THE SILVICULTURAL ASSESSMENT OF CONTAINERIZED SEEDLINGS OF ENGLISH OAK GROWN IN CONTAINERS

Abstract

Introduction. The intensive oak groves degradation requires a particular attention to the problem of their regeneration. To solve the problem, it is desirable to use the seeds of the best genotypes of plus trees for propagation, the seeds shall be grown in the containers under the conditions  of  controlled environment. When elaborating the technology for obtaining the containerized seedlings of English oak, the problem of cell volume optimization is a very important one. The goal of the research is to make a silvicultural assessment of the containerized seedlings of English oak in order to improve the industrial technology of their growing for artificial oak groves regeneration in the Middle Volga Region. English oak seedlings grown in Hiko and Plantek containers of various design and cell volumes were the object of the research. Material and methods of research. English oak seedlings grown in the greenhouse complex of Botanical Garden-Institute (Volga Tech) using various types of containers were planted in the sod- weak podzolic  light sandy loam soil. The seedlings grown under the conditions of controlled environment in Hiko and Plantek containers of various design and cell volume were planted in Spring -2016 under spade evenly in three replications. To study the influence of planting time on the establishment and growth of oak, seedlings were grown in the  Plantek 63F containers. Results. Establishment of the containerized oak grown in Hiko containers on a planting area, depending on the cell volume varies from 25.6 to 99 %. The seedlings grown in the containers of 280 сm³ cell volume showed the best results. In the  Plantek containers, the maximum figures of establishment were obtained in the containers with 210 сm³ cell volume. The influence of the mass of small roots (d < 3.0 mm) on the establishment of seedlings is stronger (R² = 0.93) than  the mass of all the root system (R² = 0.68). With the development of the mass of physiologically active roots, establishment of plants on the planting area increases. It is evident that the shape of cells of Plantek containers with side openings makes it possible for oaks to develop a larger mass of physiologically active roots on the planting area in comparison with  Hiko containers. The current increment in height of the stipitate of one-two-year old oak plantations does not depend on the volume of root covering substrate of Plantek and Hiko containers. The establishment of plants on the planting area in the first year in  the absolute majority of the variants of experiment (seedlings were planted in June-October) was almost 100 %. In the rainless May-2016 only it was 80 %. Correlation between number of  precipitation in the first decade of the month and seedlings establishment in 2016 is r=0.52. Conclusion. A silvicultural assessment of English oak seedlings grown in various containers is offered. It helps to enhance the  industrial technology for growing the seedlings with better silvicultural and economic  parameters. By a set of factors, the best performance in each group of containers was found when growing the seedlings  in Plantek 49 F (155 сm³) and Hiko V-120 SS (120 сm³) containers. The containerized seedlings of  Quercus robur can be used to establish the forest plantations during all the  frostless season. But early planting ensures better conditions for adaptation of plants on the planting area in the first year and more intensive growth of seedlings in the second year. It is important to take it into account  when  arranging the forest restoration activities.