About resistance of apple genotypes to winter unfavorable conditions

The data of 40 years study of winter hardiness in apple genotypes of foreign, domestic and people’s selection in field trials and laboratory tests with modeling the damaging factors by freezing have been summarized. Varieties resistant to unfavorable winter conditions have been picked out and the threshold of their resistance has been determined by freezing. Applying physiological and biochemical tests, the contents of starch, sugars, anthocyans, and cyanidins and the enzymatic activity in the autumn-winter period have been analyzed in the varieties with different winter hardiness. It is shown that the determination of the contents of saccharose, anthocyans and anthocyans-cyanidins in annual apple shoots in the autumn-winter period may be one of the indirect methods of the estimation of plant winter hardiness. Changes in the activity of oxidation ferments (peroxidase and polyphenoloxidase) in the autumn-winter period should also be referred to the adaptive features.