Pesquisa Agropecuária Brasileira
On-line version ISSN 1678-3921
SILVA, Enilson de Barros et al. Sources and doses of potassium on the yield and quality of green coffee. Pesq. agropec. bras. [online]. 1999, vol.34, n.3, pp. 335-345. ISSN 1678-3921. http://dx.doi.org/10.1590/S0100-204X1999000300003.
A field experiment was established on a dystrophic Dusky Red Latosol of the EPAMIG experimental farm at São Sebastião do Paraíso, MG, Brazil, in February 1993, with coffee (Coffea arabica L.) cultivar Catuaí Vermelho, line LCH 2077-2-5-44, to study the effect of sources and doses of K on the yield and quality of green coffee. A randomized block experimental design with four replications was utilized, under a split-plot scheme, using three sources of K in the plots (KCl, K2SO4 and K2SO4.2MgSO4) and four doses in the subplots (0, 100, 200 e 400 g hole-1 of K). The experiment was conducted till October 1994. In 1993 and 1994 the yield, the qualitative variables of the processed grains and the contents of K, Mg, S and Cl in the leaves and grains were evaluated. There was no response of yield along two years to the sources and doses of K. For the processed grains, K2SO4 increased polyphenoloxidase activity and decreased total titrable acidity in the year 1993. In 1994, the same trend to polyphenoloxidase activity and total titrable acidity was observed, showing an even higher color index and favorable response in the total sugar contents. The K2SO4 promoted a best quality of green coffee.
Keywords : polyphenoloxidase; color index; total titrable acidity; sulfate; sugars.