EFFECTS OF EXCESS ALUMINUM ON MINERAL UPTAKE IN MYCORRHIZAL SORGHUM

Soil acidity is often associated with toxic aluminum (Al), and mineral uptake usually decreases in plants grown with excess Al. This study was conducted to evaluate the effects of Al (0, 35, 70, and 105 mu M) on Al, phsophorus (P), sulfur (S), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn,) and copper (Cu) uptake in shoots and roots of sorghum [Sorghum bicolor (L.) Moench, cv. SC283] colonized with the vesicular-arbuscular mycorrhizal (VAM) fungi isolates Glomus intraradices UT143-2 (UT143) and Glomus etunicatum UT316A-2 (UT316) and grown in sand (pH 4.X). Mycorrhizal (+VAM) plants had higher shoot and root dry matter (DM) than nonmycorrhizal (-VAM) plants. The VAM treatment had significant effects on shoot concentrations of P, K, Ca, Fe, Mn, and Zn; shoot contents of P, S, K, Ca, Mg, Fe, Mn, Zn, and Cu; root concentrations of P, S, K, Ca, Mn, Zn, and Cu; and root contents of Al, P, S, K, Ca, Mg, Fe, Mn, Zn, and Cu. The VAM effects on nutrient concentrations and contents and DM generally followed the sequence of UT316 > UT143 > -VAM. The VAM isolate UT143 particularly enhanced Zn uptake, and both VAM isolates enhanced uptake of P and Cu in shoots and roots, and various other nutrients in shoots or roots.