Propagation of Ornamental Plants
9(2): 102-106, 2009
A COLD TREATMENT PROMOTES BOTH SPROUTING AND SINK STRENGTH OF LILY BULBLETS
Geert-Jan de Klerk
Wageningen Tissue Culture Center, Wageningen UR Plant Breeding, P. O. Box 16, 6700 AA Wageningen, The Netherlands, Fax: + 31-317-483457 E-mail: geertjan.deklerk@wur.nl
Abstract
Lily bulblets produced in tissue culture at 20 or 25ºC are cold-treated before planting to break dormancy. Bulblets produced in tissue culture at a relatively low temperature (15ºC), though, are nondormant and sprout without a preceding cold treatment. Leaves generated after planting by noncold-treated 15ºC bulblets, were relatively small and as a consequence bulblet growth after planting was limited. This was also observed for the few 20 and 25ºC bulblets that did sprout without a cold treatment. Sink-strength of bulblets was assessed as bulblet dry-weight (DW) gain per mg leaf DW. Noncold-treated bulblets had far less sink-strength than cold-treated ones. Thus, a second cause of the little growth of noncold-treated bulblets was their small sink-strength. The optimal temperatures to break dormancy and to promote sink strength were 9 and 2ºC, respectively. It is concluded that a cold treatment not only breaks dormancy but also enhances sink strength, and that these are unrelated processes.
Key words: bulb formation, dormancy, Lilium, stratification
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