Crop Management · April 2025 · 5 min read
Plant growth regulators manipulate hormone pathways to control plant height, promote branching, or influence fruit set. When used correctly, they reduce lodging risk, improve harvestability, and can increase yield in responsive crops.
Most PGRs used in field crops inhibit gibberellin synthesis, which shortens internodes and produces a shorter, sturdier plant. Others mimic or block auxin and ethylene pathways to influence fruit retention or senescence timing. The response depends heavily on application timing relative to the crop's growth stage and environmental conditions at the time of treatment.
Trinexapac-ethyl applied between Feekes 6 and Feekes 8 shortens the upper internodes of wheat, significantly reducing lodging in high-yield environments. The greatest response occurs in thick stands with high nitrogen rates where lodging risk is already elevated. Yield benefits come primarily from improved harvestability rather than direct yield enhancement.
Mepiquat chloride is the standard PGR in cotton, applied when plants begin to grow excessively tall relative to the number of fruiting nodes. Applications typically begin at early bloom and may be repeated at seven- to fourteen-day intervals based on plant mapping. Properly managed PGR programs produce compact plants that are easier to defoliate and harvest efficiently.
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