CONTENT OF NONSTRUCTURAL CARBOHYDRATES IN ORGANS OF QUERCUS ROBUR IN CONDITIONS OF SOUTHERN FOREST-STEPPE OF EUROPEAN RUSSIA

Russian. Изучено содержание моносахаров, дисахаров и крахмала в различных органах деревьев дуба черешчатого рано- и позднораспускающейся феноформ, произрастающих в южной лесостепи в двух контрастных по почвенным условиям экотопах. Проанализирована сезонная динамика содержания неструктурных углеводов и его изменения под влиянием засух и повреждений деревьев насекомыми. Выявлен максимум содержания сахаров в лубе и ветвях после распускания листьев, совпадающий с активным восстановлением системы облиственных побегов. Показано, что высокая доля сахаров в составе NSC деревьев дуба может служить чувствительным индикатором адаптационных процессов. Для оценки состояния деревьев лучше всего подходит показатель общего содержания NSC: текущего состояния – в лубе ствола и ветвях после окончания листопада и долговременного состояния – в заболони ствола в конце лета и осенью. Сделано заключение о том, что содержание крахмала в органах деревьев дуба черешчатого, особенно на засоленных почвах, более низкое, чем у других видов дуба Западной Европы и Америки, а суммарное содержание неструктурных углеводов одинаково, что говорит о более активном метаболизме.

Russian. The content of monosaccharides, disaccharides, and starch in different organs of English oak of early and late coming into leaves phenological forms, which grow in southern forest-steppe in two contrasting soil conditions ecotopes, was studied. The content of monosaccharides, disaccharides, and starch shows the regularities of the tree`s adaptation to the unfavourable factors of environment. Depending on the functions and metabolic activity of different organs of English oak, it was determined they significantly differed from each other in the content and in the composition of nonstructural carbohydrates (NSC). There are significantly less monosaccharides in the branches and roots of the trees (about 49 mg·g-1) in comparison with the soft bark of stem (84 mg·g-1), but there is twice the amount of starch (26 and 29 mg·g-1). Disaccharides are the transport form of carbohydrates. The organs of English oak contain the following content of disaccharides: leaves (30 mg·g-1), branches (14), roots (9), soft bark of stem (7), sap (3,5). There is very low content of starch in the heartwood (about 1 mg·g-1). In comparison with aegopodiosocaricosum oak groves, NSC content in solonetz oak groves is higher in all the organs except roots. The content of monosaccharides is also higher but the content of disaccharides and starch is lower in the roots of trees growing in solonetz soils. The content of monosaccharides and starch in the contrasting ecotypes by soil conditions is almost equal in the leaves of the initial crown of all levels of development. The seasonal dynamics of nonstructural carbohydrates content and its change under the influence of droughts and insects attacks was analyzed. Maximum content of saccharides in the soft bark of stem and branches after leaves flushing, matching the active system of recovery of leafed shoots, was revealed. It was showed that high content of saccharides in the NSC of oak trees could serve a sensitive indicator of adaptive processes. To assess the condition of trees, the best thing is to use the indicator of the total content of NSC: current state – in the soft bark of stem and branches after leaf fall, long-time state – in the sap of stem at the end of summer and in autumn. It was concluded the content of starch of the organs of English oak (saline soils in particular) was lower than the content of starch of other oak species growing in Western Europe and in America, but the total content of nonstructural carbohydrates was equal which was the evidence of more active metabolism.