Architectonics of a root system of young bi-axis apple trees depending on the formation of axes and their placement in the row

Abstract

To plant apple orchards with the use of the young bi-axis apple trees on vegetative rootstock is quite a promising intensification technique of contemporary horticulture. The parameters of the root system are the important indicator of the quality of the planting material of fruit crops and an apple tree in particular. A well-developed root system enables a better rooting of the young apple trees when planted in the orchard. The purpose of the research was to identify the effect of the technique of the axis formation and placement density in the row on the root system of the young bi-axis apple trees, cultivar “Florina”, on rootstock 54-118. The research was carried out in the fruit nursery of Uman National University of Horticulture (Uman NUH) in the years of 2016-2018. The formation of two axes ensured budding with: one bud with further pinching of the shoot until it becomes 10 cm long (the control); one bud with further pinching of the shoot until it becomes 20 cm long; two buds opposite each other; two buds alternately with the displacement of one relative to another at 5 cm on the rootstock axis. In the first field of the nursery, rootstock 54-118 was planted using the following schemes: 1.5 х 0.33 m (placement density 6 pcs./2 m), 1.5 х 0.45 m (5 pcs./2 m), 1.5 х 0.55 m (4 pcs./2 m), 1.5 х 0.65 m (3 pcs./2 m). The formation of a ramified root system with the roots of four orders was recorded in the one-year old bi-axis apple trees on rootstock 54-118. The total root length of the studied young apple trees ranged within 19.1–27.1 m. It was found out that the formation of axes by means of budding with one bud and further pinching of the shoot as well as extending the distance between plants in the row up to 55 and 65 cm led to a serious increase in the total length of the roots by 16–23 %. It was noted that the total root system length had a reverse correlation with the indicators of the aboveground part. Which is why, when young bi-axis apple trees are grown it is necessary to reach the balance between the formation of habitus and the root system with the optimal parameters.