GERMINATION AND SEEDLING DEVELOPMENT OF HALOPHILA-ENGELMANNII ASCHERS - (HYDROCHARITACEAE) UNDER AXENIC CONDITIONS

Seeds of Halophila engelmannii Aschers. stored in seawater in the dark after collection in Redfish Bay and Laguna Madre, TX, were germinated in the light under axenic conditions following ultrasonic and chemical (EtOH, NaOCl, HgCl2) cleaning. After germination, axenic seedlings were transplanted individually into sterile media and their development compared with seedlings under non-axenic soil culture. Seedling development in a medium composed of 10% coconut milk, 1% charcoal and 1.5% agar in artificial seawater (ASP2) approximated the rhizome production and stem and leaf pseudowhorl formation in non-axenic sediment cultures. After development under axenic conditions, rhizomal ramets with attached stems and leaf pseudowhorls were established in clonal, axenic cultures during a 6-month period following germination. The sustained culture of clones of H. engelmannii in an axenic system represents a long-sought goal for seagrass investigations and should promote efforts to understand the role of cation exchange in seagrass biology and the nature of chemical interactions with other organisms. © 1990.