Exogenous Dormancy-Breaking Compounds on Flowering Behavior, Yield, Fruit Quality and Some Chemical Constituents of “Anna” Apple Trees

Abstract

The role of dormex, mineral oil, potassium nitrate, calcium nitrate and thiourea in the acceleration of dormancy breaking in buds of "Anna" apple (Malus sylvestris, Mill) variety and their effects on metabolic changes in the contents of total chlorophyll , total carbohydrates, total protein, nitrogen, phosphorous and potassium in leaves and the contents of Total Soluble Solids (TSS), TSS/acid ratio, vitamin C, water content %, total free amino acids, total carbohydrates, total sugars and reducing sugars in fruits during bud break were assessed. The efficiency of bud break by these compounds was noticed to varying degrees. Breaking bud dormancy was correlated with the early date of bud break, the short duration of flowering, the high percentages of bud break and fruit set, and the high contents of chemical constituents. This finding was positively reflected in the tree's yield. Dormex (4%) was found to be more effective than mineral oil (5%), potassium nitrate (8%), calcium nitrate (8%) and thiourea (2%); therefore, we recommend using dormex (4%) for early bud break, short period of flowering and high percentages of bud break, fruit set, yield and fruit characters by regulating the chemical constituents of apple leaves or fruits.