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-cultivation, the plants were grown in a nutrient film technique (NFT) system and exposed to additional 0–5 μ M for a period of 8 days. The NFT system permitted undisturbed growth of the roots during monitoring. Copper experiments were carried out in a split-root setup both with a uniform and differentiated Cu supply to investigate growth responses of roots grown in a homogeneous and heterogeneous root environment, respectively. At uniform external Cu supply, average root length was affected by increased Cu concentration during the first four days while the next four days only the overall root length (product of root length and root number) was significantly reduced. During the first four days in the split-root experiments with differentiated Cu supply, additional Cu primarily reduced root number on the Cu-treated parts of the root system but at stronger Cu concentration the overall root length was also significantly reduced. In contrast, number and average root length of the part of the root system not exposed to Cu increased when 1, 2 and 5 μ M Cu was added to the other side. Growth parameters were affected differently in the beginning of the heavy metal exposure compared to later stages of exposure, which may indicate acclimatisation to Cu stress.     

Root surface/leaf area ratios in arctic dwarf shrubs

Summary Individual shoots of the shrubsLedum palustre L.,Vaccinium uliginosum L., andBetula nana L. were severed from their parent plants beneath the moss surface in an Alaskan tussock tundra. These shoots remained one year in their original position in peat moss cushions without further disturbance. After this period fine root dry weight, fine root surface area, leaf dry weight, and leaf area of these shoots were measured and compared with equivalent values from unsevered control shoots. Dry weight ratios of fine roots/leaves were similar in cut and control shoots, with the exception ofB. nana. The fine root surface/leaf area ratios showed significant differences between control and cut shoots except inL. palustre. Without tedious rootlet extractions it should be possible to estimate fine root surface area from leaf area ofL. palustre.     

Growth of Mountain Birch Seedlings in Early-Successional Patches: A Year-Round Perspective

Abstract: Seedlings of mountain birch ( Betula pubescens ssp. czerepanovii ), a subarctic tree, mainly survive and establish in early-successional patches with low vegetation cover. In particular, during the first years after seed germination, a rapid seedling growth rate is important for winter survival. Seedling growth rate is controlled by plant nitrogen (N) concentration. On a year-round perspective, the N concentration is influenced by N uptake rate during both summer and winter and by N loss during autumn. The aim of the present study was to evaluate the effects of autumn N loss and winter N uptake for seedling growth during summer. The study used young seedlings growing in situ in northern Sweden. Since the growth rate of whole plants cannot be measured in situ, it was estimated using a simple, empirical seedling growth model. The model was based on data from controlled experiments and validated using growth data from a field study. The field study included sequential seedling harvests which were carried out at two sites differing in altitude, from autumn 1994 until autumn 1996. The seedling growth model was used to simulate the effects on growth rate of autumn N losses and winter N uptake. It was found that a decrease in the amount of N lost in autumn and an increase in the amount of N taken up during winter could enhance the growth rate of mountain birch seedlings by the same order of magnitude as an increase in growing season soil temperature by 1 to 2 K.     

Comparison of tannin-binding proteins in saliva of Scandinavian and North American moose (Alces alces)

Differences in the ability of salivary proteins from Scandinavian and North American moose (Alces alces) to bind tannins from various preferred food plant sources were studied. Both Scandinavian and North American moose produce a salivary tannin-binding protein which binds only condensed tannins common in their diet. The tannins of winter-browsed stems of Pinus sylvestris and Salix pentandra were more effectively bound by salivary tannin-binding protein from North American moose than by those from Scandinavian moose. Tannins of P. sylvestris and S. pentandra stems were also more effective binding agents than tannins from S. caprea and Betula species. The interactions between salivary tannin-binding protein and plant tannins may be one factor affecting food plant choice of moose. The chemical and biochemical characteristics of plant tannins and the ability of salivary tannin-binding proteins to react with tannins should be taken into account in diet selection.     

A comparative disc electrophoretic study of pollen proteins of Betula populifolia

Pollen proteins of Betula populifolia Marsh. were separated by disc electrophoresis utilizing 7% acid and basic acrylamide gels. Significant variation in amounts of protein available for detection by disc electrophoresis were found. Statistical analysis of our data indicated that: length of storage periods do not affect acid and basic proteins equally; conformational changes in both acid and basic proteins occur with storage; significant migrations of both acid and basic proteins toward the cathode occur after storage.     

Flavonoidmuster im knospenexkret der betulaceen

In the Betulaceae, buds of the genus Alnus, Betula (Betuleae) and Ostrya (Coryleae) excrete a lipophilic “coat” consisting of terpenoids and flavonoid aglycones. The variation of the substitution pattern of these latter compounds has been investigated in relation to taxonomy. Characteristic compounds which occur are the methyl ethers of 6-hydroxykaempferol, ermanin (kaempferol-3,4′-Me), acacetin and pectolinarigenin. Other methyl derivatives of kaempferol, quercetin, apigenin and naringenin also occur more or less frequently. Evidence is given for the species-specifity of the flavonoid pattern in many of these exudates.