exogenous and endogenous gibberellin
Gibberellins are a group of plant hormones that play a role in various growth and developmental processes in plants. They are classified into two main categories: exogenous gibberellins and endogenous gibberellins.
Exogenous gibberellins are gibberellins that are applied externally to plants. They can be in the form of synthetic gibberellins or naturally occurring ones extracted from other plant species. When exogenous gibberellins are applied to plants, they can promote various growth processes such as stem elongation, seed germination, and flowering. Farmers and horticulturists often use exogenous gibberellins to manipulate plant growth and development, for example, to stimulate the growth of tall and slender crops or to induce seed germination in certain plant species.
Endogenous gibberellins, on the other hand, are gibberellins that are naturally produced within the plant. These hormones are synthesized in various parts of the plant, including the shoot tips, young leaves, and seeds. Endogenous gibberellins play a vital role in regulating plant growth and development. They are involved in processes such as cell elongation, cell division, and the transition from vegetative to reproductive growth. The levels of endogenous gibberellins in a plant can be regulated by various internal and external factors, such as light, temperature, and nutrient availability.
In summary, exogenous gibberellins are applied externally to plants, while endogenous gibberellins are naturally produced within the plant. Both types of gibberellins play important roles in regulating plant growth and development.
Exogenous and endogenous gibberellins both refer to plant hormones called gibberellins, but they differ in their sources and their effects on plants.
1. Exogenous Gibberellins:
Exogenous gibberellins are gibberellins that are applied externally to plants. They can be synthesized in laboratories and commercially available as plant growth regulators. When exogenous gibberellins are used, they are usually in the form of solutions or sprays that are applied to the plants.
Effects of exogenous gibberellins:
- Promote stem elongation: Exogenous gibberellins can stimulate cell division and elongation, leading to increased stem length in plants.
- Induce flowering: They can help induce flowering in some plant species, especially those that require a specific photoperiod or temperature for flowering.
- Improve fruit development: Exogenous gibberellins can also enhance fruit development by promoting cell division and elongation in the fruit tissues. This can result in larger and improved-quality fruits.
2. Endogenous Gibberellins:
Endogenous gibberellins are naturally produced by the plants themselves. They are synthesized in various parts of the plant, including the shoots, young leaves, roots, and seeds. Endogenous gibberellins play crucial roles in regulating plant growth and development.
Functions of endogenous gibberellins:
- Stem elongation: Endogenous gibberellins promote stem elongation by stimulating cell division and elongation in the plant's shoot apical meristem.
- Seed germination: Gibberellins are involved in the breaking of seed dormancy and the stimulation of seed germination. They can also promote the synthesis of enzymes that hydrolyze stored carbohydrates to provide energy for seedling growth.
- Flowering: Endogenous gibberellins play a role in the transition from vegetative growth to reproductive growth, triggering flower development in some plants.
- Fruit development: Similarly to exogenous gibberellins, endogenous gibberellins also contribute to fruit development by promoting cell division, expansion, and differentiation in the fruit tissues.
Overall, while both exogenous and endogenous gibberellins affect plant growth and development, exogenous gibberellins are applied externally to plants, while endogenous gibberellins are naturally produced by the plants themselves.