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 constr aints for plant growing in volcanic soils from southern Chile. This study w as conducted to evaluate the effects of arbuscular mycorrhizal (AM) fungus inoculation and liming on growth and mineral acquisition of two barley (Hor deum vulgare L.) cultivars with different tolerances to Al when they grow i n an acidic Andisol. The plants were grown in pots under greenhouse conditi ons with and without calcium (Ca) amendment [equivalent to 2 tons lime ha(- 1) as calcium carbonate (CaCO3)] and AM fungi Glomus etunicatum CH 110 (Mor ton 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, especial ly for the Al-tolerant genotype. Benefits of AM inoculation for the toleran t genotype included increases in root and shoot dry matter, and increased C a, magnesium (Mg), and phosphorus (P) concentrations and contents in shoots . No genotipic differences were noted relative to enhanced zinc (Zn) or cop per (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 acid ic volcanic soils. Roots of the Al-sensitive barley acidified nutrient solu tion more than the roots of Al-tolerant cultivar.