Sugars and Chilling Tolerance in Two Cultivars of Dry and Germinating Cucumber Seed
Various carbohydrates have been shown to be associated with stress tolerance in some plant species. Specifically, the content of soluble sugars have been correlated with desiccation tolerance and winter hardiness. We have previously demonstrated that radicles of cucumber seed become progressively more sensitive to chilling injury during the early stages of germination and that cultivar differences exist. Sucrose, raffinose, and stachyose contents of `Poinsett 76' and `Ashley' seed were determined in dry seed during imbibition and at three stages of radicle emergence. The more chilling-tolerant cultivar (Ashley) contained lower raffinose and higher stachyose contents than the less chilling-tolerant `Poinsett 76'. In both cultivars, the contents of raffinose and stachyose declined dramatically between the 1-mm and 5- to 7-mm stage of radicle emergence. At the 1-mm stage, when cultivar chilling-tolerance differences are most pronounced, `Ashley' appears to have a higher content of stachyose and lower raffinose content.