Flower initiation and duration of dormancy period are important processes during flower bud growth and, therefore, are considered critical issues in orchard management. Siah Daneshkadeh and Ferracida sweet cherry cultivars of Kamal Abad research orchard, Seed and Plant Research Institute in Karaj, were studied during this research. Flower buds were randomly collected (eight times during the year) from spurs on 2-3 years-old shoots, and changes in soluble protein as well as polyphenoloxidase and peroxidase enzymes were recorded. Results indicated that total protein concentrations were different during the months of May to February, exhibited a meaningful relationship with flower bud growth. Thus, the protein concentration displays a maximum at mid-June and then decreases gradually to a minimum in late September. Subsequently, the protein concentration increases again simultaneous with the beginning of cold season. Enzymes’ activity increases gradually from May and reaches a maximum concentration during the months of January to early February, along with a significant increase in chilling unit accumulation. Modeling of the data shows a high coefficient of determination between protein and enzyme changes, and thus can be employed as marker tolls to determine the time of flower initiation as well as beginning and end of rest period.
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