ORIGINAL ARTICLE

Autumn Moisture Stress and Winter Hardiness of Semi-cultivated Apple Trees on Different Rootstocks: the Role of Peroxidase in Resistance

This study examines the impact of autumn moisture deficit on the winter hardiness of semi-cultivated apple trees depending on the rootstock and the possible relationship between resistance and peroxidase activity. Observations were conducted at the SIFIBR experimental site in the Irkutsk District of the Irkutsk Region from 2024 to 2026. In the field experiments, the dwarf rootstock 62-396, bred by MichSAU, was used as the primary rootstock, while a clone of the Siberian berry apple (semi-dwarf) served as the control. Semi-cultivated apple trees with high winter hardiness were selected as scions: Krasa Buryatii, Alenushka, and Raiskoye. The following rootstock varieties were selected for experiments studying peroxidase activity: 62-396, 70-20-20, E56, Volga18, Ural, OB-3-14, SA-14-1, and a clone of the Siberian berry apple (CSBA).

In all rootstock x cultivar combinations studied, irrigation resulted in a decrease in the average damage score compared to the unirrigated control. Comparison of the rootstocks revealed that CSBA (a clone of the Siberian berry apple) exhibited higher winter hardiness under all conditions compared to the 62-396 rootstock. The highest peroxidase activity was found in the leaves of the Siberian berry apple clone, while the lowest was found in the leaves of the new rootstocks OB-3-14 and SA-14-1, bred by the Federal Scientific Center of Horticulture and the State Budgetary Institution of the Samara Region "Research Institute of Horticulture and Medicinal Plants "Zhigulevskie Gardens". A study of peroxidase isoforms using native electrophoresis showed that the highest number of isoforms was observed in the CSBA sample, while the lowest number of peroxidase isoforms was found in the 62-396 clonal rootstock sample.