摘要:

Single-spore isolates ofBotrytis cinereafrom commercially stored cabbage exhibited a broad range of virulence. Spore germination and hyphal growth required an exogenous source of nutrients. The ability of either spores or mycelium to cause infection of stored cabbage tissue was also dependent upon exogenous nutrients. Nutrients required for infection could be supplied in the form of glucose, cabbage leaf extract, potato dextrose agar (PDA), or by a wound at the site of inoculation. The concentration of nutrients and (or) spores influenced the ability ofB. cinereato cause tissue decay whereas spore age and bacterial populations did not. Spores on the surface of cabbage leaves germinated within 4 to 8 h in nutrient solution; an additional 8 to 16 h in nutrient solution were required for successful infection. The optimum temperature for fungal growth and for infection was 20 to 25C. The optimum relative humidity for decay was above 97%; decay did not occur at relative humidities below 93%.

ISSN:0008-4026    

DOI:10.1139/b75-085

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The generic description ofCristulariellais emended and the fungusC. depraedansis redescribed. BothC. depraedansandC. pyramidalisare characterized by multicellular propagules which are distinct from the phialides each produces in culture.Cristulariellais not a synonym ofMyrioconium, but the combinationM. depraedans(Cooke) von Arx, referring to the phialides, may be legitimate.Cristulariella depraedansis reported onAcer circinatumandAruncus sylvesterfrom British Columbia and onAcer pennsylvanicum, A. rubrum, A. saccharum, andA. spicatumfrom Ontario.

ISSN:0008-4026    

DOI:10.1139/b75-086

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Photosynthetic pigments and free amino acids have been simultaneously determined in the leaves of barley andArabidopsis, chlorophyll mutants and control plants, artificially grown under different physiological conditions. Several inverse-type relations (logarithmic, hyperbolic, or linear ones according to each case) have been determined between the concentrations of the photosynthetic pigments and those of some amino acids. The graphic plot of each of these relations is generally subdivided into two distinct curves, permitting the classification of biochemical effects due to mutations of different types and to physiological factors. The concentration of leucine undergoes large amplitude variations under dim light (400%) and, moreover, it presents specific relations with carotenoid pigments (β-carotene, lutein, violaxanthin, and neoxanthin).

ISSN:0008-4026    

DOI:10.1139/b75-087

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The relative abundance and ecology of 123 lichens, 12 liverworts, 1 peat moss, 59 mosses, and 40 vascular plants are described from the southeastern part of Prince Patrick Island, 76° N latitude. One hundred and three of the lichens, 25 of the bryophytes, and 6 of the vascular plants are first reports for the island. One lichen,Blastenia arctica, is reported for the first time from North America. One hundred and seventy of the species were found on the ground, 51 on rock, 9 on decaying plant material, 9 on bone, 5 on fossil wood, 4 on caribou dung, and 2 on mosses. Sixteen habitat types are described, based upon a relevé analysis of 31 different sites. A percentage of the lichens (95.1%), of the bryophytes (95.8%), and of the vascular plants (60.0%) encountered have a Circumpolar distribution. A percentage of the lichens (3.3%), of the bryophytes (1.4%), of the vascular plants (22.5%) have an American distribution. Eight species have an Amphi-Beringian distribution: lichens, 1.6%; bryophytes, 1.4%; vascular plants, 12.5%. One bryophyte (1.4%) and two vascular plants (5.0%) have an Amphi-Atlantic distribution.

ISSN:0008-4026    

DOI:10.1139/b75-088

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The cytotaxonomy of four species ofDrabathat are invariably confused with one another is discussed and a key is given. The species areD. crassifoliaGraham (n = 20);D. albertinaGreene (n = 12);D. nemorosaL. (n = 8); andD. stenolobaLedebour (n = 20). Characteristics of sterile artificial first-generation hybrids betweenD. crassifolia, D. albertina, andD. stenolobaare presented and analyzed.

ISSN:0008-4026    

DOI:10.1139/b75-089

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Rhytidiella baranyayin.sp. is described from corky proliferations of aspen (Populus tremuloidesMichx.) in British Columbia, Canada, and from its growth in culture. A bitunicate ascomycete, it is suspected of being the causal agent of the disease with which it is consistently associated.

ISSN:0008-4026    

DOI:10.1139/b75-090

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

In detopped plants, stump exudation resulting from root pressure provides a measure of the quantity of solutes and of water being transferred to the xylem. In dry soil the transfer of water to the xylem stops when the force required to remove the water from the soil is equal to the osmotic pull of the solutes in the xylem. In a sandy loam soil mixture, detopped tomato plants (Lycopersicon esculentumMill.) treated with urea maintained stump exudation to a soil moisture content as low as 12.1% while water-control plants ceased exudation at 15.0% soil moisture. By maintaining the transfer of solutes to the xylem, the application of urea enhanced the ability of the detopped root system to remove water from the dry soil.By watering plants to pot capacity at different times before and after detopping, a series of soil moisture levels were obtained with detopped roots of tomato. In this clay loam soil mixture stump exudation started at 10% soil moisture (about −3.0 bars potential). With increasing moisture the rate of exudation increased rapidly to reach a maximum exceeding 5 ml per hour at soil moisture contents between 20 and 25% (about −0.05 bars potential). The rate then decreased gradually to 2.5 ml per hour as the soil moisture content increased from 25 to 45%. Starting at 10% soil moisture and continuing up to 25%, solute uptake increased proportionately with increasing moisture content, and at these dry and medium soil moisture levels, the supply of water to the root determined the quantity of solutes being translocated to the stump. The depletion of oxygen and accumulation of carbon dioxide in soils containing more than 25% moisture reduced the translocation of solutes in the plants.

ISSN:0008-4026    

DOI:10.1139/b75-091

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

From a precise study of the shoot apical region ofDicksonia squarrosaSwartz, the histogenic role of the apical cell is shown. Leaves are initiated at levels where the delineations of the segments remain identifiable without ambiguity. A delay in the division of certain pluripotential prismatic cells constitutes the first indication of a future leaf initiation. The sequence of events leading to the formation of a new leaf follows a fundamental pattern, around which variations may occur; this pattern could constitute a new feature for consideration in comparative morphology. No relation between leaf initiation and apical segmentation could be established. Comparison with some other ferns (e.g. Hydropterideae, Hymenophyllaceae, Schizaeaceae) suggests the possible existence of variable relationships between leaf initiation and apical segmentation in these plants.

ISSN:0008-4026    

DOI:10.1139/b75-092

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Progeny tests of naturally pollinated pin- and thrum-form plants of two species ofAmsinckiawere conducted to determine whether net selfing, random mating, or net disassortative mating occurred in natural populations. The locus determining flower form was used as a marker gene.Amsinckia spectabilisexperienced close to random mating in a dense population, but in a small, diffuse population a high rate of selfing was indicated. Pin plants ofAmsinckia vernicosavar.furcataexperienced 44.3% net disassortative mating, and thrum plants in this species experienced complete (100%) disassortative mating.Compared withA. spectabilis, stigmas and anthers are about twice as far apart inA. vernicosavar.furcata; yet the pollinators are essentially similar, suggesting that greater separation of stigmas and anthers greatly improves the efficiency of distyly at promoting disassortative pollination. The two populations ofA. spectabilisstudied indicate that autogamy and (or) geitonogamy is much higher in diffuse populations. The results support previous studies that disassortative pollination is greater in thrum-form flowers than in pin flowers. Distyly without self-incompatibility can be an effective outbreeding system but is much more sensitive to variations in floral structure, population density, and pollinator behavior than are self-incompatible breeding systems.

ISSN:0008-4026    

DOI:10.1139/b75-093

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The cambium of balsam poplar appeared to be stimulated byRhytidiella moriformisandKeissleriella emergensinfections of bark, colonized to the outer periphery of the phloem but not beyond. Instead of producing normal xylem in groups of four cells, it produced hyperplastic and hypoplastic deformed xylem, each group consisting of variable combinations of tracheids, vessel elements, and wood parenchyma. Deformities were accompanied by composite cell structures and rapid aging of thick-walled ray cells. Tracheids and vessel elements were branched, curvate, attenuate, and short. Vessel elements without perforations had more bordered pits arranged on all sides. Perforations, if present, were often lateral and not oriented for vertical transport of solutes. Morphogenetically, host tissues are believed to be chimeral, as evidenced by stunting, incomplete cell-plate formation, and hyperplasia and hypoplasia. Changes in structure of cells and tissues of the host were caused by both pathogens, but they occur over a larger surface area of the bark and sapwood on trees infected byR. moriformisin nature.

ISSN:0008-4026    

DOI:10.1139/b75-094

出版商:NRC Research Press    

年代:1975

数据来源: NRC