Coadaptation of Plants to Multiple Stresses in Acidic Soils

Soil acidification is an increasing problem in agricultural production and ecological stability worldwide. An understanding of the mechanisms by which plants adapt to acidic soils would help address this problem. Poor plant growth in acidic soils results from a variety of factors, including proton toxicity; deficiencies in nitrogen, phosphorus, calcium, magnesium; and toxicities of various metals (aluminum (Al), manganese, iron). Aluminum toxicity is generally the primary limitation for plant growth in acidic soils. Although much research has focused on Al toxicity in recent decades, it is rarely the only limiting factor in acidic soils. The occurrence of Al toxicity depends on many other factors that coexist with Al in acidic soils. The interactions between Al and such factors are important determinants of Al toxicity to plants under field conditions. In this review, therefore, instead of focusing only on mechanisms of Al tolerance, we examine the effects of the interactions between Al and other limiting factors on plant adaptation to acidic soils. We summarize research on the interactions between Al and nitrogen, phosphorus, pH, and iron. Accordingly, three strategies are proposed to improve plant growth in acidic soils: a combined application of lime and nutrients, depending on the types of soils and plants; development of plant varieties tolerant to multiple stresses; and inoculation of plants with certain beneficial microbes. This review emphasizes the ability of plants to coadapt to multiple stresses in acidic soils.