摘要:

The vegetation of dolomitic outcrops was sampled in a maple forest of southern Quebec. Multivariate analyses have demonstrated the influence of rockiness and size of outcrop on the distribution of herbaceous and woody plants. These results allow the description of five microcommunities. The flora of small cracks and hollows is exclusively herbaceous and of low diversity. Deeper soils support tree seedlings and saplings (mostlyAcer saccharum) and also a diversified herbaceous stratum. The chemistry and mictotopography of outcrops produce mesic soils, rich in organic matter and nutrients. Soil depth segregates among plant species according to the size of their roots. Big outcrops have a more favorable microclimate. Dolomitic outcrops found in maple forests are biogeochemically rich microhabitats, which may support a more varied and abundant vegetation than does the surrounding forest floor. Primary succession on these outcrops is briefly discussed.

ISSN:0008-4026    

DOI:10.1139/b87-001

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Multivariate statistical methods were used to examine trends and interrelationships in 132 wetland stands at the southern edge of the boreal forest near Elk Lake, Ont., Canada. A total of nine vegetation types and seven species groups were recognized using cluster analysis. Nonmetric multidimensional scaling ordination of the stands indicated the underlying importance of nutrient status to the development of trends in vegetational variation. However, other factors such as the nature of the substratum, degree and periodicity of flooding, drainage, and water table level also appeared to be important. Analysis of the correspondence between vegetation types and species ecological groups indicated a trend toward the development of one-to-one relationships, suggesting that boreal wetlands may best be described as a series of relatively discrete communities. It is also suggested that species indicator values may be useful in characterizing boreal wetland stands.

ISSN:0008-4026    

DOI:10.1139/b87-002

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Monilia versiformiasp. nov. is a pleoanamorphic fungus producing two types of blastoconidia, viz., monilioid chains of dark-colored, sphaeroid conidia and lunate, hyaline conidia produced singly on simple, conidiogenous hyphae. The chains are produced in great abundance, and as the conidia mature and become pigmented, the chains break down and form a sooty mass. The fungus was isolated from a perennial canker of Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) in British Columbia, Canada.

ISSN:0008-4026    

DOI:10.1139/b87-003

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The development of microsclerotia in nonsclerotial strains ofCoprinus psychromorbidusRedhead and Traquair was studied using light, scanning, and transmission electron microscopy. On winter wheat in a controlled environment, microsclerotia originated through swelling of terminal and intercalary projections in elongate hyphae to produce small, spherical cells. These spherical cells increased in number through prolific budding. Initially they existed in leaf tissues as free cells but by 11 – 14 weeks had formed loose aggregations. At an advanced stage, further budding development was accompanied by a decrease in cell size and a small increase in cell wall diameter. Accumulation of a mucilaginous matrix and electron-dense material between spherical cells and lipid bodies and vacuoles within the cells accompanied maturation of the microsclerotium. Following near total conversion of leaf tissues to fungal thallus after 20 weeks of incubation, microsclerotia formed a single large continuous body between remnants of the epidermis. In winter wheat and fall rye plants naturally infected withC.psychromorbidus, microsclerotia were abundant and developed intercellularly and intracellularly. Often the development of the fungus was extensive near the crown tissues and microsclerotia appeared as white plaques embedded within the leaf sheaths.

ISSN:0008-4026    

DOI:10.1139/b87-004

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The hydathodes ofHillebrandia sandwicensisand ofBegonia augustinei,B.coccinea,B.phyllomaniaca,B.salicifolia, andB.vellozoanaare described. Begoniaceae have typical epithem hydathodes. Indirect measures of ploidy level (number of chloroplasts per guard cell, stomatal size) indicate that aquiferous stomata could be endopolyploid relative to aeriferous ones. The epithem comprises nonmoruliform cells, and the intercellular spaces are small. Elongated epithemial cells are intermixed with tracheids, and the stomatal chamber is lined by isodiametric epithemial cells. Elongated parenchyma cells sheath the hydathode. The enlarged vein is excentric and asymmetrical, as has been described for the "begonioid" tooth; however, the tooth is not tylate (i.e., with a pad of dense cells which would correspond to the epithem), as its apex is composed of parenchymatous cells. The hydathodes of Begoniaceae species vary in size, in position of the aquiferous stomata, in size of the chamber, and by the presence or absence of tanniferous cells or macrosclereids. Hydathodes, as well as other anatomical characters from the margin, might prove useful in taxonomic and phylogenetic studies of the Begoniaceae.

ISSN:0008-4026    

DOI:10.1139/b87-005

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Six cultivars of barley (‘Akka’, ‘Bruce’, ‘Klages’, ‘Leger’, ‘Perth’, and ‘York’) were compared for their ability to produce haploid embryos competent to produce embryogenic haploid callus. The capacity to generate such callus from scutellar epidermal cells is different among these cultivars and appears to be correlated with the developmental state–age of the embryo and associated with a rapid growth period. Histological examination of 12-, 14-, and 16-day-old embryos confirmed the meristematic nature of the callus-initiating cells and produced results which correspond well with results obtained from cultures of other similar embryos. Variability among cultivars in embryo development, root initiation from callus, and primary and secondary shoot regeneration was also identified.

ISSN:0008-4026    

DOI:10.1139/b87-006

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The warm-temperate speciesChondria baileyana,Lomentaria baileyana,Griffithsia globifera, andDasya baillouvianaare restricted, north of Cape Cod on the eastern American coast, to embayments and estuaries. The northern limit of distribution is the southern Gulf of St. Lawrence. In culture, isolates of these species from Nova Scotia survived 28 to 34 °C. In the field all reproduced during the period of maximum temperature, and inG.globiferaandC.baileyanathe progeny also reproduced. Some of the progeny ofD.baillouvianadeveloped as cold- and heat-resistant pads that survived the winter, whereas the other three species died back to perennating holdfast structures.Lomentaria baileyanawas the least successful of the group, being unable to form resistant holdfast pads in midsummer temperatures and having the most limited reproductive period and smallest population size.

ISSN:0008-4026    

DOI:10.1139/b87-007

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Colletotrichum lindemuthianumis the causal agent of anthracnose inPhaseolus vulgarisL. (French bean). The α and β races of the fungus were used in this study with French bean cultivar ‘Great Northern’. Whole plants inoculated with the α race developed brown lesions on the hypocotyls (susceptible response). The β race caused small limited lesions, indicating a more resistant interaction. Extracellular products and cell wall materials were isolated from β race cultures and extracellular products from α race cultures. The extracts were size fractionated. By using a cotyledon bioassay, elicitor activity was demonstrated on ‘Dark Red Kidney’ within fractions from the α race. Fractions from the β race had little activity on ‘Dark Red Kidney’ or ‘Great Northern’ cotyledons. Protoplasts were isolated from ‘Great Northern’ bean hypocotyl tissue and incubated with the fungal fractions. Even at low concentrations (0.01 μg glucose equivalent∙mL−1), the β race culture filtrate rapidly killed a greater percentage of protoplasts (30%) than the α race (15%). The β race wall extract had little effect upon protoplast viability. The proportion of nonviable protoplasts depended on the incubation period and the concentration of the fungal material. Heat treatment of the culture filtrates and wall extract did not decrease their lethal effects. The results suggest that protoplasts may be valuable in examining the nature of certain plant–pathogen interaction

ISSN:0008-4026    

DOI:10.1139/b87-008

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

Viable spores and ethanol-fixed basidiocarps ofArmillariaspecies were collected at eight geographic localities within the northeastern United States. Crosses among haploid hyphae grown from isolated single spores revealed that three to five intersterility groups were represented in this sample. By using spores to establish expected quantities of DNA within haploid cells, fluorescence microspectrophotometric measurements of stipe hyphae fell within the haploid range in all eight geographic isolates. Haploid monokaryotic basidiocarp tissues are unexpected in Basidiomycetes and may indicate the existence of a new pattern for the distribution of genetic material among somatic cells.

ISSN:0008-4026    

DOI:10.1139/b87-009

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

A method for rapid micropropagation of sea kale (Crambe maritimaL.) was developed. Petiole explants placedin vitroon a medium containing 0.5 mg/L indoleacetic acid (IAA), 6.0 mg/L kinetin, and 1.5 mg/L benzylaminopurine developed callus within 15 days and shoots within 28 days. Nearly four adventitious shoots could be developed within 3 weeks by placing the initial shoot on media without IAA. To develop roots, the shoots were then transferred to the basal medium containing 0.1 to 1.0 mg/L indolbutyric or α-naphthaleneacetic acid. Rooted plantlets were obtained within 2 or 3 weeks. After an acclimatization period of 6 weeks in a greenhouse in unsterilized medium, the plantlets could be set outdoors.

ISSN:0008-4026    

DOI:10.1139/b87-010

出版商:NRC Research Press    

年代:1987

数据来源: NRC