Зимостійкість та перспективи використання рослин-інтродуцентів Rodgersia aesculifolia Batalin в умовах міста Києва

Abstract

Rodgersia aesculіfolia Batalin of Saxifragaceae family characterized with ecological plasticity and high decorative quality due to the presence of large leaves, tall slender inflorescences, long flowering period, successful growth in conditions of shade and excessive soil moisture. This plant is very prospective for Kiev landscaping design. The recent distribution of R. аesculіfolia is not limited to the natural range, which is represented by the mountainous regions of China, but also has broad introduction borders. The main centers of introduction R. аesculіfolia are the countries of Western, Northern and Eastern Europe. There were not carried out scientifically based studies to determine the winter resistance of plants R. аesculifolia in terms of Kiev, because the plant is little known to a wide range of domestic researchers. The lack of information about the biological and ecological resistance of R. аesculіfolia to unfavorable environmental factors, in particular to the low temperature effect, limits the wide spread use of plants in Kiev landscaping design. Determining the level of adaptation of plants R. аesculіfolia in low temperature conditions of autumn, winter and spring periods is an important component of the evaluation results of their introduction level. This served as the main motivation for conducting research.  The purpose of the research is determination of the R. аesculifolia winter resistance under the conditions of introduction and obtaining scientifically grounded data about the plant cultivation features in terms of open soil of Kiev. The objects of the study were selected by the plants R. aesculifolia of the collection site of the Botanical Garden of the National University of Life and Environmental Sciences of Ukraine, located in the city of Kyiv. Analysis of weather conditions of the autumn, winter and spring periods of 2014–2018 years was carried out according to the information of  meteorological station of the Institute of Horticulture of the National Academy of Sciences of Ukraine. Winter resistance of plants R. aesculifolia in conditions of open soil of the city of Kyiv is due to the possibility to withstand a whole set of adverse factors of the winter, partly autumn and spring periods, in particular, low temperatures, dying of bark and cambium, soaking (lack of oxygen of roots due to prolonged constant with water) and pushing plants out of the soil due to the freezing of accumulated water in the tissues of the rhizome. In many respects the success of wintering of plants depends on the state of their preparation for the winter period: the time of the ending of growth in autumn, the conditions of plant nutrition during the growing season, level of damage to pathogens and pests. One of the main components of winter resistance of plants is frost resistance – the ability of plants to withstand non-damage short and long winter frost. Frost resistance plants of R. aesculifolia was determined in the Laboratory of Plant Physiology of the Institute of Horticulture NAAS of Ukraine according to the method of  M. A. Solovieva. According to the method of direct laboratory freezing, the parameters of frost resistance were determined by the level of damage to the rhizome of plants. The experiment was conducted three times, and the process of freezing of rhizomes – In several successive stages: gradual decrease of temperature, freezing and warming. Freezing plant roots was carried out at the temperature of  –5,0, –8,0, –10,0, –12,0, –14,0 and –16,0 °C, gradually decreasing it at a rate of 5 °С іn hour. During the studies found that autumn weather period 2014–2017 years were favorable for prepare plants to R. aesculifolia to successful wintering. It was marked by a moderate decrease in air temperature and a gradual reduction of the photoperiod, which serves as a signal for plants to stop the vegetation, accumulation of inhibitors in tissues. Positive air temperatures in the afternoon and negative in the nights in October and November stabilized hardening of plants and accumulation of nutrients. Observations on the state of plants R. aesculifolia during the winter indicate their high winter resistance. The rains during the autumn months of 2014–2017 years did not lead to the overflow of the upper layers of soil, so there were no such phenomena as dying of bark and cambium, soaking (lack of oxygen of roots due to prolonged constant with water) and pushing plants out of the soil due to the freezing of accumulated water in the tissues of the rhizome. There was no significant damage to the rhizomes of plants R. aesculifolia recorded during the winter period of air temperature changes (alternation of thaws and frosts), as the temperature of the soil during this period remained relatively stable. According to the results of comparative assessment of the R. аesculifolia plants state in terms of fluctuations in the temperature regime during the autumn-winter period it is concluded that there are sufficiently favorable conditions for their successful wintering. Analysis of R. аesculifolia plants rhizomes freezing allow to revealed: insignificant damages for –5,0 and –8,0 °C temperature (16 and 22 points); at –10,0 °C – the 40 % damage reached level of the total tissue volume (43 points); at –12,0 and –14,0 °C – severe damage (57 and 62 points), at –16.0 °C – found complete tissue death (98 points). The results of the laboratory freezing plants of  R. aesculifolia show about the high actual and potential frost resistance. That is why, the landscaping conditions of  Kiev is quite favorable for wintering plants of R. aesculifolia in the open ground. Keywords : Rodgersia aesculifolia Batalin, introduction, winter resistance, frost resistance, direct freezing method, the degree of tissues damage, winter extinction, temperature regime