Temperature - Seed Dormancy
Low temperature treatment is an essential prelude to germination in many seeds, and high temperature may be inhibitory at the time of germination. The low temperature chilling requirement is frequently met artificially by the process of stratification. The seeds are layered in trays in cold moist air for a period of several weeks or months. Temperatures between 0 and 10?C are most effective. The chilling requirement is variously located in the embryo or the seed coat, sometimes in both. The chilling requirement of apple seeds, for example, is much longer for intact seeds than for seeds with the coats removed, or for isolated embryos. Red light and GA have a synergistic effect, that is, the combination of both factors stimulates germination more than the sum of the two separately.