Abstract: Saline-sodic soil is widely distributed around the world. However, transforming it into agricultural land is challenging, resulting in waste of land resources. During the past several decades, researchers have tried to explore the improvement methods of saline-sodic soil, with remarkable achievements. There are various degrees of constraints in these enhanced methods, in terms of environment, input, and cost. As people become increasingly concerned about environmental issues, studies on the utilization of phytoremediation of saline-sodic soil grow quickly. Phytoremediation is a method of improving saline-sodic soils with both ecological and economic benefits. Although the growth and development of most plants are affected by saline-sodic stress, some species have evolved adaptation mechanisms to the saline-sodic environment. Those species can improve soil physical and chemical properties through physiological, morphological and molecular changes, and then achieve the effect of restoring saline-sodic soil. Here, we reviewed the mechanisms of phytoremediation in saline-sodic soil from six aspects: (1) the removal of salts from plant aboveground parts, (2) the improvement of soil physical properties through root growth, (3) the improvement of soil physical and chemical properties through plant residues, (4) the increase of H⁺ in root exudates, (5) root respiration, and (6) microbial synergistic phytoremediation. By systematically summarizing and collating current research, it is noted that future work should conduct more in-depth research on how to exert the restoration effect of plants in the process of phytoremediation on the basis of time and economy efficient, aiming to maximize the phytoremediation and provide scientific support for saline-sodic soil management.

Key words: saline-sodic soil, phytoremediation, carbon dioxide in root zone, root exudate, rhizosphere microorganisms