DRYING INTERFERES WITH GERMINATION OF BLACKBERRY (RUBUS SP) SEEDS IN-VITRO

To study the causes of low germinability in dried blackberry seeds, se eds harvested from fresh 'Thornless Evergreen' (TE) blackberry (Rubus laciniatus Willd.) were either air-dried (12, 24, 36, 48, 60, 72, 96, or 120 hours) or explanted directly onto growth-regulator-free medium after bleach disinfestation. Seeds were either cut in half before expl anting or kept intact. None of the intact seeds germinated. Fewer of t he halved seeds dried 12 hours or more germinated than control (fresh moist) seeds (42.7% and 54.5%, respectively). Germination decreased to <12% following >48 hours of air-drying. In a separate study, fresh se eds of TE and 'Navaho' were either dried as described or held in seale d petri dishes on moist filter paper (moist treatment) for up to 60 ho urs. After 60 hours, germination of dried seeds of both cultivars had decreased significantly; there was no significant change in germinatio n percentage for moist seeds. Since moist halved seeds germinated well and dried halved seeds did not, the inability of dried blackberry see ds to germinate is due to more factors than just the hard seedcoat typ ical of the genus.