Content Curator
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.
| Table of Content |
Key Takeaways: Vernalisation, flowering, germination in plants, Biennial plants, Apical Meristem, Devernalisation
Vernalisation Definition
[Click Here for Sample Questions]
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.
Vernilization
Read more: Biological classification
Process of Vernalisation
[Click Here for Previous Years Questions]
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.
Vernalization Process
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.
Read more: Morphology of Flowering plants
Types of Vernalisation
[Click Here for Sample Questions]
Vernalisation can be classified into the following types:
- Obligate Vernalisation: Plants must be subjected to lower temperatures for a set amount of time. For example, Cabbage.
- Facultative Vernalisation: Flowering occurs earlier in plants when they are exposed to lower temperatures. As an example, consider the annual winter triticale.
Do Check Out :
| Related Topics | ||
|---|---|---|
| movement due to growth | growth and development | Seed |
| phenolic acid | Plant - Growth and Development | Seed germination |
Factors Affecting Vernalisation
[Click Here for Sample Questions]
- 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.
NCERT Solutions : Class 11 Biology Chapter 15 Plant Growth and Development
Advantages of Vernalisation
[Click Here for Previous Years Questions]
- 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.
Read more: difference between auxin and gibberellin
Site Of Vernalisation
[Click Here for Sample Questions]
In different plants, the site that perceives the cold stimulus may differ. It could be the apical meristem in shoots, a germinating seed, or vegetative parts like leaves.
Do Check out :
| Chapter Related Topics | ||
|---|---|---|
| Plant Growth Regulators | Auxins | Gibberellins |
| Ethylene | Photoperiodism | tropic movements in plants |
| Seed Dormancy | Senescence | plant roots |
Devernalisation
[Click Here for Previous Years Questions]
Devernalisation is the reversion of the vernalisation process as a result of exposure to higher temperatures. This process is influenced by exposing vernalised buds or seeds to a wide temperature range. Lang et al. demonstrated in 1957 that using gibberellin coils instead of cold treatment for vernalisation in certain biennial plants.
Read more: Transportation in Plants
Things to Remember
[Click Here for Sample Questions]
- Vernalisation is defined as a plant's qualitative or quantitative dependence on low temperatures to bloom.
- Plants in mild climates germinate at low temperatures, whereas plants in hot climates germinate at high temperatures.
- There are two types of vernalisation, Obligate Vernalisation and Facultative Vernalisation.
- Devernalisation is the reversion of the vernalisation process caused by higher temperatures.
- Vernalisation reduces the vegetative phase in plants.
Also read: Stomata
Previous Years Questions
- A few normal seedlings of tomato were kept in...[NEET 2014]
- One set of a plant was grown at 12 hours day and 12 hours night period cycles….[NEET 2004]
- Treatment of seed at low temperature under moist ….[NEET 2006]
- Abscisic acid controls...[NEET 1990]
- Hormone connected with cell division...[NEET 1991]
- Auxin can be bioassayed by...[NEET 2015]
- Coiling of garden pea tendrils around any support….[NEET 2010]
- Cytokinins are known to….[NEET 1992]
- Dwarfness can be controlled by treating the plant...[NEET 1980]
- Flowering dependent on cold treatment is...[NEET 1992]
- Fruit and leaf drop at early stages can be….[NEET 2017]
- Gibberellins promote...[NEET 1988]
- If the apical bud has been removed observe...[NEET 2000]
- If the growing plant is decapitated….[NEET 1994]
- In a plant growing under dark condition, the leaves...[CUCET 2009]
- Transport of cytokinin in the plant body is….[CUCET 2011]
- Apical dominance in higher plants is due to….[COMEDK UGET 2007]
- The plants bend towards light because….[CUCET 2009]
- During which of the following phase of growth cell...[GUJCET 2006]
- To make stored food available for germination with which hormone….. [GUJCET 2006]
Sample Questions
Ques: What is the Vernalisation process? Mention its significance? (3 marks)
Ans: The process of vernalisation is the induction of the flowering process in plants due to prolonged exposure to lower temperatures, cold of winter, or similar conditions.
The following are the significances of vernalisation:
- Crops can be planted earlier, plants can be grown in areas where they would not normally grow.
- The plant's yield increases.
- Improved resistance to cold and frost.
- Fungal disease resistance increases.
Ques: Where does Vernalisation happen, and which hormone is responsible for it? (3 marks)
Ans: The perception of the site differs between cold stimulus plants. It could be an active metabolic embryo, a germinating seed, a shoot apical meristem, or vegetative parts like leaves. Gibberellin is a hormone that is essential for vernalization. This is due to its role in regulating plant development.
Ques: Would a plant that has been defoliated respond to the photoperiodic cycle? Why? (3 marks)
Ans: No, since the leaves only pick up photoperiodic stimuli, a defoliated plant would not respond to the photoperiodic cycle. Even a single leaf, or a portion of one, is sufficient for this purpose. The presence of leaves under an inductive photoperiod is required for perception of the photoperiodic cycle, so the hormone responsible for flowering can be formed.
Ques: Mention the Requirements of Vernalisation? (3 marks)
Ans: Vernalisation requires nutrients, aerobic respiration, and a 50-day low temperature treatment at temperatures ranging from 2°C to 12°C. Water – Plants need adequate hydration to respond to cold temperatures. Cells are actively dividing – For vernalisation to occur, the cells must be actively dividing. Because it does not work with dry seeds, they must be moistened before being exposed to low temperatures.
Ques: 'In higher plants, both growth and differentiation are open.' Explain. (5 marks)
Ans: Meristems are areas in higher plants that play a role in the formation of new cells. Plants' bodies are built in a modular fashion, with structure never being complete because the tips (with apical meristem) "are open-ended – always growing and forming new organs to replace the older or senescent ones." Growth is inextricably linked to differentiation. The precise cause of differentiation is also unknown. Not only is plant growth unrestricted, but so does plant differentiation. At maturity, the same apical meristem cells give rise to different types of cells, such as xylem, phloem, parenchyma, sclerenchyma fibers, collenchyma, etc. As a result, both processes are indeterminate, limitless, and mature into different structures, i.e., both are open.
Ques: Explain the process of Vernalisation? (5 marks)
Ans: Vernalisation is the process of inducing flowering in plants by exposing them to long periods of cold, cold weather, or similar conditions. Plants develop the ability to flower once this process is completed.
Flowering is aided by a cold treatment given to a completely hydrated seed or a growing plant during the vernalisation process. The vegetative phase of the plant is restricted due to the vernalisation process, resulting in early flowering. Plants that require vernalisation exhibit prolonged flowering or remain vegetative in the absence of cold treatment.
Ques: Why isn't any single parameter sufficient to demonstrate growth in a flowering plant throughout its life?(5 marks)
Ans: A flowering plant is made up of various organs that grow at different stages of its life cycle, such as roots, stems, and leaves. Different parameters are required for these plant organs to grow. Fresh weight is used to measure the growth of plant organs such as fruits, corms, etc. In the case of fruits, other parameters such as volume, diameter, and so on are used to measure their growth. An increase in surface area is used as a parameter for flat organs such as leaves. Stems and roots grow in length first, then in girth, so length and diameter are used to measure their growth. As a result, flowering plants exhibit a variety of parameters to illustrate growth.
Do Check Out:
Comments