AN INTERMEDIATE CATEGORY OF SEED STORAGE BEHAVIOR .2. EFFECTS OF PROVENANCE, IMMATURITY, AND IMBIBITION ON DESICCATION-TOLERANCE IN COFFEE

Seeds of four cultivars of arabica coffee (Coffea arabica L.) received from three continents survived desiccation to between 7.2% and 11.3% moisture content (wet basis), i.e. to seed water potentials of -90 MPa to -150 MPa, but further desiccation reduced germination (criterion, normal seedling development) in all seed lots. Only a few individuals from four of the lots germinated after being dried to 4-5% moisture content. Differences in desiccation sensitivity were apparent among lots within each cultivar. Desiccation sensitivity in these lots was similar to that observed in seeds of orthodox species which have begun to germinate. Seeds extracted from fruits of intermediate maturity (yellow) were able to tolerate greater desiccation than those from either ripe (red) or immature (green) fruits. Imbibed storage increased desiccation sensitivity. The results are compatible with the view that arabica coffee seeds are unable to tolerate extreme desiccation because germination has been initiated before harvest.