摘要:

The genusCortinariusFr. (Cortinariaceae, Agaricales) is divided into four or more subgenera.Dermocybe(Fr.) Sacc. has been recognized as either a subgenus ofCortinariusor a separate genus, distinguished in part by the presence of various anthraquinonic pigments. Nucleotide sequences of ribosomal DNA 5.8S and internal transcribed spacers were used to investigate the phylogenetic relationships among species ofDermocybeand selected taxa from subgenera ofCortinarius. Sequence data from 47 herbarium specimens representing 31 taxa (28 species plus 3 varieties) ofDermocybeandCortinariuswere analyzed using parsimony, maximum likelihood, and neighbor joining. In general, molecular data support the morphological groupings of the taxa, although they more closely correspond to biochemical (anthraquinone and other) analyses. Phylogenetic trees showed that, while the sectionsDermocybeandMalicoriaeare monophyletic, and the concolorous or almost concolorous red species (sectionSanguineae, such asD.sanguineaand relatives) together formed a coherent clade, the subgenusDermocybesensu lato itself is polyphyletic.Cortinarius californicusclusters with taxa inCortinarius, subgenusTelamonia, sectionArmillati.Dermocybe olivaceopictais more closely related to other subgenera ofCortinariusthan toDermocybe. Within the genusCortinarius, certain of the subgenera may actually represent coherent genera. Of the subgenera examined,Telamonia,Phlegmacium, and possiblySericeocybeappear to represent well defined taxonomic groupings. However, current assignments of taxa withinLeprocybeandMyxaciumwere inconsistent with the molecular data. Reorganization of some taxa and taxonomic groups is suggested.Key words:Dermocybe,Cortinarius, molecular phylogeny, rDNA, ITS1, ITS2.

ISSN:0008-4026    

DOI:10.1139/b97-058

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

The relationships between the responses to elevated CO2of the vegetative and reproductive phase were investigated in radish, used as a test system. The hypothesis that an increase in nonfoliar vegetative storage capacity promotes reproductive output was tested. Three cultivars ofRaphanus sativusand the wild,Raphanus raphanistrum, differing in root to shoot ratios, were grown under two levels of CO2and two levels of nitrogen fertilization. Varieties possessed different strategies of carbon storage and showed distinct responses to CO2at each vegetative harvest time. Vegetative sinks of hypocotyls, petioles, and young blades were enhanced by CO2. Nitrogen promoted vegetative shoot growth, but did not enhance the reproductive response to CO2. By the end of the reproductive phase, varieties did not differ in total biomass. Reproductive response to CO2may have been limited by the lack of an effect on the timing of flowering. Correlations in CO2enhancement ratios were examined in 12 traits of each phase. Only vegetative total leaf area correlated with reproductive mass. Foliar starch correlated with decreased abortion. Enhancements in vegetative biomass did not correlate with any reproductive response. Detailed studies of the reproductive phase are needed to understand the whole-plant response to elevated CO2.Key words: elevated CO2, plant reproduction, nitrogen, starch, carbon allocation, source–sink.

ISSN:0008-4026    

DOI:10.1139/b97-059

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Variation in the performance of 20 genotypes ofPolygonum pensylvanicumunder two nutrient treatments was studied in a garden experiment. Nutrient fertilization enhanced vegetative biomass and fruit biomass production, but did not result in significant genotype–environment interactions, suggesting that nutrient variation of the range used in the experiment has little potential as a microevolutionary factor in this species. Leaf nitrogen concentration was not affected by a nutrient pulse. The degree of transient aphid infestation that occurred during the experiment had a weak positive correlation with final reproductive biomass of plants. Mean density of aphids per leaf was negatively correlated with percent leaf nitrogen and was not affected by genotypic identity of host plants.Key words:Polygonum pensylvanicum, genotype–environment interaction, phenotypic plasticity, aphids, nutrients.

ISSN:0008-4026    

DOI:10.1139/b97-060

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Single Scots pines (Pinus sylvestrisL.) trees were subjected to elevated temperature (year-round elevation), elevated CO2(elevation from April 15 to September 15), and a combination of elevated temperature and CO2, for 4 years in open-topped chambers. Measurements and modelling were performed to determine if long-term growth at elevated CO2concentration and temperature altered water use efficiency (WE) and the responses of stomatal conductance (gs) to photon flux density (Qp), the leaf-to-air vapour pressure difference (Dv), leaf temperature (Tl), and intercellular concentration of CO2(Ci). Long-term elevation of CO2led to a significant decline in the absolute value ofgsat almost all levels ofQp,Dv,Ci, andTl. Elevated temperature treatment increased the absolute value ofgsonly at higherDvandTl. The effect of the combination of elevated CO2and temperature did not appear as a mean of the effects of the two single factors, while there was an interaction between the two factors. The modifications in the sensitivity of stomata, resulting from different treatments, did not have the same pattern as the change ings, but depended on levels ofQp,Dv, and Tl. Compared with the control treatment, elevated concentration of CO2or a combination of elevated CO2and temperature led, on average, to 50 and 30% increases inWE, respectively, which can be attributed mainly to an increase in the rate of net assimilation. In contrast, elevated temperature alone did not significantly changeWE, although transpiration rate was increased.Key words: long-term CO2and temperature elevation, stomatal conductance, transpiration, water use efficiency,Pinus sylvestris.

ISSN:0008-4026    

DOI:10.1139/b97-061

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Calamagrostis canadensisis present in the understory of most boreal forest mixed-wood stands and can rapidly dominate an area once the overstory is removed. The nature of the photosynthetic response to light was studied by investigating the stomatal response to cycles of high and low fluence light, and by developing photosynthetic light response curves for sun- and shade-grown plants. Photosynthetic light response curves did not differ between sun- and shade-grown plants. However, higher stomatal conductances, at all light intensities, were found in shade-grown plants. Stomatal conductance tracked changes in light under intermittent high and low fluence light. Average rates of stomatal opening after a change from low to high light were greater than closing rates (23 vs. 17 mmol m−2s−1/min). The faster opening response was negated by a 1 – to 2-min time lag between the onset of high light and the initiation of stomatal opening. Thus the time to reach 80% of maximal response did not differ between opening or closing. The photosynthetic system ofC.canadensisis not particularly well adapted to intermittent light conditions. The poor performance in the understory of this apparently meadow-adapted photosynthetic system is offset by the gain in the ability to rapidly recolonize the site after disturbance.Key words: gas exchange, stomatal conductance,Calamagrostis canadensis, non-steady state photosynthesis, variable light.

ISSN:0008-4026    

DOI:10.1139/b97-062

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Examination of the bark from the uppermost lateral branches of white spruce,Picea glauca(Moench) Voss, indicated that trees resistant to attack by the white pine weevil,Pissodes strobiPeck, had significantly higher number and density of vertical resin canals per unit of bark area (mm2) than susceptible trees. The number and density of resin canals were also positively correlated with tree growth rate, an indicator of tree vigor. The density of the resin canals found near the periphery of the bark (outer resin canals) had higher correlation with resistance and growth than inner resin canals. Measurements of resin canals on the bark of lateral branches correlated well with measurements on the bark of the leader of the same tree, indicating that lateral samples could be used to screen white spruce for resistance to weevils.Key words:Picea glauca,Pissodes strobi, pest management, tree genetics.

ISSN:0008-4026    

DOI:10.1139/b97-063

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Vascular understory species composition and production were studied in 36 stands in both northern and southern portions of southeastern Alaska, United States. Understory composition and production were related to site factors of soil drainage and slope and overstory factors of species composition, stand age, canopy coverage, and mass (net wood volume). Principal floristic gradients were dominated by differences in production of Alaska blueberry (Vaccinium alaskaenseHow.), skunk-cabbage (Lysichiton americanumHuit. & St. John), and lady fern (Athyrium filix-femina(L.) Roth). Soil drainage was the principal environmental factor determining understory species composition. Soil drainage also determined overstory mass and, consequently, total understory production, presumably through effects of overstory mass on light interception. Well-drained sites were more productive of trees and less productive of understory than were poorly drained sites. Relations between windthrow, soil drainage, overstory mass, and understory species composition and production are interactive in these excessively wet, old-growth forests.Key words: plant communities, biomass, forest overstory, temperate rain forest,Tsuga heterophylla,Picea sitchensis,Thuja plicata, western red cedar.

ISSN:0008-4026    

DOI:10.1139/b97-064

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Flower organogenesis inHedychium gardnerianumandHedychium coronariumbegins with the sequential formation of the sepals on a rounded–triangular apex. Growth in three regions of the apex, inside the sepals, produces three common petal – inner androecial primordia. Intercalary growth below and between these primordia produces a floral cup, the site of gynoecial formation. The common primordia separate to form petals and inner androecial members. After separation, the anterior inner androecial members fuse to form the labellum. The posterior member forms the polleniferous stamen. Up to this point in development, the flowers ofH.coronariumare slightly ahead of those ofH.gardnerianum. However, inH.gardnerianum, initiation of the two thecae of the stamen occurs immediately following the separation of the common primordia, while thecae formation inH.coronariumis slightly delayed. These results show that the relative timing of developmental events can vary even over a short developmental period. Formation of the outer androecium takes place at the apices of a triangle formed by the inner androecial members. The anterior outer androecial member aborts soon after formation, whereas the posterior outer androecial members form the two petaloid staminodes that are found on the lateral sides of the labellum in the mature flower.Key words: flower development, flower structure, inflorescence, stamen, Zingiberaceae,Hedychium.

ISSN:0008-4026    

DOI:10.1139/b97-065

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Fluorochrome-banded karyotypes of eight populations belonging to five taxa of the genusArtemisiafrom different European origins are presented. The most common basic numberx = 9 is found in six populations of two diploid and two tetraploid species, whereas two populations of one diploid species have the less frequent basic numberx = 8. The data on chromosome morphology and fluorochrome banding lead to some karyosystematic and evolutionary considerations, among others the postulation of descendent dysploidy to explain the occurrence of the two basic numbers in the genus.Key words: Asteraceae, Anthemideae,Artemisia, karyotypes, fluorochrome banding, cytotaxonomy, evolution.

ISSN:0008-4026    

DOI:10.1139/b97-066

出版商:NRC Research Press    

年代:1997

数据来源: NRC

摘要:

Epidermal cells and cells originating in the outer cortex form the surface layers of peanut (Arachis hypogaea) roots, the outermost of which separate and shed from the periphery. Shedding takes place continuously and over the whole surface of the root. Light and electron microscopic studies revealed that the shedding of surface layers involves modification of cell walls and separation of intact cells. Wall breakdown, as well as the expansion of cells resulting from wall breakdown, might facilitate the separation of intact cells. Examination of enzymes revealed that cellulase showed much higher activity in the shedding layers than in the remaining tissues. The results suggest that the cell separation process in peanut roots involves a wall-degrading enzyme-mediated mechanism.Key words:Arachis hypogaea, morphology, root, shedding, surface layers, wall breakdown.

ISSN:0008-4026    

DOI:10.1139/b97-067

出版商:NRC Research Press    

年代:1997

数据来源: NRC