Gibberellins: Definition, Structure, Function, Applications, Uses

What Are Gibberellins?

Gibberellins are members of the phytohormone group, which enables various plant growth and development processes. They are the hormones regulating the critical physiological activities of plants, including seed germination, stem elongation, flowering, and fruit development.

Chemical Properties Of Gibberellins

The chemical properties of Gibberellins are defined below:

Molecular Structure

The molecular structure of Gibberellins is very complex because it mediates a wide variety of biological effects. Hence it is imperative to be familiar with the structure to understand how it interacts with the plant cell to produce such an effect on growth.

Structure And Explanation Of Functional Groups

• Core Structure: Gibberellins have a diterpenoid skeleton with a complex structure of fused rings.

• Functional Groups: The most important functional groups are the hydroxyl (-OH), ketones in the form of C=O, and carboxyl -COOH groups, which are very vital for their activity.

• Structure: General structure of a gibberellin molecule

Physical Properties

Gibberellin's physical properties are remarkable concerning its application and stability in various environments.

State And Solubility

• State: Gibberellins mostly occur as solid crystals or powders.

• Solubility: They are easily soluble in organic solvents such as ethanol and methanol but have poor solubility in water.

Stability And Degradation

• Stability: Gibberellins are light and temperature-sensitive, thus they lose some of their stability and action depending upon the conditions they are exposed to.

• Degradation: They may degrade either with time or when introduced to an extreme condition thus reducing their biological function.

Regulation Of Gibberellin Production

The regulation mechanism is given below:

In such a process, both intrinsic and extrinsic factors act and are followed to achieve control over plant growth effectively.

Mechanisms Affecting Production

• Internal Factors: Genetical regulation and enzymatic pathways followed by the plant.

• External Factors: Light and Temperature impacts the synthesis of Gibberellin.

Factors Affecting Production

Environmental factors, therefore, regulate the synthesis and activity of gibberellins and, in turn, control plant growth.

• Light: The light environment, photoperiod, and quality alter levels of gibberellin involved in controlling such developmental events as flowering.

• Temperature: Fluctuations in temperature may alter the amount and activity of gibberellins, thus affecting growth rates.

• Water Availability: The biosynthesis and action of gibberellins occur optimally only when adequate water is available for plant growth.

Developmental Stages

The levels and activities of Gibberellin vary during different development stages of plants. It controls the growth and reproductive processes in plants.

• Seed germination: Gibberellins are required for breaking seed dormancy and initiation of germination.

• Stem elongation: They control stem growth and height.

• Flowering: Gibberellins can control the time of flowering and development.

Roles Of Gibberellins In Plants

The function of gibberellin in plants is explained below:

Seed Germination

Gibberellins are plant hormones that are essential for the proper germination of seeds and play a very significant role in the initial phase of growth of a plant.

Mechanism

• Dormancy Break: Gibberellins stimulate the production of enzymes responsible for breaking seed reserves.

• Seedling Growth: They promote the growth of the embryo and initial seedling development.

Stem Elongation

Gibberellins play an important role in stem elongation and, hence, contribute to the height and general architecture of a plant.

• Cell Elongation and Division: They increase cell growth and cell division in stems, which leads to an increase in the height of the plant.

• Examples: Gibberellins are used to achieve optimum heights of crop plants, and the response is observed in both dwarf and tall cultivars.

Flowering And Fruiting

Gibberellins regulate reproductive growth, like induction of flowering and fruit development.

Effect

• Induction of Flowering: They induce flowering in plants under favourable conditions.

• Fruit Development: Gibberellins promote fruit size and uniformity.

Leaf And Root Growth

Gibberellins also influence the leaf and root growth, thus altering the overall growth patterns of the plants.

Effects

• Leaf Size: They may have an effect on leaf size and, thereby enhance the aesthetic value of the plants.

• Root Growth Patterns: They affect the pattern of root elongation and root branching.

Gibberellins In Agriculture And Horticulture

The details are given below:

Commercial Applications

Gibberellins have several commercial applications in agriculture and horticulture, all of which are oriented toward enhancing plant growth and productivity.

Crop Management

Gibberellins are used to control plant height, fruit size, and crop yields.

• Plant Height Control: Used to regulate plant height to prevent the lodging of cereal crops.

• Fruit Size and Yield Increase: Gibberellins help increase the size of fruits and thus improve the overall crop yield.

• Examples: Applied on crops like grapes and rice for better management of growth.

Gibberellin Inhibitors And Enhancers

Inhibitors and enhancers of gibberellins control the growth process and enhance the performance of the plants themselves.

• Inhibitors: These are chemicals that inhibit the action of gibberellins, thus controlling excessive growth and development.

• Enhancers: These are chemicals that enhance the action of the gibberellins to enhance the growth and quality of crops.

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