Vernalization is the process by which certain plants require exposure to prolonged cold temperatures to induce flowering or accelerate the transition from vegetative to reproductive growth. This process ensures that flowering occurs under favorable environmental conditions, typically in spring, after the risk of frost has passed. Vernalization is commonly observed in crops like wheat, barley, and rye, as well as in biennial plants like carrots and cabbage.
Vernalization involves the exposure of plants to prolonged cold conditions to induce flowering. Here’s a step-by-step explanation of the process:
Vernalization can be classified into several types based on how plants respond to cold treatment. Seed vernalization involves exposing seeds to cold temperatures to break dormancy and promote both germination and flowering, as seen in crops like wheat, barley, and rye.
In plant vernalization, the entire plant, particularly during its vegetative stage, is subjected to cold exposure, which induces flowering in species like cabbage, carrots, and beets. Plants requiring obligate vernalization strictly depend on prolonged cold exposure for flowering, such as winter wheat and winter rye.
In contrast, facultative vernalization accelerates flowering but is not mandatory; for example, some spring wheat varieties can flower without vernalization but do so faster with cold treatment.
Another category is juvenile vernalization, where plants must reach a specific developmental stage before responding to cold, as observed in sugar beets and some biennials. Lastly, artificial vernalization is a controlled method where seeds or plants are exposed to cold conditions in laboratories or greenhouses, mimicking natural winter environments to induce flowering. These types reflect the diverse mechanisms by which plants adapt to their environments to ensure optimal growth and reproduction.
Vernalization accelerates the blooming process by exposing plants to prolonged periods of low temperatures, such as those experienced during winter. Two primary hypotheses explain the mechanism of vernalization: the Phasic Development Theory and the Hormonal Theories.
1. Phasic Development Theory
This theory suggests that plant development occurs in organized stages, each influenced by environmental factors like light and temperature. The two main stages are:
2. Hormonal Theories
According to this hypothesis, cold treatment induces the production of a floral hormone known as vernalin. This hormone is distributed to various parts of the plant, promoting blooming. Furthermore, vernalin can diffuse from vernalized plants to unvernalized ones, triggering flowering in the latter as well.
The process of vernalization is affected by the following factors –
Vernalization is derived from the Latin word “versus”, which means “of spring”. It means to make “spring-like”. It is the induction of the plant's flowering process by direction to the long periods of cold winter or such conditions. Once this procedure takes place, plants develop the capability of flowering. Regardless, they may necessitate extra seasonal weeks of growing before they flower.
Botanist P. Chouard has introduced the term vernalization.
Vernalisation is plants' qualitative or quantitative reliance on exposure to a low temperature to flower. Temperature influences flowering, metabolic activities, and germination of seeds in plants. Plants that grow in temperate weather germinate at low temperatures, whereas those in hot provinces germinate at high temperatures.
This process can aid in curtailing the vegetative phase and bring about early flowering, which applies to delicate plants and some tropical plants. Via vernalization, Kernel wrinkles of the Triticale can be eliminated.