摘要:

A survey of the literature combined with field studies and the reexamination of many historical collections reveals that the hepatic flora of Alberta is composed of 114 taxa, consisting of 26 families and 46 genera. Two species.Gymnomitrion corallioidesandScapania mucronata, are reported as new to the province. Two species are excluded from the hepatic flora as they have been incorrectly attributed to Alberta. Twenty-five taxa have been designated as hypothetical for the province as no valid voucher specimens have been located. Most (109) of the 114 taxa present are Circumpolar in distribution, 4 are American, and 1 is Amphi-Atlantic. The range of most (98) of the Alberta species includes the Boreal Forest and forested areas in the mountains; however, 57 of these species also occur in Arctic and in Alpine regions, and 22 of them occur south into temperate areas. Only a few species have other distributions: 10 are Arctic Alpine. 3 are Cordilleran, 3 are Temperate, 2 are Boreal, and 1 is Boreal-Temperate. One hundred and two species have been found in the Rocky Mountains, 59 in the Boreal Forest, 7 in the Cypress Hills, 6 in the Aspen Parkland, and 3 in the Prairies.

ISSN:0008-4026    

DOI:10.1139/b75-204

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The growth and respiration rate of excised tomato roots was determined using the following sugars as substrate: sucrose, maltose, raffinose, glucose, α-methylglucoside, fructose, β-methylfructoside, cellobiose, trehalose, melibiose, melezitose, turanose, palatinose, and inulobiose. The ability of these sugars to inhibit the growth of roots in sucrose and the ability of the roots to hydrolyze the oligosaccharides were also determined. The results are discussed in terms of the possible limiting factors for growth on different substrates.

ISSN:0008-4026    

DOI:10.1139/b75-205

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Uptake of [14C] picloram (4-amino-3,5,6-trichloropicolinic acid) from culture solution by alfalfa (Medicago salivaL.) and barley (Hordeum vulgareL.) seedlings was investigated to determine to what extent passive and (or) active mechanisms are involved in the uptake of the herbicide by roots of intact plants. The roots of both species had similar absorption patterns consisting of rapid initial uptake lasting 1 to 2 h, followed by continuing absorption at a markedly lower rate during the rest of a 12-h treatment period. Initial uptake both by roots and whole plants was not significantly reduced by 1.0 mM NaN3, whereas continuing absorption was depressed by this inhibitor. Q10values were 1.4 for alfalfa and 1.0 for barley for the first 1–2 h of uptake, whereas for subsequent periods the values were consistently greater than 2.0. Evidently, uptake during the initial phase of entry is governed by passive processes, while continuing absorption is controlled, at least in part, by active mechanisms. Much of the picloram taken up by alfalfa and barley roots during a 4-h treatment period was released rapidly to unlabelled nutrient solution. Uptake by both species was decreased in the dark and enhanced in the presence of sucrose. The results of inhibitor studies suggest that picloram absorption by alfalfa plants is more dependent on a supply of metabolic energy than is uptake by barley plants. In most instances, total accumulation of picloram in 4 h was much greater in alfalfa plants than in barley plants of nearly equivalent mass. This difference may account for at least part of the difference in susceptibility of alfalfa (sensitive) and barley (tolerant) to the herbicide. Alfalfa roots always contained a much greater proportion of the total amount of picloram in the plant than did barley roots.

ISSN:0008-4026    

DOI:10.1139/b75-206

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Clusters of abundant appressoria formed from branching hyphae of mycelial inoculum ofPythium myriotylumon the surface of bean hypocotyls and roots.Pythium aphanidermatumusually produced single appressoria, but sometimes small clusters of appressoria.Pythium ultimumproduced only single appressoria. Early pathogenesis of all species was characterized by rapid radial growth of hyphae in the epidermal cells, which was more rapid than in the cortex. These hyphae were constricted at the host cell walls. Invaded tissue and adjacent cells stained differently from healthy cells with all isolates. Aerial hyphae were produced from vesicles below the cuticle or within epidermal cells soon after infection was established. Safranin-staining materials were observed in the xylem, phloem, and tannin sacs. Zoospores ofP.myriotylumandP.aphanidermatumgerminated and produced long prepenetration hyphae, which branched and formed single appressoria. Oospores ofP.myriotylum,P.aphanidermatum, andP.ultimum, after germination, produced branched hyphae and single appressoria. Penetration, rapid advance through epidermal cells, and ramification of cortical and vascular tissue were identical with those of mycelial inoculum. Sporangia of all three species formed intercellularly and intracellulary within 48 h and predominantly in the epidermis and upper cortex. Oogonia were produced intercellularly and intracellularly in 4 day s throughout the tissue, but mainly in the inner two thirds of the cortex. Sporangia ofP.myriotylumandP.aphanidermatumin infected bean hypocotyls germinated within 3 h when flooded with tap water and produced zoospores within 6 h. When similar tissue was air-dried for 3 days or rapidly dried for 3 h. there was neither germination nor zoospore production.

ISSN:0008-4026    

DOI:10.1139/b75-207

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Cultures ofHelminthosporium maydis, race T, grown on modified Fries' medium under 1300 ft-c of continuous light produced at least 7 times more toxin than those grown in the dark. Thin-layer chromatography of the chloroform extracts of culture filtrates revealed that light has a general effect on metabolism of the fungus rather than a specific effect on toxin production. Light-grown cultures were found to be richer in chloroform-extractable metabolites including the toxin. The defined medium suggested by Karret al. (5) was found to be unsuitable for high yields of toxin production.

ISSN:0008-4026    

DOI:10.1139/b75-208

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The septal pore apparatus ofRhizoctonia solaniwas studied in hyphae of different ages by scanning electron microscopy. The formation of the septal pore apparatus begins with an annular swelling followed by the development of a dome-shaped perforated pore cap, which usually has three apertures. In older hyphae, the septal pore apparatus is absent, and the septal pore may be plugged. In some cases, four apertures are observed in the pore cap.

ISSN:0008-4026    

DOI:10.1139/b75-209

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The hypothesis that exogenous gibberellic acid (GA3) increases height growth in tree species partly because it stimulates the rate of net photosynthesis (PN) was investigated in the conifer balsam fir (Abies balsameaL.). In long-term experiments, the normal growth pattern of 4- and 5-year-old potted trees was changed by GA3applied in both an aqueous soil drench (20 mg per tree, thrice weekly; or 50 mg per tree, twice weekly) and a foliar spray (1000 ppm, weekly) for about 3 months. Effects included increased longitudinal and radial growth in the leader and longest lateral in the uppermost whorl, enhancement of shoot apical dominance, increased needle length, and decreased root weight – top weight ratio. Nevertheless, thePn and productive capacity of the current and 1-year-old needles in the GA3-treated and control trees were the same, measured during and at the end of the treatment period. In short-term experiments, the 1000-ppm GA3spray did not affectPNof current-year needles, measured 3 h up to 7 days after one or two applications.PNof current-year cuttings also was not altered by feeding through the basal end (1) 0.25, 2.5, 25, or250 ppm GA3for 4 h; or(2) 10 or 100 ppm GA3for24 h. Feeding25 or250 ppm GA3for 48 h through the distal portion of an attached, current shoot decreasedPNin the proximal portion. Collectively, the results indicate that exogenous GA3increases height growth in balsam fir by altering the normal distribution of photosynthate, not through increasing photosynthate production.

ISSN:0008-4026    

DOI:10.1139/b75-210

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Meiosis of pollen mother cells begins in October of the year in which cones are initiated. They reach pachytene then become dormant until the next March. Meiosis is complete and the winged pollen mature by mid-June. Meiosis of the megaspore mother cell occurs in May, forming a linear tetrad of megaspores. The female gametophyte undergoes free nuclear division at pollination in mid-June. No pollination drop is present; rather, the pollen adheres to the sticky, splayed edge of the micropyle, where it germinates and pollen tubes grow toward the nucellus. The nucellus elongates into the micropylar canal, forming a nucellar beak, which makes contact with the pollen tubes. Several pollen tubes penetrate the nucellus.At the time of fertilization early in August, each ovule contains two to four aichegonia each having two to four neck cells in one tier. Pollen tubes penetrate the neck cells and two male gametes are formed. The ventral canal cell breaks down and fusion occurs in the center of the archegonium. Four free nuclei form and migrate to the base of the archegonium. cell walls form, and a 16-celled proembryo develops. Both simple and cleavage polyembryony occur. Rosette cells divide but do not form complex embryos. The embryo and seed are mature in October and the cones dry and open during October and November. Mature cones averaged 70 seeds, of which 46% were filled.Reproduction in mountain hemlock (Tsuga mertensiana(Bong.) Carr.) is similar to that in other species ofTsugaexcept for the presence of winged pollen. Any attempt to place the species in the genusPiceaor place it as a hybrid midway betweenPiceaandTsugais unfounded based on all of the more-conservative reproductive and embryological characteristics.

ISSN:0008-4026    

DOI:10.1139/b75-211

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

Species included in the taxonDelitschiaare loculoascomycetes with dark, two-celled ascospores. Each cell of the ascospore is provided with an elongated germinal slit and each spore is surrounded by a hyaline gelatinous layer. A total of 46 species ofDelitschiaare recorded in an analytical key. Descriptions and illustrations are provided for the following 26 new species ofDelitschiafound on diverse substrata of herbivores from Canada, United States, and Mexico:D. anisomera, D. anomala, D, arestospora, D. chodocola, D. chorizomera, D. chrysina, D. crinita, D. didymastra, D. didymella, D. flavida, D. hexaspora, D. illinoisensis, D. intonsa, D. lachnothecium, D. lamprorhynchia, D. limasepta, D. megatetraspora, D. melanotricha, D. nephrospora, D. oligospora, D. pachylospora, D. simulans, D. tetrasporella, D. tomentosa, D. variispora, D. xanthodera.The remaining 20 species represent established and recognized taxa; for 11 of these, descriptions are vague and (or) inadequate. Species descriptions have been emended and illustrations are provided for 11 species:D. caninaMout.,D. chaetomioidesKarst.,D. consociataMout.,D. excentricaGriff.,D. furfuraceaNiessl,D. marchaliiBerl. & Vogl.,D. niessliiSpeg.,D. perpusillaSpeg., andD. polysporaGriff. Data are provided for one recently published species,D. myriasporaBreton & Faurel. For nine well-known species included in the key there are no descriptions provided; however, literature citations and photographs of type species are included. These species are as follows:D. araneosaCain,D. didymaAuersw.,D. gigasporaCain,D. griffithsiiCain,D. leporinaGriff.,D. leptosporaOud.,D. timagamensisCain,D. vulgarisGriff., andD. winteriPhill. & Plowr.

ISSN:0008-4026    

DOI:10.1139/b75-212

出版商:NRC Research Press    

年代:1975

数据来源: NRC

摘要:

The process of frost burl formation is explained on a cellular and somatic level. Somatic changes in cells consisting of fragmentation, loss of translocatable centromeres, formation of micronuclei. and numerical changes and rearrangement of chromosomes lead to the establishment of a chimeral condition induced by low temperatures. Chimeral tissue is characterized by deformed cells with complete and incomplete cell plates, hyperplasia, hypoplasia, senescence of storage cells, and realignment of tissues.

ISSN:0008-4026    

DOI:10.1139/b75-213

出版商:NRC Research Press    

年代:1975

数据来源: NRC