Differential Physiological Characteristics and Fungal Composition of Alfalfa under Salt Stress in Degraded Grasslands

Abstract

Alfalfa (Medicago sativa L.) is an important source of livestock feed used to address the imbalance between livestock and forage production in China. However, much of the grasslands have a high salt content, which seriously affects the quality and yield of alfalfa. There are many kinds of fungi that play an important role in alfalfa growth and nutrient synthesis. The response of the fungi of alfalfa to salinity is poorly understood. In this study, the physiological characteristics and the fungal community composition of alfalfa under different salt stress conditions were investigated. Salt stress had a great impact on the physiological characteristics and the fungal community composition of alfalfa. The activity of invertase increased significantly under salt stress; the content of water and starch decreased; and the content of crude protein (CP) and soluble sugar increased under mild salt stress. With the increase in salt stress, the relative abundance of Ascomycetes increased, while the relative abundance of basidiomycetes decreased. This showed that the changes in the fungal community may be related to the adaptability of alfalfa plants to salt stress. These findings contribute to a better understanding of alfalfa physiological characteristics and nutrient synthesis under salt stress and deepen our understanding of alfalfa–fungi interactions in the saline soil environment of grasslands.