INOVULO EMBRYO CULTURE OF TULIP (TULIPA L) - EFFECTS OF CULTURE CONDITIONS ON SEEDLING AND BULBLET FORMATION

Seedling formation and bulblet production from immature ovula of tulip (Tulipa gesneriana L.) were studied. Percentage germination, on a modified Murashige and Skoog (MS) medium, was increased by prolonging the 5-degrees-C chilling period, given at the beginning of the culture, from 8 to 12 weeks. Culture in continuous darkness was superior to 16 h light in producing good quality stolon and bulblet formation from the seedlings. The use of a thin layer of medium, approximately 6 mm thick, prevented the stolons from entering into the medium and from growing thick and turgid, and improved bulblet formation. Improvement of bulblet formation was also observed when the growing temperature was lowered from 24 to 12-15-degrees-C. The optimal concentration of sucrose in the growing medium was 6% (w/v). Ultimately, under the improved conditions, up to 90% bulblet formation was obtained, with an average dry weight of approximately 50 mg. Transfer to soil was only possible if bulblets were used, but these frequently became sclerotic or developed abnormally. Percentage of second-year bulblet production after transplantation was 12-30%, depending on the genotype used.