MONITORING COPPER-INDUCED CHANGES IN FINE-ROOT GEOMETRY OF BIRCH (BETULA-PENDULA) USING NUTRIENT FILM TECHNIQUE (NFT)

Effects of copper on fine root geometry (number, length) and K and Cu content in birch (Betula pendula Roth) were studied. After pre-cultiva tion, the plants were grown in a nutrient film technique (NFT) system and exposed to additional 0-5 mu M Cu for a period of 8 days. The NFT system permitted undisturbed growth of the roots during monitoring. Co pper experiments were carried out in a split-root setup both with a un iform and differentiated Cu supply to investigate growth responses of roots grown in a homogeneous and heterogeneous root environment, respe ctively. At uniform external Cu supply, average root length was affect ed by increased Cu concentration during the first four days while the next four days only the overall root length (product of root length an d root number) was significantly reduced. During the first four days i n the split-root experiments with differentiated Cu supply additional Cu primarily reduced root number on the Cu-treated parts of the root s ystem but at stronger Cu concentration the overall root length was als o significantly reduced. In contrast, number and average root length o f the part of the root system not exposed to Cu increased when 1, 2 an d 5 mu M Cu was added to the other side. Growth parameters were affect ed differently in the beginning of the heavy metal exposure compared t o later stages of exposure, which may indicate acclimatisation to Cu s tress.