bluuebunny/crossref_metadata_2025 huggingface dataset:
A gas-exchange system for measuring the productivity of plant populations in controlled environments
Authors: Bate G. C. , Canvin D. T.
Published: September 2008

An open gas-exchange system that will continuously measure the CO2 exchange of a small population of plants is described. The plant chamber was a controlled environment cabinet; air supply to the cabinet was measured by a venturi and differential pressure transducer and the CO2 differential between entering and exiting air was measured with an infrared gas analyzer. Carbon dioxide gain or loss by the population of plants was calculated from the CO2 differential and the air flow to the cabinet. The accuracy of the CO2 monitoring system was determined by comparing the carbon gain calculated from the CO2 measurements to the carbon gain determined by a harvest procedure. In four experiments, the gas-exchange system measured 85–99% of the actual carbon gain by the plants. Since the gas-exchange system provides a measure of absolute rather than relative productivity it is useful for examining the effect of various treatments on plant productivity.
A technique for measuring the light profile in a lichen canopy
Authors: Kershaw K. A. , Harris G. P.
Published: September 2008

A technique is described for measuring the light gradient within a lichen mat by embedding in Araldite, slicing, and measuring the mean absorbance of the slices at 644 nm. The method is illustrated with three species of Cladonia, each with its own characteristic light profile.
Injury on roadside trees: leaf injury on pine and white cedar in relation to foliar levels of sodium and chloride
Authors: Hofstra G. , Hall R.
Published: September 2008

Severe injury was observed on white cedar and several species of pine adjacent to highways in southern Ontario in the spring of 1970. Foliar injury, measured quantitatively as the ratio of brown to total leaf tissue, and foliar levels of sodium and chloride higher than background levels occurred on trees up to 120 m from the highway, particularly on the downwind side of the highway, on the windward side of the tree, and on trees in exposed positions. Injury and foliar levels of sodium and chloride progressively declined at greater distances from the highway. For a given level of sodium or chloride more damage occurred on the windward side than on the sheltered side of the tree. The data suggest that salt applied to highways in the winter is whipped up in a spray by traffic, blown onto vegetation, and contributes to leaf injury. Wind and lower than average winter temperatures also appeared to contribute to the injury observed in 1970. At similar foliar concentrations of sodium and chloride white pine showed twice as much injury as white cedar. Of the pines close to the highway, damage was greatest on white pine and red pine, intermediate on Scots pine, and least on Austrian pine and Mugo pine. At similar levels of damage all pines contained similar foliar levels of sodium and chloride.
Radiation-induced translocations in Prunus avium cv. Lambert
Authors: Whelan Ernest D. , Hornby C. A.
Published: September 2008

Meiosis, pollen viability, and growth changes were investigated in two of six radiation-induced reciprocal translocation mutants of Lambert sweet cherry (Prunus avium L.).Meiosis in mutant 19-23-1CL was characterized by a quadrivalent which was evident from pachynema to metaphase I. A circle-4 configuration normally was observed, and alternate and adjacent configurations occurred with equal frequency. Pollen stainability tests indicated 28% normal pollen, as compared to 58% for the parental Lambert clone. Changes in growth habit were evident, the onset of meiosis and flowering were delayed, and only 2% of the blossoms set fruit. Any fruit retained was poor in color, noticeably pointed, and had a prominent longitudinal dorsal ridge.Meiosis in mutant 16-4E was more complex than in 19-23-1CL. Quadrivalents rarely were observed, and most meiocytes contained a trivalent and a centric fragment, or a univalent and centric fragment. Meiotic abnormalities associated with these defects frequently were evident throughout meiosis. Pollen stainability tests indicated about 34% normal pollen. No marked changes in growth habit, onset of meiosis or flowering were evident. Fruit drop was about four times that of normal Lambert. Fruit retained appeared normal.
A fundamental thermostable cyanide-sensitive phosphoenolpyruvate acid carboxylase in photosynthetic and other organisms
Authors: Pan David , Waygood E. Roy
Published: September 2008

A thermostable 'phosphoenolpyruvate carboxylase' has been isolated from leaves of Zea mays different from phosphoenolpyruvate carboxylase (EC. 4.1.1.31) in that its optimum pH is 5.4, it does not liberate orthophosphate during the reaction, and it is inhibited by cyanide. The enzymic reaction has an optimum temperature of 70–75C and has been purified through steps including acidification to pH 4.6, heat treatment to 50C, and DEAE-cellulose and Sephadex G-200 column chromatography. Three fractions were active in the Sephadex eluate, but only fraction III was free from a thermostable acid phosphatase which catalyzes the liberation of orthophosphate from the substrate and the end product which is suggested to be a C4 phosphocarbonyl compound, although phosphohydroxypyruvate appears by either spontaneous or enzymic decarboxylation. The enzyme is assayed by the formation of a phenyl-hydrazone at 325 nm. The enzyme is localized and tightly bound in both the parenchyma bundle sheath and mesophyll chloroplasts, which are free from the thermostable acid phosphatase. Similar concentrations of the enzyme have been found in all plant species tested including C3 plants, ferns, bryophytes, algae, fungi, and even in calf liver. The enzyme must have considerable evolutionary significance.
Tryptophan synthase: purification, and some properties of an inhibitor from pea roots
Authors: Chen James , Boll W. G.
Published: September 2008

An undialyzable, thermostable inhibitor of tryptophan synthase from pea plants, Escherichia coli, and Neurospora crassa occurs in the filtrate from acetone extraction of pea tissue. A procedure is described for purification of the inhibitor extracted from roots. The final, purified preparation is homogeneous as shown by disc electrophoresis on acrylamide gel. The molecular weight, estimated by gel filtration on Sephadex G-200, is about 18 000. The inhibitor is stable even on heating at pH 7.0 in a water bath at 100 °C and has a characteristic ultraviolet absorption spectrum. The inhibitor shows some protein-like properties and acid hydrolysates were found to contain substances sensitive to ninhydrin. However, the hydrolysates also contain substances, presumably sugars, sensitive to benzidine reagent, appreciable sugar in galactose equivalents, and some fluorescent substances. The inhibitor was also found in shoot tissue. In both root and shoot the inhibitor increases, on a protein basis, with age of the tissue.
Heat transfer between Phaseolus vulgaris and the environment
Authors: Saldin T. F. , Barthakur N.
Published: September 2008

Heat transfer was studied from intact leaves of greenhouse-grown Phaseolus vulgaris L. under still and forced air conditions. Microwaves were used to heat the leaves without disturbing the thermal equilibrium of the environment. Leaf temperatures were measured by thermocouples and an infrared radiometer. Convective heat transfer coefficient for a leaf was obtained by two experimental methods and compared with the theoretical results. The unsteady-state method proved to be quite satisfactory.Typical values of heat transfer coefficient for free convection varied from 1.86 × 10−4 to 3.64 × 10−4 cal cm−2 s−1 °C−1, as the temperature difference between the leaf surface and the surrounding air increased from 1.0 to 3.9 °C. Forced convective heat transfer coefficient, however, increased to about 10 × 10−4 cal cm−2 s−1 °C−1 at 610 cm s−1.
Four new genera of cleistothecial Ascomycetes with hyaline ascospores
Authors: Malloch David , Cain R. F.
Published: September 2008

Four new monotypic genera of cleistothecial coprophilous Ascomycetes are described: Eremomyces bilateralis gen. and sp. nov. found on dung in Ontario, California, and Kenya, has hyaline, one-celled ascospores and is accommodated in Eremomycetaceae, a new family of the Loculoascomycetes; Mycorhynchidium saccatum gen. and sp. nov. found in Kenya belongs to the Nectriaceae and is similar to Mycorhynchus Sacc.; Cleistothelebolus nipigonensis gen. and sp. nov. found on wolf dung in Ontario, and Lasiobolidium spirale gen. and sp. nov., represented by four collections on horse and cow dung from Nevada and Wyoming are members of the Eoterfeziaceae.
The genus Kernia
Authors: Malloch David , Cain R. F.
Published: September 2008

The Ascomycete genus Kernia is emended according to revised concepts. Five species, K. bifurcotricha Saxena & Mukerji, K. hippocrepida sp. nov., K. nitida (Sacc.) Nieuwland, and K. pachypleura sp. nov., are included and a key to the species given. Two species, K. brachytricha (Ames) Benjamin and K. geniculotricha Seth, are placed in synonymy with K. nitida. Three species, K. bartlettii (Massee & Salmon) Benjamin, K. furcotricha Tandon & Bilgrami, and K. spirotricha Benjamin, are excluded from Kernia. K. bartlettii belongs in Lophotrichus Benjamin and is transferred to that genus as L. bartlettii (Massee & Salmon) Malloch & Cain. K. furcotricha is considered a possible species of Chaetomidium (Zopf) Sacc. K. spirotricha belongs in Chaetomidium and is transferred as C. spirotrichum (Benjamin) Malloch & Cain. As a result of studies of the type specimen of Fairmania singularis Sacc, since a Fairman collection under that name was included in K. hippocrepida, the new combination Microascus singularis (Sacc.) Malloch & Cain is proposed.
New cleistothecial Sordariaceae and a new family, Coniochaetaceae
Authors: Malloch David , Cain R. F.
Published: September 2008

The family Sordariaceae is briefly defined and a list of cleistothecial genera given. Two species of Anixiella Saito & Minoura ex Cain, A. endodonta sp. nov., and A. monospora sp. nov. are described and a key to the four species of the genus included. Apodus deciduus gen. et sp. nov. is described. Two new combinations in Echinopodospora Robison, E. spinosa (Cailleux) Malloch & Cain and E. verruculosa (Cailleux) Malloch & Cain, are proposed to accept transfers from Tripterospora Cain and are followed by a key to species of Echinopodospora. The concept of Zopfiella Winter is broadened to include Z. pleuropora sp. nov. and three new combinations, Z. inermis (Cailleux) Malloch & Cain, Z. latipes (Lundqvist) Malloch & Cain, and Z. leucotricha (Speg.) Malloch & Cain, transferred from Tripterospora. A key to the six species of Zopfiella is presented. The new family Coniochaetaceae is proposed to accommodate the new genus Coniochaetidium and Coniochaeta (Sacc.) Massee. Two species of Coniochaetidium are described, C. ostreum sp. nov. and C. savoryi (Booth) Malloch & Cain, comb, nov., based on Thielavia savoryi Booth.
Growth-regulating properties of picloram, 4-amino-3,5,6-trichloropicolinic acid
Authors: Eisinger W. R. , Morré D. J.
Published: September 2008

Picloram, 2,4-D (2,4-dichlorophenoxyacetic acid) and IAA (indole-3-acetic acid) cause similar stimulations of polarized cell elongation in stem and coleoptile sections floated on solutions containing the growth regulator. Picloram, like 2,4-D and IAA, supports growth of tissue explants in culture, inhibits root growth, induces cell wall loosening, produces stem curvature and other formative effects, promotes loss of chlorophyll, and regulates abscission and rooting responses. A kinetic analysis of root growth inhibition indicates a common mode of action for picloram and 2,4-D. Picloram meets the minimal structural requirements for auxin activity. The greater herbicidal effectiveness of picloram is attributed to increased mobility and resistance to breakdown within the plant. The ability of picloram to increase markedly the growth of intact shoot cuttings is not shared by either 2,4-D or IAA and neither picloram nor 2,4-D are readily transported in a polar manner in the Avena curvature test. We conclude that picloram functions as a growth regulator of the auxin type with a herbicidal action similar to that of 2,4-D.
The genus Gymnosporangium in Western Canada
Authors: Parmelee J. A.
Published: September 2008

Eleven species of Gymnosporangium native to Western Canada and two exotic species, one of European and one of Asian origin from cultivated junipers imported into Canada, are described and illustrated from Canadian material. Species occurring in adjacent United States but not known in Canada are briefly mentioned. Results of inoculations carried out in 1966 and 1969 are compared with dates of aecial maturation from field observations. Times required for aecial maturation are used in a key to this stage; and telia are keyed primarily on macroscopic characters usable in the field.
Occurrence and distribution of some zoosporic fungi from soils of Hibben and Moresby Islands, Queen Charlotte Islands
Authors: Booth Tom
Published: September 2008

Zoosporic fungi are reported for the first time from soils of the Queen Charlotte Islands. Seventy-two species in 21 genera from 128 sites are included in this report. Developmental details and taxonomic problems are discussed for selected species.
Chemotaxonomic investigations on Dryopteris fragrans
Authors: Widén C.-J. , Britton D. M.
Published: September 2008

The phloroglucinol derivatives in four collections of Dryopteris fragrans var. remotiuscula Komarov from Finland, Ontario, and Newfoundland were investigated. The collections from two localities in Ontario gave different results, which indicate either chemical variability in the variety, or the possibility that var. remotiuscula in Ontario might be re-evaluated.
Sciniatosporium Kalchbr., and its synonyms Marcosia Syd., Stigmina Sacc, Thyrostroma Höhnel, and Thyrostromella Syd., non Höhnel
Authors: Morgan-Jones G.
Published: September 2008

The type species of Sciniatosporium Kalchbr. (1866), Stigmina Sacc. (1880), Thyrostroma Höhnel (1911), Marcosia Syd. (1916), and Thyrostromella Syd. (1924) non Höhnel, are considered to be congeneric. The name Sciniatosporium has priority. A revised generic diagnosis is given to include the type species of these generic names. Three fungi which were originally placed in Coryneum Nees ex Fr., two in Sporidesmium Link ex Fr., and three in Stegonsporium Corda, together with M. ulei Syd., the type species of Marcosia, and most species recently disposed in Stigmina, are transferred to Sciniatosporium. A new species, Sciniatosporium verrucosum, is described.
Notes on Hyphomycetes. I. An addition to the genus Sporidesmium Link
Authors: Morgan-Jones G.
Published: September 2008

Helminthosporium stromatoideum Dearness is considered best classified in Sporidesmium Link and is transferred to that genus. The fungus is redescribed and illustrated.
The distribution of Phyllophora in the North Atlantic and Arctic regions
Authors: Newroth P. R.
Published: September 2008

The distributions of five species of Phyllophora Greville (Order Gigartinales) were examined in the North Atlantic and Arctic regions. Less detailed distributional observations of Phyllophora were made in the Mediterranean and Black Seas. Distributional records, based on extant specimens from extensive personal field observations in the United Kingdom and eastern North America and from collections in various herbaria, are recorded in tables and on maps; these records are discussed.
Establishment and spread of Polyporus tomentosus in pine and spruce plantations in Wisconsin
Authors: Myren Donald T. , Patton Robert F.
Published: September 2008

Polyporus tomentosus Fr. was found in the roots of stumps in a thinned red pine plantation and in roots of living and dead trees in established root rot pockets in a white spruce plantation. Infection apparently originated in the root collar or in declining roots of stumps or weakened trees. Direct stump top invasion was not evident. Localized spread of the fungus occurred through root contacts or grafts. Presence and approximate margins of root rot pockets in a white spruce plantation were indicated by sporophores. In 13 permanent plots embracing root rot pockets observed during a 4-year period, the reduction in number of living dominant trees was 2.1%, codominants 2.4%, intermediates 15.4%, and suppressed trees 48.5%. In control plots only the number of suppressed trees decreased by 29.3%. Of the remaining living dominant and codominant trees within the disease plots 26.8% probably were infected. Expansion of 10 of the infection pockets was measured showing an increase in area of 58.3%. During the 4-year period 18 new infection centers appeared in the stand.
Variability of Thielaviopsis basicola in culture
Authors: Huang H. C. , Patrick Z. A.
Published: September 2008

The fungus Thielaviopsis basicola (Berk. & Br.) Ferraris exhibited considerable variability when grown on potato dextrose and V8 juice agars. Variants were frequently obtained from single chlamydospore cells. In general, many different cultural variants were obtained from the grey wild biotype. These arose from single chlamydospore cell isolations, from sector and patch variants, and from colonies which initially were of single spore origin. The variants differed from their respective parents and from each other in macroscopic and microscopic characteristics including colony appearance, color, zonation, growth rate, production of spores, and shape and number of cells in the chlamydospores. Some variants were less pathogenic than the parents from which they arose; in others pathogenicity was not significantly changed, and others exhibited higher pathogenicity.Contrary to earlier reports, it was found that the typical brown type can be derived in culture from the grey wild biotype. This brown type is similar to the brown wild biotype in cultural behavior and in relative pathogenicity to red clover.
Leakage of metabolites from mycelium of a low-temperature basidiomycete at a supramaximal temperature
Authors: Ward E. W. B.
Published: September 2008

Colonies of a low-temperature basidiomycete (W1) growing on agar media at 15 °C ceased growth when transferred to 30 °C. Viability was retained during at least 7 days exposure to 30 °C since growth resumed after a lag when colonies were returned to 15 °C. Measurements were made of the leakage of metabolites at 15 °C and 30 °C from mycelium of young shake cultures during a 5-h incubation period. Leakage of ninhydrin-positive material, almost negligible at 15 °C, was rapid at 30 °C. Increases in leakage of carbohydrate and ultraviolet-absorbing material occurred during the first hour at 30 °C. Subsequent leakage of carbohydrate at 30 °C, but not of ultraviolet-absorbing material, was at a slightly higher rate than at 15 °C. The possibility that these results indicate loss of cell membrane function at the supramaximal temperature is discussed.
New names in Entoloma
Authors: Morgan-Jones G.
Published: September 2008

Four new names in the genus Entoloma are proposed. Entoloma gainsvillae nom. nov., E. hesleri nom. nov., E. floridense nom. nov., and E. globispora nom. nov.
Avena occidentalis, a hitherto overlooked species of oats
Authors: Baum B. R.
Published: September 2008

Avena occidentalis Dur., hitherto known from only one specimen, was found to occur in three islands of the Canaries and in one locality in Portugal. The speculation that this might indicate a greater past distribution is strengthened by a few examples of species with a similar present distribution in the Canaries and with known fossil records from Europe. Some morphological character states of A. occidentalis are described and they are compared with character states from homologous organs in morphologically similar species. The possible importance that A. occidentalis might have for the understanding of the cytogenetical relationship between the Avena species is stressed, and the possible value of this species to agriculture is mentioned.
Genotypic variation within a phenotype as a possible basis for somatic hybridization in rust fungi
Authors: Hartley M. J. , Williams P. G.
Published: September 2008

It is generally considered that the production of new strains of rust by somatic hybridization cannot be adequately explained by hyphal anastomosis and nuclear exchange. Such a mechanism would account for the observed recombination if, as is proposed, the rust fungi in their dikaryophase carry multiple haploid genotypes within any one phenotype. Such hidden variation could arise through whole chromosome exchange between the nuclei of a dikaryotic cell. Possible ways of generating genotypic variation within a phenotype are suggested by the results of recent investigations of Puccinia graminis f. sp. tritici in axenic culture.
Discharge and germination of Eutypella parasitica ascospores
Authors: Lachance Denis
Published: September 2008

Perithecia of Eutypella parasitica on cankered sugar maple in natural stands, discharged ascospores only when rainfall occurred. However, there was no relationship between amount of rainfall and intensity of spore discharge. High relative humidity alone did not induce spore ejection, but wetting of perithecia did. Variations in summer temperature appeared not to influence spore release. In laboratory studies, spore discharge from wetted clusters of perithecia on excised pieces of bark kept in moist chambers, was heavy at 20 °C, light at 12 °C, and nil at 4 °C. Although near-freezing temperature inhibited ascospore discharge, exposure to warm temperature of previously frozen perithecia quickly induced release of viable ascospores. Ascospores germinated readily in water or on common agar media. Germination was rapid at 20 °C, slow at 12 °C, and nil at 4 °C. Ascospores remained viable for several months when stored dry at 4 °C; up to 13% still germinated after 20 months of storage. Ascospores stored dry at 20 °C germinated poorly after 5 weeks.
Seed production and dormancy in Rumex crispus. I. The effects of removal of cauline leaves at anthesis
Authors: Maun M. A. , Cavers P. B.
Published: September 2008

Defoliation of the panicle of Rumex crispus L. (curled dock) at anthesis had little effect on the number of seeds (nuts) produced but lead to a very severe reduction in total seed weight per panicle and in the size of individual seeds. In particular the proportion of larger seeds was reduced drastically. The seeds from defoliated plants germinated more rapidly and had less precise requirements for germination than those from untreated plants. They did not suffer any loss of viability. A microscopic examination of cross sections of seeds revealed that seeds from defoliated plants had thinner walls (investing structures). They also exhibited a higher absorptive capacity for water. This information provides an important basis for further studies on the biological control of this weedy species.
Growth, and patterns of growth and division, in cell suspension cultures of bush bean (Phaseolus vulgaris cv. Contender)
Authors: Liau Deng-Fong , Boll W. G.
Published: September 2008

Changes in cell number, cell size, fresh weight, and dry weight were recorded for the growth cycle of a serially subcultured cell suspension culture derived from hypocotyl of bush bean (var. Contender). The various cell types and growth patterns from single cells were also recorded. The culture showed unique features including a relatively sharp separation of a phase of exponential cell division from a phase of cell expansion. Complete separation of cell clumps gave a free cell culture, of viable cells, by day 16. The growth cycle, cell types, and growth patterns are compared with those in other plant cell suspension cultures. The potential value of the culture for study of growth regulation is discussed.
Tryptophan synthase: a two-component enzyme from pea plants (Pisum sativum cv. Alaska)
Authors: Chen James , Boll W. G.
Published: September 2008

Evidence is presented showing that tryptophan synthase (L-serine hydro-lyase (adding indole), EC. 4.2.1.20) from pea is composed of two components, A and B, analogous to the protein subunits reported for bacteria, algae, and tobacco enzyme. Separation of the two components was achieved by gel filtration on Sephadex G-100. In contrast with enzyme from tobacco the two components could not be separated by ammonium sulfate precipitation. However, the A component was removed by heating at 70 °C for 5 min. The B component, alone, catalyzed the condensation of L-serine plus indole to tryptophan (reaction 2) at a significant level. A combination of the A and B components was necessary for the formation of tryptophan from indole-glycerol phosphate (reaction 1); and conversion of indole-glycerol phosphate to indole (reaction 3). Reaction 3 could only be demonstrated with partially purified enzyme extract, and the reaction proceeded well in the absence of added pyridoxal phosphate but was increased by its presence. The relative rates of the reactions were in the ratio of 30:100:1.5 for reactions 1, 2, and 3, which is in agreement with studies with microbial TSase. However, in contrast, some free indole was isolated from reaction 1. The reversal of reaction 3 could not be detected. It is suggested that reaction 1 is probably the one of physiological significance as is believed to be the case in microorganisms.
Initiation and development of western red cedar cones in response to gibberellin induction and under natural conditions
Authors: Owens J. N. , Pharis R. P.
Published: September 2008

Both seed and pollen cones in Thuja plicata Donn. are found at the tips of small lateral branches and form as a result of the transition of previously vegetative apices. The vegetative apex shows a cytohistological zonation similar to that found in other Cupressaceae and vegetative buds are not enclosed in scales. The first sign of pollen cone initiation occurred 13 days after the initial GA3 treatment under long days. Transition of the apex was marked by a slight increase in rate of cell division in all zones resulting in the formation of a mantle of small uniform cells several cells thick covering the surface of the apex. The apex increased in height and the long internode between the last-formed pair of leaf primordia and first pair of microsporophylls formed a short stalk at the base of the cone. The transition of a vegetative apex to a seed cone apex occurred 27 days after initial GA3 treatment and was similar to that for pollen cones. Bract primordia are initiated closer to the summit of the apex and are larger in initial stages than microsporophyll primordia, and longer internodes remain between successive pairs of bracts. Ovule initiation occurs when bracts have just begun upward growth. All microsporophylls, bracts, and ovules are formed during the few weeks after cone initiation and before cones become dormant. No anatomical changes occurred in either cone type during subsequent short-day cold treatment. A return to long-day warm conditions promoted normal cone development. Under natural conditions in the Victoria area, pollen cones are initiated early in June under long days and increasing day length while seed cones are initiated early in July under similar long days but decreasing day length. Development of both pollen and seed cones occurs during long days and decreasing day length. The possible relationship between sexuality of cones, gibberellin, auxin, and day length is discussed.
Hydrarch succession and net primary production of oxbow lakes in central Alberta
Authors: Valk A. G. van der , Bliss L. C.
Published: September 2008

The plant communities in a series of 15 oxbow lakes were examined to determine their successional sequence and productivity. Twelve communities were recognized as a result of analyses carried out on the phytosociological data. Water chemistry and water level fluctuations caused by periodic flooding are the major factors controlling plant distribution and succession.The maximum above-ground standing crop of communities follows a definite pattern with succession: from submerged (ca. 200 g/m2), through floating-leaved (ca. 210 g/m2), to the emergent community (ca. 465 g/m2), there is a stepwise increase in annual production, which declines in the meadow community (ca. 325 g/m2).Leaf area index does not change with succession: it remains between 3 and 4 in all the stages examined. Chlorophyll follows a pattern similar to standing crop, except that submerged communities contain more chlorophyll than floating-leaved: submerged (0.24–0.92 g/m2), floating-leaved (0.29–0.80 g/m2), emergents (0.62–2.13 g/m2), and meadow (0.54–1.42 g/m2).
Effect of balsam woolly aphid, Adelges piceae, infestation on the food reserves of grand fir, Abies grandis
Authors: Puritch George S. , L'Armee M. Talmon-De
Published: September 2008

Effects of balsam woolly aphid infestation on the concentration of ethanol-soluble and -insoluble carbohydrates were investigated in four age classes of needles and six age classes of twigs of grand fir, before and after bud break.In March, before bud break, sugars made up about two-thirds of the total carbohydrate content of the foliage. Aphid infestation did not affect the concentration of sugars in needles but reduced starch by 28%. In twigs, sugar concentrations were less in infested trees while starch concentrations were unaffected. Both older needles and twigs contained higher concentrations of starch than younger needles and twigs.After bud break in June, starch constituted the major form of carbohydrate, accounting for 65% of the total carbohydrate in non-infested foliage and 53% in infested foliage. Total carbohydrate content increased over that in March, in both infested and non-infested foliage, but the non-infested tissue showed the greatest increase. Starch content of infested foliage was reduced by 36%, while starch concentration of infested twigs was reduced by 18%.
Resistance to Cronartium ribicola in Pinus monticola: short shoot fungicidal reaction
Authors: Hoff R. J. , McDonald G. I.
Published: September 2008

Growth of the blister rust (Cronartium ribicola J. C. Fisch. ex Rabenh.) mycelium down a secondary needle of certain resistant Pinus monticola Dougl. seedlings proceeds normally until hyphae reach the short shoot. At this point, a resistance mechanism is triggered that causes host cell necrosis and fungal death. Thus, normal canker development is prevented and the stem remains disease-free.
Estimates of inbreeding in Pinus banksiana
Authors: Sittmann K. , Tyson H.
Published: September 2008

A new analysis of Teich's (1970) data on cone serotiny in jack pines indicated that inbreeding coefficients calculated by Teich for natural populations (27% ≤ F ≤ 74%) are probably much too large because of substantial misclassification of heterozygotes. Simultaneous estimation by the maximum likelihood scoring method of the degree of self-fertilization (s), of the gene frequency in cross-fertilizing pollen, and of the average rate of misclassification gave an estimate of s = 9.6 ± 10.4% for the progeny of 27 mother trees. For a population in Hardy-Weinberg equilibrium, this estimate corresponds to 5.0 ± 5.7% inbreeding arising from self-fertilization in one generation.
On the life histories of some brown algae from eastern Canada
Authors: Edelstein T. , Chen L. C.-M. , McLachlan J.
Published: September 2008

The life histories of five phaeophycean species were completed in culture. Isthmoplea sphaerophora, Melanosiphon intestinalis, Hecatonema maculons, Elachista lubrica, and Ralfsia verrucosa replicated directly the parent plants. Some field observations on the above mentioned species are reported.
Photorespiration and the postillumination CO2 burst
Authors: Bulley N. R. , Tregunna E. B.
Published: September 2008

An open system of gas analysis was used to study the kinetics of the short postillumination CO2 burst (PIB) from soybean leaves. After correcting for the sample volume in the gas analyzer (IRGA), we found that the maximum measurable rate of CO2 evolution occurred within 8 s after the sudden reduction in light intensity, lasted for about 6 s, and then declined rapidly. The corrected rate was 45% higher than the rate indicated by the IRGA output. The maximum rate of the PIB was proportional to the effect of light intensity on the preceding apparent rate of photosynthesis in 21% O2 and 350 ppm CO2. A similar proportionality was found between the PIB and the light intensity in each of the five parts of the visible spectrum which were tested. No PIB was found when the O2 concentration was reduced to less than 2% O2. The effect of 21% O2 on the rate of CO2 evolution after 8 s in the dark relative to the rate in 2% O2 was about 20% greater than the effect of 21% O2 on apparent photosynthesis in the preceding light period. This difference may be ascribed to internal refixation during photosynthesis.The results supported the theory that photorespiration continues for a short period longer than photosynthesis after a sudden reduction in light intensity. This period is much shorter than previous papers have indicated. The action spectrum for the PIB provides no support for flavin-activation as the mechanism of the light effect.
Salinity-related polymorphism in the brackish-water diatom Cyclotella cryptica
Authors: Schultz Mary E.
Published: September 2008

The brackish-water diatom Cyclotella cryptica is a polymorphic species. Nine clones are capable of producing the valve pattern characteristic of the species C. meneghiniana, as well as the C. cryptica pattern. A study of the effects of salinity and freshwater conditions on the morphology of the valve shows that the cryptica pattern is produced in salinities of about 4.3‰ to full-strength seawater, 28.7‰. The "meneghiniana" pattern is the freshwater or low salinity (1.4‰) form. Characteristics of the valve morphology and life history stages which distinguish C. cryptica from C. meneghiniana and Cyclotella sp., clone 03A, are presented and discussed.
Relationships among species of Verticillium: protein composition of spores and mycelium
Authors: Pelletier Gilles , Hall Robert
Published: September 2008

Buffer-soluble proteins extracted from six morphologically different isolates of Verticillium were separated by polyacrylamide gel-electrophoresis. Protein patterns from the six isolates were different from one another whether extracts were prepared from conidia, from young colonies composed of mycelium and conidia, or from 6-day-old mycelium. However, the nature of the patterns, and therefore the degree of differences among species patterns, was influenced by the types of cells from which the extracts were prepared.Patterns of proteins from V. tricorpus, V. nigrescens, and an isolate of uncertain identity (isolate 2) which produced chlamydospores and dark mycelium were clearly different from one another whether extracts were prepared from conidia or mycelium. In contrast, conidia of V. albo-atrum, of V. dahliae, and of an isolate which did not produce pigmented structures produced very similar patterns which differed by only a few protein bands. This close similarity of patterns supports the view that V. albo-atrum and V. dahliae are genetically closely related.The protein composition of conidia differed from that of mycelium. In V. albo-atrum, spore extracts contained at least three proteins not detected in mycelium extracts. Differences between spores and mycelium were even greater in V. nigrescens and isolate 2. Analysis of V. dahliae showed differences between spores, 3-day-old mycelium, and 6-day-old mycelium.Our results support the view that gel-electrophoresis of proteins is useful as a taxonomic tool provided attention is given to the degree of morphological differentiation of the materials to be compared.
An open gas-exchange system for the simultaneous measurement of the CO2 and 14CO2 fluxes from leaves
Authors: Ludwig L. J. , Canvin D. T.
Published: September 2008

An open gas exchange system that uses an infrared gas analyzer and an ionization chamber to measure CO2 and 14CO2 is described. The system will continuously measure the CO2 and 14CO2 exchange from a leaf within 30 s after the 14CO2 gas mixture is supplied to the leaf. Measurements are obtained under steady rate conditions since the 14CO2 gas mixture is supplied at a constant composition from pressurized cylinders. Methods of determining true photosynthesis, apparent photosynthesis, CO2 evolution, and the specific activity of the 14CO2 evolved are clearly described. The rate of CO2 evolution in the light was not affected by the CO2 concentration and the evolved CO2 was derived from the early products of photosynthesis.
Histological studies of ectomycorrhizae and root nodules from Cercocarpus montanus and Cercocarpus paucidentatus
Authors: Hoeppel R. E. , Wollum II A. G.
Published: September 2008

The ectomycorrhizae of Cercocarpus montanus Raf. and Cercocarpus paucidentatus Britt. displayed morphologies ranging from single swollen short lateral roots on long roots to terminal pyramidal clusters. Most short roots appeared to be mycorrhizal, although C. paucidentatus was only infected under growth chamber conditions. Histological sections revealed a conspicuous fungal mantle, averaging 30 μ in thickness, and a Hartig's net.The root nodules appeared as swellings on lateral roots, and later formed compact coralloid orange-colored masses several centimeters in diameter. Histological analyses indicated that both species of Cercocarpus harbored a similar endophyte. Three developmental stages were noted in cortical tissue, including (a) hyphal masses in apical nodule cells; (b) hyphae terminating in 3 × 4 μ club-shaped vesicular swellings; and (c) older structureless hyphal masses in cells of mature nodule branches. The older hyphal masses did not appear to be absorbed by the host plant. The endophyte possessed branching filaments 0.5 μ in diameter and was considered to be an actinomycete.
Carbon dioxide exchange by native Great Plains grasses
Authors: Redmann Robert E.
Published: September 2008

Carbon dioxide exchange in relation to light and moisture stress was determined for dominants of three grassland plant communities of western North Dakota. These range from Bouteloua gracilis on very dry sites to Stipa viridula on less dry positions to Sporobolus heterolepis in moist ravines. Maximum net photosynthesis of sod transplants ranged from 10 to 12 mg CO2 g−1 h−1 (6 × 104 lx), corrected for soil respiration of about 3 mg CO2 dm−1 h−1. In B. gracilis and S. viridula, net photosynthesis declined steadily to 25% of maximum when moisture stress was increased to −30 bars soil matric water potential. Net photosynthesis declined less rapidly in S. heterolepis when moisture stress increased to −10 bars, but decreased to zero when stress reached −30 bars. The implications regarding distribution of the species are discussed.
Dormancy studies in seed of Avena fatua. 7. The effects of light and variation in water regime on germination
Authors: Hsiao A. I-Hsiung , Simpson G. M.
Published: September 2008

Light can regulate the germination of seeds of Avena fatua L. In low volumes of water, seeds are inhibited by white light and in high volumes they are promoted, when compared to seeds in darkness. Blue, red, and far-red light also inhibited germination of seeds in low volumes of water; in high volumes of water there were no differences between these three bands of light and darkness. Degree of dormancy and presence or absence of hulls and of gibberellin all interacted with water status of the caryopsis and light to modify germination. Suppression of germination by white light induced a concomitant reduction in the rate of increase of water potential in these seeds compared with similar seeds germinated in darkness.
A new species of Dinemasporium from Ontario
Authors: Morgan-Jones G.
Published: September 2008

A new species of Dinemasporium Lèv., D. canadense, is described and illustrated from dead, decorticated twigs in Ontario. Its relationship with other species of the genus is discussed.
Studies on lichen-dominated systems. I. The water relations of Cladonia alpestris in spruce–lichen woodland in northern Ontario
Authors: Kershaw K. A. , Rouse W. R.
Published: September 2008

The water relations of Cladonia alpestris in spruce–lichen woodland in northern Ontario is described. The rate of drying of the lichen canopy was measured by resistance grids inserted into the canopy and monitored during the drying cycle. The effects of dew were measured in a similar fashion and shown to form an insignificant proportion of the total annual metabolism of the lichen. The lichen mat showed a very high stratified resistance to water loss and the effective mulching properties produce a high level of water availability under the lichen mat. This was confirmed using neutron attenuation techniques and the significance of this discussed in relation to the development of lichen woodland. The physiological response of the lichen to conditions of varying levels of saturation is also discussed.
Effects of mineral nutrients on ozone susceptibility of Lemna minor
Authors: Craker Lyle E.
Published: September 2008

Susceptibility of Lemna minor L. to ozone injury was influenced by the mineral nutrients available to the Lemna plants. Additional nitrogen or additional iron in the nutrient media respectively enhanced or reduced chlorophyll loss of Lemna plants fumigated with ozone. Lemna plants growing on a nutrient medium lacking copper had significantly less injury from ozone fumigation than Lemna plants growing on a complete nutrient medium. There were apparent interactions among phosphorus and potassium nutrient levels in determining the Lemna plant's susceptibility to ozone.
Some physiological effects of cycloheximide in soil on the tomato plant
Authors: Thorn G. D. , Richardson L. T.
Published: September 2008

Cycloheximide applied as a drench to the soil of potted tomato plants caused reduced transpiration, and a marked reduction of exudate volume from the stumps of detopped plants. The exudate of treated plants showed increased levels of γ-aminobutyric acid and reduced levels of glutamine and α-ketoglutarate; Na ion concentration was increased and K ion concentration lowered. These effects were apparent within 2 h of application of cycloheximide.
Studies on ectomycorrhizae of pine. I. Production of volatile organic compounds
Authors: Krupa Sagar , Fries Nils
Published: September 2008

The mycorrhizal fungus Boletus variegatus Fr. was grown in pure culture and its production of volatile organic compounds studied. Maximal production of volatile organic compounds was associated with actively growing mycelia. The major volatile compounds identified in the culture filtrate were ethanol, isobutanol, isoamyl alcohol, acetoin, and isobutyric acid. Of these, isobutanol and isobutyric acid are known to possess fungistatic activity. Volatile organic compounds were also extracted from the whole root systems of Pinus sylvestris L. (Scots pine) seedlings grown in pure culture with and without the fungal symbiont. Infection of the roots by the fungus resulted in production and (or) accumulation of volatile compounds in concentrations two to eight times greater than that of non-inoculated controls. These compounds were identified by combined gas chromatography and mass spectrometry. They were primarily terpenes and sesquiterpenes. Volatile compounds produced by the mycorrhizal root system of Scots pine collected from a nursery were essentially the same as those obtained from the plants grown in pure culture. Many of these are known to be fungistatic compounds. A hypothesis has been proposed to explain a possible role of the host plant in disease resistance of mycorrhizal root systems to root pathogens and in the development of the symbiotic state.
Oat crown rust race differentiation: replacement of the standard differential varieties with a new set of single resistance gene lines derived from Avena sterilis
Authors: Fleischmann George , Baker R. J.
Published: September 2008

A review of the physiologic races of oat crown rust, Puccinia coronata f. sp. avenae, isolated in surveys since 1967 indicated a continuing trend toward increased virulence on the standard differential varieties of oats, Avena sativa. Because of this trend and because the inheritance and interrelationships of resistances in the standard differential set are not completely known, a new set of oat crown rust differentials has been introduced. The new set comprises 10 near-isogenic lines of the common oat variety 'Pendek,' into which single resistance genes from Avena sterilis had been transferred. A system of race nomenclature which reflects the pattern of virulence on the new set is proposed.
Further evidence for two modes of carboxyl transfer in plants with C4-photosynthesis
Authors: Downton W. J. S.
Published: September 2008

Pulse–chase studies show that some species with the C4-dicarboxylic acid pathway of photosynthesis transfer carbon from malic acid to the Calvin cycle. Others transfer carbon from aspartic acid.
An addition to the genus Discogloeum Petrak
Authors: Morgan-Jones G.
Published: September 2008

Exosporium concentricum Heald and Wolf is redescribed, illustrated, and transferred to Discogloeum Petrak.
The culture of four species of Fucus under laboratory conditions
Authors: McLachlan J. , Chen L. C.-M. , Edelstein T.
Published: September 2008

Mature thalli of Fucus distichus, F. edentatus, F. serratus, and F. vesiculosus were obtained in unialgal culture from zygotes and were grown in an enriched seawater medium. The two former species were maintained in culture for more than 2 years, in which time the length of thalli of F. edentatus never exceeded 4 cm. The other species grew reasonably well with a maximum rate of elongation of about 1 cm per month for F. serratus. In all species the rates of growth were less than that observed in nature. Fertile receptacles with viable gametes were formed in F. distichus, but the other species never attained reproductive maturity. All specimens retained their characteristic morphology under identical conditions of culture, and it is suggested that morphological variation amongst Fucus spp. is due mainly to hybridization rather than to environmental conditions. There was no indication that any of these species required intertidal conditions, and no unique nutritional requirements were identified.
Net primary productivity of bog vegetation in southeastern Manitoba
Authors: Reader R. J. , Stewart J. M.
Published: September 2008

The net primary productivity of bog vegetation was determined for a peatland site located in south-eastern Manitoba. The productivity of non-vascular species (55.4 g/m2 per year) was small compared to the total calculated for vascular species (1777.5 g/m2 per year), with 82% of the vascular production associated with subsurface plant components. The total productivity of 1942.9 g/m2 per year was greater than the values previously reported for peatlands.
The occurrence of Chytridium marylandicum on Botryococcus braunii in School Bay of the Delta Marsh
Authors: Masters Margaret J.
Published: September 2008

Chytridium marylandicum Paterson is a highly specific saprophyte which grew only in the mucilage of colonies of Botryococcus braunii. During the summers of 1965–1968, Chytridium multiplied on the Botryococcus population as the alga was approaching the maximum. The year 1968 was a particularly good summer for both the alga and the fungus. The fungus maximum occurred shortly after the algal maximum and at this time 79.5% of the observed Botryococcus colonies supported fungus thalli. At this time as many as 25 Chytridium thalli were occasionally observed on a single Botryococcus colony. During the 1968 Chytridium bloom, it was observed as well that the composition of the fungus population changed with time. A marked increase in germinated zoospore cysts every 5 days suggested that the asexual development of the fungus under these apparently optimum conditions took 5 days. Botryococcus population levels showed positive correlations with conductivity and temperature. Similarly Chytridium showed positive correlations with conductivity and temperature and with increasing Botryococcus numbers. The appearance of Chytridium marylandicum, therefore, was favored by conditions optimum for Botryococcus braunii.