Dry matter production, root growth and calcium, phosphorus and aluminum absorption by coffea canephora and coffea arabica under influence of aluminum activity in solution
This study had the objective of evaluating the dry matter production, root growth, and the absorption and distribution of Ca, P and Al in the leaves, stem and roots of two Conilon (Coffea canephora) coffee clones (Mtl 25 and Mtl 27) and the coffee variety Catuaí Amarelo (Coffea arabica) grown in nutrient solution with increasing Al3+ activity. The plants were cultivated in 5 L pots, containing modified Hoagland & Arnold nutrient solution. After eight days of adaptation, the plants were subjected to Al concentrations of 0, 500, 1.000 and 2.000 mol L-1, which corresponded to Al3+ activities of 20.68, 50.59, 132.9, and 330.4 mmol L-1, respectively in solution, estimated by the program GEOCHEM. The Ca, Al and P contents were quantified. The root system was separated to estimate area and length. The variety Catuaí Amarelo (Arabic Coffea) was less Al3+ sensitive than the Conilon (Coffea canephora) clones and Conilon Mtl 25 clone was less Al3+ sensitive than Mtl 27. A higher Al3+ activity resulted in a reduction of the P and Ca content in the coffee leaves and roots, especially in the clones Mtl 25 and Mtl 27. Al accumulation in the root system and the restriction of the transport to the aerial part are important factors in Al3+ tolerance of coffee plants.