Two experimental trials have been carried out in germination chambers to check, at the seedling stage, coffee plant reaction to the presence of aluminum; the first has been set up to determine the Al concentration that would best differentiate the genotypes under study while, in the second, twenty-six genetic materials have been tested at the Al concentration previously defined, as to their reactions to the stress. In the first experiment, seeds of two genotypes (UFV 2237 and UFV 3880) were germinated in the presence of increasing Al levels (0, 25, 35 and 65 mg.L-1), using the solution-paper method, and lengths of primary roots measured after 40 days. The best differentiation was achieved at 35 mg.L-1 Al concentration, in which UFV 2237 revealed to be more sensitive than UFV 3880. In the second, also using the solution-paper method and a 45 mg.L-1 aluminum level, lengths of primary roots were measured after 42 days. The results allowed the classification of the twenty-six coffee genotypes into four different groups, based on primary root length percentage reductions, through Al reaction comparisons, for each genotype, in the presence and absence of stress. The high genetic diversity present strongly indicates the future success, in the selection for this character, in plant breeding programs.
coffee; aluminum; tolerance; screening
