The tall cultivar IAC-227 (P1), tolerant to aluminum toxicity was crossed with the semidwarf Mexican genotypes: CMH 79.481/CMH 77A.917 (P2), sensitive to aluminum toxicity and CMH 80A.747 (P3), tolerant. Parents and F1 seedlings as well as F2 and F3 generations from the crosses P1 x P2 and P1 x P3 and F2 generation from the backcrosses (P1 x P2) x P1, (P1 x P2) x P2, (P1 x P3) x P1 and (P1 x P3) x P3 were evaluated in nutrient solutions containing 3 mg.L-1 of Al3+. It was considered tolerant the plant that showed root regrowth of the central primary root in the complete nutrient solution after a treatment of 48 hours in a solution containing 3 mg.L-1 of Al3+. The cultivar IAC-227 differed from the genotype CMH 79.481/CMH 77A.917 by one pair of dominant genes for the tolerance to the presence of this aluminum concentration into the nutrient solution. The genotypes IAC-227 and CMH 80A.747 did not differ in relation to the number of loci for the tolerance. The genotype CMH 80A.747 can be utilized as source of a genetic tolerance to aluminum toxicity besides other agronomic characteristics in breeding programs.
tolerant and sensitive genotypes; dominant genes
