摘要:

The fungusVerticillium dahliaeapparently utilizes injured cortical tissue to reach the vascular elements in eggplant roots. The two major sources of such root injury in sandy soils of Ontario are the damage caused mechanically in the transplanting of the seedlings to the field and the root lesions caused by the nematodePratylenchus penetrans. Transplant injury may be the more important factor early in the season and nematode injury later in the season. The effect of either of these two factors, acting independently, on incidence of disease, however, appears to be about the same.

ISSN:0008-4026    

DOI:10.1139/b65-067

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Additional information on the morphology ofCeratocystis fimbriataand its distribution is provided.

ISSN:0008-4026    

DOI:10.1139/b65-068

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Tests with eight isolates ofT. mesentericaFr. indicate that secondary control of conjugation in this species is by means of diffusible substances, i.e., hormones. The experiments suggest that at least two such substances are responsible for initiation of conjugation tube development. TheAandamating types each produce a substance or substances effective in initiating tube growth in the opposite type. The diffusing substances are nonvolatile, heat stable, and dialyzable; tube length appears to be correlated with the amount of diffusate present. It is suggested that, in addition to the substances initiating tube growth, one or more less stable substances regulate directional growth of the tubes as they approach one another.

ISSN:0008-4026    

DOI:10.1139/b65-069

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Study of the type ofDimerosporium balsamicola(Peck) Ell. & Ev. (≡Meliola balsamicolaPeck) revealed that this species is a melioline hyperparasite. The fungus is transferred toDimerium, redescribed, illustrated, and distinguished fromPhacocryptopus nudus(Peck) Petrak,Asterinasp., and fromEpipolaeum abietis(Dearness) n. comb. (≡Dimerosporium abietisDearness), which also occur onAbiesin North America. In all, four species ofEpipolaeumthat occur on conifer needles are treated:Epipolaeum abietisonAbies grandis(Dougl.) Lindl. andAbies amabilis(Dougl.) Forb. in western North America, onAbies albaMill. in France, and onKeteleeria davidianaBeiss. in Formosa;Epipolaeum tsugae(Dearness) n. comb. onTsuga canadensis(L.) Carr. in eastern North America, and onTsuga heterophylla(Raf.) Sarg. andTsuga mertensiana(Bong.) Carr. in western North America;Epipolaeum pseudotsugae(V. M. Miller & Bonar) n. comb. onPseudotsuga taxifolia(Poir.) Britton from western North America;Epipolaeum terrieri(Petrak in Terrier) n. comb. onAbies albain Switzerland.

ISSN:0008-4026    

DOI:10.1139/b65-070

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Many conditions affect the production of mature apothecia ofCiboria acerinain culture. In this investigation four factors were studied: age of isolate, temperature at which the cultures were grown, host from which the cultures were isolated, and the absence or presence of light. It was found that no apothecia were produced when the isolate was more than 18 months old. The temperature at which the stroma ofC. acerinadeveloped was significant in apothecium production. Stroma grown at 14 °C produced apothecia while stroma grown at 5 °C did not. However, apothecia matured over a temperature range of 5–22 °C. Apothecia were produced in cultures isolated fromAcer, Alnus, andPopulus. The quality of light received did not affect apothecium production. The absence of light at all stages of the growth of this fungus from the time of inoculation to the appearance of mature fruit bodies was not a limiting factor. Mature apothecia ofCiboria acerinawere formed under artificial conditions in darkness.

ISSN:0008-4026    

DOI:10.1139/b65-071

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Six types of plant mitochondria have been isolated by improved techniques and examined with the electron microscope by the thin-section and negative-staining techniques. In general, the mitochondria appeared well preserved. There was minimal contamination by endoplasmic reticulum but some plastids were present. The morphology of the plant mitochondria is compared with that of animal cell mitochondria. Negative staining showed that the inner membranes were covered with projecting knob-like subunits, as previously described for animal and insect cell mitochondria. The outer membrane showed a characteristic pitted appearance that was apparently due to 28 Å holes in the membrane. A preliminary report is also given of the appearance of negatively stained membranes of chloroplasts.

ISSN:0008-4026    

DOI:10.1139/b65-072

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

Chromosome numbers and taxonomic discussions are given for North American material of species in the generaBrayaandCardamine. The following chromosome numbers are reported for the first time:Braya humiliss.l.,n = 14 and 2n = 28;Cardamine angulata, n = 20, and 2n = 40;C. cordifolia, 2n = 24;C. microphylla, 2n = 32;C. occidentalis, n = 32 and 2n = 64;C. oligosperma, 2n = 16;C. pensylvanica, 2n = 64;C. umbellata, n = 24 and 2n = 48. It is concluded that the base number ofBrayaisx = 7 notx = 8 and that North American species ofCardaminehave the base numbersx = 6, 8, and 10.

ISSN:0008-4026    

DOI:10.1139/b65-073

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The limosphere (nebenkern) of thePolytrichumandrocyte is a complex structure composed of a plastid that is partially enclosed in a mitochondrial shell. This shell forms by the coalescence of the mitochondria found in the young spermatogenous cell. During or subsequent to the fusion of the mitochondria, a portion of the mitochondrial mass separates from the aggregate and becomes the apical body that is later attached to the anterior of the androcyte nucleus. A three-parted structure, the Dreiergruppe (DG), is found associated with the apical body and the flagellar bases. The element of the DG nearest the flagellar bases is composed of a band of parallel tubules, ca. 150 Å in diameter. These tubules extend over the surface of the nucleus for some distance and are thought to be the so-called filamentous appendage reported for bryophyte sperms, and the analog of flagellar "roots" found in certain algal cells.

ISSN:0008-4026    

DOI:10.1139/b65-074

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The extent of visual damage on leaves ofNicotiana tabacum, var. White Gold, treated with ozone under controlled environmental conditions, was found to be associated with the levels of sucrose and reducing sugars and the width of stomatal openings of the leaf. Leaves containing 5–14 mg sucrose per g dry weight were more susceptible than those of higher sucrose content. Leaves with 5–35 mg reducing sugars per g dry weight were also more sensitive to ozone than those with lower reducing sugar content. Introducing soluble sugars into the leaf varied sensitivity to ozone depending on the concentration of sugars, duration of sugar treatment, and conditions of the leaf itself. Ozone damage was positively correlated with the width of stomatal opening; but under certain conditions stomatal closure did not prevent leaf injury. High levels of sucrose and reducing sugars were associated with closure of stomata. Independently of the osmotic effect on stomatal movement, increasing sucrose content beyond the optimum for high sensitivity prevented damage from ozone.

ISSN:0008-4026    

DOI:10.1139/b65-075

出版商:NRC Research Press    

年代:1965

数据来源: NRC

摘要:

The internal organization of the radicle, tuber, secondary roots, and haustoria is described forGaiadendron punctatum(Ruíz & Pavon) G. Don. The root is characterized by a distinct root cap, an endodermis, and a tetrarch vascular pattern which is to some degree perpetuated after secondary growth sets in. Root hairs are absent from radicle and secondary roots. Haustoria are of the santalaceous type although a "gland" has not yet been found. Anatomical features confirm a close relationship of the genus withAtkinsoniaandNuytsiaand emphasize the primitive position of these three genera within Loranthaceae–Loranthoideae.

ISSN:0008-4026    

DOI:10.1139/b65-076

出版商:NRC Research Press    

年代:1965

数据来源: NRC