Sample Determination Chilling and Heat Requirement of Some apricot cultivars (Prunusarmeniaca)

Background and object: One of the most important factors affecting the distribution of plants is physiological dormancy phenomenon. An apricot tree (Prunusarmeniaca) is one of the most important horticultural crops in Iran, particularly Azerbaijan region. Apricot tree is an early- flowering and susceptible to chilling tree and due to early-flowering of this tree in planting and processing of this product, susceptibility to chilling injury during the flowering, is a limiting factor.
Material and To determine the heat and chilling requirement of flowering in four apricot cultivars (Tabarzeh, Asgaraabad, Shekarpareh, Shamloo) an experiment was carried out in Agricultural Research Stations “Khalaat Pooshan” in 2013-2014. Annual shoots with equal diameter and length were removed from trees and transferred weekly to the growth chamber. Sprouts status of phonological stages, and fresh and dry weights was examine dateachstage of sampling. To calculate the chilling requirements of cultivars several models were used. To estimate the heat requirement from, growth degree hours (GDH) model was used.
Results showed hat in allmodels, Tabarzeh and Shamloo cultivars had the highest chilling requirement and Asgaraabad cultivar had the least chilling requirement. The amount of heat required, Cultivars of Tabarzeh and Shamloo with 3060 GDH had the least heat requirement and the Asgaraabad cultivar with 3254 GDH had highest heat requirement. Fresh and dry weight of buds before and after exposure to growth chamber showed significants difference at different sampling dates. Research of pro line changes in cultivars during dormancy proved that pro line amount at different sampling dates showed that significant difference between the cultivars and different sampling dates. Therefore, Tabarzeh cultivar had the least free pro line amount and the highest free pro line belonged to the Shamloo cultivar.
Considering the cold weather of most of the Azerbaijan regions, selection and planting of apricot varieties with high chilling and heat requirement seems to be important. In this respect, knowledge of the chilling and heat requirement, selection of varieties and top genotype with high chilling and heat requirement to reduce the risk of late spring frosts increases production.