摘要:

The starch, lipid, cytochrome oxidase (EC 1.9.3.1), succinic dehydrogenase (EC 1.3.99.1), peroxidase (EC 1.11.1.7), and acid phosphatase (EC 3.1.3.2) levels were determined periodically by histochemical methods in transverse sections of cut stem of the rose,Rosa hybridaL. cv. Forever Yours, kept in water or in an aqueous preservative solution containing 4% sucrose, 100 ppm sodium isoascorbate, and 100 ppm 8-hydroxyquinoline sulfate. Senescence of the cutrose stem, including leaves and flowers, was delayed by use of the sugar solution. The levels of cytochrome oxidase and succinic dehydrogenase were not significantly affected by either of the treatments. Starch, lipid, peroxidase, and acid phosphatase levels decreased in the tissues of rapidly senescing stems kept in water. In tissues where senescence was retarded by use of sugar solutions the lipid content and peroxidase were maintained at a relatively high level; starch, and acid phosphatase levels steadily increased. It is suggested that in cut rose stems, the onset or retardation of senescence is not related to the activities of acid phosphatase or peroxidase.

ISSN:0008-4026    

DOI:10.1139/b77-075

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Plectronidiumgen.nov. is described to accommodate two species:P. minorsp.nov. andP. sinensesp.nov.

ISSN:0008-4026    

DOI:10.1139/b77-076

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Seasonal changes in aboveground and belowground life history ofCarex lacustriswere determined and used to study primary production and nutrient cycling in the ecosystem. Seasonal aboveground production was estimated to be about 965 g/m2per year, with a peak rate of 20.9 g/m2per day reached in late July. Belowground production was estimated to be 208 g/m2per year for a total production estimate of 1173 g/m2per year.Nitrogen, phosphorus, and potassium begin the season with high percentage concentrations in green overwintering shoots but the percentages decline to only about one-third of the original at death in December. Early growth in spring is characterized by a redistribution of these nutrients in the shoots, some translocation from belowground tissues, and uptake from the soil. Calciumand magnesium do not show any important translocation patterns during the year.The yearly budget of uptake and loss of nutrients during a year is estimated to be 15.9 g/m2nitrogen, 1.9 g/m2phosphorus, 16.6 g/m2potassium, 2.9 g/m2calcium, and 1.5 g/m2magnesium.

ISSN:0008-4026    

DOI:10.1139/b77-077

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The maximum rate coefficients for the vegetative phase of growth in dry weight of shoots and roots were independent of the photoperiod in plants grown at six different light intensities of 12- or24-h duration at 20 °C. The strict dependence of plant growth on only the total daily incident radiant energy was proved by the superposition of hyperbolic plots of growth coefficients obtained for five different photoperiods and for the different light intensities. Root growth was very sensitive to photoperiod at moderate light intensity. Growth kinetics changed from first to zero order in plant dry weight at a 12-h photoperiod with a light intensity of 150 ft-c (3750 ergs cm−2 s−1) depending on pretreatment. The light compensation point of plant growth occurred at16 × 107 ergs cm−2day−1; that for shoots was lower, and that for roots was higher.

ISSN:0008-4026    

DOI:10.1139/b77-078

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Culture of surface-sterilized needles from a stand of old-growth Douglas fir trees on the western slope of the Oregon Cascades revealed the presence of latent fungal infections in all needles examined older than 3 years. Scanning electron micrographs of cut needle surfaces seen in transverse section showed occasional intercellular fungal hyphae in the needle parenchyma. Two species of fungi,Phyllostictasp. and a suspected member of the Hemiphacidiaceae, appeared as the major colonizers of the needle blade; a third species, as yet unidentified, commonly grew out from the needle petiole. Endophytes were widespread in needles throughout the watershed regardless of the elevation and exposure of the individual trees sampled. Similarly, height of the needles in the tree canopy showed little correlation with the frequency of internal infections. Individual needles were cut into 10 segments before culture, and patterns of endophyte distribution within the needles were observed. The data are consistent with the hypothesis that needles are multiply infected during their 1st year. The initial rise in endophyte frequency occurs between November and March on 1st-year needles, a pattern suggesting waterborne spores as agents of infection. BothPhyllostictaand the hemiphacidiaceous fungus are known to produce gloeoid conidia, which are thought to be dispersed by rain. With increasing age, all needle segments become infected with endophytes.

ISSN:0008-4026    

DOI:10.1139/b77-079

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A polymorphism for leaf spots has been described for populations ofCollinsia grandiflorain southwestern British Columbia. The spotted morphs have been found mainly on the Vancouver Island Coast between Miracle Beach and Crofton. There is considerable variation in the spotted class. Most evident is the distinction between heavy and faint morphs. Genetic studies have demonstrated that heavy spotting is due to a single dominant gene, that the heavy-spotting system is genetically distinct from that for faint spotting and that the heavy-spotting system maintains its simple Mendelian inheritance pattern even in the presence of the faint-spotting determinants. The precise, genetic determination for faint spotting is uncertain but several models are consistent with the data. The reason for the existence of the polymorphism is not known.

ISSN:0008-4026    

DOI:10.1139/b77-080

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Zygospore development inGilbertella persicaria(Eddy) Hesseltine was studied by light microscopy and by transmission and scanning electron microscopy. Cell walls of apically conjugating progametangia lose their separate identities in the fusion septum. Gametangial septa are formed, asynchronously to synchronously, on either side of the fusion septum by the centripetal coalescence of vesicles. Secondary thickening of these septa is more rapid and continues longer on the side towards the zygospore. The multilayered wall of the zygosporangium ultimately consists of outer and inner primary walls, a warted layer, and a smoothing or tertiary layer. Ahyaline quaternary layer with conical projections (zygospore wall) is formed within the zygosporangium. The observations obtained are correlated with existing ultrastructural information on zygosporogenesis in the Mucorales.

ISSN:0008-4026    

DOI:10.1139/b77-081

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Conidia ofAlysidium resinae(Fr.) M. B. Ellis (=Torula ramosaPeck) arise enteroblastically from polyblastic, ampulliform conidiogenous cells aftermechanicalrupture of the conidiogenous cell wall and are produced in either branched or unbranched acropetalous chains, successively younger conidia being produced enteroblastically from the immediately older conidia. There is no indication that conidial evagination occurs via enzymatically produced channels in the parent wall, protrusion being exclusively mechanical. Attention is drawn to the controversy surrounding the enteroblastic tretic mode of conidiogenesis.

ISSN:0008-4026    

DOI:10.1139/b77-082

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Standing stock andin situprimary production of the southern Beaufort Sea phytoplankton were determined during the summers of 1973, 1974, and 1975. They decreased with increasing distance from shore and the Mackenzie river mouths. The phytoplankton community was composed largely of diatoms and flagellates with diatoms dominating in the coastal waters and flagellates being more abundant in the waters farther off shore. Dinoflagellates and chrysophytes occurred in relatively low numbers except in a few cases when blooms were observed. Blue-green algae were found occasionally in very low numbers. Seventy-two species of phytoplankton were identified, most of these being diatoms.

ISSN:0008-4026    

DOI:10.1139/b77-083

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Osmiophilic inclusions were frequently observed in cells ofCeratocystis ulmi(Buism.) C. Moreau in its hosts and in culture. These inclusions vary in shape, size, or their degree of compactness and are composed of fibrillar material and dense granules that are generally 150 Å in diameter. The inclusions are present in vacuolar areas which often appear to be completely or partially devoid of a membrane. Vacuolar areas may also contain aggregates of a similar texture, which often appear to have connections with nearby cytoplasm. Inclusions and (or) aggregates are often adjoining layers of membranes next to or extending within the vacuole. After thymidine labeling, radioautographic grains were observed over these bodies, thus suggesting the presence of DNA. The possible origin of these inclusions from transforming fungal cytoplasm and their importance in the infection process of Dutch elm disease are discussed. A mimeographed English version of the paper is available from the junior author.

ISSN:0008-4026    

DOI:10.1139/b77-084

出版商:NRC Research Press    

年代:1977

数据来源: NRC