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Silver Birch Seedlings (silver + birch_seedling)
Selected AbstractsAssessment of UV Biological Spectral Weighting Functions for Phenolic Metabolites and Growth Responses in Silver Birch SeedlingsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2009Titta Kotilainen In research concerning stratospheric ozone depletion, action spectra are used as biological spectral weighting functions (BSWFs) for describing the effects of UV radiation on plant responses. Our aim was to evaluate the appropriateness of six frequently used BSWFs that differ in effectiveness with increasing wavelength. The evaluation of action spectra was based on calculating the effective UV radiation doses according to 1,2) two formulations of the generalized plant action spectrum, 3) a spectrum for ultraviolet induced erythema in human skin, 4) a spectrum for the accumulation of a flavonol in Mesembryanthemum crystallinum, 5) a spectrum for DNA damage in alfalfa seedlings and 6) the plant growth action spectrum. We monitored effects of UV radiation on the concentration of individual UV absorbing metabolites and chlorophyll concentrations in leaves and growth responses of silver birch (Betula pendula) seedlings. Experiments were conducted outdoors using plastic films attenuating different parts of the UV spectrum. Chlorophyll concentrations and growth were not affected by the UV treatments. The response to UV radiation varied between and within groups of phenolics. In general, the observed responses of phenolic groups and individual flavonoids were best predicted by action spectra extending into the UV-A region with moderate effectiveness. [source] The effects of calcium on stem lesions of silver birch seedlingsFOREST PATHOLOGY, Issue 2 2007A. Lilja Summary In this study, we tested the hypothesis that decreased liming of growth medium has a role in the increase of stem lesions and top dying caused by Phytophthora cactorum in containerized silver birch seedlings (Betula pendula) in Finnish forest nurseries. The effect of limestone dose rates on growth and the nutrient status was also monitored. An index based on severity of symptom expression was used to compare the effect of different liming treatments on P. cactorum infection. Limestone amended into the sphagnum peat growth medium increased the amount of calcium in the seedling stems. Liming did not significantly decrease the disease severity although index values in most cases decreased with the increased limestone dose rates. In general, the lesions were restricted after out-planting and the mortality of seedlings was low. Only inoculated seedlings on which the lesions had spread around the stem in the nursery died. Phytophthora cactorum appears to be a nursery pathogen, as it did not survive under conditions present in the field. Four years after out-planting, the tallest birches were those grown in sphagnum peat amended with the highest limestone dose of 8 kg m,3. [source] Adult large pine weevils Hylobius abietis feed on silver birch Betula pendula even in the presence of conifer seedlingsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2006Riitta Toivonen Abstract 1,The feeding preference of the adult pine weevil Hylobius abietis (L.) (Coleoptera: Curculionidae) for Betula pendula Roth was studied in no-choice and paired-choice feeding experiments. 2,In the first no-choice test, large quantities of silver birch bark in Petri dishes were consumed; on average, the daily consumption of each weevil was 67 mm2. 3,In the second no-choice test, the weevils were offered 1-year-old silver birch seedlings for 6 days. Initially, the weevils fed mostly on the stem bases; later, they moved upward to feed on other parts of the stems. In addition to the main shoots, scars caused by gnawing were also found on leaf bases, blades, veins and petioles. Feeding resulted in the death of the main stems in 15% of the seedlings. 4,In the paired-choice tests, the conifers were preferred to silver birch, even though a large amount of silver birch was also consumed in the presence of conifers. 5,In the paired-choice tests, equal amounts of Scots pine and Norway spruce were always consumed. When hybrid aspen was offered, only small amounts were gnawed. [source] | ||||||||||