Effects of arbuscular mycorrhizae and liming on growth and mineral acquisition of aluminum-tolerant and aluminum-sensitive barley cultivars

Acidification and aluminum (Al) phytotoxicity are the most important constraints for plant growing in volcanic soils from southern Chile. This study was conducted to evaluate the effects of arbuscular mycorrhizal (AM) fungus inoculation and liming on growth and mineral acquisition of two barley (Hordeum vulgare L.) cultivars with different tolerances to Al when they grow in an acidic Andisol. The plants were grown in pots under greenhouse conditions with and without calcium (Ca) amendment [equivalent to 2 tons lime ha(-1) as calcium carbonate (CaCO3)] and AM fungi Glomus etunicatum CH 110 (Morton and Bentivenga). Another experiment was conducted in nutrient solution for studying root pH changes produced by the same barley cultivars. The AM treatment appeared to ameliorate Al phytotoxicity more than CaCO3, especially for the Al-tolerant genotype. Benefits of AM inoculation for the tolerant genotype included increases in root and shoot dry matter, and increased Ca, magnesium (Mg), and phosphorus (P) concentrations and contents in shoots. No genotipic differences were noted relative to enhanced zinc (Zn) or copper (Cu) acquisition. Decreases in the Al/P, Al/Ca, and Al/Mg molar ratios in shoots indicated that AM enhanced Al-tolerance of plants growing in acidic volcanic soils. Roots of the Al-sensitive barley acidified nutrient solution more than the roots of Al-tolerant cultivar.