Efficient plant-growth-promoting rhizobacteria (PGPR) used as biofertilizers and biological control agents are promising substitutes for minimizing the application of synthetic agrochemicals in crop production. We studied the effect of PGPR strain Bacillus velezensis BS89 alone and in combination with three forms of nitrogen fertilizers (ammonium nitrate, carbamide, and ammonium sulfate) on the productivity of two strawberry varieties in three-year field experiments. We first showed that the application of PGPR Bacillus velezensis BS89 on strawberries demonstrated the same effect as the application of nitrogen fertilizers. Use of the strain BS89 increased the chlorophyll content in plant leaves by 2.7–6.8%, and also increased the yield of berries by 6.7–36.4% for cv. Rusich and 7.5–19.3% for cv. Troitskaya depending on the form of nitrogen fertilizer. The best results in the yield of strawberry plants of the cv. Rusich were achieved in the variant BS89 + ammonium nitrate (41.9–57.4%), and the cv. Troitskaya—in the BS89 + carbamide variant (8.1–38.8%). Three-year use of strain BS89 for cv. Rusich resulted in an increase of runner’s weight by 212.1%, and also the weight of the roots by 120%, thereby significantly improving the mineral nutrition of plants. This is mainly associated with the plant growth-promoting activity of Bacillus velezensis BS89, which was able to produce a high amount of IAA—494.1 µg/mL. We believe that the PGPR strain BS89 can be successfully used for growing strawberries. However, each variety requires careful selection of the composition of nitrogen fertilizers and analysis of the compatibility of fertilizers and the PGPR strain.

Biomodified mineral fertilizers (BMFs) were produced by enriching the ammophos fertilizer with PGPR Bacillus velezensis BS89 with the use of two technologies: BMF 1, the ammophos fertilizer with the addition of spores of Bacillus velezensis BS89 on a dry carrier (diatomite); and BMF2, ammophos granules treated with spores of Bacillus velezensis BS89 in a cell suspension. The effects of BMFs on maize growth and productivity and the rhizosphere bacterial community were assessed. BMFs significantly increased maize growth, dry matter, minerals, starch and protein contents in maize grain. The application of biomodified mineral fertilizers resulted in the significant increase in the yield and some parameters of maize plants such as ear length and number of kernels in the row. The yield was increased by 7.5–7.6%, ear length by 9%, and number of kernels in the row by 6.7–7%, as compared with ammophos. However, we found no considerable differences in the composition of the bacterial community of the maize rhizosphere after the use of BMFs as compared with the use of ammophos at the level of the phyla, which was confirmed by the ecological indices of biodiversity: the Shannon index and the Simpson index. Comparison of the experimental variants with bulk soil showed differences in the microbiome composition of the dominant bacterial phyla. A greater abundance of Proteobacteria and Bacteroidetes and a lower abundance of Chloroflexi was registered in bulk soil as compared with the other experimental variants where maize plants were present. The highest percentage (5.3%) of unidentified taxonomic phyla was also found in bulk soil. Our studies showed that maize is the main structuring factor during formation of the microbiome composition in the rhizosphere. The application of biomodified fertilizers BMF1 and BMF2 considerably increased the abundance of bacteria representing the minority of the community, namely, those from the phyla Verrucomicrobia, Chloroflexi, Planctomycetes, Proteobacteria, Firmicutes and Chlamydiae, as compared with the use of ammophos. Thus, the application of biomodified mineral fertilizers is a promising agronomic and ecological strategy for boosting maize yield and the quality of grain under field conditions.

Apple is one of the most common fruit crops in the Russian fruit-growing industry, with huge varietal diversity and a vast cultivation area. The key regions for industrial-scale apple cultivation are the Central, Central Chernozem, and North Caucasian Districts. The main disadvantage of the relevant apple cultivars, especially the ones intended for intensified horticultural practices, is their low resistance against abiotic stresses and the fruit’s low quality and poor marketable condition. In Russia, apple is a crop of strategic importance that is consistently included in the household food basket, so fruit producers hold new varieties to higher standards and expect them to outperform their predecessors in terms of yield per plant, resistance against abiotic and biotic stresses, and quality, as well as show strong competitiveness and a more rapid return on investment, while satisfying stricter requirements. The objective of the present study was to summarize the data on the phenotypic manifestations of economically valuable traits of the apple cultivars approved for use in the Russian Federation depending on the region of cultivation; to determine the parametric characteristics of the most valuable traits in the form of a model of an “ideal” regionally adapted industrial cultivar, and to identify the sources of the traits in the regions suitable for their production. A regionally adapted model of commercial apple cultivars, characterized by 28 features and properties divided into three groups and defining the cultivar’s resistance against abiotic and biotic stresses, yield per plant, product quality, and suitability for mechanized harvesting, is presented in this paper. In the European part of Russia, the optimal parameters of a commercial apple tree cultivar are as follows: plant height on a medium-sized rootstock under 3 m; potential yield per plant of at least 25–50 kg; high fruit uniformity above 80%; winter and late-winter harvest maturity period; high storability of over 210 days and good transportability; average fruit mass from 120 g to 220 g; juicy and shattering crisp pulp; small seed cavity; fragrant fruits with taste rating of at least 4.5 points; appearance rating of 5 points and attractive, mostly red, glossy color with natural wax bloom; regular, symmetric, but diverse shapes; content of sugar above 10%, ascorbic acid above 15 mg/100 g, organic acids up to 1% (for dessert varieties); content of soluble dry solids of at least 20%. The cultivars that come closest to the regionally adapted model of an ideal variety based on the set of features discussed are as follows: Feya, Soyuz, Orfej, Margo, Sirius, Noktyurn, Vasilisa Karmen, Florina, Dayton, Early Mac, Gala and Gala Schniga in the North Caucasian District; Svezhest’, Orlovskoe Poles’e, Aprel’skoe, Ven’yaminovskoe, Bolotovskoe, Vympel, Uspenskoe, Fregat, Bylina, Flagman, and Akademik Kazakov in the North Caucasian District; and varieties Imrus, Mayak Zagor’ya, and Bolotovskoe in the Central District. These cultivars are characterized by high resistance against weather anomalies, scab immunity, high yields, marketable quality, and storability. In addition, in southern regions, a prolonged bloom period acts as a protective adaptive response to low-temperature stress.

In a vegetation experiment, the effect of bacterial preparations Extrasol, Fitosporin-M based on bacterial strains Bacillus subtilis and bacteria strains of the genus Pseudomonas – P. chlororaphis OV17, P. protegens 38a, P. putida О9-10 on the number of rhizosphere microorganisms, growth and development of regenerant plants of apple clone rootstocks in ex vitro conditions was studied. After 90 days of growing plants, the greatest number was found in the P. protegens 38a strain – 0.56 million CFU/g roots. Artificial inoculation of the roots of regenerant plants contributed to a significant increase in the total number of native microorganisms as compared to the control. The most diverse bacterial population in terms of cultural and morphological characteristics was revealed in the variant with the treatment of plants with the P. putida O9-10 strain. The introduced bacterial strains contributed to an increase in the adaptive capacity and had a phytostimulating effect on the development of plants. The plant survival rate in the process of adaptation to ex vitro conditions is most influenced by the P. putida 09-10 strain compared to the control. The bacterial preparation Fitosporin-M contributes to the improvement of biometric parameters of plant growth.

The phylogenetic diversity of the endophytic bacterial component of the clonal apple rootstock microbiome 57-490 and 54-118 was studied for microplants and 5-year-old plants grown from the same tissue culture and growing on sod-podzolic soils of different granulometric composition with different chemical, physicochemical and physical properties. Proteobacteria (91.6%) in rootstock 57-490, Proteobacteria (52.5%) and Firmicutes (47.4%) in rootstock 54-118 are the predominant phylum of endophytic bacteria in apple rootstock plant tissues in vitro culture. The relative amount of phylum Firmicutes endophytic bacteria, in comparison with in vitro culture, decreases in the roots to 0.7-2.0%, and even more significantly in the leaves (to 0-0.2%). At cultivation on heavy loamy soil, endophytic bacteria belonging to the phylum Actinobacteriota (11.7%) are found in the studied rootstock roots, the relative content of which, when grown on medium loamy soil, in the roots decreases to 2.7-4.1%, in the leaves – to 0,1-0.2%. The data show that in the endosphere of the culture in vitro, the diversity and uniformity of the community of endophytic bacteria is significantly lower (Shannon index 0.42-1.00) than in the roots of rootstocks grown in the outdoor growing (1.34-2.08). For leaves, the Shannon index is characterized by the lowest values (0.06-0.13).