摘要:

Fibulocoelaform-gen. nov., withF. indicaform-sp. nov., is proposed to accommodate a coelomycetous anamorph of an unknown Basidiomycete from India. It is compared withDacrymyces conglobatusPeck which is congeneric withDitangiumKarst. and a known anamorph ofCraterocollaBref.

ISSN:0008-4026    

DOI:10.1139/b78-173

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Soybeans and cotton were subjected to humidities from 40 to 80% at 23 °C and to soil drought during early vegetative growth under controlled conditions. Measurements were made of leaf water potentials, leaf expansion rates, leaf diffusive resistances to water vapor, and whole-shoot net photosynthesis rates. Net assimilation rates were calculated from harvest data. Low humidity resulted in low leaf water potential and low turgor in all cases and resulted in reduced leaf expansion rates in some, but not all, cases. Low humidity reduced dry weight growth only where leaf expansion rates were reduced. Net photosynthesis rates per unit leaf area were unaffected by low humidity, despite up to 1.5-fold increases in diffusive resistance to water vapor. During soil water stress, leaf expansion rates were reduced 1–2 days before net photosynthesis rates per unit leaf area were reduced, but leaf expansion continued at night after net photosynthesis rates were severely reduced by stress. As a result, the relative importance of leaf area expansion and net assimilation rate to growth in dry weight during soil water stress was dependent on the degree and duration of stress.

ISSN:0008-4026    

DOI:10.1139/b78-174

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Cladonia rangiferina(L.)Wigg.,Cladonia mitisSandst., andUmbilicaria muhlenbergii(Ach.) Tuck, were extracted with acetone while damp and after three different drying procedures. The extracts were chromatographed and scanned spectrophotometrically. Some of theC. rangiferinacompounds were not extractable from damp material. All of the lichen substances studied here decreased significantly in thalli which were dried in an oven at 80 °C, some to the point of imperceptibility. There was no qualitative difference between the complement of compounds found in lichen material dried at 22 °C and at 40 °C. We recommend that drying be carried out at a temperature not exceeding 40 °C. Chemical variability among thallus regions of different ages was studied inCladonia rangiferina, C. mitis, Umbilicaria muhlenbergii, andLasallia papulosa(Ach.) Llano. Fumarprotocetraric acid, atranorin, and usnic acid were present in significantly higher amounts in younger tissue than in older. Protocetraric acid inC. rangiferinawas detectable only in the older portions and would have been overlooked if young branches had been analyzed exclusively. In neither of the two umbilicate lichens was there any significant difference in the concentration of gyrophoric acid between younger and older thallus parts. Chemical variability among different-aged thallus parts was thus greater in the fruticose species than in the umbilicates examined here.

ISSN:0008-4026    

DOI:10.1139/b78-175

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Species of buried, germinating seeds and species occurring in the vegetation are compared for two Colorado subalpine forest stands, one dry and one mesic, both over 325 years old. The total numbers of seeds found were small and the correspondence with species in the vegetation was poor. This is consistent with reports from other old-growth forests and may be accounted for by a combination of low seed input and rapid loss of viable seeds from the soil reservoir for old-growth forest species.

ISSN:0008-4026    

DOI:10.1139/b78-176

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Modern pollen rain was studied at 98 sites distributed in a belt transect some 250 km wide running a distance of 425 km between La Push on the Pacific coast and Grand Coulee on the Columbia Plateau. Sites are located in a variety of plant communities from thePicea sitchensisZone near sea level to the Alpine Tundra Zone at 2285 m in the Cascades. The purposes of the study are (1) to establish the nature of the pollen rain and its relation to vegetation sources and (2) to develop further the pool of potential analogs of fossil pollen spectra for use in the reconstruction of Quaternary environments.Relative frequencies are shown for the pollen ofPinus, Picea, Abies, Tsuga, Pseudotsuga, Cupressaceae,Alnus, Gramineae, Cyperaceae, Chenopodiaceae,Artemisia, and Compositae. Results indicate the pollen rain to be related to source vegetation at the collection sites except for certain instances of infiltration by extraneous types, of whichPinusis most conspicuous.Alnusis the dominant pollen in the Puget Lowland and the western Coast and Cascade Ranges;Tsuga heterophyllais most prominent in the Coast Range; andPinusranks foremost in the eastern Cascades and on the Columbia Plateau. On the Columbia Plateau, the Gramineae,Artemisia, Compositae, and Chenopodiaceae are also distinctive. Subalpine forest types and nonarboreals are generally characteristic of the Timberline and Alpine Tundra Zones.

ISSN:0008-4026    

DOI:10.1139/b78-177

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Isolates ofEutypella parasiticaDav. and Lor. obtained from mycelial fans, infected bark tissue, and ascospores from different maple cankers produced conidia in culture on most standard media when exposed to light but not in the dark. Hyaline, one-celled, crescent-shaped, spores 1.3–1.8 μm wide and 25–32 μm long were extruded in gelatinous yellow or butterscotch cirri from pycnidiumlike structures or more open labyrinthiform structures which developed within the mycelium. Spores were borne terminally on branched conidiophores. The shape of these spores varied among different isolates. Conidia did not germinate when placed on several media, including host tissue, or when incubated over a wide temperature or pH range. The perfect state was not induced in culture despite various treatments, including incubation of mixed cultures for 2 years.

ISSN:0008-4026    

DOI:10.1139/b78-178

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Suberized sleeves of epidermal–hypodermal cells have been isolated by enzymic digestion from roots of onion. The average permeability coefficients of the sleeves to calcium and phosphate ions were 1.8 × 10−3 mm s−1and 1 × 10−3 mm s−1. respectively, while the diffusive permeability coefficient for tritiated water was 2.6 × 10−3 mm s−1. If the cell wallsin vivohave properties similar to those in the isolated sleeves, then it is concluded that diffusion of small molecules in the apoplast is subject to less resistance than diffusion across plasma membranes. Using a range of compounds differing in lipid solubility and molecular weight (MW), it was found that permeability was inversely related to MW. It is concluded that the suberized walls of the sleeves are microporous, having hydrophilic channels traversing them. The results accord with some published information on onion rootsin vivobut contrast with the very low permeability of the hypodermis found in some other situations.

ISSN:0008-4026    

DOI:10.1139/b78-179

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Development of excised coremia ofDoratomyces purpureofuscus(Fries) Morton and Smith requires the presence of living mycelium at the coremium base. Relations between the vegetative hyphae and the synnema are established by means of anastomosis. Coremial development is controlled by an intramycelial factor which is one or several small thermostable molecules.

ISSN:0008-4026    

DOI:10.1139/b78-180

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The relationship between leaf water potential (ψL) and transpiration rate (T) was investigated using indoor-grown cassava plants (Manihot esculentaCrantz cv. Llanera). Leaf water potentials were measured with in situ dew-point hygrometer and transpiration rates by gas exchange analysis technique.Regression analyses of the data showed thatTwas consistently linearly related to ψL(r2 = 0.94). This implies that the plant resistance to flow was constant and hence that an Ohm's Law analog is valid for the transpiration range studied. Extrapolated values of leaf water potential at zero transpiration were close to the osmotic potential of the nutrient solution. Calculated resistance values (slope of regression line for individual plants) varied between 2.90 and 3.05 bars dm2 h g−1(1 bar = 100 kPa).

ISSN:0008-4026    

DOI:10.1139/b78-181

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Two cultivars of soybeans (Glycine max(L.) Merr.) differing widely in their resistance to ozone were exposed to 0.5 μl/ℓ ozone for 2 h in growth chambers.In vivonitrate reduction was depressed by more than 50% in the primary leaves of Dare, the ozone-sensitive cultivar, but was not significantly altered in Hood, the ozone-resistant cultivar. Sucrose, up to 1.5% (w/v), added to excised seedlings of the Dare cultivar during exposure to ozone eliminated the ozone depression ofin vivonitrate reductase activity and also reduced foliar injury. Addition of two glycolytic intermediates, glyceraldehyde-3-phosphate and fructose-1,6-diphosphate, to the infiltration medium recovered somein vivonitrate reduction in treated Dare leaves. The levels of extractable nitrate reductase and glyceraldehyde-3-phosphate dehydrogenase in the primary leaves of both cultivars were unaltered by ozone fumigations. These observations led to the conclusion that ozone depression ofin vivonitrate reduction is not due to ozone inactivation of nitrate reductase or of the enzymes coupling nitrate reduction to glycolysis, but may be caused by an inadequate supply of photosynthetic sugars. It was also noted that ozone depression ofin vivonitrate reduction only occurred with treatments which subsequently caused the development of visible foliar injur

ISSN:0008-4026    

DOI:10.1139/b78-182

出版商:NRC Research Press    

年代:1978

数据来源: NRC