Gibberellic Acid Application Enhances Seed Yield, Biomass, and Plant Growth in Kentucky Bluegrass Production

Abstract Kentucky bluegrass ( Poa pratensis L.) is a cool‐season grass used for forage and turf with seed production occurring primarily in the Pacific Northwest region of the United States. Climate change in this region, characterized by warmer winters, threatens Kentucky bluegrass flowering and seed yield due to altered vernalization patterns. This 2‐year field study investigated the effects of gibberellic acid (GA 3 ), specifically RyzUp Smartgrass, on seed yield, biomass accumulation, and turf performance of the Kentucky bluegrass cultivar Midnight. Treatments included fall and spring applications with untreated control along with three GA 3 doses (35, 70, and 140 g/ha) under three application schedules (early, late, and early + late). Seed yield significantly increased during the first‐year fall applications, with the 35 g/ha early and late treatments improving yield by 116% and 100%, respectively. However, spring applications did not enhance seed yield, and high‐dose treatments negatively impacted yield in the second spring. Biomass accumulation significantly improved, especially with spring GA 3 applications. The highest biomass increase (144%) occurred with the 140 g/ha double spray in the first year. Instant biomass visual assessments 2 weeks post‐application indicated rapid vegetative responses to GA 3 across treatments. Additionally, spring GA 3 treatments significantly increased plant height, row spreading, and visual turf color quality. No negative impacts on seed vigor, viability, or 1000‐grain weight were observed. This study highlights GA 3 ’s potential as an agronomic tool for enhancing Kentucky bluegrass seed yield and biomass, particularly when applied during the fall at lower doses and in spring for rapid turfgrass establishment and renovation.