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Gibberellic acid (also called
Gibberellin A3,
GA, and
GA3) is a
hormone found in plants and fungi.
[1] Its
chemical formula is C19H22O6. When purified, it is a white to pale-yellow solid.
Plants in their normal state produce large amounts of GA3. It is possible to produce the hormone industrially using microorganisms.
[2] Nowadays, it is produced by submerse fermentation, but this process presented low yield with high production costs and hence higher prices. One alternative process to reduce costs of the GA3 production is Solid-State Fermentation (SSF) that allows the use of agro-industrial residues.
[1] Gibberellic acid is a simple
gibberellin, a
pentacyclic diterpene acid promoting growth and elongation of cells. It affects decomposition of plants and helps plants grow if used in small amounts, but eventually plants develop tolerance to it.[
citation needed] GA stimulates the cells of germinating seeds to produce
mRNA molecules that code for
hydrolytic enzymes. Gibberellic acid is a very potent hormone whose natural occurrence in plants controls their development. Since GA regulates growth, applications of very low concentrations can have a profound effect while too much will have the opposite effect.
[3] It is usually used in concentrations between 0.01 and 10 mg/L.[
citation needed]
GA was first identified in Japan in 1926, as a metabolic by-product of the plant pathogen
Gibberella fujikuroi (thus the name), which afflicts
rice plants.
Fujikuroi-infected plants develop
bakanae ("foolish seedling"), which causes them to rapidly elongate beyond their normal adult height. The plants subsequently
lodge due to lack of support, and die.
[2]
Gibberellins have a number of effects on plant development. They can stimulate rapid stem and root growth, induce
mitotic division in the leaves of some plants, and increase seed germination rate.
[4]
Gibberellic acid is sometimes used in laboratory and
greenhouse settings to trigger
germination in seeds that would otherwise remain
dormant.
[3] It is also widely used in the grape-growing industry as a hormone to induce the production of larger bundles and bigger grapes, especially
Thompson seedless grapes. In the
Okanagan and
Creston valleys, it is also used as a growth replicator in the cherry industry. It is used on Clementine Mandarin oranges, which may otherwise cross-pollinate with other citrus and grow undesirable seeds. Applied directly on the blossoms as a spray, it allows for Clementines to produce a full crop of fruit without seeds."