Vernalization

Vernalization:- It is the artificial exposure of plants or seeds to low temperatures in order to stimulate flowering or to enhance seed production. Gibberellin is a hormone that replaces vernalization. The metabolically active apical meristems are the sites of perception of temperature to initiate flowering. The younger leaves are more susceptible to the process of vernalization. The shoot apex of mature stems or embryo of seeds receives low temperature stimulus.

Mechanism of Vernalization:- Through vernalization, there is an advancement in the process of blooming as a result of the delayed period of low temperatures, for instance, that which is attained in winter. To describe the mechanism of vernalization, there are two main hypotheses –

a. Phasic development theory

b. Hormonal theories

a. Phasic Development Theory:- As per this hypothesis, there is organization of stages in the plant’s improvement. Each stage is under the impact of environmental elements such as light, temperature etc. Here, in turn, there are two main stages –

i.Thermostage:- It depends on temperature, wherein vernalization accelerates thermostat. Thermostage is the vegetative phase requiring low heat, aeration and enough dampness

ii. Photostage:- It necessitates high temperature. Here, vernalin assists in producing florigen.

b. Hormonal theories:- As per this hypothesis, the freezing treatment propels the development of a floral hormone referred to as vernalin. Such a hormone is imparted to various parts of the plant. The vernalin hormone diffuses from the vernalized plants to the unvernalized plants, prompting blooming.