Gibberellins

Gibberellins are another kind of promotory PGR. There are more than 100 gibberellins reported from a wide range of organisms, including fungi and higher plants. They are denoted as GA1, GA2, GA3 and so on. Gibberellic acid (GA3) was one of the first gibberellins to be discovered and remains the most intensively studied form. All gibberellins (GAs) are acidic, and they produce a wide range of physiological responses in plants.

Some important effects and applications are:

• Their ability to cause an increase in the length of the axis is used to increase the length of grape stalks.
• Gibberellins cause fruits such as apple to elongate and improve their shape.
• They delay senescence, so fruits can be left on the tree longer, extending the market period.
• GA3 is used to speed up the malting process in the brewing industry.
• Spraying a sugarcane crop with gibberellins increases the length of the stem, thereby increasing the yield by as much as 20 tonnes per acre (sugarcane stores its carbohydrate as sugar in the stem). …