Gibberellin Treatment toward off-crop season as a practical tool to increase yield in “Orri” Mandarin
A recent study published in HortScience (Vol. 60, Issue 2, 2025) by researchers from the Volcani Center and the Hebrew University of Jerusalem explored how mild gibberellin (GA₃) treatments can help increase yields in ‘Orri’ mandarintrees during off-crop years.
‘Orri’ mandarins, like many citrus cultivars, experience irregular bearing cycles- years of heavy fruit loads (on-crop) often followed by years of reduced yields (off-crop). This research investigated whether low-frequency, low-concentration GA₃ applications during winter could help stabilize yields by promoting more mixed-type inflorescences– the leafy flowering structures most responsible for fruit production.
The findings revealed that trees treated with 25 ppm GA₃ twice in December showed an average 40% increase in fruit number and total yield during off-crop seasons, without negatively affecting fruit size. Importantly, no yield change was observed during on-crop years, suggesting the treatment’s value lies in improving productivity specifically during low-bearing cycles.
These insights suggest that carefully timed gibberellin applications may serve as a practical tool to reduce alternate bearing and improve profitability for citrus growers- particularly those managing ‘Orri’ mandarin orchards.