Abstract

Aluminum (Al) is a biotoxic which often influences the absorption of nutrients by plants in strongly acidic soils. In this experiment, the effect of Al on root growth, absorption of macronutrients; phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and micronutrients; iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) by two pineapple cultivars (ig. Al-resistant Cayenne and Al-sensitive Tainung No.17) were studied. Four levels of Al concentration treatments were imposed to the hydroponic solutions containing 0, 100, 200 and 300 μM AlCl₃. After treatments with Al for four weeks, the root elongation of Cayeen was increased with Al concentration, however, Tainung No.17 was decreased. The dry weight of Cayenne and Tainung No.17 was increased and decreased with Al concentration, respectively. The absorptions of macronutrients and micronutrients were not affected in Al-resistant Cayenne. However, the absorption of Ca, Mg and K were inhibited when AlCl₃ was 200 μM, and Fe, Mn and Cu absorption were inhibited significantly when AlCl₃ was 300 μM in the Al-sensitive Tainung No.17. On the other hand, Ca, Mg and K absorption increased significantly in Cayenne when AlCl₃ was 200 μM. It is possible that Ca, Mg and K uptake was an important clue for Al-resistant pineapple to resist Al in root.

Key words: Acid soils, Al toxicity, macronutrients, micronutrients, absorption.