摘要:

Root rot caused byPoria weiriiMurr. occurred when healthy roots of Douglas fir came into contact with inoculum in infected roots of the previous stand. Mycelium grew ectotrophically on the bark of the Douglas fir roots, frequently well in advance of growth in the wood, and penetrated to living tissues directly through sound as well as injured bark. Spread of the disease to adjacent trees took place where healthy and diseased roots were in contact, the mycelium apparently spreading to only a very limited extent through natural soil. It was shown that mycelium could invade roots of trees felled for at least 12 months and Douglas fir heartwood that had been buried in soil for at least 12 months. Viable Poria mycelium was isolated from infected roots as small as 2 cm in diameter 11 years after the trees had been cut. While Douglas fir and western hemlock appeared to be quite susceptible to infection, western red cedar, red alder, and bigleaf maple showed considerable resistance.

ISSN:0008-4026    

DOI:10.1139/b65-001

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Rhizothyrium abietisNaoumoff occurs on needles ofAbiesunder conditions of host suppression. Its distribution is recorded for northeastern North America and a description is given for the species on a new host,Tsuga canadensis(L.) Carr., in eastern Ontario.

ISSN:0008-4026    

DOI:10.1139/b65-002

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The increase in the leaf area ratio during early growth and the later decrease were primarily caused by an initial increase in the growth of leaves relative to stems and roots and a later rapid increase in stem growth associated with flowering. Changes in leaf thickness with time had little effect on the leaf area ratio.Increasing temperature from 10 to 25 °C increased the leaf area ratio because the growth of leaves was promoted to a greater extent than the growth of stems and roots, and because leaves were thinner. A further increase in temperature to 30 °C lowered the leaf area ratio because of an increased proportion of stem and thicker leaves.Increasing light intensity from 200 to 2500 ft-c decreased the leaf area ratio because of an increase in the relative proportion of stem and root and increased leaf thickness.These effects of the environment were mostly independent of changes in the rate of development of the plant.

ISSN:0008-4026    

DOI:10.1139/b65-003

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Effects of decapitation and treatment with indoleacetic acid (IAA) were studied in etiolated pea seedlings. The relationship between epicotyl swelling and bud growth inhibition was examined and found to be incomplete: concentrations of IAA which totally inhibit bud growth induce marked epicotyl swelling, but a lower concentration (5 p.p.m.) was shown to induce swelling without affecting bud growth. Swelling is a result of a change in polarity of cell expansion; the time of this change was unaffected by increasing the IAA concentration. Large increases in fresh and dry weight accompany the swelling.In mature (non-swelling) epicotyls treated with IAA, this substance tends to prevent the loss of reducing sugars brought about by decapitation. It is suggested that decapitation and IAA application affect the nutritional status of the epicotyl, and that this effect must be considered in constructing hypotheses dealing with apical dominance.

ISSN:0008-4026    

DOI:10.1139/b65-004

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

A newCeratocystisand itsVerticicladiellaconidial state are described and illustrated. This fungus has been frequently isolated from necrotic lesions associated with attacks by the bark beetleDryocoetes confususonAbies lasiocarpa, and is believed to be an important pathogen.

ISSN:0008-4026    

DOI:10.1139/b65-005

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Botryosphaeria piceaen. sp. is a parasite which causes perennial cankers ofPicea sitchensis(Bong.) Carr. andP. engelmanniiParry in British Columbia. The affected branches may remain alive for many years. The fungus has been found only in the sexual state, producing ascospores chiefly in early spring.

ISSN:0008-4026    

DOI:10.1139/b65-006

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Acetate-1-C14and acetate-2-C14were supplied to slices of developing castor bean endosperm. The molecules were extensively incorporated into long-chain fatty acids, water-soluble compounds, and protein. Oleic acid was the fatty acid initially labelled from acetate and it was the precursor of ricinoleic acid. Aerobic conditions were required for the formation of oleic acid and for the conversion of oleic acid to ricinoleic acid. Under anaerobic conditions the incorporation of acetate carbon into fatty acids was inhibited more than 90% and almost all of the C14was found in stearic and palmitic acids. Stearic acid appeared to be formed first and palmitic acid appeared to be derived from it through a shortening of the chain. The position of linoleic acid in the fatty acid interconversions was not clear except that it was not a free intermediate in the conversion of oleic acid to ricinoleic acid.Malonate-C14was only absorbed slightly by the tissue and although absorption could be increased by the use of diethyl malonate the metabolism of the compound was not facilitated. Because of its poor utilization by the tissue the role of malonate in long-chain fatty acid synthesis in this tissue could not be ascertained.

ISSN:0008-4026    

DOI:10.1139/b65-007

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Plants of rape, safflower, sunflower, flax, and castor bean were grown at temperatures of 10, 16, 21, and 26.5 °C for the period of seed development. Oil content of sunflower, safflower, and castor bean was not affected by temperature. Highest oil content in rape and flax was found at the lowest temperature and a continual decrease was observed with increases in temperature. Fatty acid composition of the oil from safflower and castor bean was not affected by a change in temperature. In the other three species the amount of the more highly unsaturated fatty acids decreased as the temperature was increased. This decrease was accompanied by an increase in oleic acid. The levels of saturated fatty acids in all of the species were not affected by changes in temperature.

ISSN:0008-4026    

DOI:10.1139/b65-008

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Acetate-1-C14was supplied to developing seeds of flax, rape, and safflower in short term kinetic experiments. Oleic acid was the first long-chain fatty acid to become radioactive and it appeared to be the precursor of the other unsaturated fatty acids in these oil seeds. Stearic acid was unlabelled and palmitic acid appeared to be derived by a pathway independent of that leading to oleic acid.

ISSN:0008-4026    

DOI:10.1139/b65-009

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

This paper presents a comparative anatomical study of callus tissue produced on stem cuttings of balsam poplar (Populus balsamiferaL.) grown in distilled water and in saturated solutions of CaSO4from 6.0 to 11.0 pH. Striking differences in callus morphology, hardness, and cellular structure were observed. The fact that acidity retards and alkalinity accelerates the rate of calcification suggests that calcification or hardening of the middle lamellae could be a function of the rate at which the pectic acid component is neutralized.The emergence and subsequent growth of adventitious roots decreased markedly with increasing alkalinity, until at pH 11.0 most callus masses appeared to be rootless. However, sectioning usually revealed a well-developed root embedded some distance below the surface. Failure of most adventitious roots to emerge in a strongly alkaline calcium solution was attributed to the hard compact nature of the surrounding callus.

ISSN:0008-4026    

DOI:10.1139/b65-010

出版商:NRC Research Press    

年代:1965

数据来源: NRC