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

What Is Plant 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. 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.

What Are the Factors Affecting Plant Growth?

The factors regulate major processes such as cell division, cell enlargement, differentiation and development. Plant growth is influenced by:

• Intrinsic factors such as genes, hormones, differentiation

• Extrinsic factors such as light, temperature, water, soil nutrients

Internal Factors Affecting Plant Growth

Internal factors affecting plant growth include hormones which regulate processes like cell division, elongation, and differentiation. Genetic makeup also influences growth.

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.

Genetic Factors

Genetic makeup also influences growth by determining traits such as growth rate, flowering time, stress tolerance, and overall developmental patterns.

Differentiation & Dedifferentiation

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.

External Factors Affecting Plant Growth

Plant growth is significantly influenced by the environment. It is necessary to 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 a 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 include nitrogen, phosphorus, and potassium are those nutrients that are required in larger amounts for growth and development.

• Micronutrients are the elements 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.

Development (Growth + Differentiation)

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.

Factors Affecting Plant Growth NEET MCQs (With Answers & Explanations)

Important topics for NEET are:

• Factors affecting growth

• Development

Practice Questions for NEET

Q1. The occurrence of more than one type of leaves in rooted emergent water plant is known as

1. Phyllotaxy

2. Heterophylly

3. Aestivation

4. Anisophylly

Correct answer: 2) Heterophylly

Explanation:

The occurrence of multiple leaf types in rooted aquatic plants is termed heterophylly. This phenomenon is categorized into three distinct types:

1. Developmental Heterophylly: This involves the formation of varied leaf types during different growth phases of the plant, such as juvenile and adult stages.
2. Environmental Heterophylly: Here, leaf morphology is influenced by external conditions, with specific leaf types developing in response to environmental factors like water depth. For instance, submerged leaves might differ from those that emerge above water.
3. Habitual Heterophylly: In this case, the plant exhibits dissimilar leaf types across various regions of its structure, such as underwater, floating, and above-water parts.

Examples of heterophylly can be seen in species like Potamogeton and water lilies. These emergent water plants have large, broad leaves that extend above the water surface for photosynthesis. In contrast, their submerged leaves are often more intricately divided or structurally adapted to enhance their functionality within the water column. This dual-leaf strategy allows them to efficiently inhabit and thrive in their aquatic surroundings.

Hence, the correct answer is option 2) Heterophylly.

Q2. Plants display

1. Definite growth

2. Indefinite growth

3. Fixed growth

4. Steady growth

Correct answer: 2) Indefinite growth

Explanation:

Having meristems—areas of actively dividing cells—allows plants to expand indefinitely. Located at the tips of roots and shoots, these meristems enable plants to continue developing for the duration of their lives. By becoming taller, extending their roots, or spreading their branches as necessary, this kind of growth aids plants in adjusting to their surroundings.

Hence, the correct answer is option 2) Indefinite growth.

Q3. What happens to seeds when favourable conditions for growth are absent?

1. They grow rapidly

2. They enter a period of suspended growth or rest

3. They continue metabolic activities

4. They form roots

Correct answer: 2) They enter a period of suspended growth or rest

Explanation:

Seeds enter a period of dormancy or rest when conditions for growth are not favourable, such as in the absence of adequate moisture, temperature, light, or oxygen. During dormancy, metabolic activities in the seed are greatly reduced, and the seed remains in a state of suspended growth. This dormancy period is a survival mechanism, allowing the seed to wait for optimal environmental conditions before beginning germination. The seed coat, hormones like abscisic acid (ABA), and other factors regulate this dormant state. Once the conditions are favourable, such as when water, temperature, and light signals are appropriate, the seed can overcome dormancy and begin the germination process.

Hence, the correct answer is option 2) They enter a period of suspended growth or rest.

Also Read:

• MCQs on Plant Growth and Development

• Plant Growth Regulators

• Auxin Biosynthesis

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