INFLUENCE OF TEMPERATURE PRIOR TO SEED RIPENING AND AT GERMINATION ON ROSETTE FORMATION AND BOLTING OF EUSTOMA-GRANDIFLORUM

Rosette formation and subsequent bolting of Eustoma grandiflorum are influenced by temperature conditions prior to seed ripening and after germination has commenced. Rosette formation was decreased if parent plants were matured at 23/18-degrees-C (day/night) temperature and was increased at 33/28-degrees-C. Further low temperature seed treatment of hydrated seeds at 3-degrees-C or 10-degrees-C for 5 weeks decreased rosette formation and enhanced subsequent seedling bolting. Different cultivars responded differently to the various seed temperature treatments. Cultivars which formed rosettes easily, showed less of a response to low temperature after harvest. However, if seeds were ripened under a cooler environment, then germinated at low temperatures and seedlings grown in a cool environment, rosette formation of seedlings in E. grandiflorum was essentially eliminated.