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.

1992

Abstract

Identical pair crosses, including reciprocals, in Pinus sylvestris L. (Scots pine) were made on ramets of the same clones in three clonal archives (seed orchards) in Sweden: Svar (64N), Rskr (59.5N), and Degeberga (56N). The offspring were used to test the hypothesis that the parental environment could affect the performance of the progeny (aftereffects). Growth and freezing tests were performed in the controlled conditions of the Stockholm Phytotron. Parental environment affected seed weight: the heaviest seeds came from Rskr and the lightest seeds, from Degeberga. Height development was affected in the two growth periods tested: seeds from Svar produced the shortest plants and seeds from Rskr, the tallest plants. There was an effect on the autumn frost hardiness in the first growth period that disappeared after the second growth period. The most hardy progenies came from Svar. The aftereffects of the parental environment were less than the maternal effects on seed weight and also less than the effects of full-sib families on growth and autumn frost hardiness. Small but mostly significant reciprocal effects were found for height and height increment during the second growth period. There was a significant reciprocal effect for seed weight. Seed weight differences could explain only a small part of the effects on growth and none of the effects on hardiness.

Abstract

Healthy Norway spruee trees were investigated over 130 weeks following successful attack by the bark beetle Ips typographus in a study of fungal invasion. The study was undetaken in southeastern Norway during an epidemic period. Sapwood moisture was measured and the tree reaction and beetle activity were noted. Fungal invasion was examined in disc samples taken 1, 5, 10 and 15 m above stump height. The fungal penetration in the sapwood started very slowly, but accelerated during the fouth week after attack. The leading edge of fungal penetration was a few millimeters in advance of the visible blue-stain until the heathwood was reached. The development of blue-stain was similar in Lardal, 1979, and at S, 1980, but with some differenees relatea to the air temperature. Fungi were found to invade the sapwood successively. The pathogenic species, Ophiostoma polonimm, was the primary invader occurring during the first week, followed by other beetletransmitted species. The secondary invaders, O. bicolor; Graphium sp. 1, O. penicillatum and O.ainoae, entered the sapwood during the first three weeks after attack and reaehed a peak within ten weeks. The tertiary invaders, probably also beetle transmitted, were not as common as the secondary colonizers. The first Hymenomycetes, rather weak white-rotters, appeared among the tertiary invaders. Later succession was dependent on the moisture content of sapwood. Strong decaying whiterotters entered the sapwood near the base where the moisture content remained favourable, while cf. Trichoderma viride dominated in the drier parts of the trees, where the sapwood moisture declined to fibre saturation point 75 weeks after attack. The heavy beetle attack, averaged 3.7 entrance holes per dm2 over more than ten meters of the stem, overwhelmed the trees rapidly and no secondary resinosis occurred.