ВЗНАЧЕННЯ ТА ОЦІНКА СТУПЕНЯ ЖАРОСТІЙКОСТІ РОСЛН КУЛЬТВАРІВ THUJA OCCIDENTALIS L.



Г. А. Кривохатько

Анотація


DETECTION AND EVALUATION OF HEAT RESISTANCE DEGREE OFCULTIVARS OF THUJA OCCIDENTALIS L. PLANTS

H. A. Kryvokhatko, master of vocational training of the Botanical Garden of the National University of Life and Environmental Sciences of Ukraine

 

Global changes of temperature regime, an increased concentration of carbon dioxide and other greenhouse gases in the atmosphere is the most important and complex problem in the field of environmental protection, so a comprehensive, in-depth study of the form diversity, biological and environmental features of Th. occidentalis L. cultivars in general use and special purpose planting is relevant and expedient, and widespread use of cultivars will allow the creation of highly decorative green plantations, resistant to harmful atmospheric emissions - soot, smoke, gases.

Woody plants react differently to effect of not only low, but also high temperatures of air and soil.

Detection of heat resistance of Th. occidentalis plants and its nine cultivars in conditions of Kyiv City was conducted in the second decade of July 2017 by the method of F. P. Matskov in our modification.

The evaluation of the heat resistance degree of cultivars of Thuja occidentalis L. plants was determined by the degree of feofitinization of leaf mesophilic cells. Th. occidentalis plants and its cultivars were research objects, as follows: Th. oc. 'Wagneriana', Th. oc. 'Wareana Lutescens', Th. oc. 'Ericoides', Th. oc. 'Ellwangeriana', Th. ос. 'Lutescens', Th. ос. 'Columna', Th.oc. 'Globosa', Th. oc. 'Spiralis', Th. oc. 'Smaragd'. Determination of heat resistance of plants was done in accordance with the method of Matskov F. P.

Heat resilience is the ability of plants to withstand high temperatures, overheating without significant harm to themselves. It depends largely on the duration of high temperatures and their absolute value.

The effect of high temperature on vegetative plants manifests itself in different ways. The temperatures, higher 450C, can cause irreversible coagulation of biocolloids and, consequently, death of organism through direct influence on colloidal systems; At the same time for different plants, the lethal temperatures range from 45 to 600C and higher. Disastrous effect of high temperatures may be not direct, but intermediary.

Intermediary influence is may appear in violation of the plants’ enzymatic system. Some enzymes increase their activity, while others, on the contrary, reduce it. In these cases, the decay processes begin to prevail over the synthesis processes, cells accumulate decay products, which do not keep pace for further transformation. As a result, plants are poisoned and killed even when the temperature is not so high to cause coagulation of biocolloids. Accumulation of ammonia is especially dangerous for plants, which is not involved in the synthesis of proteins. Ammonia poisoning is usual result of high temperatures influence on plants.

The plants with a thick cuticle, wax coating, hair, which reduce surface heating and drying of plants, can withstand heat. The most resistant to heat plants have low water content in cells and high heat resistance of plasma cellular.

The aim of the study was to make diagnostics of heat resistance of selected plants of Thuja occidentalis cultivars and select the most resistant to high temperature cultivars for use in urban plantations.

During the study the leaves of experimental plants (10 copies of each cultivar) were immersed in the water bath, and kept there during 30 minutes, maintaining a temperature of +400 C. One example of each cultivar was taken out from the first sample and transferred to the crystallizer with water at room temperature. Then the temperature of the water bath was increased by 10С and after 10 minutes the following samples were taken. The procedure was repeated several times, gradually bringing the temperature to +60С. In order to obtain more accurate results, the temperature in the water bath was raised to +68С, further the temperature was increased by 2С, bringing it to +80С. Then the water in the crystallizer was changed for 0,2 n. HCl and experimental examples were immersed for 10-20 minutes. Then the samples were washed with water and laid out on white paper in order of increasing the area of brown color.

The degree of heat resistance of the samples was determined by the proportion of brown color on leaf blade. Absence of brown color was marked as «–», weak brown color – «+», leaf  blade which had more than 50% brown color «++» and fully brown «+++».

Results of the research showed that during determining of the heat resistance degree of the plants of Th. occidentalis and its cultivars the needles of plants Th. ос. 'Lutescens', Th. ос. 'Columna', Th. oc. 'Spiralis', Th. oc. 'Smaragd' received poor slight color  at temperature +72С, at the same time the needles of plants Thuja occidentalis, Th. oc. 'Wagneriana', Th. oc. 'Wareana Lutescens', Th. oc. 'Ericoides', Th. oc. 'Ellwangeriana', Th.oc. 'Globosa' were not damaged at all.

All the cultivars except Th. ос. 'Lutescens', Th. ос. 'Columna', Th. oc. 'Spiralis', Th. oc. 'Smaragd' got slight brown color at a temperature +74-760 С. Their leaf blade was colored in brown more than 50% of +760 0C.

All experimental plants received more 50% damage of leaf blade at the temperature of +78С. The temperature of +80С was fatal for all taxons, which caused a total browning of the leaf blade.

On bases of the research it can be said, that the most resistant to effects of high temperatures were the plants as follows: Thuja occidentalis, (not cultivar)  Th. oc. 'Wagneriana', Th. oc. 'Wareana Lutescens', Th. oc. 'Ericoides', Th. oc. 'Ellwangeriana', Th. oc. 'Globosa'. These plants are promising for use in urban plantations for creating garden and park objects.

 

Thus, the study of heat resistance of Th. occidentalis and its cultivars showed that all the studied taxons are sufficiently heat-resistant, the lethal temperature is +80С for all cultivars.


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Посилання


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