Cold acclimation was partially impaired in boron deficient Norway spruce seedlings |
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Authors: | Mikko Räisänen Tapani Repo Tarja Lehto |
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Institution: | (1) Faculty of Forestry, University of Joensuu, P.O. Box 111, 80101 Joensuu, Finland;(2) Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 68, 80101 Joensuu, Finland |
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Abstract: | Susceptibility of trees to freezing injury has been suggested to increase in boron (B) deficiency but there is no experimental
evidence to support this proposition. In this study, Norway spruce (Picea abies L. Karst.) seedlings were cultivated for two growing seasons in deficient, intermediate and ‘optimal’ B levels. Cold hardening
of the seedlings was measured after the second growing season. Freezing tolerance in tips of shoots, needles, stems and roots
was determined by controlled freezing tests and electrolyte leakage method, and that of buds, in addition, by differential
thermal analysis (DTA). Electrical impedance was used to monitor changes in the apoplastic space during cold acclimation.
Root dry weight and shoot height growth were lower in B deficiency. Cold acclimation of buds and stems was reduced by B deficiency.
When hardened seedlings were subjected to subzero temperatures for 3 weeks, extracellular electrical resistance of stems became
the highest at the lowest B supply which was probably due to decreased desiccation tolerance. As a conclusion, susceptibility
to freezing damage may be increased by B deficiency in Norway spruce trees. |
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Keywords: | Boron deficiency Cold hardiness Controlled freezing test Differential thermal analysis Electrical impedance Picea abies |
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