Artificial freezing was used to evaluate diploid and triploid apple cultivars from the All Russian

No abstract

Sea buckthorn (Hippophae rhamnoides L.) genotypes of different ecological and geographical origins were tested. Frost hardiness extent was determined during winter by artificial freezing, which allowed identify varietal differences in frost hardiness of buds and tissues of sea buckthorn shoots. In order to identify differences in adaptation to low temperature we determined the fractional composition of water in annual shoots; and proline and malone dialdehyde concentration and total amylase activity in bark of shoots of female and male genotypes. In December, the sea buckthorn genotypes were in deep dormancy, when maximum frost hardiness of buds and tissues of annual shoots occurred. During the next months, the frost hardiness of buds and shoot tissues decreased during the state of exogenous dormancy. The performed experiment gave an opportunity to select hardy genotypes ‘Kenigsbergskaya’, ‘Surpriz Baltiki’, B 23-34, and ‘Prima Dona’ for use in further breeding, as they had demonstrated stable hardiness during the whole winter period according to all of the components of winter hardiness.

The purpose of this research was to study apple cultivars obtained from Luke (previously MTT Piikkiö, Finland) in order to have good candidates for breeding within the central zone of Russia. The studies were carried out in accordance with the methods of cultivar study and artificial freezing by modeling damaging factors using a freezing chamber. The assessment of the cultivars by yield, commodity and consumer qualities of fruit, resistance to adverse abiotic factors of the winter period is given. The ‘Vuokko’ cultivar was identified with a yield significantly higher than Antonovka. By modeling winter damage factors, ‘Sandra’, ‘Samo’ and ‘Make’ cultivars were identified with the resistance of the cambium and wood at the level of ‘Antonovka’, when the temperature in the of mid-winter dropped to –40 °C after hardening off, with the ability to keep the frost resistance at –25 °C after thaw and ability to restore the hardy state by lowering the temperature to –30 °C after thaw and re-hardening off. Cultivars ‘Sandra’, ‘Samo’ and ‘Make’ are recommended for creating new hardy cultivars with high-quality fruits for the temperate continental climate of Europe.

The research was carried out at the sites of production study of VNIISPK in the period from 1990 to 2016. The plots were located on gray and dark gray forest soils of medium-loamy mechanical composition with the capacity of the humus horizon of 30-50 cm. The climate is temperate-continental with the vegetation period of 175-185 days. Average annual air temperature is 4.6⁰C, minimal temperature in winter is -40⁰C, maximal temperature in summer is +38⁰C. The study was conducted in accordance with generally accepted methods of variety investigation and frost resistance study in the laboratory using a freezer “ESPEC” PSL-2 KPN. The possibility of obtaining low-sized apple trees on the roots of vigorous seed rootstocks with the intercalary inserts of a low-sized clone rootstock was established. The insertion components of a low-sized clone rootstock provided the significant weakening of tree growth and precocity in comparison with a vigorous seed rootstock. High precocity was revealed in Orlovim, Ranneye Aloye, Zhelannoye and Yubilar (on the level of Papirovka). Imrus and Orlik showed high specific load per unit of cross-sectional area of the trunk (2.0). Annual or non-sharp periodical fructification in those varieties were developed at the expense of flower bud laying on the growth of fruit bags of twigs in the year of fruiting with good foliage, and the alternation of fruiting of some branches and trees. The best variety-rootstock combinations were revealed: summer varieties Zhelannoye/3-3-72, Orlovim/3-3-72, Ranneye Aloye/3-3-72 and winter varieties Imrus/3-3-72 and Orlik/3-3-72.