Determination of Chilling and Heat Requirements and Changes in Buds Weight in Several Cultivars of Sweet and Sour Cherry

The most important factors affecting the blossoming of trees in temperate regions is the amount of temperature received by the buds. In order to evaluation of chill and heat requirement in flower buds of three cultivars of sweet cherry (Zard mash-had, Zoodras and Siah Shabestar) and one genotype of sour cherry, an experiment was conducted at the flower biology laboratory of faculty of agriculture, Tabriz University in 2015.From the 3rd of Aban, branches of one year old with diameter and length of about 1 and 30 cm recpectively, each week after harvest from the tree were transferred to the growth chamber. The weight changes of buds during the dormancy were evaluated weekly and analyzed in a randomized complete block design with 5 replications so that each cultivar was selected as a main plot and four varieties and different sampling dates were selected as sub factor.5 different models were used for estimating of chilling requirement and also GDH model was the basis for determining the heat requirement of the bud. In all models sour cherry had the lowest (752 hours) and Siah Shabestar (961 hours) had the highest chilling requirement, and also Zoodras and Zard Mash-had were 780 and 867 hours. Sour Cherry and Siah Shabestar had the least and the most heat requirement (4053 and 5458 GDH) respectively and the value of this feature was 5421 and 4614 respectively, for Zard Mash-had and Zoodras. Also the highest and lowest fresh and dry weights before and after placement in the growth chamber were observed in Siah Shabestar and sour cherry respectively.