СЕЗОННА ДИНАМІКА ВМІСТУ ФОТОСИНТЕТИЧНИХ ПІГМЕНТІВ У СТРОКАТОЛИСТИХ ФОРМ BERBERIS THUNBERGII DC.

The work deals with the peculiarities of seasonal dynamics of the content of photosynthetic pigments in leaves and their parts with various colouring in variegated-leaf forms of Berberis thunbergii DC. Three forms were studied: green-leaf, purple-leaf 'Harlequin', and form 'Coronita', which has three colour patterns of leaves and their different parts (peripheral and central) with substantial differences in colouring. The photosynthetic pigments were extracted from leaves and their parts using dimethyl sulphoxide; in given extracts, the quantity of these pigments was measured by spectrophotometer SF-2000. We determined general and specific peculiarities of the content of chlorophyll and carotenoids in the leaves of one- and two-year-old shoots of three forms of B. thunbergii during growth and heterogeneity of their quantity in differently coloured parts of the leaf blade of 'Coronita'. In the yellow margins of pink-coloured leaves of one-year-old shoots of “Coronita”, the content of green and yellow pigment was usually lower than in the peripheral part of purple-coloured leaves. The maximum content of both types of photosynthetic pigments in this part of leaves of one- and two-year-old shoots was noted in the first half of the growing season. The same applies to the middle parts of the pink- and purple-coloured leaves; the lowest content of the pigments is typical of hot and dry months. The yellow-green- and brown-coloured leaves of form 'Coronita' differ from the other two leaf types in that the content of chlorophyll and carotenoids is at the highest in the second half of the growing season, and it is significantly higher. The ratio of chlorophyll a/chlorophyll b in the leaves of three forms recorded in September-October increases in comparison with such ratio in May-July. It shows that, at the end of the growing season, catabolism of chlorophyll b takes place faster than one of chlorophyll a. With regard to the ratio chlorophyll/sum of carotenoids, this index decreases in autumn in comparison with the first half of the growing season; it shows that green pigments have more active catabolism than yellow ones. The maximum content of chlorophyll in the leaves of B. thunbergii is generally recorded in the first half of the growing season; this index decreases in the hot and dry second half, but when the heat drops, the quantity of carotenoids increases slightly. In this regard, variegated-leavf form 'Coronita' stands out; it is characterized by high endogenic variability in the content of pigments within leaf blades depending on the colouring of different parts of a leaf.