Abstract
The current significant increase in the volume of growing ornamental seedlings in container culture in tree nurseries is conditioned by a number of significant advantages of planting material with an uninjured root system. At the same time, the agricultural technology for the production of such seedlings in container culture is much more complicated, compared to the traditional one. First of all, this is conditioned by growing them in a space limited by the size of containers and using an artificially prepared substrate. The purpose of the study was to conduct biotesting of three modifications of the substrate composition for the container culture of Spiraea japonica ‘Goldflame’, Tamarix tetrandra Pall. ex Bieb., Forsythia ovate Nakai and different doses of starter fertilisers “Nitroamofoska” and “Plantacote”. The study used both general scientific methods of analysis, synthesis, and active experimentation, as well as applied research methods such as biometric, phenological, soil, and agrochemical. Studies have established the presence of species-specific reactions of experimental plants with different fastidiousness to soil conditions, to the composition of the substrate and the types and doses of starter fertiliser used in container culture. A conclusion was made regarding the increase in the profitability of their cultivation due to the use of cheaper local components for the preparation of the substrate. The conducted studies showed a number of advantages of using organo-mineral slow-release fertilisers in container culture as a starter, in particular, “Plantacote” at a dose of 2.5-5.0 g∙l-1. That the mass production of decorative planting material with a closed root system should be preceded by research on establishing species-specific reactions of cultivated plants to cultivation conditions, which are the basis for optimising the composition of the substrate and the level of mineral nutrition of cultivated plants in order to increase the efficiency of the production of decorative seedlings in container culture. The obtained results will be useful for producers of planting material and the scientific community working towards the development of container culture of ornamental plants