摘要:

A stem canker of suppressed western hemlock (Tsuga heterophytta(Raf.) Sarg.) was found at Powell River and Turnour Island, British Columbia. The canker, which appears to be annual, is irregularly elliptical with conspicuous resinosis in the early stages of development. A species ofCephalosporiumwas consistently isolated from the canker. Inoculation of western hemlock with this fungus produced cankers similar to those of natural origin. The growth and hyphal characters and the temperature–growth relations of the fungus are described. Attempts to produce the perfect stage in culture were unsuccessful.

ISSN:0008-4026    

DOI:10.1139/b53-028

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The kinetics of wheat leaf invertase have been investigated as a basis for its quantitative estimation. No evidence was obtained which indicated that wheat leaf invertase consists of a phosphorylase and a phosphatase. Solid preparations of the enzyme may be made by precipitating the invertase with ammonium sulphate from wheat leaf juice which has been previously freed from chlorophyll by precipitation with acetate buffer at pH 4.5. A study of the distribution of this enzyme in the first leaf of wheat shows that the enzyme reaches its maximum concentration in the leaf just at the close of the period of elongation. The enzyme is more abundant in the basal part of the leaf than the tip and this condition is taken to indicate that the enzyme is associated with the vascular tissue (phloem or phloem parenchyma) rather than the chlorenchyma.

ISSN:0008-4026    

DOI:10.1139/b53-029

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The 19 pollen profiles from the Gaspé and the St. Lawrence Valley show close correlation with known facts in glacial geology of this region. Marine invasions and persistence of the Laurentian icecap prevented forest occupation until climate had warmed considerably. The warm period was followed by a deteriorating climate as shown by rise in spruce and fir. During the succeeding very warm period, spruce and fir became rare, pine increased in the Gaspé region, and hemlock and broadleaved trees associated with pine became important in the St. Lawrence Valley, while the forests on the lower Laurentian Shield were composed primarily of pine penetrated by hemlock and broadleaved genera as minor elements. During most recent times the climate has become colder. Spruce and fir show a decided peak, especially in the Gaspé and on the Shield, pine declined in all parts of Quebec, but broadleaved genera, including chestnut in some areas, became prominent in the St. Lawrence Lowland, while decline of hemlock and pine and increase of spruce, fir, and yellow birch mark the forests on the southern slopes of the Shield. Pollen profiles are favorably correlated with forest divisions of Halliday.

ISSN:0008-4026    

DOI:10.1139/b53-030

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Observation ofLycopodiumspores in glass vessels of various sizes and shapes subjected to winds ranging from 0.6 to 7.1 meters per second showed that spores are blown from funnel or egg-cup-shaped vessels more readily than from rectangular vessels or horizontal glass slides.Lycopodiumspores were not visibly dispersed from a conical funnel with mouth 4 cm. diameter at wind speeds below 3 meters per second. Soredia of the lichenCladoniawere blown out of their funnel-shaped podetia by winds of 1.5–2 meters per second (3.3–5.3 miles per hr.) although no soredia were blown from a horizontal glass slide at the same wind speeds. When smoke flowed over conical glass funnels in a wind tunnel, two eddy systems were observed. The first took the form of twin vortices with almost vertical axes, one on either side of the median line in the funnel. Each vortex was smallest at the narrowest part of the funnel and widened upwards. The second system was a single permanent elliptical eddy with horizontal axis near the funnel mouth. The upper side of this eddy moved with the wind, the lower against it. Thus, across the median line of the funnel parallel with the air stream but in the opposite direction, there is a flow of air made up of the mingling of the bottom part of the permanent elliptical eddy and the inner edges of the two vortices. It is assumed that, in nature, the two eddy systems created by wind blowing over funnel-shaped plant structures will effectively remove spores and bodies of comparable size. The twin vortices suck spores from the bottom of the funnel and the rotation of the upper elliptical eddy raises the spores along the upwind wall of the funnel and ejects them into the wind above. In a hemispherical plant structure, a single permanent eddy carries spores backwards and up the upwind surface. This kind of dispersal could occur in a variety of plants, including Discomycetes and wind-pollinated plants.

ISSN:0008-4026    

DOI:10.1139/b53-031

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A study was made of the effect of certain nutritional and environmental factors on the growth and pigmentation of the mycelium, the sporulation, and the germination of the conidia of a "convoluted" isolate ofElsinoe veneta(Burkh.) Jenkins, the fungus responsible for the anthracnose disease of raspberries. This isolate utilized with varying degrees of efficiency various mono-, oligo-, and polysaccharides as well as certain organic alcohols as its sole source of carbon for growth. Either a nitrate, ammonium, amino, or imidazole nitrogen compound supported the fungus in culture. Maximum growth of the mycelium occurred in the presence of soluble starch and asparagine, whereas optimum sporulation of the conidia was obtained on media containing potato starch and sodium nitrate. In general, the production of conidia was markedly reduced on media favorable for excessive vegetative growth. Both a decrease in the volume of the medium and in the concentration of either a specific nutrient or of total nutrients adversely influenced the production of mycelium. Temperatures above 30 °C. and below 21 °C. decreased the percentage germination of conidia and restricted the growth of the fungus. Growth and sporulation occurred over a wide range of pH values. The optimum initial pH for both growth and sporulation was 4.0.E.venetaproduced conidia and grew as well in continuous darkness as in alternate diffuse light and darkness. Young potted raspberry plants growing in the greenhouse, when inoculated with conidia produced in culture, developed typical anthracnose lesions on the canes.

ISSN:0008-4026    

DOI:10.1139/b53-032

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Culture filtrates of five species ofAlternariawere antagonistic toPhytophthora erythroseptica. Those ofA.radicinaexerted the greatest effect and they were followed in order of effectiveness byA.dianthicola,A.solani,A.brassicicola, andA.tenuis. The antagonistic principle in the filtrate ofA.radicinawas readily removed by activated carbon. By extracting this carbon with acetone, substantial yields were obtained of colorless, needlelike crystals, quite insoluble in water, but readily soluble in acetone, ethyl alcohol, ether, benzene, concentrated sulphuric acid, and 10% sodium hydroxide. The m.p. of the crystals, 204 °C. to 208 °C, and the deep pink color in solutions of sodium hydroxide distinguish the substance from alternaric acid. Water suspensions of the crystals were much less antagonistic toP.erythrosepticathan the original filtrate and had little or no effect upon several species of bacteria.

ISSN:0008-4026    

DOI:10.1139/b53-033

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Evidence is presented that IAA is oxidized with the liberation of hydrogen peroxide, and that the rate of oxidation is limited by a light-activated step. Methyl umbelliferone, maleic hydrazide, and 2,4-D stimulate IAA oxidation, presumably by accelerating the light-activated step. The stimulatory action of all three substances is overcome to a greater or less extent by scopoletin, which competitively inhibits the oxidation of IAA. It is suggested that maleic hydrazide and methyl umbelliferone may inhibit growth by causing an excessive oxidation of IAA. The importance of fluorescent coumarin derivatives on the photooxidation of IAAin vivois discussed.

ISSN:0008-4026    

DOI:10.1139/b53-034

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A review of the method developed in this laboratory in 1943 for the nutritional classification of soil bacteria has suggested slight amendments in certain differential media: (1) the substitution of vitamin-free casamino acids for a combination of amino acids, and (2) the addition of vitamin B12to the growth factor media. In a comparative study with a newly proposed scheme of classification, the more selective plating medium advocated was found to be less suitable for the isolation of soil bacteria than the nonselective soil extract agar in the original method. Furthermore, the replacement of potassium nitrate with diammonium phosphate as source of inorganic nitrogen in the basal medium failed to cause any significant change in the nutritional grouping. Results from the nutritional classification of some 600 isolates by the two methods showed that the new procedure represents only a slight modification of the original system.

ISSN:0008-4026    

DOI:10.1139/b53-035

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Swamp, marsh, wet meadow, saline meadow,Drepanocladusbog, andSphagnumbog are characterized and related aquatic vegetation is described briefly. There is succession from different kinds of swamp and marsh, through wet meadow, toAgropyron–Carexgrassland and to various wooded communities, and also of marsh, throughDrepanocladus–Carexbog to aLarix laricinaassociation. The main bog sere of the region is initiated by some kind of aquatic or marsh phase and passes throughSphagnumbog stages to bog forest (Picea mariana) climax. Ecological aspects ofSphagnumspecies are considered in relation to succession and a regeneration cycle. Retrogression caused by burning is described for marshes, bogs, and bog forests. Many bogs in the northern part of the region have large mounds and ridges that retain frozen peat below the surface mantle during the summer. The significance of these permafrost areas is discussed. Brief consideration is given to phytogeographical features of the region.

ISSN:0008-4026    

DOI:10.1139/b53-036

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The anomalous complexity of the annual rings of young trees which generally disqualifies them from use in growth studies is, inP.resinosa, found to arise from a remarkably thorough organization of ring width and therefore of cambial activity in the tree under the influence of intrinsic determinants. The pattern is manifest when the widths of the internodal wood rings of a single year are followed in sequence from internode to internode down the tree from the apex. A similarly patterned view of the rings is obtained when the ring widths are traced in the ring sequence, conventional for growth studies, that passes from ring to ring in a given internode. The controlling intrinsic factors are held to be nutritional gradients in the axis inferred from the distribution of foliage and light along the axis of trees growing in the forest and in the open.In both types of sequence the pattern obscures the variations induced by random extrinsic factors and severely limits the value of these sequences for examining the effect of such factors. This disability can be avoided by the use of a third sequence of ring widths in which each term is the width of a ring which was laid down in an internode different but of the same age at the time of ring formation as the others in the sequence. Such sequences have never been used in growth studies. Yet they are found to be unpatterned and the effect of the fluctuating extrinsic factors can be examined effectively in them and in them alone.The complex relation between the responses of the cambium thus determined and those of the apical growing point to the random extrinsic factors is found to derive from the discontinuity of terminal growth introduced by the winter pause between bud formation and axial extension. These two stages of terminal growth are influenced by the extrinsic factors of the two different years. The effect on the cambium is simpler than this but is determinably related to that on the apical growing point.The results afford the ground for a first advance toward the removal of the disqualification of the use of young trees in studies of growth and of its factorial control.

ISSN:0008-4026    

DOI:10.1139/b53-037

出版商:NRC Research Press    

年代:1953

数据来源: NRC