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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

1993

Abstract

Embryogenic cultures of red spruce (Picea rubens Sarg.) and Norway spruce (Picea abies (L.) Karst.) were initiated from dissected mature zygotic embryos. The tissues were grown on either proliferation medium or maturation medium. On proliferation medium, the embryogenic tissue continued to produce early stage somatic embryos (organized meristems attached to elongated, suspensor-like cells), whereas on maturation medium fully mature embryos developed from the embryonic tissue. Analysis of polyamines in tissues grown on these two media showed that: both putrescine and spermidine concentrations were always higher in cultures grown on proliferation medium than in cultures grown on maturation mediumin both species, spermidine concentrations declined with time in the tissues grown on maturation medium spermine was present in only minute quantities and showed only a small change with time. The presence of difluoromethylomithine in the culture medium had little effect on polyamine concentration, whereas the presence of difluoromethylarginine caused a decrease in putrescine concentrations in both red spruce and Norway spruce tissues grown on proliferation medium or maturation medium.

Abstract

The measurements were carried out with Warburg manometric technique on excised leaf discs. The plants had been grown for six weeks in varying temperature in continuous light. Photosynthetic rates were also measured at elevated CO2 level. The relationship between gas exchange rates and chemical composition was studied by multiple regression analysis. In accordance with earlier studies a strong acclimation effect of temperature was found. Long-term low temperature treatment caused a reduction in photosynthetic rates in all birch populations, and increased respiration rates in the two broadleaf species. There was a strong reduction in the temperature coefficient of dark respiration with decreasing acclimation temperatures in mountain birch leaves from southern populations. There was also a relatively high soluble sugar content and low chlorophyll content in low temperature treated plants. Birch from Central Norway (62 N) showed relatively high net photosynthesis rates compared with the populations from southern Norway (60 N) and higher chlorophyll content per unit area.

Abstract

The relationships between temperature and growth and between growth and and carbon exchange rates are reviewed and evaluated, and supplied with experimental evidence from field and greenhouse studies on birch provenances. Adaptations to changing temperature and photoperiod are shown on birch from different altitudes and latitudes in Scandinavia.