Aluminum toxicity assessment in Coffea arabica cv. Catiguá MG2 under hydroponic conditions

Abstract

Aluminum is an element commonly found in acid soils, notably known by their pH values ranging around 5. At soil pH values at or below pH 5, aluminum may drastically interfere with phosphorus uptake by plants, inhibit root growth, and induce cell death. This study aimed to assess the tolerance of Coffea arabica cv. Catiguá MG2 seedlings in a solution containing Al under hydroponic conditions using a simple, relatively fast protocol. Seedlings at 6 months of age, established in vitro, were cultivated in Hoagland solution (¼ strength and pH 4.0) supplemented with different concentrations of Al (0; 0.888; 1.666; and 2.499 mM) provided from the source AlK(SO4)2.12H2O for 30 days. The higher Al3+ concentrations caused more evident symptoms of toxicity, unlike the 0.888 mM that caused little damage to the roots. The control seedlings did not exhibit any symptoms of nutritional deficiencies. Although the protocol has been used only for a specific coffee cultivar, it is expected to be useful in the assessment of Al-caused toxicity in other coffee materials when exposing seedlings to Al in the hydroponic system with a dilution of Hoagland solution, and could be useful for the quick identification of coffee genotypes with certain Al tolerance.