FROST RESISTANCE OF NEW CULTIVARS AND FORMS OF ORNAMENTAL PEACH

The purpose of this work was to evaluate the frost resistance of generative buds in new cultivars and breeding forms of ornamental peach in connection with the prospects of their use in further breeding and landscaping. The objects of research were 23 new genotypes of Prunus persica, P. mira, P. davidiana, and P. amygdalus, which were compared with four closely related cultivars. Frost resistance was determined by the method of artificial freezing of shoots in a climatic chamber, taking into account the rates of microsporogenesis. After exposure to temperatures of -19 о C at the end of January, when the generative buds of most taxa were in deep dormancy, from 11.3 to 84.5 % of the buds survived. Freezing at –15 о C in mid-February (the stage of the beginning of pollen formation), which was carried out after prolonged elevated temperatures, revealed from 9.8 to 93.5 % of living generative buds. When exposed to frost of –14 о C in mid – February, 83.9–100 % of intact bus remained in 21 genotypes after a consistently cold period. As a result of freezing shoots at –11 о C in early March, the number of surviving buds at the stage of microspore formation and meiosis ranged from 22.2 to 97.4 %. The group of David peach cultivars turned out to be the most sensitive to frost from the taxonomic groups; late-flowering genotypes showed greater frost resistance from the groups in terms of flowering time. The highest resistance in all freezing variants was shown by ‘Carmen’ and the H6-2/1 hybrid with a slow rate of development of generative buds (their safety averaged 92.2 and 84.2 %, respectively). On average, 9 cultivars and forms were characterized by increased frost resistance (71.8–79.8 % of surviving buds), but three consistently providing decorative flowering (‘Ave Maria’, H5-12/3, H5m-3/1). The selected genotypes are recommended for testing in landscaping and further breeding.