Foliar-applied dormancy-breaking chemicals change the content of nitrogenous compounds in the buds of apple (Malus sylvestris Mill. cv. Anna) trees

Abstract

SummaryDormancy breaking agents (DBA) are typically applied to deciduous fruit trees to overcome the adverse effect of warm late-Winter temperatures on buds. The ability of hydrogen cyanamide (Dormex™), potassium nitrate (KNO3), or mineral oil (MO) to break dormancy in buds of apple (Malus sylvestris Mill.) ‘Anna’ trees, and their impact on metabolic changes in the contents of total proteins, total free amino acids, and organic amino-nitrogen compounds (OA-NC) in buds during bud break were determined. The ability to break dormancy occurred after two foliar applications of Dormex™, KNO3, or MO at concentrations of 4% (v/v), 8% (w/v), or 6% (v/v), respectively. In general, Dormex™ was more effective than KNO3 or MO at breaking dormancy, shortening the duration of flowering, increasing the percentages of bud break and fruit-set, fruit yield, and the contents of total free amino acids, and OA-NC. Our results indicated that Dormex™ provided an effective early treatment for stimulating bud break, reducing the flowering period, increasing fruit yield and regulating the contents of nitrogenous compounds in apple buds.