INFLUENCE OF VARIOUS TYPES OF LIGHT ON GROWTH AND PHYSICOCHEMICAL COMPOSITION OF BLUEBERRY (Vaccinium corymbosum L.) LEAVES

It is important to use light that has a positive effect on plants. For plant growers, achieving the lowest possible cost of shrub production is crucial. We investigated the influence of light (white and violet LEDs as well as fluorescent white and red light) on the rooting and growth of blueberry cuttings (V. corymbosum L.) 'Aurora' and 'Huron'. Blueberry cuttings (4 cm tall) were planted into boxes with peat, which were placed in a phytotron at 22 degrees C and illuminated for 16 hours a day. The plants died under the red fluorescent light source and, therefore, we discontinued its use. The other three light sources had a positive effect on plant growth and development. The light source had little effect on the content of macroelements in the leaves. Plants grown under white fluorescent and white LED light did not significantly differ in the height (22.0-25.8 cm), proline (4.67-7.23 mu mol g-1), and polyphenol content (4987-5212 mg 100 g-1). In both cultivars, the violet LED light reduced plant growth and increased the content of polyphenols (6,448 mg 100 g-1) and proline (8.11- 9.06 mu mol g-1) in the leaves, which may indicate abiotic stress. During the rooting of highbush blueberry cuttings, it is advisable to use white LED light. It has a positive economic impact on crop production due to low electricity consumption and it benefits the environment by eliminating mercury. The plant quality is similar to that of fluorescent white light.