摘要:

The outer epidermal cell walls of the leaf blade of the licuri palm tree were studied by light microscopy, scanning electron microscopy, and transmission electron microscopy, with special attention to the epicuticular waxes. On the intensely green adaxial surface, the wax adheres in the form of a smooth, flexible, varnish-like layer. On the pruinose, dull, greenish or bluish abaxial side, the wax appears as a thin amorphous layer from which rodlets and columns protrude. Very curved rodlets, in compact rows, border each stoma, sometimes almost completely closing its aperture. Numerous pores, not resolvable with the light microscope, were detected in both cuticular membranes. Comments are presented concerning the possible functions of several configurations of epicuticular waxes.Key words: epicuticular waxes, wax micromorphology,Syagrus, licuri, epidermal wall.

ISSN:0008-4026    

DOI:10.1139/b95-207

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Growth and photosynthetic capability of the eastern Asiatic shrubLonicera maackii(Rupr.) Herder were measured in shadehouses and in artificial canopy gaps. In shadehouses providing 5, 25, and 100% of full sun, total dry mass, and leaf area of seedlings increased with light availability; specific leaf area and leaf area ratio decreased with light availability. When small suppressed shrubs were transplanted from a forest site to the shadehouse environments, rapid (13 day) acclimation in existing leaves initially produced the highest mean photosynthetic rate (8.12 μmol∙m−2∙s−1) and the highest mean relative stem growth at 25% light. However, maximum mean photosynthetic rate (10.36 μmol∙m−2∙s−1), higher mean stomatal density, and increased mean leaf thickness were measured only in new leaves formed in 100% light. This plastic response was associated with higher relative stem growth later in the experiment. Naturally established seedlings in both artificial canopy gaps and sites with intact canopies had low and negative relative stem growth, presumably as a result of light limitation. The results support the observation thatL.maackiiis a shade intolerant species that performs best in forests where large disturbances or edge effects create enhanced light availability.Key words: acclimation, forest edge, invasive species,Lonicera maackii, plasticity, shade to

ISSN:0008-4026    

DOI:10.1139/b95-208

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Flavonoid profiles were determined for 11 species representing five genera of Calyceraceae:Acicarpha,Boöpis,Calycera,Gamocarpha, andNastanthus. Kaempferol, quercetin, 6-methoxykaempferol, and 6-methoxyquercetin (patuletin) were unequivocally identified. Kaempferol and quercetin occurred as 3-O-mono- and 3-O-diglycosides, whereas the latter two flavonols were observed only as aglycones. Several unidentified phenolic compounds were also noted. The simplest profile in the family consisted solely of the kaempferol and quercetin glycosides inAcicarpha,Gamocarpha, and one specimen ofCalycera leucanthema. Morphological evidence suggests thatAcicarpharepresents prototypical Calyceraceae and that a close relationship exists between primitive Calyceraceae and some basal members of Asteraceae (subfamily Barnadesioideae). This last possibility is reinforced by the similarity of flavonoid profiles ofAcicarphaand members of Barnadesioideae.Key words: Calyceraceae, Asteraceae, Compositae, Barnadesioideae, flavonoids.

ISSN:0008-4026    

DOI:10.1139/b95-209

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Vallisneria americanadeclined in backwaters of the Upper Mississippi River, U.S.A., after a drought in 1988. To determine whether viable seeds ofV.americanaoccurred in the seed bank of navigation pool 7, Lake Onalaska, the upper 5 cm of sediment was collected from 103 sites in May 1990. These sediment samples were kept in pots at a depth of 0.4, 0.8, and 1.2 m in an outdoor pond for 12 weeks.Vallisneria americanaseeds germinated from sites throughout the lake, and some seedlings produced overwintering buds by the end of the study. Seeds, spores, or fragments of 12 other species of aquatic plants also germinated. Seed germination trials with fresh and stored seeds in both greenhouse and ponds in which light availability was reduced with shade cloths indicated that seed germination was insensitive to light level. To determine the light requirements for seedling survival and bud production, sediment from Lake Onalaska was incubated in ponds under neutral density shade screens reducing light to 2, 5, 9, and 25% of full sun. Seeds germinated under all shade treatments but survival was significantly higher in the 9 and 25% light treatments, and bud production was restricted to these light levels.Key words: aquatic macrophytes, seeds, germination, light response.

ISSN:0008-4026    

DOI:10.1139/b95-210

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Rod-shaped particles, approximately 30 nm in width and 1000 nm or more in length, were found in cells of the red algaAudouinella saviana(Meneghini) Woelkerling. Parallel in orientation and hexagonally packed, these inclusions were located within dilated cisternae of rough endoplasmic reticulum. The rods consisted of an electron-dense central element surrounded by a thick-walled tube that appeared to be composed of repeating granular subunits. Although uninfected controls of the same species were not available, the morphology and substructure of the inclusions, the absence of such inclusions in other species ofAudouinella, and the apparent connection of these particles with cellular abnormalities and necrosis suggest that these inclusions may be viral in nature. Among the unusual and possibly cytopathic features of cells containing particles were ropy, fibrillar structures free in the cytoplasm, corrugated mitochondrial cristae, amorphous mitochondrial inclusions, highly convoluted photosynthetic membranes, and loss of integrity of the nuclear envelope. This is the first report of the presence of possible rod-shaped virus-like particles in red algae.Key words: Acrochaetiales,Audouinella saviana, Rhodophyta, ultrastructure, virus-like particles.

ISSN:0008-4026    

DOI:10.1139/b95-211

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Two new species of fungi mycorrhizal with terrestrial orchids native to the Canadian prairies are described and illustrated.Ceratorhiza pernacatenasp.nov., from mycorrhizas ofPlatanthera praeclara, produces globose monilioid cells linked by narrow, tubular, connections that contain the septum between adjacent cells. Hyphae are binucleate, 5–7 μm in width, regularly septate with perforate parenthesomes. Cellulase is produced, but polyphenol oxidase production is low to absent.Epulorhiza calendulinasp.nov., from mycorrhizas ofAmerorchis rotundifolia, is distinguished from otherEpulorhizaspecies by the orange to ochre colour of colonies on potato dextrose agar. On corn meal agar, clavate to irregular monilioid cells are produced in short, branched, chains arising from lateral hyphal branches. Runner hyphae are binucleate, 3.0–4.7 μm in width, regularly septate, with flattened, imperforate parenthesomes. Polyphenol oxidase production is lacking, but cellulase is produced.Key words: orchid mycorrhizas,Amerorchis rotundifolia,Platanthera praeclara,Rhizoctonia.

ISSN:0008-4026    

DOI:10.1139/b95-212

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

Although dichogamy is a prevailing feature of the angiosperms, the simultaneous change from male to female phases among hermaphrodite flowers within a plant (i.e., synchronous protandry) has been reported for only a few families (e.g., Araliaceae, Umbelliferae). Here we present an example of synchronous protandry at the ramet level in the Alstroemeriaceae. Dichogamy was analyzed in clonalAlstroemeria aureaat the flower, ramet, and at the whole flowering patch level.Alstroemeria aureais self-compatible but totally dependent on biotic agents for pollen transfer. There was evidence of strong inbreeding depression expressed during seed development. Comparisons of seed set in open-pollinated flowers with those obtained after hand selfing and outcrossing resulted in a selfing rate of 0.3. At the flower level protandry was complete. The male phase lasted about 4 days and the female phase lasted about 3 days. Between the female and male phase, there was an approximately 1-day long "neuter" phase. Flowering ramets produce a terminal inflorescence bearing one or more whorls of flowers. Within a ramet, flowers of the same order opened within a period of 1–2 days, and male and female phases of different flowers did not overlap. When inflorescences held two whorls of flowers, the ramet went through two alternating non-overlapping male–female cycles. Using spatial autocorrelation techniques, we found little evidence for pairs of neighboring ramets expressing the same sexual phase beyond random expectations at any scale ranging between 0.25 to 15 m. By ensuring pollen interchange between flowering ramets, synchronized protandry at the ramet level could be an important feature in reducing selfing inA.aurea.Key words:Alstroemeria aurea, dichogamy, synchronous protandry, inbreeding depression.

ISSN:0008-4026    

DOI:10.1139/b95-213

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The hybrid nature ofLycium ciliatum×cestroidesHieron. is supported through experimental crosses. UsingL.ciliatumSchlecht. as a female parent, 57% of crosses set fruit with hybrid seeds, whereas reciprocal crosses were unsuccessful. Seeds had a high germination rate (76%). F1plants obtained agree with the herbarium specimens previously cited as putative hybrid and with a living plant we found in Córdoba (Argentina). Leaf, stem, and flower anatomy, karyotype composition, and chemical nectar composition were analyzed in the artificial and the natural hybrid. Results were compared with similar data on the parental species. Most of the studied features were intermediate between those of the parental species, as supported by principal component analysis. The origin of this hybrid may be due to pollen transfer mediated by bumblebees that occasionally visit both parental species. The distribution of the parental species overlaps in a wide Chaco region showing no spatial, environmental, or external reproductive isolating mechanisms. Results indicate there is a hybrid breakdown in the progeny of the hybrid that would restrict the natural interspecific gene flow.Key words:Lycium ciliatum×cestroides, hybrid, karyotype, anatomy, crosses, flower visitors.

ISSN:0008-4026    

DOI:10.1139/b95-214

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The susceptibility of bananas to phytoparasitic nematodes, the damages caused by nematodes, and the plant defense reactions can be evaluated respectively by the multiplication rate of parasites, the plant growth and metabolism, and the modifications of the secondary metabolism. The comparison, through multivariate analyses, of these four groups of parameters between two banana cultivars (Poyo and Gros Michel), differently susceptible to nematodes, helps to hierarchize the importance of these groups. So, the variables associated with shoot and root growth and the variables associated with plant physiology (photosynthesis, carbon metabolism, nitrogen and mineral absorption) are quite bad parameters because they evolve anarchically with the initial nematode population pressure. On the opposite, the final nematode population pressure and the variables associated with host defense reactions (secondary metabolism) are more reliable because they give more homogeneous results. It is then possible to assess the usefulness of the parameters describing banana susceptibility to nematodes and to give reliable criteria to geneticians for nematode resistance breeding programs.Key words: banana, defense reactions, phytoparasitic nematodes, resistance, tolerance, cultivar behaviour. [Traduit par la rédaction]

ISSN:0008-4026    

DOI:10.1139/b95-215

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

A general pattern for the dynamics of K in decomposing leaf and needle litters is described, based on 139 litter decomposition studies carried out in forests of northern and central Europe and the northern United States. We distinguished an initial phase of fast changes in K concentration and a later one in which the litter was close to humus and all K appeared to be immobile. In the initial phase the rate of change in K concentration was related to the initial K concentration: the higher the initial concentration, the faster its decrease and the faster the quantitative release of K. For litters with particularly low initial K concentrations, an increase in concentration was observed from the very start of decomposition. In the late phase a slight increase in concentrations was observed. After ca. 60% accumulated mass loss, K concentrations approached similar levels in various litter types, irrespective of the litter type and initial concentrations. We also estimated a theoretical equilibrium state at which no change in K concentration should be expected. According to our estimates these equilibrium concentrations ranged from approx. 0.8 mg/g dry mass of litter for Scots pine to approx. 1.2 mg/g dry mass for deciduous litter types. The estimate of K concentration in Scots pine litter in late decomposition stages was very close to that measured in the humus at the same site. Based on the wide variety of litter types and sites studied we conclude that the pattern suggested for K dynamics in decomposing litter holds at least for European coniferous forests north of the Alps and the Carpathians.Key words: potassium, dynamics, release, litter, humus, decomposition.

ISSN:0008-4026    

DOI:10.1139/b95-216

出版商:NRC Research Press    

年代:1995

数据来源: NRC