Controlled hydration for priming in coffee (Coffea arabica L.) seeds

A methodology for control of coffee seed hydration was determined in the Seed Laboratory at the Federal University of Vigosa, Brazil. Seeds of the Catuai MG-44 cultivar were used in the study, which involved three experiments. In the first, seeds without the endocarp were imbibed in water, in manitol (44, -0.6 and -0.8 MPa) solutions and in PEG-6000 at -0.2, -0.4 and -0.6 MPa solutions for 30 days at 25degreesC. In the second experiment, seeds with and without endocarp, removal were imbibed in water and in PEG-6000 solutions (-0.4, -0.6; and -0.8 MPa) for 30 days at 25degreesC. Counting was performed on a daily basis during 30 days and germinated seeds were removed. Seed moisture content for each treatment was monitored. In the third experiment, imbibition curves were drawn for seeds with the endocarp imbibed in water and in PEG-6000 at -0.4 MPa, at 25degreesC, for 0, 1, 3, 6, 9, 12, 24, 48, 72, 96, 120, 144 and 168h. PEG-6000 was more efficient than manitol as a conditioning agent. The emergence of the radicle in coffee seeds without the endocarp happened when the seed moisture content reached values close to 55%. Seeds with the endocarp imbibed in PEG-6000 at -0.4 MPa for periods of 50 to 168h remained at lag phase of the imbibition.