Influence of the temperature factor on the phenological rhythms of clematis growth and development

 Relevance. Establishment of regularities of growth and development, determination of the influence of the temperature factor on the individual phases of clematis ontogenesis for a reasonable prediction of the timing of their occurrence in the conditions of the Stavropol upland.

Methodology. The paper presents the results of studies of the onset of certain phases of growth and development of clematis varieties of the garden group Integrifolia in the Stavropol Botanical Garden. The data of phenological observations and meteorological indicators of 2016–2020 are analyzed.

Results. It is established that representatives of this group, in the climatic conditions of the Stavropol upland annually pass all stages of seasonal development. According to the results of long-term observations, the degree of adaptation to new natural and climatic conditions was revealed. The influence of the temperature factor on the dates of occurrence of phenological phases were analyzed. The weather conditions of the growing season cause the shift of the phenophases to earlier or later periods. In our studies, the dates of the onset of the “beginning of vegetation” phase vary,  due to the instability of meteorological conditions. The earliest date of the beginning of the growing season was marked on 04.03.2016, the latest — on 29.03.2019. The sum of active air temperatures above 0 °C for this period was 185–198 °C. The sum of effective temperatures above +5 °C required for the beginning of the budding and flowering phases has been determined. The duration of the interphase period from the beginning of the growing season to budding is on average 67 days. The interphase period from the beginning of budding to flowering is 18 days, the sum of effective  temperatures above +5 °C for this period was 220 °C. To predict the timing of the onset of the “flowering” phase, the necessary sum of effective temperatures above +5 °C for the interphase period from the beginning of the growing season to the beginning of flowering is calculated — 681 °C. The sum of the active temperatures above 0 °C, before flowering, was — 1212 °C. 

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