Mechanisms of adaptation of plants to acid soils

Abstract

Major constraints for plant growth on acid mineral soils are toxic concentrations of mineral elements like AI, of H ÷, and/or low mineral nutrient availability either as a result of solubility (e.g. P and Mo), low reserves, and impaired uptake (e.g. Mg 2÷) at high H ÷ concentrations. Inhibition of root growth particularly by A1 leads to more shallow root systems, which may affect the capacity for mineral nutrient acquisition and increase the risk of drought stress. Of the two principal strategies (tolerance and avoidance) of plants for adaptation to adverse soil conditions, the strategy of avoidance is more common for adaptation to acid mineral soils. Examples are (i) root-induced changes in the rhizosphere such as pH increase, (ii) release of chelators for A1, higher activity of ectoenzymes (acid phosphatases), and (iii) increase in root surface area via mycorrhizae. In order to have a better understanding of the principles of the mechanisms by which plants adapt to acid mineral soils more attention should thus be given to conditions at the root-soil interface.

Redox potential (Eh) and pH as drivers of soil/plant/microorganism systems: a transdisciplinary overview pointing to integrative opportunities for agronomy

“…Some plants such as sweet potato (Ipomea batatas), cassava (Manihot esculenta), and tea (Camellia sinensis) are known for their ability to grow under acid soil conditions. Strong acidity or highly alkaline conditions affect plant growth, mainly because pH strongly influences nutrient availability and the risk of ion toxicity (Brady and Weil 2010;Marschner 1991).…”

New genetic sources of resistance in the genus Phaseolus to individual and combined aluminium toxicity and progressive soil drying stresses

“…1A). The major Al toxicity symptom observed in plants is inhibition of root elongation rate calculated from the comparison of root elongation rate with and without toxic Al (Marschner 1991;Ryan et al 1993;Delhaize and Ryan 1995). TRER was inhibited by 21.3-60.7%, with an average of 42.7%.…”

Soil Chemical Quality and Forest Dieback

“…Therefore, the plants growing on soils with poor microbial activity are very often subjected to nutrient and toxicity problems. Extreme acidic conditions in the soil even causes direct root damages [19]. Mycorrhizal associations in plant roots which are considered to be a natural survival strategy of forest vegetation are also affected by severe soil acidity [20].…”