Production and Biological Assessment of VNIISPK Cultivars of Various Ploidy for the Zone of Temperate Continental Climate

Increasing the reliability of fruit crops in unstable weather conditions of a temperate continental climate has become particularly relevant. This research was carried out based on a bioresource collection from the Russian Research Institute of Fruit Crop Breeding (VNIISPK BRC). Apple cultivars (diploids and triploids) of different maturation periods were studied. Triploid cultivars (3×) of summer maturation were developed using diploid gametes of the ‘Papirovka tetraploid’ cultivar as a donor (2-4-4-4×), triploids of winter maturation were developed using 13-6-106 (Suvorovetz: open pollination), and ‘Wealthy tetraploid’ (2-4-4-4×) or ‘Giant Spy’ (2-4-4-4×) were used as donors of diploid gametes. ‘Antonovka’ and ‘Melba’ were taken as control cultivars. The aim of this work was to evaluate the apple breeding cultivars according to the main economic and biological indicators and to determine the threshold of resistance to unfavorable conditions of the winter period for possible cultivation in specific conditions of a temperate continental climate. As a result of using the method of modeling damaging factors, apple cultivars that withstood not only the critical temperatures of January, but also especially dangerous frosts after thaws at the end of winter were identified, with the stability of vital tissues at the level of ‘Antonovka’ (a control cultivar), scab immune cultivars (RVi6) ‘Ivanovskoye’, ‘Zdorovie’ and ‘Pamyati Hitrovo’, and immune triploids (3×) ‘Vavilovskoye’, ‘Aleksandr Boyko’, Rozhdestvenskoye’ and ‘Academic Saveliev’. During the whole winter, the winter resistance of summer scab immune triploids, ‘Zhilinskoye’, ‘Maslovskoye’, ‘Yablochny Spas’ and ‘Spasskoye’, was at the level of ‘Antonovka’, but was higher than ‘Melba’. The high precocity of scab-immune cultivars, ’Afrodita’, ‘Ivanovskoye’, ‘Veniaminovskoye’, and ‘Yubiley Moskvy’, and triploids ‘Patriot’ and ‘Rozhdestvenskoye’, have been identified. Triploid cultivars are superior to diploid cultivars and control ‘Antonovka’ in fruit size. According to the complex of characteristics, promising apple cultivars were identified for planting in intensive orchards of the temperate continental climate zones, namely ‘Avgusta’ and ‘Solnyshko’ (summer cultivars), and ‘Aleksandr Boyko’, ‘Vavilovskoye’, ‘Venyaminovskoye’, ‘Ivanovskoye’ and ‘Rozhdestvenskoye’ (winter cultivars).