Growth is the permanent, irreversible increase in the size of an organism. This feature is observed in all organisms, accompanied by several metabolic processes.
In plants, the seeds germinate and develop into a new seedling, which finally develops into an adult plant. Plants display indefinite growth.
Phases of Plant Growth
There are the following phases of plant growth:
Plants grow by cell division. The pre-existing cells divide to give rise to new cells. The process of cell division in plants is known as mitosis. It is carried out in two steps:
- Division of Nucleus or Karyokinesis
- Division of Cytoplasm or Cytokinesis
In higher plants, the division of cells begins in the meristematic region.
Cell Enlargement and Differentiation
The size of the cells, tissues and organs increases at this stage by the formation of protoplasm, absorption of water, developing vacuoles, and addition of cell walls to make it thicker and permanent.
The enlarged cells acquire a definite shape and form at this stage. This helps in differentiating different cells and tissues.
Factors Affecting Plant Growth
The important factors affecting the growth of plants include:
- Temperature: Growth is accelerated with the increase in temperature.
- Light: Light intensity, duration of light and the quality of light influences many physiological processes occurring in a plant.
- Water: Water is an essential factor for plant growth. They grow well in sufficient amount of water. They even respond to the scarcity of water.
- Soil Nutrients: Plants require adequate amount of nutrients for proper growth. The quality and quantity of nutrients affect plant growth.
- Plant Growth Regulators: Various plant growth regulators such as auxin, cytokinin, gibberellins, etc are added to plants to regulate their growth.
Differentiation is the process in which the cells specialize into morphologically and physiologically different cells. Mature cells can divide and differentiate again and this is known as dedifferentiation. This usually occurs in wounded tissues. The parenchyma cells are dedifferentiated and thus, the wound is repaired.
Development includes all the changes that take place during the life cycle of a plant. There are different pathways followed by plants in response to the environment and form different structures. The leaves of a young plant have different structures as compared to the mature plant.
Development is the sum total of growth and differentiation. It is regulated by extrinsic and intrinsic factors.
Growth, differentiation, and development are closely related events. A plant cannot develop if the cells do not grow and differentiate.
The following topics will help you understand more about the growth and development of plants.
- Seed Germination
- Phases of Plant Growth
- Differentiation and Development in Plants
- Plant Growth Regulators
- Seed Dormancy
- Photoperiodism and Vernalisation
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