MECHANISMS OF ADAPTATION OF SMALL GRAINS TO SOIL ACIDITY*

ABSTRACT: Acid soils limit crop production on 30—40 % of the world's arable land and up to 70 % of the world's potentially arable land. Over 60 % of the total arable lands in Serbia are acid soils. Soil acidity is determined by hydrogen (H+) in soil solution and it is influenced by edaphic, climatic, and biological factors. Major constraints for plant growth on acid mineral soils are toxic concentrations of mineral elements like Al of H+ and/or low mineral nutrient availability due to low solubility (e.g. P and Mo) or low reserves and im-paired uptake (e.g. Mg2+) at high H+ concentrations. Aluminum (Al) toxicity is primary fac-tor limiting crop production on acid soils. This review examines our current understanding of mechanisms of Al-toxicity, as well as the physiological and genetic basis for Al-toxicity and tolerance. Inhibition of root growth by Al 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. At the same, the short view of the most important genetics tolerance mecha-nisms, developed and determined in some small grains genotypes, is showed as well. KEY WORDS: acid soils, adaptation mechanisms, small grain