Research progress and prospects of foxtail millet salt tolerance

With the adjustment of the agricultural planting structure, foxtail millet — a drought-resistant and barren-tolerant crop, has attracted increasing attention in arid and saline-alkali areas. Systematic and deep understanding of the salt tolerance as well as physiological and ecological response characteristics of foxtail millet under salt stress has important guiding significance for maximizing the excellent properties of foxtail millet, increasing its yield in saline-alkali areas, and improving farmers’ income. This paper reviewed the research progress worldwide in detail from three aspects, namely, the screening index and evaluation of foxtail millet salt tolerance, the change law of plant growth and development and physiological-ecological response under salt stress, and the discovery of foxtail millet salt tolerance genes. At present, a single indicator of salt tolerance in foxtail millet is used, which mainly depends on the germination rate during germination. Other physiological and ecological indicators have not been fully considered. Because of the differences in foxtail millet varieties and soil salinity, there are differences in aboveground and underground agronomic characteristics, photosynthetic characteristics, enzymes related to scavenging reactive oxygen species, and the hormone response law of foxtail millet plants. Therefore, it is difficult to establish comprehensive evaluation indexes. The expression and function of foxtail millet salt tolerance genes are related to environmental conditions such as high salt, drought, and abscisic acid. The salt tolerance of foxtail millet was improved by synthesizing specific proteins to enhance the antioxidant system, protect cells from damage, and improve the ability to resist osmotic stress. Based on the results, we recommend that the establishment of quantitative standards and platforms for the comprehensive evaluation and selection of foxtail millet salt tolerance, the in-depth research on the regulation mechanism of foxtail millet salt tolerance, and further research and development of foxtail millet salt tolerance cultivation technology systems are important future research directions.