INTERSPECIFIC VARIATION IN SEED STORAGE BEHAVIOR WITHIN 2 GENERA - COFFEA AND CITRUS

Classification of the variation in seed storage behaviour among specie s, especially within a genus, is required before alternative methods o f ex situ conservation can be evaluated for efficacy. Seeds of robusta coffee (Coffea canephora Pierre ex Froehner) and liberica coffee (Cof fea liberica Bull ex Hiern) were tested for germination following desi ccation and subsequent storage for up to one year at three temperature s (-20 degrees C, 0 degrees C, 15 degrees C) with 5 to 13% (robusta) o r 5 to 14% (liberica) moisture content. Robusta coffee seeds extracted from ripe (red) or almost ripe (yellow) fruits were less sensitive to loss in viability from desiccation than those immature (green) fruits . Even with seeds from red fruits, however, in which desiccation to 11 .3% moisture content reduced viability by 22% and further desiccation to 7.0% killed all but 2% of the seeds, survival in the best (of those tested) hermetic storage environment of 15 degrees C with 11.3% moist ure content was poor with only 4% viability after 12 months. Viability was lost more rapidly during storage the lower the temperature below 15 degrees C and the lower the moisture content below 11.3%. Seeds of liberica coffee were very much more sensitive to desiccation, with onl y 6% surviving desiccation to 13.5% moisture content, and no seeds sur viving as few as six months' storage in any of the 15 environments tes ted. We conclude that liberica coffee shows recalcitrant seed storage behaviour, but that robusta coffee shows an intermediate category of s eed storage behaviour similar to (though with poorer survival than) th at shown by arabica coffee (Coffea arabica L.). Evidence is collated w hich suggests similar interspecific variation in seed storage behaviou r within the genus, and that the intermediate category is discrete rat her than a continuum between orthodox and recalcitrant.