STUDIES ON THE DEVELOPMENT OF THE DESICCATION-SENSITIVE (RECALCITRANT) SEEDS OF AVICENNIA-MARINA (FORSSK) VIERH - THE ACQUISITION OF GERMINABILITY AND RESPONSE TO STORAGE AND DEHYDRATION

Germinability and responses to storage and dehydration were studied throughout the development of the desiccation- sensitive seeds of Avicennia marina. Seeds acquired the ability to produce roots at 55 d after fruit set (DAFS) which is shortly after histodifferentiation, but the capacity for full germinability (seedling establishment) was not attained until 70 DAFS, which is midway through the phase of growth and reserve accumulation. Pre-mature seeds showed a germination lag that was equivalent to the period between harvest and full maturity, but, following short-term storage, this was reduced to that of mature seeds. At no stage, however, would seeds with an intact pericarp germinate. Once seeds were fully germinable, storage lifespan under non-desiccating conditions was independent of developmental stage, but was considerably reduced by the presence of the pericarp, probably because of fungal contamination. Prior to the acquisition of full germination capacity, the seeds were unable to tolerate any dehydration but became tolerant to slight water loss once they became fully germinable, after which desiccation sensitivity was not influenced by the stage of development. If rapidly dried, excised axes of germinable seeds survived to lower watercontents than did axes removed from seeds following slower drying. © 1993 Annals of Botany Company.