摘要:

Discharge ofPucciniastrum goeppertianum(Kühn) Kleb. basidiospores from witches' brooms on lowbush blueberry (Vaccinium angustifoliumAit. andV. myrtilloidesMichx.) in central New Brunswick occurred at irregular intervals from mid-May to late June in 1973 and 1974, but more than 75% of the total catch occurred in a 1-week period each year. Annual timings were related to spring weather variation so that discharge peaks each year coincided with shoot elongation of the aecial host, balsam fir (Abies balsamea(L.) Mill.). Measurable rainfall preceded all major discharge peaks; relative humidity and temperature were factors only as they affected the rate of drying of the hypertrophied twigs. Basidiospore concentration at 15, 90, and 150 cm above the ground level brooms decreased at a ratio of 7:2:1.

ISSN:0008-4026    

DOI:10.1139/b77-089

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A single foliar spray of a morphactin (n-butyl-9-hydroxyfluorene-(9)-carboxylate) was applied at a concentration of 1, 10, 100, or 1000 ppm to 6-week-old plants of ribbed gourd (Luffa acutangulaRoxb.), a monoecious cultivar, Pusa Nasdar. Growth of the main axis was only stimulated at 1 ppm and was increasingly inhibited at higher concentrations. Morphactin weakened apical dominance and increased the number of lateral branches. The production of pistillate and staminate flowers was increased and then decreased by morphactin, up to a concentration of 100 ppm. At the same concentrations it also increased femaleness, number of fruits, and therefore the yield. A drastic inhibition of total flowering, fruit-set, and therefore yield was recorded at 1000 ppm. Parthenocarpic fruits developed only at 100 and 1000 ppm.

ISSN:0008-4026    

DOI:10.1139/b77-090

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

New taxa reported are as follows:Amphisphaeria argentinensissp. nov.;Catenophora yuccaesp.nov.; andHyphopolynema tropicalesp. nov., typifyingHyphopolynemagen. nov.

ISSN:0008-4026    

DOI:10.1139/b77-091

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Electron microscopy has been used to study conidium ontogeny ofPestalotiopsis neglecta, an annellidic coelomycete, to compare it with previously studied phialidic fungi. It was found that phialidic fungi produce a multiplicity of conidia from a fixed conidiogenous locus within the conidiophore, but annellidic fungi produce conidia individually from progressively different, usually higher, loci within the conidiophore. With the exception of the primary phialidic conidium, both types of organism produce conidia enteroblastically.

ISSN:0008-4026    

DOI:10.1139/b77-092

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

InMarchantia, the mucilage papillae are initiated by differential divisions occurring in marginal cells of scales at early stages of their development. Establishment of a new polarity axis was observed in mucilage papilla mother cells as well as in their daughter cells, which were destined to develop into mucilage papillae. During polarization the marginal cells synthesize cytoplasm and free ribosomes; subsequently, the cells grow outwards. Concomitantly, organelles migrate to the apical region, where some rough endoplasmic reticulum (ER) membranes and dictyosomes are polarly placed. The subplasmalemmal microtubules become reoriented during polarization.The spindle-shaped preprophase and prophase nucleus of the mucilage papilla mother cell is surrounded by two distinct microtubular systems: the preprophase band of microtubules and an extranuclear sheath of microtubules; the latter is aligned along the spindle axis, close to the nuclear membrane and convergent at polar areas which contain ER membranes.Among the first structural signs of mucilage papillae differentiation are the following: increase of cytoplasm, free ribosomes, rough ER membranes, and dictyosomes; preferential association of plastids with ER membranes and mitochondria, as well as the transverse orientation of subplasmalemmal microtubules. As differentiation ensues the cells acquire more cytoplasm and their organelles proliferate markedly, while new specific organelle relationships become evident.The increase of rough ER membranes predominates and keeps pace with dictyosome proliferation. Among the organelles the ER membranes display a key role in diverse mucilage papilla differentiation and an intermediary one in their secretory activity.The particularly active secretory phase of mucilage papillae is marked by an hypersecretory activity of dictyosomes which produce abundant vesicles. Histochemical staining revealed polysaccharides in the larger vesicles, the space between plasmalemma and cell wall, and within the wall.Ultimately, the mucilage papillae either undergo a partial degradation of protoplasm or even degenerate. In the former case they undergo an intense vacuolation and finally appear structurally similar to other cells of scales.

ISSN:0008-4026    

DOI:10.1139/b77-093

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The study of the chromosome numbers of over 112 individuals belonging to theAchillea millefoliumL. complex (Compositae) and the examination of the pollen of about 200 herbarium specimens have led to the following conclusions; theA. millefoliumcomplex, in Quebec, includes tetraploids (2n = 36), hexaploids (2n = 54), and various hybrid types. Tetraploids could be divided into two taxa: the southernmost isA. lanulosaNutt. with small pollen grains and light brown or yellowish-margined phyllaries while the northern or alpine plants, corresponding toA. nigrescens(E. Mey.) Rydb., possess large pollen grains and dark-margined phyllaries. The two species, in contact zones, seem to hybridize freely. Hexaploids comprise purple-flowered introduced individuals escaping from cultivation, white or pink individuals, also introduced, and possibly a native taxon. The introduced hexaploids belong toA. millefoliums.str. and the purple-flowered variety frequently hybridizes withA. lanulosagiving rise to pentaploids (2n = 45) apparently almost sterile. A few plants from Maine (U.S.A.) have also been studied. This paper finally reports cytological observations related particularly to spontaneous mitotic abnormalities (fragmentation, fusion of chromosomes) affecting root tip cells of seedlings.

ISSN:0008-4026    

DOI:10.1139/b77-094

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Rates of gas exchange were measured for cultures ofChlorella pyrenoidosa, Chlamydomonas reinhardtii, andAnabaena flos-aquae, which were suspended in moist air on an artificial leaf made with nylon bolting cloth. A14CO2–12CO2technique was used to measure net and gross photosynthesis and light and dark respiration in air or nitrogen. Rates of gas exchange on the artificial leaf were equal to maximum rates obtainable for the same algae suspended in culture medium. Rates were stable, and the artificial leaf could be maintained for many hours.The algae did not exhibit conventional photorespiration. However, they did have a variable rate of light respiration that frequently equalled, but did not exceed, the rate of dark respiration. This light respiration appeared to be a continuation of normal dark respiration in light. It was affected by CO2concentration, declining to zero if the cells were illuminated in the absence of CO2. Unlike higher plants, recent photosynthate is not a substrate of light respiration in these algae.

ISSN:0008-4026    

DOI:10.1139/b77-095

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Evidence is presented to support the transfer ofProtascus subuliformistoMyzocytium. Based on the nature of the sporangiospores and the method of attacking the host, the known species ofMyzocytiumparasitic on nematodes are divided into five series. The major characteristics and possible biological advantages of each of these series are outlined. A key to the species of nematophagousMyzocytiumspecies is included.

ISSN:0008-4026    

DOI:10.1139/b77-096

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Soil contained in 5.6 × 2.0 × 10.5 cm Plexiglas soil containers was separated from solutions of polyethylene glycol (PEG) 6000 by a Pellicon ultrafiltration membrane glued over the inside of 3.8-cm-diameter holes in two sides. Flow rate through the membrane was 4.4 ml day−1 cm−2for a 1.0-bar potential difference across the membrane. At the end of 2 weeks, the average matric potential in the soil adjacent to the membranes for soil cells immersed in −0.2-, −1.0-, and −2.0-bar PEG solutions was −0.3, −1.1, and −2.3 bars respectively. The relatively constant potential and vigorous plant growth during the period indicated that sufficient water was passing through the membrane to meet the plant's water requirements. The Pellicon membrane's tolerance to microbial deterioration will permit the use of this technique in longer term studies than previously has been possible.

ISSN:0008-4026    

DOI:10.1139/b77-097

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Zoosporangia ofPolymyxa betaeKeskin are plurilobate and develop cross walls. During ripening they show dark zones at the contact points with the host cell wall at the light microscope level. With the electron microscope these zones appear to correspond to single uninucleate compartments separated by a wall from the zoosporangium itself. These compartments give rise to exit tubes while the zoosporangial contents differentiate into zoospores. At the beginning of exit-tube formation, the thallus wall in contact with the host cell wall becomes thinner and softened. At the same time, thallus cytoplasm shows membrane-bound vesicles, the endoplasmic reticulum increases, and vacuoles enlarge. Vesicles are concentrated in the area of exit-tube formation and this suggests that they are involved both in host and thallus wall lysis. Wall microfibril profiles indicate that at this point mechanical forces have also been applied. A papilla, surrounded by a wall which appears to be continuous with the inner layer of the zoosporangium wall, is formed. The papilla elongates and becomes tubular, forming the zoospore exit tube. The same lytic and mechanical sequence described for thallus and host cell wall demolition at the site of exit-tube emission, also takes place in the demolition of zoosporangial cross walls.

ISSN:0008-4026    

DOI:10.1139/b77-098

出版商:NRC Research Press    

年代:1977

数据来源: NRC