Effects of aluminum on root growth and absorption of nutrients by two pineapple cultivars [Ananas comosus (L.) Merr.]

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 mu M AlCl3 center dot 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 mu M, and Fe, Mn and Cu absorption were inhibited significantly when AlCl3 was 300 mu M in the Al-sensitive Tainung No. 17. On the other hand, Ca, Mg and K absorption increased significantly in Cayenne when AlCl3 was 200 mu M. It is possible that Ca, Mg and K uptake was an important clue for Al-resistant pineapple to resist Al in root.