Effects of plant growth regulators on the yield and fruit quality of the apple tree cultivar ‘Red Chief’

The demands of apple consumers force producers, especially during weather anomalies, to use technologies that ensure high-quality apples.
The experiment examined the influence of plant growth regulators (PGRs): gibberellins (GA₄+GA₇), cytokinins (6-BA), and Metamitron, applied under their respective trade names and recommended doses (Perlan^® 0.5 L ha^‑1, Sitis^® 1.5 L ha^‑1, and Brevis^® 1.8 kg ha^‑1) on yield and fruit quality of the apple ‘Red Chief’. The experimental design was: T0 – Untreated control, T1 – double application of gibberellins and cytokinins during flowering and Metamitron at fruitlet diameter 12-16 mm, T2 – application of benzyladenine at fruitlet diameter 8-12 mm and Metamitron at fruitlet diameter 12-16 mm, T3 – double application of gibberellins and cytokinins during flowering, benzyladenine at fruitlet diameter 8-12 mm and Metamitron at fruitlet diameter 12-16 mm.
The most favorable treatment was T1, in which gibberellins and cytokinins were combined during flowering, resulting in the largest fruit set, the highest total yield, the largest length, diameter, and mean fruit weight, and the most elongated fruits.
Metamitron applied at the stage 12-16 mm of fruitlet diameter did not show any thinning effect.
Benzyladenine applied at a fruitlet diameter of 8-12 mm did not significantly improve fruit set, but did increase yield and improve fruit structure compared to the control.
However, the effect of this treatment was much weaker than that of using gibberellins and benzyladenine together during flowering.

EHC2024: International Symposium on Fruit Production Systems for Sustainable and Resilient Development

I. Szot, T. Lipa

Malus domestica Borkh., PGR, cytokinins, gibberellins, Metamitron, yield, size of fruit, fruit set

https://doi.org/10.17660/ActaHortic.2026.1457.48