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.
2004
Authors
Nina Elisabeth Nagy Carl Gunnar Fossdal Paal Krokene Trygve Krekling Anders Lönneberg Anders Lønneborg Halvor SolheimAbstract
Polyphenolic parenchyma cells (PP cells) in Norway spruce (Picea abies (L.) Karst.) stem phloem play important roles in constitutive and inducible defenses. To determine whether anatomical and molecular changes in PP cells are correlated with tree resistance, we infected two Norway spruce clones with the pathogenic fungus Ceratocystis polonica (Siem.) C. Moreau. The fungus induced significantly different lesion lengths in the two clones, indicating that one clone was more resistant to the fungus (short lesions) than the other (long lesions). After infection, the cross-sectional area of PP cells and their vacuolar polyphenol bodies increased in the three most recent annual rings of PP cells in both clones. The more resistant clone had larger PP cells with denser polyphenol bodies than the less resistant clone, whereas the less resistant clone accumulated relatively more polyphenols after infection. Compared with the less resistant clone, the more resistant clone contained higher starch concentrations before infection that were reduced more quickly after infection before returning to original values. Low transcript levels of chalcone synthase were detected in uninfected tissues of both clones, but the levels increased dramatically after infection. Transcript levels were higher and peaked 6 days earlier in the more resistant clone than in the less resistant clone. The activity of at least one highly basic peroxidase isoform was greatly enhanced after infection, and this increase occurred earlier in the more resistant clone.
Authors
J.W. Hudgins Erik Christiansen Vincent R. FranceschiAbstract
Conifers have evolved constitutive and inducible defense mechanisms to help in both wound healing and defense against attack by bark beetles and other organisms. These defenses include oleoresin, phenolics, and static structures in secondary phloem, such as lignified cells and calcium oxalate crystals, that create physical barriers. We used a phylogenetic approach to investigate the defense anatomy of conifer stems of 13 species from five families following treatment with methyl jasmonate (MJ), a compound that induces defense responses in stems of several Pinaceae species.Methyl jasmonate induced a response similar to wounding except that the response was not accompanied by lesion formation, necrosis or a hypersensitive response. In the Pinaceae species studied, MJ induced polyphenolic parenchyma (PP) cell activation and xylem traumatic resin duct (TD) formation. Members of the Taxodiaceae, which are not known to produce large quantities of resin, showed massive xylem TD formation and surface resinosis following MJ treatment.Treatment with MJ caused members of the Araucariaceae and Cupressaceae to form axial phloem resin ducts but not xylem ducts, whereas Podocarpaceae species showed no induction of resin-producing structures. All species treated with MJ showed phenolic deposition in PP cells, and early lignification of phloem fibers was observed in most of the non-Pinaceae species.We conclude that, although evolution of resin-producing structures occurred independently in conifer lineages, MJ seems to induce resin production regardless of tissue location, as well as inducing deposition of phenolic compounds. Co-evolution of conifer defensive strategies and bark beetle pests is discussed.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Inger Sundheim Fløistad Ketil KohmannAbstract
When spring frost occur on recently planted forest sites, severe damage may occur to the seedlings. The aim of the present study was to test how different levels of nutrient concentrations in the seedlings affected spring frost hardiness and time of bud break.Seedlings were grown in a greenhouse for one season and supplied with fertiliser containing 22, 43 and 72 mg N per litre respectively. The treatments resulted in needle nitrogen concentrations ranging from 0,9 to 1,8 % in the autumn.After winter storage at 0C, bud break was recorded on seedlings growing in greenhouse, outdoors and in growth chambers at 12C and at 17C. Freezing tests were performed on seedlings directly removed from winter storage and following one week growth in the greenhouse. Seedlings receiving fertiliser with 43 mg per litre had less freezing injury than the two other fertilisation treatments. The ealiest bud break occurred in seedlings receiving 72 mg per litre.
Authors
Guro BrodalAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Peder GjerdrumAbstract
With wood, the moisture content is an intrinsic volatile property - constantly changing in accordance to the environment. For the efficient use of timber, knowledge about the MC is increasingly being requested, and the sawmill being required to reveal such information. This paper presents an algorithm for estimating, on a weekly basis, the running MC and MC variation of a timber lot. Input variables are the MC of the lot when leaving the kiln, storage condition and running weather observations. The model, described in mathematical terms, is valid for timber stored on stickers, i.e. under homogeneous air circulation, and meant for implementation in the sawmill’s MPS.
Authors
Peder Gjerdrum G. Arrighetti Mauro BernabeiAbstract
Resin pocket is a natural property considered one of the main drawbacks of spruce timber, particularly important for appearance and joinery applications. The resins, viscous by nature, might only be solidified at temperatures superior to conventional kiln drying.Induced in the active cambium by traumas of unknown origin, size as well as location of resin pockets are random. Surrounding annual rings appear unaffected, while on the microscopic scale discrepancies in cell structure are easily recognised. Ca. 200 resin pockets per m3 timber have been reported in Scandinavian timber. More resin pockets were experienced in boards sawn from the ca. 16% of logs demonstrating resin pocket in the crosscuts.