TEMPERATURE EFFECTS ON IMBIBITION AND GERMINATION OF CUCUMBER (CUCUMIS-SATIVUS) SEEDS

Unlike horticulturally mature fruit of 'Dasher II' and 'Poinsett 76' cucumbers (Cucumis sativus L.), two cultivars that differ significantly in their level of chilling tolerance, imbibing and germinating seeds of these two cultivars responded similarly to chilling temperatures (e.g., increases in fresh weight, time to radicle emergence, and root growth). 'Dasher II' and 'Poinsett 76' seeds were imbibed and germinated at 10 to 30C, and seeds germinated at 25C for 24 h were chilled at 2.5C for various durations. In comparison, seeds from an aged lot of 'Poinsett 76' seed (1989) responded very differently from the 1992 seed lots in all experiments. The chilling tolerance level of germinating 'Poinsett 76' seed varied with the seedling age as measured by resumption of root growth. Our results suggest that some factor that confers chilling tolerance is gradually lost during the early stages of germination following imbibition.