The effect of mineral oil alone or in combination with Dintro-ortho-cresol (Universal) with different concentrations at early reaching break dormancy in buds of ‘Astrachan’ apple (Malus sylvestris, Mill) trees was investigated. Also, their effects on metabolic changes in the content of buds from promoter and inhibitor substances during their release from dormancy were detected. The efficiency of early bud break was noticed in varying degrees with mineral oil or Universal at different concentrations. It was observed that all applied concentrations lead to early bud break, short flowering duration, high percentages of bud break and fruit-set. In addition, high contents of total indoles, indole-3-acetic acid, gibberellic acid, total and conjugated phenols, as well as, low content of abscisic acid and free phenols were achieved. According to the results, it is recommended using 6% of mineral oil as operator safer bud break promoters for reach to the early break dormancy in buds of ‘Astrachan’ apple trees under Egyptian winter conditions and the maximum yield by regulating the hormonal and phenolic content in buds.
Apple; Dormancy; Mineral oil; Universal; Hormones; Phenols; Yield.