introduction of flowering by low temp. in plants is

1. cryobiology
2. vernalization
3. phototropism
4. pruning

Vernalization is the artificial exposure of plants (or seeds) to low temperatures in order to stimulate flowering or to enhance seed production. By satisfying the cold requirement of many temperate-zone plants, flowering can be induced to occur earlier than normal or in warm climates lacking the requisite seasonal chilling. Knowledge of this process has been used to eliminate the normal two-year growth cycle required ofwinter wheat. By partially germinating the seed and then chilling it to 0° C (32° F) untilspring, it is possible to cause winterwheatto produce acropin the same year.