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Aluminum effects on growth, photosynthesis, and mineral nutrition of cacao genotypes

Quinteiro Ribeiro, Miguel Antonio, Furtado de Almeida, Alex-Alan, Mielke, Marcelo Schramm, Pinto Gomes, Fábio, Pires, Marcel Viana, Baligar, Virupax C.
ARS USDA Submissions 2013 v.36 no.8 pp. 1161
Theobroma cacao, aluminum, calcium, chemical constituents of plants, culture media, genetic variation, genotype, leaves, magnesium, metal tolerance, mineral content, nitrogen content, phosphorus, photosynthesis, phytotoxicity, plant nutrition, potassium, stems, stomatal conductance
A solution culture experiment was conducted in a greenhouse with two cacao genotypes (Catongo and Theobahia). Plants were subjected to seven aluminum (Al) concentrations and Al effects on growth, photosynthesis, and mineral content were assessed. Inter-genotypic differences for Fo, Fm and Fv fluorescences, as well as for Fv/Fm, were observed with increasing Al concentrations. There was a decreasing of Fo, Fm, Fv and Fv/Fm for the Catongo. Increasing Al concentration decreased photosynthetic rate, stomatal conductance and leaf transpiration rate, however, inter-genotypic differences in these parameters were not observed. The Al-treatments decreased content of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in different plant parts, with the exception of K content in stems of Theobahia and in leaves of both genotypes. Theobahia showed higher tolerance to Al phytotoxicity, manifested mainly in the higher levels of Al in the growth medium. Inter-genotypic differences were observed in the growth and mineral nutrition.