Gibberellin is a type of plant hormone which regulates growth. There are 126 known gibberellins, divided into two classes, and many more may be discovered in the future. Plants produce these hormones naturally through biosynthesis as they grow, ensuring that they have the hormones they need to develop normally, and these hormones can also be applied to plants by gardeners and farmers to achieve specific desired outcomes.
Existence of gibberellin was first hypothesized in 1926, when Japanese researchers were struggling to understand why some rice plants would randomly shoot up to such great heights that they would collapse, becoming impossible to harvest. They discovered that the plants were infected with a fungus which seemed to affect growth, and in 1935, a Japanese researcher successfully isolated gibberellin for further study.
One of the primary functions of gibberellin in a plant is to regulate the growth of the stems. Many members of the cabbage family, for example, release gibberellin when they “bolt” to produce long flowering stalks. These hormones can also influence sex expression, and they appear to be capable of breaking dormancy and promoting germination of seeds. These traits make gibberellins very useful for people who are attempting to tightly control their crops.
Applications of gibberellin to crops can also allow them to produce seedless fruits. The ever-popular seedless grape, for example, wouldn't fully develop and mature without an application of hormones at the right time. These hormones can also force plants to flower, which can be useful in settings where the timing of flowering needs to be precise.
When plants are bred as dwarf cultivars, these cultivars have genetic variations which either inhibit the production of gibberellin, or prevent the plant from utilizing the hormone as it normally would. The genes which deal with gibberellin have been isolated in many plant species to provide more information about how dwarf cultivars work, and how they can be more precisely bred and controlled for reliable performance in the garden or on the farm. In some cases, applying gibberellin to a dwarf plant will cause it to grow like full-sized relatives.
Understanding the mechanics of plant hormones is important for a number of reasons. In the agricultural industry, knowing how, when, and why hormones work can be critical to long-term success, and it's also interesting from a purely scientific standpoint. Many researchers around the world work on gibberellins, identifying new varieties and exploring existing types for more information.