5. Cold Hardiness of the Rootstocks for the Sweet Cherry and its Transfer onto the Scion (Literature Review)

Over the last 20 years, an exceptionally great variety of the sweet cherry rootstock composition has occurred, which led to the distribution of this crop into habitats, untypical until recently. That is why we consider it a necessity, on the basis of the research worldwide, including in Bulgaria, to present information about the hardiness of a great number of rootstocks and their influence in this respect on the grafted cultivar. Information has been presented on the cold hardiness of both the main rootstocks – wild cherry (P. avium L.), mahaleb (P. mahaleb L.), ordinary sour cherry (P. cerasus L.), and of some rootstocks selected at a later time, such as: F 12/1, SL-64, Colt, P-1, M x M 2, M x M 14, M x M 39, M x M 60, ИК-M8,ИК-M9, PHL-A, PHL-B, PHL-C, Weiroot 10, Weiroot 12, Weiroot 13, Weiroot 14, Weiroot 53, Weiroot 72, Weiroot 158, Gisela 4, Gisela 5, Gisela 6, Gisela 7, Gisela 8, Gisela 12, Êàramy, Vladimirska vishna, etc. The knowledge in this field could be very useful in relation to the establishment of new sweet cherry plantations, including intensive ones.