Effects of two growth regulators on breaking dormancy in 'Dorsett Golden" under climatic conditions of Taroudant, South of Morocco

In this study we evaluated the effects of hydrogen cyanamide (Dormex), alone or combined with mineral oil, and Gibberellic acid on bud break of "Dorsett Golden" apple trees in "Taroudant" area southern of Morocco. The treatments, Dormex alone at (1,5, 2,5 and 4%) of the formulated product, or at 0,5% in association with mineral oil at (2 or 4)%, and Gibberellic acid (GA₃) at 460 mg/1, were applied on the 21^st of December. The control trees were sprayed with water. The chemicals advanced the date of bud break, improved its rate and that of flowering and enhanced vegetative growth. The fruit yield and size were also significantly improved. Thus, Dormex alone or combined with mineral oil and Gibberellic acid (GA₃), advanced and grouped bud break and improved the fruit yield and fruit of Dorsett Golden apple trees. The effectiveness of the mixture [Dormex + mineral oil] associated with its lower cost make of this treatment a potential solution for the lack of chilling in the Moroccan areas characterized by mild winters.

Keywords: Morocco - Apple - Bud break - Dormex - Mineral Oil - Gibberellic acid - Flowering - Fruit set - Production