DIFFERENTIAL CHILLING SENSITIVITY IN CUCUMBER (CUCUMIS-SATIVUS) SEEDLINGS

Cucumber (Cucumis sativus L. cv. Poinsett 76) seeds were chilled at 2. 5 degrees C in a study of the chilling sensitivity and recovery of rad icle tissue. The effect of chilling on radicle growth and the producti on of carbon dioxide and ethylene was measured. Chilling sensitivity o f radicles increased as they grew from 1 to 7 mm in length. The length , not the age of the radicles, determined the level of chilling sensit ivity. Apical tissue was most sensitive to chilling and slowest to rec over from chilling, followed by sub-apical and basal tissue. Our data demonstrate that the chilling sensitivity of young seedling radicles d iffers along their length and that the rapid chilling-induced inhibiti on of elongation is probably due to an inability of meristematic cells to remain viable and active when chilled.