Application of Plant Growth Regulators in Managing Fruit Drop in Citrus Orchards of Kogi State

Premature fruit drop is a persistent challenge in citrus (Citrus spp.) orchards across North Central Nigeria, causing significant economic losses for commercial citrus farmers in Kogi State. Plant growth regulators (PGRs), including synthetic auxins, gibberellins, and cytokinin-based compounds, have been used globally to mitigate fruit drop by regulating abscission zone development. This study evaluates the effectiveness of three PGR treatments, 2,4-D at 15 ppm, gibberellic acid at 50 ppm, and a combined auxin-cytokinin formulation, applied at petal fall, early fruit set, and pre-harvest stages on fruit retention in Navel orange orchards in Lokoja, Kogi State. A randomized complete block design with four treatments including untreated control and three replications was used. Fruit retention percentage, fruit size, and yield per tree were measured at three-week intervals. Results indicate that gibberellic acid applied at early fruit set produced the highest fruit retention rate, while 2,4-D applications reduced pre-harvest drop by 38 percent compared to the control. The combined auxin-cytokinin treatment showed the most consistent performance across application timings. The study recommends the use of gibberellic acid at early fruit set as a primary PGR strategy for citrus orchards in Kogi State, with annual treatment scheduling integrated into commercial orchard management calendars. Keywords: plant growth regulators, citrus, fruit drop, gibberellic acid, Kogi State