1. Introduction
Due to global climate change and increasing population pressure, 33% of global soil is moderately to highly degraded through erosion, salinization, compaction, acidification, chemical pollution, and nutrient depletion, hampering soil functions and affecting food production (Abogadallah, 2010; Mao et al., 2016). Soil salinization causes damage not only to natural resources, but is also a major factor restricting the development of agricultural production and improving land-use efficiency, and is also a threat to organisms and ecosystems (Liu et al., 2018; Yu, Liu, Yang, Fan & Zhou, 2018; Xia, Ren, Zhang, Wang & Fang, 2019). Nevertheless, saline soils are widely distributed on the earth surface, covering approximately 7-8% of the world land area, making them a potentially important land resource (Shrivastava & Kumar, 2015; Jiang et al., 2019).
In saline soils, salinity as well as alkalinity damage plant roots very seriously. Roots play an important role in plant growth. Roots extract nutrients and water from soil, and also exude a variety of organic and inorganic compounds into the rhizosphere soil. These exuded compounds change the chemistry and biology of the rhizosphere soil, making it significantly different from the bulk soil further away from roots (Marschner, 1995; Zhang, Li, & Wang, 2007). Plants form a specific bacterial community structure in the rhizosphere soil through specific root exudation, and the secondary metabolites produced by some rhizosphere bacteria can promote plant growth (Sturz & Christie, 2003). Furthermore, soil microbes also play an important role in maintaining the stability of ecosystems; they reflect the evolution of soil quality and are one of the indicators of the ecosystem health (Diacono & Montemurro, 2010).
Jerusalem artichoke (Helianthus tuberosus L.), which belongs to the Asteraceae family, is a tuber-forming perennial distributed worldwide (Shi et al., 2011). Jerusalem artichoke is an excellent crop because it has strong resistance to abiotic stresses (drought, salinity, etc.), high photosynthetic efficiency, low fertilizer and water demand, great ecological restoration capacity, and high commercial value. It is easily grown in saline and alkaline soils, and it can also be used for soil and water conservation and fixing terraces and unstable sand (Long et al., 2010; Shao et al., 2019).
In this paper, we aimed to explore an in situ remediation technology using Jerusalem artichoke to improve the micro-ecological environment of saline soils varying in salinity in the southeast China. Through the quantification of the area of root channels, rhizosphere secretions and soil microbiome, the change of carbon and nitrogen in the saline soil was analyzed, and the modifying effect of Jerusalem artichoke cultivation on the micro-ecological rhizosphere environment in saline soil was elucidated.