摘要:

Seedlings of Douglas fir, grand fir, western larch, western red cedar, and western white pine were grown in modified environments for four growing seasons to see whether characteristic growth responses of roots and shoots might suggest a cause for pole blight of white pine. Environments included three soil profiles (topsoil, hardpan, and rock) and two moisture regimes (adequate and deficient).Of several variable characteristics of growth, total root weight was the only significant source of variation in diameter and height growth of white pine. Of all five species, white pine also appeared least efficient in competing for moisture on all soil types and was least able to adapt to soils having inadequate available moisture and low potential for recharge. The lack of response to poor environment can result in imbalance of root/shoot ratios. If this imbalance of root/shoot ratios can subsequently cause internal physiological stresses during droughty periods, these stresses, in turn, may cause deterioration of the root system and consequent decline in tree vigor, both of which usually precede appearance of pole blight.

ISSN:0008-4026    

DOI:10.1139/b66-020

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Microorganisms occurred in samples of decay-free heartwood from a living Alpine fir. Mycelial growth ofStereum sanguinolentumwas partially inhibited when inoculations were made on untreated samples of heartwood or in plates of dry heat (oven-sterilized) sawdust containing the untreated parts of aqueous suspensions from heartwood tissues. Inhibition was not observed in inoculations on oven-sterilized samples of heartwood or in plates of oven-sterilized sawdust containing the Millipore-filtered or autoclaved parts of the suspensions. It appeared that the success or failure ofS. sanguinolentumto colonize the test substrates may have been due in part to microbiological factors in untreated heartwood.The fungus successfully colonized oven-sterilized samples of heartwood at all water contents investigated (51–171%, dry weight basis). However, greater inhibition ofS. sanguinolentumwas observed in untreated samples at higher water contents (131–187% dry weight basis). The results suggested that wetter microenvironments involving the interactional phenomena between heartwood tissues and associated microorganisms may have been most effective in preventing the growth ofS. sanguinolentum.

ISSN:0008-4026    

DOI:10.1139/b66-021

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

In certain media the production of normal perithecia by the pathogen of strawberry leaf blotch,Gnomonia fructicola, was dependent upon the exhaustion of the glucose source of carbon at, or soon after, perithecial initiation. Many normal perithecia developed on media from which the nitrate source of nitrogen was not depleted. The inhibition by high concentrations of glucose was not specific for normal perithecia were produced in the presence of glucose when the usual concentration of nitrate was reduced and was exhausted by the fungus from the medium.Results suggest that the initiation of perithecia is determined by the establishment within the mycelium of a favorable balance between stimulatory substances (supplied by an extract of strawberry petioles or a mixture of vitamins in the medium) and other mycelial constituents and that subsequent normal development of perithecia is dependent on curtailment of vegetative growth processes.

ISSN:0008-4026    

DOI:10.1139/b66-022

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Chaetomium trigonosporumproduces mature perithecia and aScopulariopsis-like conidial state in cultures derived from single ascospores. The perithecial primordium consists of a central ascogonium surrounded by a vegetative sheath. Division and tangential growth of the peridial cells results in enlargement of the perithecium and the development of a central cavity. The ascogonium initial which typically arises from a single uninucleate cell of the vegetative mycelium soon develops into an ascogonium consisting of several uninucleate cells. Several cells of the ascogonium become multinucleate. From these cells the ascogenous hyphae branch more or less dichotomously toward the apex of the perithecium. The cells of the ascogenous hyphae are uninucleate and apical cells develop into asci directly, without the crozier stage.C. trigonosporumhas a "Xylariatype" centrum characteristic ofChaetomiumand distinct from the "Ophiostomatype" centrum found inMicroascus.

ISSN:0008-4026    

DOI:10.1139/b66-023

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

An unidentified volatile substance, released by smut fungi, their host plants, and facultative pathogenic fungi, changed the germination type from sporidial to mycelial inUstilago kolleri, U. avenae, U. hordei, andU. nigra. Imidazole caused similar changes.U. maydisdid not respond to either the gas or imidazole. These compounds increase sexual affinity, which is expressed by fusion of compatible promycelial cells. The gas and similarly acting solid compounds seem to be responsible for the change in germination type of spores that germinate on host tissue or in the soil, thereby immediately initiating the parasitic dikaryophase. The importance of high sexual affinity for the maintenance of the dikaryophase of smut fungi both on artificial media and in the host is discussed.

ISSN:0008-4026    

DOI:10.1139/b66-024

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Spores, pollen grains, and other microfossils are described from the Skonun Formation of Queen Charlotte Islands, situated off the western coast of British Columbia. The microfossil assemblage, apparently late Miocene to early Pliocene in age, is analyzed and compared with both other fossil floras and the extant flora. Results indicate the presence of distinctive genera and species, some of whose living equivalents are found only in Asia, Central and South America, or Eastern North America. The phytogeographic and paleoecologic implications of the microfossils are discussed, and reconstructions are attempted for both the climate and the physiography during the time of deposition.

ISSN:0008-4026    

DOI:10.1139/b66-025

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

This report deals with the frequency of anticlinal (multiplicative) divisions in fusiform cambial cells, cell length at the time of division, and ring width as determined mostly inSequoia sempervirens. The general relationships between these anatomical features resembled those observed in other conifers, but the frequency of anticlinal division was relatively high and the cells were long. Accordingly, the rate of cambial cell lengthening in the repetitive cycle of anticlinal division and cell elongation was found to exceed that in other conifers. Upward in the lower part of the stem the rate of anticlinal division decreased and cell length increased. A comparatively high rate of anticlinal division was maintained in the peripheral growth of large boles in both species, but cell length was greater inS. sempervirensthan inS. gigantea.

ISSN:0008-4026    

DOI:10.1139/b66-026

出版商:NRC Research Press    

年代:1966

数据来源: NRC