Coping with global warming effects on reduced winter chilling for deciduous fruit trees

Deciduous fruit trees require exposure to chilling during their dormancy prior to their bud break.
This environmental requirement was developed by evolution to allow these trees to endure the low winter temperatures in temperate climates and to avoid too early bud break.
With global warming, duration and depth of chilling are gradually reduced, leading to levels where the chilling requirement will not be met as in the past.
In subtropical weather, like that of Israel, such conditions exist.
The desire to grow existing high-quality cultivars led to finding ways to compensate for the lack of chilling and get a good bud break in spite of limited exposure to chilling.
Since the middle of the 20^th century, various chemicals have been developed to overcome this problem.
Over the years, many chemicals were taken out of the market, mostly because of human toxicity.
During the last 7 years, we have conducted trials in Israel with new, safer chemicals that could compensate for the lack of chilling.
These chemicals are Oil emulsion (EW) with the addition of Thidiazuron (C₉H₈N₄OS) (TDZ), Meptyldinocap in oil emulsion with and without TDZ, and ammonium nitrate sprayed with Armobreak (alkyl amine polymer) as Penetrator.
Experiments were conducted on the pome fruits Pyrus communis ‘Coscia’ pear and Malus × domestica ‘Golden Delicious’ apple and the stone fruits Prunus persica ‘Summer Snow’ and ‘SunSnow.’

XII International Symposium on Integrating Canopy, Rootstock and Environmental Physiology in Orchard Systems

O. Crane, A. Sar Shalom, A. Erez

dormancy, ammonium nitrate, meptyldinocap, oil emulsion, apple, pear, peach

https://doi.org/10.17660/ActaHortic.2022.1346.12