gibberellineremmers

Gibberellin inhibitors, or gibberellin antagonists, are a class of plant growth regulators that suppress the action or synthesis of gibberellins, a group of hormones that promote stem elongation, seed germination, and other developmental processes. Most commercial inhibitors work by blocking enzymes in the gibberellin biosynthesis pathway or by interfering with gibberellin signaling. Common examples include paclobutrazol, uniconazole, and chlormequat chloride (CCC), which act primarily as biosynthesis inhibitors, as well as daminozide (B-Nine) and mepiquat chloride, used as growth retardants in various crops.

Mechanism of action and effects

Gibberellin inhibitors typically reduce endogenous gibberellin levels or block receptor signaling, resulting in shorter, more compact plants. The primary observable effect is reduced internode elongation and overall plant height, though effects can vary with species, developmental stage, and environmental conditions. Some inhibitors also influence leaf expansion, flowering time, and fruit set, and prolonged use can affect vigor if not carefully managed. In many cases, the compounds are applied as foliar sprays, soil drenches, or trunk injections, depending on the crop and target tissue.

Applications

Gibberellin inhibitors are used in horticulture and agriculture to produce compact, lodging-resistant plants, improve transport and handling, and optimize orchard or vineyard canopies. They are common in ornamentals (container-grown plants, roses, chrysanthemums), fruit crops (grapevines, apples, citrus), and cereals where reduced height can enhance yield stability. In cotton, mepiquat chloride is widely used to limit excessive vegetative growth. Regulatory and consumer considerations, as well as crop-specific responses, guide the choice and timing of application.

Safety and regulation

Gibberellin inhibitors can persist in soil and plant tissues and may affect non-target organisms if misused. Proper label directions, crop sensitivity, and local regulatory statuses determine approved uses, withdrawal periods, and residue considerations.