摘要:

Vitamin and amino acid requirements have been established forArthrobacter terregensn. sp., an organism found to require an unknown growth factor present in soil extract, liver extract, and culture filtrates ofArthobacter pascensn. sp. Apart from this unknown factor, concentrates of which promote growth at less than 0.1 μgm. per ml., biotin, thiamine, and pantothenic acid were found to be essential. With adequate mineral supplement the nitrogen requirements could be fulfilled byl-glutamic acid, though the latter could be replaced by combinations of other amino acids.

ISSN:0008-4026    

DOI:10.1139/b53-015

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Euphorbia cyparissiasL., a European species originally introduced into North America as an ornamental, is now firmly established on roadsides and pastures in Eastern Canada. The Canadian distribution is mapped from specimens in three herbaria. Plants with a somatic chromosome number of 20 and plants with the number 2n = 40 occur in eastern Ontario and adjacent Quebec. According to all available evidence for this region, the diploid plants never set seed, whereas the tetraploid populations are highly fertile. The cells of the upper leaf epidermis of the tetraploid plants are conspicuously larger than those of the diploid plants. By means of this criterion, the probable chromosome number of herbarium specimens was determined. The distribution of the diploid and tetraploid plants in Ontario and western Quebec is mapped. Tetraploid plants are known from eight locations in this area; five of these infestations are serious. It is believed that the sterility of the diploid populations is due to a genic condition which may interrupt normal pollen development.

ISSN:0008-4026    

DOI:10.1139/b53-016

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

By using evidence derived from the relationships with smut fungi (CintractiaandPlanetella) that attack its members, new light has been shed on the phylogeny ofCarex. The genus is believed to be essentially monophyletic and derived fromKobresia. It has been found necessary to erect a new subgenus,Kuekenthalia, composed principally of those sections with persistent styles and bladdery perigynia that were formerly placed inEucarex.Unciniais shown to be an offshoot of the evolutionary line that gave rise toKuekenthalia.

ISSN:0008-4026    

DOI:10.1139/b53-017

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The study of decay and decay relationships of white pine was undertaken to provide forest authorities in Ontario with information essential to the management of even-aged stands. Of 1012 white pine trees examined in 10 1-acre plots, located in even-aged white pine stands, 52% contained decay. A well-defined relationship existed between age and decay. The proportion of trees with decay increased gradually with age from 40% in the 60-year age class to 100% in the 220-year age class. The loss in merchantable volume increased from 4% at 60 years to 40% at 200 years. No consistent relationship between percentage of decay and diameter was found. The incidence of decay in vigorous and non-vigorous trees was about the same but the percentage of volume lost through decay was considerably higher in slow-growing, less vigorous trees. The pathological rotation, as indicated by the maximum periodic increment, was 160 to 170 years. A number of methods of estimating the volume of decay in logs are compared. Regression lines, which define the percentage of cull allowances at all ages, are presented. Thirteen wood-destroying fungi were found to be associated with the decay of living white pine in Ontario.Fomes pini(Thore) Lloyd was responsible for 90% of all loss in trunks and butts of living trees. External signs of decay were rare, except in cases of advanced white pocket rot caused byF.pini.

ISSN:0008-4026    

DOI:10.1139/b53-018

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A strain-specific and polyvirulent phage forPseudomonas pisiSackett have been isolated from peas. The latter phage lyses also strains ofP.glycineaCoerper,P.lachrymans(Smith and Bryan) Carsner, andP.phaseolicola(Burk-holder) Dowson. The polyvirulent phage has been used successfully in detecting the presence of bacterial blight (P.pisi) in pea seed and plant tissue from infected fields. Specific phages forP.atrofaciens(McCullouch) Stevens andP.coronafaciens(Elliott) Stapp have been obtained, respectively, from wheat and oat seeds. Phages specific forXanthomonas translucensf. sp.hordei,secalis, andhordei-avenaewere isolated from barley and oat seed. Attempts to isolate viruses forX.translucensf. sp.cerealisandundulosawere not successful.

ISSN:0008-4026    

DOI:10.1139/b53-019

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Yeast extract and vitamin-free casamino acids were found to be equivalent as sources of nitrogen for the growth ofPseudomonas hydrophilain a glucose – mineral salts medium. The addition of a mixture of thiamine, riboflavin, pantothenic acid, pyridoxine, nicotinic acid, para-aminobenzoic acid, biotin, and folic acid to the medium containing vitamin-free casamino acids did not stimulate growth. About 67% as much growth was obtained with a mixture of 20 amino acids and asparagine as with the vitamin-free casamino acids and the mixture could be replaced by any one of asparagine, aspartic acid, serine, and alanine. Of the 11 simple nitrogen compounds tested, including urea, nitrates, and ammonium salts, only ammonium citrate and dibasic ammonium phosphate were utilized appreciably. A simple synthetic medium consisting of ammonium citrate, glucose, and mineral salts was found to give approximately the same amount of growth as the more complex yeast extract – glucose – mineral salts medium.

ISSN:0008-4026    

DOI:10.1139/b53-020

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Spruce, tamarack (larch), balsam fir, pine, and poplar communities of the region are described in terms of floristic composition and ecological relationships. The white spruce (Picea glauca) association is regarded as the climax type of the region. Of four phases or faciations presented by the white spruce association, the feather moss faciation appears to be the climax to which the other faciations tend to develop. Two black spruce (Picea mariana) communities are recognized, the black spruce – feather moss association and the black spruce–peat moss association. Of these, the former is characterized by "feather mosses" such asHylocomium splendensand has developed on relatively level terrain without much peat formation, whereas the latter has aSphagnumfloor and has arisen in definite depressions through acid bog stages with the production of considerable peat. The black spruce – bog moss community is interpreted as subclimax, with natural succession to the black spruce – feather moss association. The tamarack (Larix laricina) community has many features in common with the black spruce – peat moss association but differs markedly, not only in its dominant species, but because of its development from aDrepano-cladus–Carex–Betulabog under persisting wet conditions. Succession to black spruce commonly occurs. Balsam fir (Abies balsamea) is relatively rare in the region and usually grows in mixed stands with white spruce, paper birch, aspen, and balsam poplar. Two divisions of the pine association are recognized, the jack pine (Pinus banksiana) and the lodgepole pine (P.contortavar.latifolia) consociations. For each of these, two phases are described, the pine – feather moss faciation on the more shaded sites and the pine–heath faciation on the more open and drier areas. Knowledge of the ranges of these two pines in northern Alberta and concerning hybrids between the species is extended. The poplar association, classified as aspen (Populus tremuloides) and balsam poplar (P.balsamifera) consociations, is considered in relation to other vegetation, especially prairie grassland and white spruce. Encroachment of aspen poplar upon native grassland is counteracted by various factors, notably burning. Natural succession of poplar and pine to white spruce is impeded chiefly by forest fires. Some attention is given to phytogeographical problems of this transition region.

ISSN:0008-4026    

DOI:10.1139/b53-021

出版商:NRC Research Press    

年代:1953

数据来源: NRC