Plant Growth Promoting Microorganisms Useful for Soil Desalinization

The salinization of cultivable soils is a major issue that humankind will soon haveto face. It has been estimated that around 20% of the world’s land is cultivable, and over 30%, at present, is affected by salinization. Moreover, it has been calculated by economists and agronomists that each year, about 10% of arable soils increase their own salt content, due, for instance, to irrigation with salted water and the use of incorrect agricultural practices, such as abundant use of mineral fertilizers. Consequently, it is conceivable that in the next thirty years, more than 50% of them will be severely affected by a high salt content, causing a reduction in crop yields and also their palatability. It has been recognized that a relevant role to maintain and improve plant health is played by rhizosphere microorganisms colonizing the fine plant roots. The new-generation sequence (NGS) technique, able to sequence up to the whole genome of every kind of living being, has revealed an unknown world of microorganisms that inhabit the rhizosphere, and many of them carry out the function of plant growth promoters (PGP microorganisms), reducing either biotic or abiotic stresses, such as that caused, for instance, by soil salinization. The tolerance to high salt concentrations of certain microorganism strains and their capability to improve the plant wellness have been demonstrated by several studies, also reported in this Special Issue, which, in fact, has collected papers focused on the interactions among plants and microorganisms when they are exposed to salty and/or arid soil.