Phases of growth in plants: Definition, Process & Phases

Phases Of Growth

Plant growth refers to the process involved in increasing the number of cells in the plant body. It is a general, progressive development of the plant. Understanding the phases of growth will enable farmers to know at which time to apply a given practice for maximum results, that is, obtaining yields from crops and also for good health of the plants.

The major growth stages are germination, which consists of a seed sprouting to become a seedling; vegetative growth, where there is the development of leaves, stems, and roots; and reproductive growth, marked by flowering, fruiting, and formation of seeds. Each of the phases is influenced by different internal and external factors. Being able to recognize these stages helps manage plants effectively for productivity.

The Five Phases Of Plant Growth

These phases are explained below:

Germination

Definition and significance

Germination is the process whereby a seed develops into a new plant. It initiates the plants' life cycle; hence, it assures continuity.

Key stages of germination

• Stages of germination: Basically, there are imbibition, activation of enzymes, and the emergence of the seedling as stages of germination.

• Imbibition: This is the first stage where the seed has imbibed water to expand and soften, hence initiating the trigger of metabolic processes.

• Enzyme activation: Upon rehydration, the enzymes become active to hydrolyze stored food materials in the seed for energy and nutrient supply to the developing embryo from the seeds.

Vegetative Growth

This period of vegetative growth involves root growth, stem elongation, and leaf expansion.

Definition and role in plant development

Vegetative growth is the growth stage of a plant during which it increases in size and mass through the formation of roots, stems, and leaves. This period is of particular importance in setting the general structure of a plant and for peak photosynthetic potential.

Root development

These roots elongate and branch to anchor the plant and absorb water and nutrients from the soil.

Stem elongation

The stem will elongate to support leaves and flowers, and transportation of nutrient water between the roots and leaves.

Leaf expansion

Leaves increase in size to expand photosynthesis which provides energy to the plants.

Factors affecting vegetative growth

Light, water, and nutrients are factors which influence vegetative growth.

Light

This factor is very crucial for photosynthesis and generally for good plant conditions.

Water

Adequate water must be available for the transportation of nutrients, turgor pressure, and maintaining the shape and biochemical reactions.

Nutrients

The essential nutrients, both macro- and micro-requirement are very critical for the growth and development of plant tissues.

Budding

Terminal, axillary; Budding is a process by which new structures in plants, leaves, flowers, or shoots grow from buds. There exist mainly two types of buds, namely the terminal and axillary. The former applies to those at the tips of stems, while the latter refers to those at the point on the stem where the leaf joins.

Role in plant development

It caters to the growth and reproduction of a plant. Thus, the terminal buds lead to vertical growth and elongation of the plant, while axillary buds result in branching and new shoots. In this way, it contributes to the structure of the plant, enhancing its possibilities for photosynthesis and, hence, reproduction.

Flowering

Flowering is the process by which plants form flowers.

The reproductive structures are not dispensable in sexual reproduction. It is a very important process in the generation of fruits and seeds, thus in the survival of a plant species.

Flower development stages:

Bud formation

That stage at which flower buds have formed from the meristematic tissues.

Blooming

This is the time or process that flowers open up to expose their reproductive organs to the outside environment.

Pollination

This is the transfer of pollen from the anther (male) into the stigma, the female part, for fertilization to occur.

Factors influencing flowering:

Temperature

Many plants require specific temperatures for flowers to form.

Light duration

Photoperiod, the length of day or night, controls the time of flowering in many species. Some have to be grown for a long day, whereas others may require a short day.

Fruit And Seed Development

Fruit and seed development is the process following fertilization whereby the transformation of the ovary to a fruit and seeds mature therein. This process offers protection, nourishment, and dispersal of seeds to ensure the propagation of the plant species.

Stages of fruit development

• Fruit growth: This is the stage in which fruit grows in size by cell division and cell expansion.

• Ripening: This is the final stage of the process when the fruit has matured, softened and, in most cases, become sweeter and more palatable; there will be a change in colour in some cases.

Seed formation and dispersal mechanisms

Seeds form within the fruit and contain the embryo with some stored nutrients, while the dispersal mechanisms are wind, water, animals, and self-ejection that help scatter the seeds around to new growing locations

Growth Rates

Definition: Growth rates refer to the speed by which a plant grows through different stages of its life cycle.

Usually measured in height, biomass, and leaf area over time

Factors Affecting Growth Rates:

• Genetics Growth potential is inherent due to the species and cultivar of the plant.

• Environmental Conditions Light, temperature, water, nutrients

• Soil Quality Soil fertility, pH levels, structure.

• Diseases: Pests and other stress factors are not present in the plants.

Stages of Plant Growth:

• Germination: During this period growth is slow as the seedling gets established.

• Vegetative Growth: An increase in size and biomass happens rapidly.

• Reproductive Phase: As the resources are partitioned for flower and fruit production, the growth rate slows down.

• Monitoring: It is the process of observing and measuring anything regularly. This optimises growing conditions to raise the productivity of plants.

Applications: These are significant in agriculture, horticulture and forestry to reap better yields from crops and also to manage plant health properly.

Conditions For Plant Growth

The conditions required for plant growth

Environmental Factors

• Light: This factor is responsible for photosynthesis and controls flowering and growth.

• Water: It is necessary for nutrient transportation and for carrying out cellular changes; it provides turgor pressure to the plants.

• Temperature: It controls the rates of enzymatic reaction and growth; the optimum temperature range varies from species to species.

• Soil: It provides nutrients and physical support; it has a profound effect on root development and water-holding capacity due to its quality, particularly the pH and structure.

• Nutrients: Essential macronutrients and micronutrients; balanced soil fertility is the key.

Internal Factors

• Genetic Makeup: It provides for growth potential and environmental adaptation.

• Hormones: These are responsible for the control of cell division, elongation, and all other procedures. The main important hormones include auxins, gibberellins, and cytokinins.

• Water Status: This provides for cell turgor, gives the force for growth, and requires proper uptake and transport.

• Nutrient Status: Maintaining properly balanced levels of internal nutrients to sustain metabolic functions

• Age and Developmental Stage: Rates and needs vary at the life stages of a plant- seedling, vegetative, and reproductive.

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