Vernalisation – Class 11 | Chapter – 15 | Biology Short Notes Series PDF

Vernalisation: The term “vernalisation” comes from the Latin word “vernus,” which means “spring.” It simply means “to make spring-like.” Vernalisation is defined as a plant’s qualitative or quantitative dependency on exposure to low temperatures to blossom. Flowering, metabolic activities, and seed germination in plants are all affected by Temperature.

Vernalisation is the process of inducing flowering in plants by exposing them to long periods of cold weather, or similar conditions. Plants develop the ability to flower once this process is completed. Many plants grown in temperate areas require vernalization, or a period of cold temperatures in the winter, to start or speed up the flowering process. This ensures that reproductive development and seed production take place in the spring and winter instead of the autumn. Other than light, one more factor that influences flowering in plants is Temperature, which is known as Vernalisation.

Vernalisation Cycle

Types of Vernalisation

Vernalisation can be classified into the following types:

  1. Obligate Vernalisation:  Plants must be subjected to lower temperatures for a set amount of time. For example, Cabbage.
  2. Facultative Vernalisation: Flowering occurs earlier in plants when they are exposed to lower temperatures. As an example, consider the annual winter triticale.

Factors Affecting Vernalisation

  • Nutrients
  • Aerobic Respiration
  • 50-day Low: Temperature treatment at temperatures ranging between 2°C to 12°C
  • Water: Plants require appropriate hydration to respond to cold temperatures
  • Actively dividing cells: The cells must be actively dividing for vernalization to occur. It doesn’t work on dry seeds, so they must be moistened before being exposed to low temperatures.
  • Vernalisation helps plants grow in areas where they would not normally grow
  • It aids in the removal of wrinkles from Triticale kernels (wheat and rye hybrid)
  • Plants are prevented from maturing very early in the growing season. As a result, they have sufficient time to mature.
  • Early flowering is induced, and the vegetative phase of the plant is reduced.
  • It enhances plant yield and provides resistance to cold and disease.
  • It allows biennial plants to behave similarly to annual plants.

Process of Vernalisation

Plants grown in mild climates germinate at low temperatures, whereas plants in hot climates germinate at high temperatures. Some plants require low temperatures to germinate. Furthermore, exposing a plant to low temperatures during the growing season can be induced to flower. As a result, it shortens the vegetative phase and accelerates flowering in plants.

Wheat and barley, for example, have a ‘spring variety’ and a ‘winter variety.’ The ‘spring variety’ is typically planted in the spring. As a result, it has flowered and produced grains by the end of the growing season. On the other hand, the ‘winter variety’ is planted in the autumn. It sprouts in the winter, grows in the spring, and is harvested in the summer. In contrast to the spring variety, the winter variety will not flower or start producing grains during the flowering season if planted in spring.

Process of Vernalisation

Biennial plants are those that flower every two years. In the first year, they develop leaves, stems, and roots before dormancy during the cold months. They require this period of cold or vernalisation to flower in the following months. Biennial plants eventually flower, produce fruit, and die next spring or summer. Carrots, sugarbeets, and cabbages are some examples.

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By Team Learning Mantras