Tolerance to the Late Spring Frost in some Quince (Cydonia oblonga Mill.) Genotypes in Karaj Climate

Among various species of pome fruits, quince trees are considered as a late blooming species, however late spring frosts cause damage on flower buds in some years. Damage level caused by a -8ºC spring frost occurred in the mid-April of 2014 in Karaj were evaluated on 36 five years old quince genotypes grown in the collection garaden of Kamalshahr before bud burst stage. The evaluated genotypes had been collected from Khorasan Razavi, Isfahan, Guilan, Ardabil and Tehran provinces. Based on the results, the highest levels of spring frost damage (10 up to 80%) were recorded on the genotypes originated from low altitudes of Isfahan, Khorasan and Guilan provinces, while the frost damage was not observed on the genotypes originated from high altitudes of these provinces. Correlation analysis of evaluated characteristics of the genotypes revealed the highest negative correlation between length of bud flower and level of frost damage, while severity of frost damage had not significant correlation with tree yield and final fruit size of the genotype. Regarding the results of this investigation, it seems that for introduction of new quince cultivars for regions with late chilling damages on the flower buds, the genotypes originated from Ardebil are more suitable. The quince genotypes of Ardebil demonstrated high fruit quality and late blooming period that could be considered as useful traits in selection and breeding of quinces.