Influence of mineral, organic, organomineral fertilization on winter hardiness components of columnar apple tree (<i>Malus domestica</i> Borkh.)

Abstract

Intensive biological technologies of apple-tree cultivation with application of organic and mineral fertilizers form high nitrogen nutrition, thus leading to prolonged growth of fruit plants and reducing their winter hardiness. Columnar apple tree fail to demonstrate high potential for winter hardiness. Therefore, research into regularities and mechanisms behind the influence of nutritional status of columnar apple tree on indicators of plant winter hardiness is considered relevant. The research was aimed at establishing the influence of mineral, organic, organomineral fertilization on the components of winter hardiness of columnar apple trees grown on podzolic soil. Materials and methods. The research involved the ‘Triumph’, ‘President’, ‘Ostankino’ columnar apple varieties, as well as organic and mineral fertilizers. The experiment was conducted in 2016–2021 in the agrochemical experiment station of the Federal Horticultural Center for Breeding, Agrotechnology and Nursery (Moscow region) on podzolic soil of medium-loam particle size distribution. The experimental design included 4 variants: 1) control without fertilizers; 2) N90K90; 3) organic fertilizers 100 t/ha; 4) N90K90 organic fertilizers 100 t/ha. Naa (ammonium saltpeter), KCl mineral fertilizers were applied annually, organic fertilizer (horse manure with sawdust) was applied in 2014. Winter hardiness components and plant samples were analyzed according to generally accepted methods. According to the research into the influence of mineral, organic, organomineral fertilization on the components of winter hardiness of columnar apple tree (Malus domestica Borkh.) grown on podzolic soil in the conditions of the Moscow region, the fertilizer is found inefficient in terms of providing the optimal level of nitrogen nutrition of columnar apple tree plants, except for ‘Triumph’ variety when getting organic fertilizers at a dose of 100 t/ha. In January, fructose prevailed in the sugars of annual shoots of columnar apple tree plants. The ‘Triumph’ and ‘President’ varieties showed a tendency to increase in the content of fructose and glucose as compared with the control when getting organic fertilizers and their combination with mineral fertilizers. The same tendency was observed in the ‘Ostankino’ variety for the content of ascorbic acid in annual shoots, whereas this indicator of the ‘Triumph’ and ‘President’ varieties demonstrated the opposite trend. The ascorbic acid content in annual shoots in winter appeared consistent with its content in August shoots and remained independent on the content in leaves in August. With a decrease in temperature to -40 °C (component II of winter hardiness), the ‘Triumph ‘and ‘Ostankino’ varieties suffered reversible damage to the vegetative buds from 0 to 2.0 points, the ‘President’ variety introduced with 100 tons/ha organic fertilizers demonstrated an increase in damage to the vegetative buds to 3.17 points. The greatest damage to reproductive buds in the ‘President’ and ‘Ostankino’ varieties (3.85-3.91 on the control) was observed in component II of winter hardiness. The application of mineral and organic fertilizers increased these damages to complete death of reproductive buds. Injuries to bark, cambium in all variants of the studied varieties did not exceed 2.0 points. Wood appeared more damaged in the ‘Ostankino’ variety (up to 4.03 points in the combined application of N90K90 and 100 t/ha of organic fertilizers) as well as in the Triumph variety (up to 3.80 points in the N90K90 variant). As for component III of winter hardiness, an irreversible damage was noted for reproductive buds of the studied varieties in all variants of the experiment. In terms of component IV of winter hardiness, irreversible changes occurred in reproductive buds to the greatest extent (complete death in the ‘Triumph’ and ‘President’ varieties); in the tissue under reproductive buds, to the greatest extent in the ‘President’ variety (3.07 points in the variant of 100 tons/ha of organic fertilizers) and in the ‘Ostankino’ variety (2.76 points in N90K90), at the core, the maximum damage was noted in the N90K90 variant in the ‘Triumph’ (3.22 points) and ‘Ostankino’ (2.76 points) varieties.