摘要:

Concentrations of 50 and 500 p.p.m. gibberellin were used alone and in combination with 2,4-D sodium salt solutions ranging from 0.00001 to 8000 p.p.m. acid equivalent, in Petri dishes, with dormant seeds of stinkweed (Thlaspi arvenseL.), to determine the effects of these treatments or of subtoxic amounts of 2,4-D alone, on germination and growth. About 90% germination within 2 weeks was induced by the 50 p.p.m. gibberellin and was not augmented by the very dilute concentrations of 2,4-D. Complete germination occurred within only 8 days with 500 p.p.m. gibberellin alone. Strengths greater than approximately 0.02 p.p.m. of 2,4-D retarded shoot elongation and concentrations greater than about 0.5 p.p.m. of 2,4-D progressively reduced germination associated with either 50 or 500 p.p.m. gibberellin. Concentrations of 2,4-D higher than approximately 200 p.p.m. prevented both concentrations of gibberellin from causing any true germination. Beyond 200 p.p.m. of 2,4-D there was still, however, a broad range within which gibberellin was able to cause a definite initial phase of the germination process characterized simply by rupture of the seed coat without protrusion of root and stem. This response could not be prevented by 2,4-D at concentrations lower than 4000 p.p.m. in counteraction with 50 p.p.m. gibberellin, or at dosage lower than about 7000 p.p.m. in association with 500 p.p.m. gibberellin. Potential practical significance of the work is considered.

ISSN:0008-4026    

DOI:10.1139/b60-075

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Optimum growth of etiolated pea stem sections was obtained in a basal solution of 3-indoleacetic acid, cobalt chloride, and sucrose. The final length of pea stem sections was increased when sucrose was added 2, 4, or 6 hours after 3-indoleacetic acid and cobalt were added to the test solution. Benzimidazole at 100 to 200 p.p.m. and kinetin at 1 p.p.m. added to the basal solution inhibited growth of etiolated pea stem sections. Growth.of the pea stem sections was inhibited when they were treated for 4 hours with kinetin plus 3-indoleacetic acid, then transferred to the basal solution for 14 hours. There was no growth inhibition when pea stem sections were treated for 4 hours with kinetin alone, followed by 14 hours on the basal solution. Similar results with kinetin were obtained when barley coleoptiles were used and 2,4-dichlorophenoxyacetic acid was the growth-promoting substance. Ether and hot water extracts of pea stem tissue pretreated with kinetin and 3-indoleacetic acid did not appear to contain a growth inhibitor.

ISSN:0008-4026    

DOI:10.1139/b60-076

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Urediospores ofPuccinia helianthiSchw. collected from sunflower plants in the field and stored in glass vials at 5° C in a refrigerator survived for 846 days. In a freezer at −10° to −22 °C their ability to infect plants and to germinate on agar appeared unimpaired after 1652 days' storage. Storage under mineral oil decreased spore longevity at both refrigerator and freezer temperatures. Viable spores dispersed in oil germinated well on agar and induced heavy infections on sunflowers.The longevity of dry spores ofP. helianthistored at −10 °C to −22 °C and the high level of viability retained greatly exceed those reported for other species of rusts.

ISSN:0008-4026    

DOI:10.1139/b60-077

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Growth ofPullularia pullulansin shake culture on a synthetic medium, composed ofD-glucose,l-asparagine, and mineral salts, was shown to be dependent on a supply of thiamine. The thiamine could be replaced by a combination of equivalent amounts of thiazole and pyrimidine, but not by either alone.

ISSN:0008-4026    

DOI:10.1139/b60-078

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Cellular dedifferentiation and redifferentiation are studied in leaves of the moss gametophore. Changes in the size and number of some cellular constituents as well as changes in their position are observed. Cell division, the plane of new wall formation, and factors affecting them are considered. Isolation of the leaf initiates events leading to the dedifferentiated state of the component cells. These changes include increase in the size of the nucleus and nucleolus and decrease in the size of the chloroplasts accompanied by an increase in chloroplast numbers. Changes in the position of cellular components are initiated by intravacuolar cytoplasmic layer formation leading to systrophe. Systrophe is considered to be an important event in dedifferentiation representing the final topography of the cellular constituents in the dedifferentiated cell. The distribution of clusters is observed, indicating loss of cellular polarity. In order for redifferentiation to take place, a new axis of polarity must be initiated. Redifferentiation leads ultimately to cell division. This division is characterized and the distribution of planes of new wall formation is shown.

ISSN:0008-4026    

DOI:10.1139/b60-079

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

A fungus isolated from a yellow, stringy decay of white spruce and other conifers in Western Canada was at first identified asFlammula conissanssensu Ricken. This fungus was compared with an authentic isolate ofFlammula conissans(Fr.) Gillet obtained from Europe. They were shown to be separate species through comparison of cultures, fruit bodies, spores, and the factors affecting fruiting in culture, as well as by pairings of monosporous mycelia. The Canadian fungus was identified asFlammula alnicola(Fr.) Kummer. Basidio-spores ofF. alnicolagerminated after cold treatment at −7 °C. The requirement of moderate cold-treatment for spore germination may account for the occurrence of the fungus only as a root-rot pathogen.

ISSN:0008-4026    

DOI:10.1139/b60-080

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

The type species ofPiricaudais illustrated and redescribed from the type collection.

ISSN:0008-4026    

DOI:10.1139/b60-081

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

A new method of inducing apogamy in normal fern gametophytes ofPteridium aquilinumhas been demonstrated. Entire plants, apparently isolated sporophytic members, and structures of an intermediate nature between sporophyte and gametophyte were produced. The method involved growing gametophytes in sterile culture on a nutrient medium containing a suitable concentration of glucose. A series of experiments was carried out in which the concentration of glucose was varied from 0–8% and the optimum concentration was established to be 2.5%. Prothalli grown in the absence of glucose, which have only their photosynthate as an energy source, produced no apogamous structures. It was found that sucrose, maltose, or fructose could be substituted for the glucose in the induction of apogamy. Four other strains ofPteridium, and strains ofOsmunda cinnamomeaandAdiantum pedatum, also responded to the sugar treatment by producing apogamous plants. The osmotic pressure of the medium has been shown to have no effect on the induction of apogamy but it does appear to cause the decline in the response at the higher concentrations of sugar. The role of the sugar would therefore seem to be as a respiratory substrate, which in some way favors the induction of apogamy.

ISSN:0008-4026    

DOI:10.1139/b60-082

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

Four new species and one variety are added to the form-genusRhizoctoniafrom the study of over 60 isolates obtained from forest nurseries in Saskatchewan and Manitoba; these areRhizoctonia dichotoma, R. endophytica, R. endophyticavar.filicata, R. globularis, andR. hiemalis. They are chiefly characterized by chlamydospores in chains produced singly and in sporodochia. The chlamydospore characters were consistent within the species, and are therefore considered of dependable diagnostic value. The sporodochia, however, exhibited considerable variability in character and size depending largely on the substrate, and are of little use for taxonomic purposes.

ISSN:0008-4026    

DOI:10.1139/b60-083

出版商:NRC Research Press    

年代:1960

数据来源: NRC

摘要:

The following fungi are newly reported from Ontario:Cryptosporella paucispora(Pk.) Berl. & Vogl.,Diaporthe taleola(Fr.) Sacc.,Diaporthe leiphaemiavar.raveneliana(De Thüm. & Rehm) Wehm.,Apioporthe anomala(Pk.) Höhn., andValsa salicis(Fuckel) Winter.The status of the family Cryptosporellaceae sensu von Arx and Müller is briefly discussed.

ISSN:0008-4026    

DOI:10.1139/b60-084

出版商:NRC Research Press    

年代:1960

数据来源: NRC