Microbial population and enzymatic activity were positively correlated with each other at significant level, and they were both negatively correlated with salinity injury index at significant level (P<0.05). 【Conclusion】 Inoculating the strawberry roots with AMF improved microbial population and enzymatic activity in its rhizosphere, thereby improving its resistance against soil salinity and the yield.

Keywords

• salinity stress
• amf
• strawberry
• microbial numbers
• enzymatic activity