Helen J. Jozefek. (1989). The effect of varying levels of potassium on the frost resistance of birch seedlings. Silva Fennica vol. 23 no. 1 article id 5369. https://doi.org/10.14214/sf.a15528

Keywords: frost hardiness; Betula pendula; electrical impedance; cold tolerance; potassium fertilizer

Abstract | View details | Full text in PDF | Author Info

Seven hundred one-year-old Betula pendula Roth seedlings were given different concentrations of potassium fertilizer. Over the study period seedlings were subjected to artificial growing and dormant phases. Frost resistance of the seedlings was assessed by artificial freezing tests and electrical impedance measurements on stem cuttings. In general, high concentrations of potassium fertilizer reflected a low tolerance to frost. Pre-freezing impedance readings decreased with increasing potassium fertilizer dosages. Results from pre-freezing impedance measurements were found to be in broad agreement with the hypothesis that high impedance readings indicate a frost hardy tissue whereas low readings imply the opposite.

The PDF includes an abstract in Finnish.

Jozefek, E-mail: hj@mm.unknown

article id 5351, category Article

Tapani Repo. (1988). Physical and physiological aspects of impedance measurements in plants. Silva Fennica vol. 22 no. 3 article id 5351. https://doi.org/10.14214/sf.a15508

Keywords: developmental stage; electrical impedance; cross-sectional area; frost resistance; temperature acclimation; physiology

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Electrical impedance characteristics of plant cells are dependent on such physiological factors as physiological condition, developmental stage, cell structure, nutrient status, water balance and temperature acclimation. In the measurements also such technical and physical factors as type of electrodes, frequency, geometry of the object, inter-electrode distance and temperature have an effect. These factors are discussed especially with respect to the impedance method in frost resistance studies of plants.

The PDF includes an abstract in Finnish.

Repo, E-mail: tr@mm.unknown

Category : Research article

article id 328, category Research article

Pedro J. Aphalo, Markku Lahti, Tarja Lehto, Tapani Repo, Aino Rummukainen, Hannu Mannerkoski, Leena Finér. (2006). Responses of silver birch saplings to low soil temperature. Silva Fennica vol. 40 no. 3 article id 328. https://doi.org/10.14214/sf.328

Keywords: biomass; Betula pendula; photosynthesis; electrical impedance; mineral nutrients; soil temperature; stomatal conductance; water relations

Abstract | View details | Full text in PDF | Author Info

Two-year-old silver birch (Betula pendula) saplings were grown for a third growing season in controlled-environment rooms (dasotrons) at three soil temperatures (5, 10, and 20 °C). All trees grew the first flush of leaves, but the growth of the second flush was almost completely inhibited at the two lower temperatures. The dry weight of the second-flush leaves was 50 times larger at 20 °C than at 5 and 10 °C, with about 100 times more nitrogen. Root growth was less affected than shoot growth. Chlorophyll content, net assimilation rate and stomatal conductance were lower at low soil temperatures. The value of the cytoplasm resistance estimated from the electric impedance spectra was lower at 5 °C than at 10 or 20 °C. Leaf water potential was highest at the lowest soil temperature, and intercellular carbon dioxide concentration was only slightly lower in saplings growing in cooler soil. We conclude that the effect of long-term exposure to cold soil on net assimilation and growth was not caused by stomatal closure alone. It is likely to be additionally mediated by the limited nitrogen acquisition at the low soil temperatures, and perhaps additionally by some other factor. As the growth depression of aboveground parts in response to low soil temperature was more significant in silver birch than what has earlier been found in conifers, the relative changes in air and soil temperature may eventually determine whether birch will become more dominant in boreal forests with climate change.

Aphalo, University of Helsinki, Department of Biological and Environmental Sciences E-mail: pja@nn.fi
Lahti, The Finnish Forest Research Institute E-mail: ml@nn.fi
Lehto, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland E-mail: tarja.lehto@joensuu.fi
Repo, The Finnish Forest Research Institute E-mail: tr@nn.fi
Rummukainen, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland E-mail: ar@nn.fi
Mannerkoski, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland E-mail: hm@nn.fi
Finér, The Finnish Forest Research Institute E-mail: lf@nn.fi

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