Factors Affecting Plant Growth: Definition, Types, Factors Affecting, Examples

What Is Growth?

The basic life processes of plant growth and development are primarily involved in the plants' existence and sustenance in any kind of environment. They include mechanisms whereby plants increase in size through cells produced by meristems, differentiate into special kinds of cells, and hence adapt to different environmental conditions.

Plant Growth

Growth is the characteristic shared among all living things, including plants. It is defined as the irreversible increase in size and mass, through cell division and cell expansion. In plants, growth is a necessary process for:

• Nutrient Uptake: Growing higher and developing root systems, plants can assimilate more nutrients and water from a larger area.

• Competition: Growth enables plants to obtain the sunlight, water, and other nutrients essential for survival from neighbouring plants.

• Protection: With increased size, vital organs and tissues can be protected from herbivores and various sorts of abiotic stressors.

One of the classic cases of plant growth is seed germination, whereby a passive seed absorbs water, swells, and finally breaks through the soil to emerge as a seedling.

The Phase Of Plant Growth

Plant growth has well-marked phases of development, each phase being dominated by different biological processes.

Formative Phase

This is the first stage of rapid cell division, occurring primarily in the meristematic regions of plants. There are two major processes combined in this process of cell division, namely:

• Karyokinesis: It is the process of nucleus division; at the end, each daughter cell contains the same set of chromatids.

• Cytokinesis: It is the actual division of cytoplasm to form two separate daughter cells.

At this growth stage, it is mostly influenced by genes and the environment.

Cell Enlargement And Differentiation

After cell division through mitosis, the new cells increase in size, causing tissue and organ growth. This cell enlargement is caused by :

• Absorption of Water: It is the turgor pressure in the cells due to water absorption that triggers the cell to stretch.

• Formation of Vacuoles: Vacuoles, acting as storage organs of water and other nutrients, contribute towards cell enlargement.

• Cell Wall Thickening: In this process, cellulose and other building blocks are manufactured, increasing the strength of a cell wall, and allowing cells to bear more inner pressure.

This is where cells begin to differentiate functions, which is crucial in performing the chosen role of the plant.

Cell Maturation

This is the stage at which the cells finally reach their true shape and form and acquire specific features to perform certain functions. The differentiation leads to the formation of various tissues, including:

• Parenchyma: Involved in storage and photosynthesis.

• Collenchyma: Provides mechanical support.

• Sclerenchyma: Provides rigidity and strength.

Maturation of cells is crucial to the proper execution of major plant functions, such as photosynthesis, nutrient transport, and providing mechanical support.

Factors Affecting Plant Growth

Plant growth is significantly influenced by environmental and biological factors. It would be appropriate to learn and familiarise with these factors to obtain maximum health and productivity of plants.

Temperature

Temperature is a critical factor in plant growth since it controls metabolic rates. Most plants have temperature optimum in which the enzymatic activities for growth are maximized. Extreme temperatures will thus inhibit or cause damage to growth.

Light

Light is necessary for photosynthesis, by which green plants manufacture chemical energy from light energy. Key features of light, influencing plant growth, include:

• Light Intensity: Up to a point, the more intense the light, the more photosynthesis will be able to occur.

• Duration of Light: The length of time the plants remain in the light, the photoperiod, will stimulate flowering and other growth responses.

• Light Quality: The different wavelengths of light will have different effects on plant growth. Examples include the fact that red and blue light are effective in photosynthesis.

• Water: Water has a role in many physiological processes, including the transport of nutrients, photosynthesis, and maintenance of turgor pressure. Plants therefore have to maintain a proper water balance. The stress caused by both excess and deficient water conditions is illustrated, which affects the growth of the plant adversely.

Soil Nutrients

For the healthy growth of plants, the availability of nutrients has to be taken into consideration. The essential nutrients include:

• Macronutrients: Nitrogen, phosphorus, and potassium are those nutrients that are required in larger amounts for growth and development.

• Micronutrients: These elements are required only in small amounts but are of equal importance to carry out several biochemical processes. Examples include iron, manganese, and zinc.

Soil quality, pH, and nutrient profile directly impact plant health and productivity.

Plant Growth Regulators

Plant growth regulators are naturally occurring or synthetic hormones which can alter growth and development. The important ones are:

• Auxins: Induce cell elongation and root growth.

• Cytokinins: Cell division and shoot formation.

• Gibberellins: Stimulate stem elongation and seed germination.

These plant growth regulators can be used to promote growth, increase yield, and regulate plant development.

Differentiation

It is the process wherein cells become more specialized to form specific kinds of cells with characteristic morphology and functions. It is a must for producing all tissues in plants that include:

• Dermal Tissue: It covers the surface of the plant.

• Vascular Tissue: It conducts water, nutrients, and sugars.

• Ground Tissue: It consists of photosynthetic storage or mechanical tissue.

This dedifferentiation of mature cells, mostly in response to injury, can lead to change from specialized cells into a less specialized state. This ability is significant in the healing of wounds and regeneration in plants.

Development

Development includes all the changes that take place in the lifetime of a plant. It brings together growth and differentiation. It includes:

• Seed Germination: It is the transformation from a quiescent seed to a growing seedling

• Morphogenesis: Development of shapes and structures of plants.

• Reproductive Development: Formation of flowers, fruits and seeds.

Developmental behaviour is controlled by intrinsic genetic factors as well as by extrinsic environmental factors like light, temperature, and availability of water.

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