Determination of Adaptive Capabilities of Various Species, Forms, and Varieties of Apple Trees Based on Endophytic and Epiphytic Microbiota Indicators

The research aimed to identify the most resistant species, forms, and varieties of apple trees based on the developmental specifics of the various types of microbiota. The research was conducted in 2014-2023 at the Michurin Federal Scientific Center, Michurinsk, Tambov oblast. The year of planting was 2009 with the planning scheme 6 × 3 m, and the rootstock was 54-118. The objects of the research were Malus robusta species; forms 25-8, 64-143, and 54-118; varieties Korichnoe polosatoe, Orlovim, Iyulskoe Chernenko, and Slava Michurinska. The soil type was leached mediumpower black soil with a loamy mechanical composition. Pseudomonas syringae bacteria prevailed in resistant plants: 96.6% in Malus robust hybrid apple, 89.3% in Korichnoe polosatoe variety, and 88.7% in the 25-8 form, which was by 9.7, 2.4, and 1.8% respectively, higher than the average value among the test objects. In the 64-143 form and Slava Michurinska variety, the indicators were lower than the average by 5.5 and 4.2%, respectively. A mixed microbiota in Malus robusta was not observed (0.0%). This indicator was below the average value by 0.7% in Korichnoe polosatoe variety, it was lower by 1.3% in the 25-8 form, and it was higher by 11.4% in the 64-143 form, which was by 4.5% higher than the average. The rate of negative tests ranged from 3.4% (Malus robusta) to 6.2% (Iyulskoe Chernenko), which did not exceed the average value. Samples 64-143, 54-118, and Slava Michurinska had values higher than average values by 1.0, 2.0, and 4.0%, respectively. According to the complex of indicators of microbiota yield and the percentage of negative tests, Malus robusta, Korichnoe polosatoe variety, and the 25-8 form had a high potential for environmental resistance. They were recommended for further breeding for resistance to adverse environmental factors.