bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of sprout growth in the potato. Effect of humidity and water supply
Authors: McIntyre Gordon I. , Quick William A.
Published: September 2008

The growth of apical sprouts of potato tubers, var. Norland, kept in darkness at 15 °C, was significantly increased either by increasing the relative humidity (RH) from approximately 40 to 100% or by supplying water to the basal cut end of the tubers. These two treatments showed a significant interaction, the response to the external water supply being considerably greater at the higher RH. The growth response was closely correlated with increases in the dry weight and the water content of the sprouts, expressed on either a sprout or dry weight basis. The high RH plus water treatment also eliminated the inhibition of sprout growth by light, the length of the sprouts in this treatment being almost 160% greater than in the light at low RH and 60% greater than in the dark. These results are consistent with the hypothesis that when the tuber has no external supply of water, the growth of the sprouts is determined primarily by their water content, and thus by the effect and interaction of factors affecting the supply of water from the tuber and its rate of loss from the sprouts by transpiration.
Leaf survival of woody plants in deciduous broad-leaved forests. 2. Small trees and shrubs
Authors: Kikuzawa Kihachiro
Published: September 2008

Leaf survival of 29 species of small trees and shrubs was described in and around deciduous broad-leaved forests in Hokkaido, northern Japan. Twenty-four species had green leaves in the summer (summer green) and the other five species had green leaves in winter. Among the latter, three species were evergreen, one had green leaves in the winter and no leaves in the summer (winter green), and the other had two types of shoots: evergreen and summer green (heteroptosis). In summer-green species of the understory, both leaf emergence and leaf fall lasted only a short time. Duration of leaf emergence was long in open-site species and was intermediate in gap species. Leaf survival can be considered as part of the adaptive strategy of each species. The leaves of understory species emerged in a flush; that pattern could be adaptive to the strongly seasonal illumination of the forest floor. Evergreen and winter-green habits, as well as heteroptosis, were also assumed to be adaptive to life in the understory of deciduous broad-leaved forests, since full sunlight in early spring can be utilized by their overwintering leaves. Leaf survival of gap species was presumed to be more flexible than that of forest understory species. Leaf survival of open-site species was considered to be a strategy to occupy the available open spaces as widely as possible.
Bertia moriformis and its varieties
Authors: Corlett Michael , Krug J. C.
Published: September 2008

Examination of Canadian, United States, and European collections of Bertia moriformis in DAOM, TRTC, and other herbaria revealed the existence of two distinct forms distinguished solely by differences in ascospore morphology and dimensions. Bertia moriformis var. moriformis occurs mostly on deciduous wood in Europe and North America and is characterized by narrow, uniseptate, straight to gently curved ascospores, 4.5–6.5 μm wide. Bertia moriformis var. latispora, described as new, occurs principally on coniferous wood; the collections with one exception are from North America. Within the ascus, the ascospores of var. latispora are indistinguishable from those of var. moriformis, but when mature and free of the ascus, they are wider, 6–8.5 μm, and geniculate. Germinating ascospores of var. latispora apparently become pluriseptate prior to germination. Bertia moriformis var. multiseptata Sivanesan, with multiseptate ascospores, is briefly redescribed and illustrated.
Effects of atmospheric fluorides on foliage, flower, fruit, and seed production in wild raspberry and blueberry
Authors: Staniforth R. J. , Sidhu S. S.
Published: September 2008

Reproductive and vegetative characteristics of raspberry and blueberry plants were monitored at six sites downwind from a phosphorus plant which emitted gaseous and particulate fluorides. Atmospheric fluoridation rates ranged from an average of 347.4 μg F∙dm−2∙week−1 (or 11.38 μg F∙m−1) at 1.4 km to 2.5 μg F∙dm−2∙week−1 (or 0.08 μg F∙m−3) at 18.7 km from the source. The highest fluoridation levels were in July, the month in which flowering in the two species reached its peak. At the most polluted site, flower mortality was 89% for blueberry and 78% for raspberry; this accounted for most of the loss in reproductive potential. Comparative values of the control site (18.7 km from source) were 27 and 26%, respectively. There were 21- and 10-fold decreases in seed production per plant in blueberry and raspberry, respectively, as well as significant decreases in the size, number, and dry weight of fruit. Fluoride damage to blueberry plants did not result in any effects being passed on to seedlings, except for a slightly accelerated germination rate. Fluoride accumulations in the foliage of plants 1.4 km from the source were 403 ppm for raspberry and 216 ppm for blueberry but only 8 and 9 ppm, respectively, at the control site. Fluoride-affected raspberry plants also showed foliar injury, enhanced vegetative spread, and delayed leaf fall in the autumn.
Haploid monokaryotic basidiocarp tissues in species of Armillaria
Authors: Peabody Robert B. , Peabody Diane Cope
Published: September 2008

Viable spores and ethanol-fixed basidiocarps of Armillaria species were collected at eight geographic localities within the northeastern United States. Crosses among haploid hyphae grown from isolated single spores revealed that three to five intersterility groups were represented in this sample. By using spores to establish expected quantities of DNA within haploid cells, fluorescence microspectrophotometric measurements of stipe hyphae fell within the haploid range in all eight geographic isolates. Haploid monokaryotic basidiocarp tissues are unexpected in Basidiomycetes and may indicate the existence of a new pattern for the distribution of genetic material among somatic cells.
Aquatic hyphomycete spora in 10 streams of New Brunswick and Nova Scotia
Authors: Bärlocher Felix
Published: September 2008

Aquatic hyphomycete communities of 10 soft-water streams in Nova Scotia and New Brunswick were investigated with a foam sampling technique. The number of identifiable species varied between 26 and 42. Alkalinity, conductance, pH, and content of Ca2+, Mg2+, Na+, and K+ were measured in all streams. No significant correlation was found between number of fungal species and any of the chemical parameters. Combining the data with those of an earlier study revealed a significant, negative correlation between species number of a stream and its pH. The number of aquatic hyphomycetes appears to decline slowly, if at all, between 5 and 7. This is followed by a more rapid loss at values above 7.
Floral induction in date palm seedlings (Phoenix dactylifera var. Deglet Nour) cultured in vitro
Authors: Ammar Saïda , Benbadis Abdellatif , Tripathi Bal Krishna
Published: September 2008

Flower bud initiation in 5-month-old seedlings of date palm (Phoenix dactylifera L. var. Deglet Nour) was studied under controlled conditions. Normally inflorescence formation in mature plants takes 8 to 10 years. In juvenile plants inflorescence formation was induced in a 16-h day at 28 °C, by a combination of 6-benzylaminopurine, indoleacetic acid, and glucose or sucrose. The present investigation has determined favourable cultural conditions for floral induction in date palm in vitro at a very early stage of ontogeny. Both male and female flowers were induced on young plants. Floral induction usually occurred only when root formation was completely inhibited. The apparent antagonism between root formation and floral development suggests a possible competition in the young plant for growth substances, although production of floral inhibitory substances from the root cannot be precluded. These observations on the induction of precocious flowering in date palm seedlings suggest a model of development, corresponding to neoteny, of this tree as an herb.
Marine fungi from Aldabra, the Galapagos, and other tropical islands
Authors: Kohlmeyer Jan , Volkmann-Kohlmeyer Brigitte
Published: September 2008

Saprobic higher marine fungi were collected in Aldabra (8 species, 1 variety), Galapagos (10 species), Hawaii (17 species), and Tobago (22 species). The material includes 26 ascomycetes, 1 basidiomycete, and 5 deuteromycetes. Lindra hawaiiensis (Maui) and Massarina thalassiae (Aldabra, Belize, Florida, Galapagos, India (Madras), Mexico (Baja California)) are new species. Distribution maps for the following species are presented: Cytospora rhizophorae, Didymosphaeria rhizophorae, Halosphaeria cucullata – Periconia prolifica, Lindra thalassiae, and Massarina thalassiae. Endemic marine fungi with saprobic modes of life have not been encountered.
Orchidaceous rhizoctonias from roots of nonorchids: mycelial and cultural characteristics of field and pot culture isolates
Authors: Milligan M. J. , Williams P. G.
Published: September 2008

This paper reports the field isolation of orchidaceous rhizoctonias similar to those found recently in pot cultures of vesicular–arbuscular endophytes. The paper describes the morphology and growth of field and pot-culture isolates on different natural and synthetic media and reports light microscope observations on the nuclei and septal pores of hyphal cells. All isolates were the same in regard to the utilisation of simple and complex carbohydrates and different forms of nitrogen. They were all multinucleate and had an inconspicuous septal pore. Consistent differences were found among isolates in the morphology and frequency of chlamydospores and monilioid hyphae and in the rate of growth, shape, type of margin, and colour of colonies. By using these criteria, the fungi were segregated into 10 entities. The observations are discussed in relation to the natural distribution of the fungi and their resemblance to other fungi in the form-genus Rhizoctonia.
Taxonomy of the Carex lenticularis complex in eastern North America
Authors: Standley Lisa A.
Published: September 2008

The Carex lenticularis complex is a morphologically, anatomically, and cytologically distinct subgroup within Carex sect. Phacocystis Dumort. This complex consists of two taxa in eastern North America, C. lenticularis Michx. var. lenticularis and C. nigra (L.) Reich. Although previous treatments have recognized five infraspecific taxa within C. lenticularis var. lenticularis and two within C. nigra, analyses of morphological data using histograms, clustering techniques, and principal components analysis indicate that both species are variable but monotypic in eastern North America. Distribution maps and illustrations of both taxa are provided. A new chromosome count for C. lenticularis var. lenticularis (2n = 86) is reported, and previous records for C. nigra (2n = 84) are confirmed. Although these species are sympatric over most of the range of C. nigra, no natural hybrids are known.
Microbouturage in vitro de jeunes poiriers issus de pépins de ‹Passe Crassane›
Authors: Maarri K. Al , Arnaud Y. , Miginiac E.
Published: September 2008

Vegetative multiplication of 'Passe Crassane' pear seedlings was obtained by micropropagation in vitro. Two clones (6 and 14) were selected on the basis of their rooting ability. This article describes optimal culture conditions to obtain a rate of multiplication greater than 6 shoots per month, together with good elongation, no morphological abnormalities, and a high degree of rooting, stable in time and of good quality.
Rooting of peatland black spruce and tamarack in relation to depth of water table
Authors: Lieffers V. J. , Rothwell R. L.
Published: September 2008

Rooting of Picea mariana Mill. BSP. and Larix laricina (Du Roi) K. Koch trees was examined in four peatlands with different depth of water table. Peat blocks, 60 cm deep, 1.0 m from the base of each tree, were excavated and sectioned into 10-cm horizontal strata and the roots extracted. The presence of and depth to frost and the depth of water table were determined on each peat block. The periodic annual increment in basal area of each tree was determined. Rooting depth was strongly correlated with depth to water table. On wet sites, roots of both black spruce and tamarack were confined to hummocks, while on dry sites, roots penetrated to 60 cm. The deep roots were generally <2 mm in diameter and held in frozen peat layers until late June. There was a strong positive correlation between fine root biomass and depth of water table; however, total root biomass was not correlated with depth to water table. In general, growth rates of both black spruce and tamarack were positively correlated with water table.
Effects of the lampricide 3-trifluoromethyl-4-nitrophenol on diatoms in two southern Ontario streams
Authors: Beamish F. W. H. , Jeffrey K. A. , Kolton R. J. , MacMahon P. D. , Kowalchuk K. A.
Published: September 2008

Diatom colonies were established on glass slides in Rouge River and Wilmot Creek before application of the lamprecide 3-trifluoromethyl-4-nitrophenol and their abundance was monitored for 21 and 55 d, respectively, after treatment. A total of 105 species of diatoms were identified from the Rouge River; of these, 23 were particularly abundant. Samples from Wilmot Creek yielded 80 species, of which 21 were dominant. Growth of the diatom community at the treated sites of Rouge River declined following chemical treatment, 8.7 mg 3-trifluoromethyl-4-nitrophenol per litre, but recovered within 21 d. Community structure and abundance in Wilmot Creek were not significantly altered by the addition of 5.3–6.7 mg 3-trifluoromethyl-4-nitrophenol per litre. No species identified from either stream exhibited particular sensitivity to the concentrations of 3-trifluoromethyl-4-nitrophenol applied. Temporal and spatial patterns of change are discussed.
An evaluation of statistical techniques for discriminating Picea glauca from Picea mariana pollen in northern Alaska
Authors: Brubaker Linda B. , Graumlich Lisa J. , Anderson Patricia M.
Published: September 2008

Two statistical procedures, linear discrimination and maximum likelihood discrimination, were evaluated for use in estimating percentages of Picea glauca and P. mariana pollen in lake sediments of northern Alaska. Each procedure is based on a comparison of the dimensions of unclassified Picea pollen grains with those of reference pollen of each species. The reference pollen collection in this study consisted of 675 P. glauca and 600 P. mariana grains, representing 51 trees at 24 sites in Alaska. The reference collection was divided into two approximately equal parts; one was used to derive the discriminant functions of each technique and the other was used to test the accuracy of each function on populations of known composition. The maximum likelihood procedure produced unbiased estimates across the entire range of test populations (P. glauca: P. mariana ratios ranging from 5:95 to 95:5). The linear discrimination estimates were strongly biased in favor of the less frequent species in populations having less than 25% of either species. We applied both techniques to measurements of Picea pollen in surface sediments of 62 lakes in the boreal forest of northern Alaska. Picea pollen percentages estimated by maximum likelihood discrimination more closely revealed the distribution of Picea trees in the landscape.
The cottonwood mushroom (Tricholoma populinum): a food resource of the Interior Salish Indian peoples of British Columbia
Authors: Turner Nancy J. , Kuhnlein Harriet V. , Egger Keith N.
Published: September 2008

Tricholoma populinum Lange is identified for the first time as one of the edible mushroom species traditionally eaten by Interior Salish Indian peoples of British Columbia. A description of this species is given, and harvesting and preparation information is provided based on its use by contemporary Native people. Nutrient composition data are also reported. This mushroom continues to be an important food source for some Native people in British Columbia.
Taxonomic studies of the Halosphaeriaceae: Ceriosporopsis, Haligena, and Appendichordella gen.nov.
Authors: Johnson R. G. , Jones E. B. Gareth , Moss S. T.
Published: September 2008

Five species of Ceriosporopsis and two species of Haligena of the Halosphaeriaceae have been examined histochemically and at the scanning and transmission electron microscope levels, as part of our review of the taxonomy of marine Pyrenomycetes (Ascomycotina). Three species are retained in Ceriosporopsis: C. halima Linder (the type species), C. cambrensis Wilson, and C. tubulifera (Kohlm.) Kirk in Kohlmeyer. The genus is characterised by an outer exosporic sheath through which mucilaginous appendages are released. Great variation exists in the origin of the polar appendages and in the structure of the exosporic sheath. Only one species is retained in the genus Haligena: H. elaterophora Kohlm., while a new genus, Appendichordella, is described for Haligena amicta (Kohlm.) Kohlm. et Kohlm.
Seasonal variations of growth in the red alga Chondrus crispus on the Atlantic French coasts. I. A new approach by fluorescence labelling
Authors: Chopin Thierry , Floc'h Jean-Yves
Published: September 2008

The seasonal variations of growth in Chondrus crispus Stackhouse were studied by using a vital, fluorescent, cell-wall stain called Cellufluor. In situ growth is not only apical but is extended at least to the upper half of the thallus; it is slow at the beginning of spring, increases towards the end, slows down at the beginning of summer, and increases again to reach a maximum in autumn. It is minimal during winter. The same pattern of growth occurs for the two dissimilar studied forms of the alga, although the rate is greater in the infralittoral than in the midlittoral form.
Evidence for relatedness between Puccinia graminis f.sp. secalis and P. graminis f.sp. tritici from two-dimensional polypeptide mapping
Authors: Kim W. K. , Howes N. K. , Martens J. W.
Published: September 2008

Two-dimensional electrophoretograms of detergent-soluble polypeptides extracted from dormant urediospores were used to compare interspecific and intraspecific relationships among nine races of rye stem rust (Puccinia graminis f.sp. secalis) and a hybrid between rye stem rust and wheat stem rust (P. graminis f.sp. tritici) and its parents. More than 280 polypeptides were detected in each race of rye stem rust. The nine races differed by one to five genes for virulence and by five to seven polypeptides, but these differences were not correlated. The rye–wheat stem rust hybrid, rye stem rust parent, and wheat stem rust parent differed by 12 polypeptides. The polypeptide patterns of the rye stem rust races were similar to those previously found for wheat and oat stem rusts. Rye stem rust and wheat stem rust had 270 polypeptides in common and differed by 17 polypeptides. In contrast, 92 polypeptides separated rye and oat stem rusts. The considerable homology in polypeptide patterns is consistent with the view that these three cereal stem rusts are related and that rye stem rust and wheat stem rust have the closest genetic relationship.
Fungi associated with halophytes of an inland salt marsh, Manitoba, Canada
Authors: Muhsin Tawfik M. , Booth Tom
Published: September 2008

Six halophytic plants including Atriplex patula, Glaux maritima, Hordeum jubatum, Puccinellia nuttalliana, Salicornia rubra, and Suaeda depressa were collected at various growth stages throughout the growing season of the summers 1982 and 1983 from an inland salt marsh at Delta, Man. Washed root and shoot pieces of each plant species were plated on culture medium, incubated, and surveyed for cauloplane and rhizoplane fungi. A total of 31 taxa were isolated including 3 asco-mycetes, 2 coelomycetes, 1 zygomycete, and 25 hyphomycetes. Morphological features, plant type, cultures, and taxonomic deposition are presented for each fungal taxon.
An experimental system for studying interrelationships between the embryo and megagametophyte of Pinus strobus during seed germination
Authors: Tabor Christopher A. , Barnett Neal M.
Published: September 2008

An experimental culture system was devised that provided a reliable means for conducting quantitative studies on interrelationships between embryos and megagametophytes of Pinus strobus L. during germination and early seedling development. By controlling imbibition rates, it was possible to synchronize germination of intact megagametophytes and obtain cultures with uniform morphological characteristics for use in biochemical studies. Early seedling development was affected by time of removal of the megamametophytes from the embryos; organs were larger if magagametophytes were left intact for longer periods of time. By using a nitrate reductase semimicro assay, enzyme activity was detected in embryos and shoots of intact megagametophytes, but activity declined as the seedlings aged. Activity within roots increased as seedlings matured and may be localized in the root tip. Nitrate was produced within the megagametophyte; however enzyme activity was dependent upon sustained, direct access to the inducing substrate, nitrate, in the culture medium. When megagametophytes remained intact for the initial 8 days of germination, seedlings developed epicotyls, and nitrate reductase activity within the roots was significantly greater than in 6-day cultures; in essence, by 8 days these seedlings appeared to have passed a threshold and were autotrophic.
Seasonal variation in foliar and bud monoterpenes in Sitka spruce
Authors: Brooks J. E. , Borden J. H. , Pierce Jr. H. D. , Lister G. R.
Published: September 2008

As part of a study on the relationship between the monoterpene composition of Sitka spruce, Picea sitchensis (Bong.) Carr., and resistance to the white pine weevil, Pissodes strobi Peck, seasonal differences in the relative monoterpene content of developing buds and 1-year-old foliage were followed. In 2nd-year foliage of four trees from the University of British Columbia Research Forest, Maple Ridge, B.C., α-pinene and camphene levels increased in May and returned to their original levels by September. Myrcene, isopentenyl isovalerate, and camphor levels decreased in May. Isopentenyl isovalerate and camphor levels increased over the summer, but myrcene continued to decline, offsetting rising levels of 3-carene and β-pinene. To obtain representative monoterpene distributions, foliar samples should be taken after September 30, when trees are dormant for the winter. There was significant developmental variation in buds from 20 trees from Say ward, B.C. α-Pinene and β-pinene were prominent initially and then declined, while myrcene increased to become the major volatile component of the elongating buds. β-Phellandrene levels declined and then increased as the season progressed. There was no significant difference in percent monoterpene composition between buds from resistant and susceptible trees.
Experimental hybridization of Palmaria palmata (Rhodophyta) from the northeast and northwest Atlantic Ocean
Authors: Meer John P. van der
Published: September 2008

Isolates of Palmaria palmata from the Canadian Maritimes and isolates of two varieties of P. palmata from Ireland (var. palmata and var. sobolifera) were crossed in pairwise combinations within and between these geographic locations. Crosses between plants from a single location always yielded normal tetrasporophytes and normal F1 gametophytic progeny; however, within the Irish group there was a complex phenotypic segregation for gametophytes from var. palmata × var. sobolifera hybrids. Robust "transatlantic" hybrids were obtained without difficulty in crosses between gametophytes from Canadian and Irish isolates. These hybrids had normal morphology and vigorous growth; however, their tetraspores were poorly viable, and those that germinated produced a variety of abnormal sporelings. In sporangia of the hybrid tetrasporophytes, the meiotic chromosomes were tangled in complex arrangements suggestive of multiple heterozygous chromosome rearrangements. Despite the complex chromosome pairings and abnormal sporelings, some genetic recombination was observed between a Mendelian mutation for green color and the sexual phenotype of the plant. It is concluded that the Irish and Canadian plants belong to a single species, but one that is in the process of splitting into sibling species as a consequence of geographic separation and the diverging karyotypes of its constituent populations.
Le cycle des Nostoc des genres Peltigera et Collema en cultures in vitro et dans le thalle lichénique
Authors: Boissière Jean-Claude , Boissière Marie-Claude , Champion-Arnaud Patrick , Lallemant Richard , Wagner Jean
Published: September 2008

The isolation and culture of Nostoc symbionts of four Peltigera and of Collema tenax has revealed the presence of a biological cycle. Our observations, taken in conjunction with those of other authors on free-living species, suggest that the photosymbiont of Peltigera canina, P. rufescens, P. horizontalis, and P. spuria is Nostoc punctiforme (Kütz.) Hariot, that of Collema tenax is Nostoc commune Vauch. In the lichen thallus, Nostoc is at the stage called "punctiforme." This stage stays stable as long as the thallus is undamaged. If wounding occurs, the opening of the polysaccharide sheath of the trichomes causes motile hormogonia to escape. These, in nature, colonize the squamuliform isidia of Peltigera praetextata and, in culture, they allow isolation of Nostoc strains from the lichens studied.
Growth response of goldenrod, Solidago canadensis (Asteraceae), to periodic defoliation
Authors: McBrien H. L. , Harmsen R.
Published: September 2008

Intensive grazing by Trirhabda spp. on the goldenrod, Solidago canadensis L., was simulated by manual defoliation experiments to estimate quantitatively the effects of various levels of grazing. Mean stem length per clump, measured as the sum of the lengths of the main stem and branches below the inflorescence, and the number of stems per clump were significantly reduced toward the end of the growing season. Inflorescence development was either retarded or prevented. By spring of the year following treatment, plants receiving repeated defoliation had both lower mean leaf biomass per stem and mean stem length and fewer stems per clump. There was also some clump mortality. These results corroborate the observation that repeated defoliation of Solidago canadensis during an outbreak of beetles of the genus Trirhabda is followed by a major reduction in goldenrod in old-field communities.
The structure of the stem endodermis in etiolated pea seedlings
Authors: Sack Fred D.
Published: September 2008

Differentiation of the endodermis was examined in third internodes of etiolated Pisum sativum L. cv. Alaska seedlings. The endodermis in young internodes contains large, sedimented amyloplasts; in older internodes, a casparian strip differentiates and the endodermis becomes depleted of starch except for the proximal region of the stem, which retains sedimented amyloplasts and remains graviresponsive. Sedimentation occurs in the hook but does not occur consistently until cells reach the base of the hook, where the axis becomes vertical, rapid cell elongation starts, and amyloplast diameter increases substantially. Contact between endoplasmic reticulum and amyloplasts was observed. Endoplasmic reticulum is not distributed polarly with respect to gravity. No symplastic or apoplastic blockages exist in the endodermis at the level of the stem where lateral gradients may be established during tropic curvature.
Larix laricina and Picea mariana: relationships among leaf life-span, foliar nutrient patterns, nutrient conservation, and growth efficiency
Authors: Tyrrell Lucy E. , Boerner Ralph E. J.
Published: September 2008

This study compared how two tree species with different leaf life-spans differ in their adaptations to low nutrient availability in a Wisconsin bog. Seasonal patterns of foliar nutrient concentration, nutrient resorption, leaching loss to simulated rainfall, and growth efficiency were determined for Larix laricina and Picea mariana during 1983 and 1984. Concentrations of foliar nitrogen and phosphorus in Larix leaves increased slightly during summer; this was followed by strong autumnal resorption. Calcium concentration of Larix leaves increased throughout the entire life-span of the leaves. Concentrations of nitrogen and phosphorus were highest in new (age-class 0) Picea leaves and declined with each successive leaf age-class, whereas calcium leaves increased in older leaf age-classes. Winter–spring resorption of nitrogen and phosphorus occurred from all age-classes of Picea leaves; this was followed by a summer increase in foliar nutrient concentrations. Resorption of nitrogen was greater in Larix than in Picea. There were no significant differences in phosphorus resorption or nutrient growth efficiencies between species. Foliar nutrient losses to leaching by artificial rainwater were less than 1% of the total foliar nutrient content. As there was no significant difference in the relative growth rates or growth efficiencies between the two species, the persistence of deciduous Larix in nutrient-poor bogs among species with longer leaf life-spans might be linked to its greater nitrogen conservation.
Patterns of branching and extension growth of vigorous saplings of Japanese Acer species in relation to their regeneration strategies
Authors: Sakai Satoki
Published: September 2008

The patterns of branching and extension growth of vigorous saplings of eight Japanese Acer species were studied in relation to gap sizes where they regenerate in late-successional forests. Three types were recognized: sympodial-spread type, elongate type, and monopodial-spread type. In the sympodial-spread type, long and short shoots do not occur, and the amount of extension growth is small. These characteristics are more adapted to producing an efficient photosynthetic surface area than height growth. Extension growth is determinate. Determinate species flush leaves simultaneously at budbreak, which ensures a long duration of photosynthesis in a year. This type regenerates in small gaps with its shade-tolerant growth mode. In the elongate type, long and short shoots occur, and the amount of extension growth is large. These characteristics are more adapted to height growth than producing an efficient photosynthetic surface area. Extension growth is indeterminate. Indeterminate species start rapid height growth earlier than determinate species. This type responds to the occurrence of gaps and regenerates in large gaps with this competitive growth mode. In the monopodial-spread type, long and short shoots do not occur, the amount of extension growth is large, and extension growth is indeterminate. This type regenerates in middle-sized gaps with a growth mode intermediate between the previous two types.
Seasonal growth of Laminaria groenlandica as a function of plant age
Authors: Druehl Louis D. , Cabot Eric L. , Lloyd Katherine E.
Published: September 2008

The seasonal growth of Laminaria groenlandica (Laminariales, Phaeophyta) on the west coast of Vancouver Island, B.C., Canada, was investigated as a function of plant age, using plants maintained at a constant depth on rope structures. First-year plants, which become macroscopically visible in March, had a delayed seasonal peak of maximum blade size relative to the older year classes (April–May) which initiated growth in January. This resulted from the 1st-year plants' lower susceptibility to distal blade erosion and prolonged net growth season. All year classes obtained their greatest wet weight at the same time (July–August). For 1st-year plants, this represented a balance between blade erosion and elongation; for older plants, storage product synthesis and blade thickening and elongation balanced against erosion appeared responsible for determining maximum biomass. The 2nd-year class dominated the other year classes in blade dimensions and few plants survived their 3rd year of growth. The instantaneous growth rates of L. groenlandica were most closely associated with temperature, followed by photon flux density, and changes in growth rates were associated with temperature and salinity.
Biomass-allocation patterns in populations of Trillium erectum and T. grandiflorum in southern Ontario
Authors: Chmielewski Jerry G. , Ringius Gordon S.
Published: September 2008

Biomass-allocation patterns to aerial tissues were examined among six populations for each of Trillium erectum L. and T. grandiflorum (Michx.) Salisb. in southern Ontario. Total biomass did not differ among populations of T. erectum, but androecial proportions and reproductive effort generally decreased from southwest to northeast. Total biomass of T. grandiflorum varied significantly among populations and its pattern of reproductive effort was the reverse of that of T. erectum. Androecium–gynoecium ratios decreased across southern Ontario from southwest to northeast for both species. These results suggest that there may be a shift from allogamy to autogamy in a northeasterly direction across southern Ontario.
Periodicity of epiphytes on Zostera marina in two embayments of the southern Gulf of St. Lawrence
Authors: Novaczek I.
Published: September 2008

Growing and cast leaves of Zostera marina were sampled from May through December and in February in two embayments of the southern Gulf of St. Lawrence to determine the species composition and temporal pattern of macroalgal epiphytes. Thirty-eight species were identified. Some occurred sporadically on Zostera while being present on other substrata throughout all or most of the growing season; other species were ephemeral, being discernible for only 1–3 months. A number of species overwintered on cast leaves. Four epiphytes, Eudesme, Desmotrichum undulatum, Leathesia difformis (all Phaeophyta), and Rhodophysema georgii (Rhodophyta) were studied in culture. The phenological patterns of these four species appeared to be governed by water temperature rather than day length.
Optimal conditions for the isolation and culture of protoplasts from a cell suspension culture of an isoleucine–valine-requiring auxotroph of Datura innoxia
Authors: Saxena Praveen K. , King John
Published: September 2008

Conditions have been standardized for obtaining high yields of viable protoplasts from cell suspension cultures of an isoleucine–valine-requiring auxotroph (IV-1) of Datura innoxia P. Mill. Isolation of protoplasts critically required the use of a salt solution, containing sodium chloride and potassium chloride (0.125 M each), as osmotic stabilizers. The yield, viability, and divisional activity of the protoplasts isolated with mannitol or sucrose were poor. Protoplast-releasing enzymes used to isolate IV-1 protoplasts could be used twice without any loss in the yield or viability of the protoplasts. Cultured protoplasts developed cell walls and underwent sustained divisions in a modified Murashige and Skoog medium enriched with organic acids. Pretreatment of isolated protoplasts with glycine (0.1 M) and calcium chloride (0.05 M) prior to culture increased the frequency of cell colony formation. Protoplast-derived cells developed calli on transfer to agar-solidified medium.
The germination of Tmesipteris spores
Authors: Whittier Dean P. , Given David R.
Published: September 2008

Spores of Tmesipteris elongata Dang, germinated in axenic culture on a nutrient medium containing mineral elements and 0.2% glucose after 8 months in the dark. No spores germinated in cultures kept in the light. Initiating germination, the monolete laesura (scar) split in the middle. As the laesura ruptured to its ends, the cell bulged out. The first division was perpendicular to the polar axis of the spore and formed distal and proximal cells. At one end of the proximal cell, brown materials accumulated in the wall. Transfer of the two-celled gametophyte to new media did not support further growth.
Étude ultrastructurale des modifications induites par Exserohilum turcicum chez le limbe de Zea mays – Effet du gène de résistance Ht-1
Authors: Gélie B. , Petitprez M. , Souvre A. , Albertini L.
Published: September 2008

Ultrastructural changes induced by Exserohilum turcicum (Pass.) Leonard et Suggs in maize leaf cells are observed 24 to 72 h after inoculation, in a comparative study between two isogenic lines with or without the Ht-1 gene. In the susceptible plants (without Ht-1), the plasmalemma and the tonoplast of the mesophyll cells are the first cellular components altered, followed by disorganisation and alteration of organelles, which become scattered throughout the cell. Chloroplasts in particular seem to be very sensitive to the toxic action of the pathogen, which causes disruption of their envelope and grana. Bundle sheath cells are altered later and to a lesser extent than the mesophyll cells. In Ht-1 monogenic resistant inbred lines, cytoplasmic residues of prematurely dead cells surround healthy mesophyll cells protecting them and stimulating their activity and resulting in stabilization of the pathotoxic process 36 to 48 h after inoculation.
An evaluation of Fusarium oxysporum from crucifers based on pathogenicity, isozyme polymorphism, vegetative compatibility, and geographic origin
Authors: Bosland Paul W. , Williams Paul H.
Published: September 2008

A global collection of 123 putative isolates of Fusarium oxysporum from crucifers was examined for pathogenicity, isozyme polymorphism, and vegetative compatibility. Of these isolates, 103 were found to be pathogenic on one or more of six differential crucifer cultivars. Three patterns of isozyme polymorphism (electrophoretic types) were found and by means of a nitrate reductase complementation test, three major vegetative compatibility groups were identified that could differentiate among the F. oxysporum pathotypes. Complete correspondence was found among pathotype, electrophoretic type, and vegetative compatibility. It seems appropriate to classify isolates from the Cruciferae into the subspecific taxa, F. oxysporum f.sp. conglutinans, F. oxysporum f.sp. raphani, and F. oxysporum f.sp. matthioli, based on their naturally infected host species, Brassica oleracea, Raphanus sativus, and Matthiola incana, and on estimates of genetic identity. Within formae speciales, races can be identified based on intraspecific host specialization. Geographic origin was not found to be associated with the vegetative compatibility, isozyme phenotype, or pathotype. Isozyme polymorphisms also differentiated among four F. oxysporum formae speciales from other host families and among various Fusarium species.
Ultrastructure of the Lagena radicicola zoospore, including a comparison with the primary and secondary Saprolegnia zoospores
Authors: Barr Donald J. S. , Désaulniers Nicole L.
Published: September 2008

The zoospore fine structure of Lagena radicicola Vanterpool & Ledingham is compared with the primary and secondary zoospores of Saprolegnia diclina Humphrey. The L. radicicola zoospore is broadly pyriform, it has two subapically attached flagella, a pyriform nucleus that has a fine fibrillar attachment to the posterior kinetosome, and a Golgi body next to the nucleus. There are various vesicles including dense body vesicles and several small expulsion vacuoles but there are no U- or K-bodies. It has a well-organized rootlet system comprising anterior and posterior doublet microtubules, a ribbed triplet that probably provides a cytoskeletal frame for the plasmalemma, and a multistranded, band-shaped rootlet of 4 to 10 microtubules. Cytoplasmic microtubules are very sparse. Interpretation of the rootlet systems was aided by computer graphics; 3-D images of the rootlet system were produced as stereo pairs on a Kontron image analyzer. Based on cell shape, position of the flagella, and angle of kinetosomes classification of the L. radicicola zoospore as either a primary or secondary type is imprecise; however, the various kinds of rootlets are similar to those found in the secondary zoospore of S. diclina but differ in structural detail and orientation. The transition zone in the flagellum of L. radicicola is simple and lacks the typical concertina body found in most oomycete flagella. The relationship of L. radicicola to the Oomycetes and various heterokont algal groups, based on comparative zoospore ultrastructure, is discussed.
Selection for a specific tobacco mosaic virus variant during bolting of Nicotiana sylvestris
Authors: Khan Iqrar A. , Jones Gary E.
Published: September 2008

In an isolate of tobacco mosaic virus, TMV U1, a small subpopulation of virus that invokes the hypersensitive reaction on Nicotiana sylvestris Spegaz. & Comes exists and is strongly selected for during replication in plants that are undergoing development of shoot axes during bolting. Virus of this phenotype (NL) can infect and move systemically in rapidly developing parts of N. sylvestris plants and is strongly selected for in upper tissues of the plants only during the development of the shoot axis. This selection results in a dramatic change in the genetic composition of the virus population in the upper part of the plant. No accumulation of NL-type virus occurred when N. sylvestris plants were inoculated with TMV204, a clonal population derived from RNA transcripts of a plasmid carrying a cDNA copy of the TMV genome.
Mechanism and pattern of spore release by Endocronartium harknessii
Authors: Chang Kan-Fa , Blenis P. V. , Hiratsuka Y.
Published: September 2008

Hourly measurements of spore release by Endocronartium harknessii (J. P. Moore) Y. Hiratsuka on Pinus contorta Doug. var. latifolia Engelm. were obtained during 2 years. Two spore traps were placed beside both of two sporulating galls and electronic data loggers were used to record environmental data. On rainless days, most spores were trapped between 0900 and 2200, when vapor pressure deficit, temperature, light intensity, and wind velocity were high. A similar pattern of spore release occurred under simulated daytime and nighttime conditions in a growth chamber. On rainy days, most spores were released, on average, over a longer time interval than on dry days. Within 9 h of being placed in a dew chamber, the previously intact peridia on a single gall had ruptured, presumably from pressure caused by spore production. Further evidence that spore production is stimulated by low vapor pressure deficit was obtained by moving 11 galls alternatively between humid and dry conditions. Thus, it is proposed that the diurnal periodicity of spore release on dry days results from the production of spores during the night and the subsequent passive release of those spores during the next day.
Temperature control of dormancy and germination in embryos isolated from seeds of dormant and nondormant lines of wild oats (Avena fatua)
Authors: Sawhney Ramma
Published: September 2008

The question of whether the embryo is the site of the observed effect of low and high temperatures during seed maturation on the final dormancy of ripe seeds of wild oats (Avena fatua L.) was investigated. Embryos isolated from seeds of dormant lines germinated within 2–3 weeks of incubation at an optimum temperature (4 °C), irrespective of maturation temperature. However, whole seeds were dormant for several months except for the temperature-sensitive line, AN 86, where relatively high maturation temperatures significantly reduced the period of primary dormancy. There was no difference between the germinative capabilities of embryos isolated from the temperature sensitive AN 86 and the relatively less sensitive line AN 51. Thus, the mechanisms underlying the dormancy of whole seeds, as well as the temperature effects on dormancy, do not appear to reside within the embryo. Further experiments were conducted to resolve the apparent discrepancy between earlier conclusions that embryos of dormant wild oats are dormant and the present findings that they are not. The earlier hypothesis was based on lack of germination in embryos of a nonlocal line, Montana 72, incubated at 20 °C. In the present study, embryos of Montana 72 were not dormant when incubated at 4–12 °C, but were induced to thermodormancy when incubated in temperatures above that range. Embryos of local lines (AN 265, AN 51, and AN 86) germinated readily at all temperatures below 24 °C, but showed thermodormancy above it. Thus, isolated embryos of dormant lines are capable of germination at optimum temperatures, but are thermodormant at relatively high temperatures.
Les bruyères in vitro. VII. pH du milieu de culture et morphogenèse de L'Erica ×darleyensis. Méthode d'interprétation des données
Authors: Beaujard F. , Viémont J. D.
Published: September 2008

Erica ×darleyensis grown in vitro presents a rhythmic growth. A method of study has been devised to relate the pH evolution of the culture medium and plant development. We found this method useful for proper interpretation of the influence of pH on our cultures.
Zoospore encystment pattern and germination on onion roots, and the colonization of hypodermal cells by Pythium coloratum
Authors: Shishkoff Nina
Published: September 2008

The behavior of the fungus Pythium coloratum Vaartaja on onion (Allium cepa L.) roots with a hypodermis of long and short cells was studied. Frequency of encystment adjacent to long versus short cells was compared in live and heat-killed roots. To determine whether the state of suberization of hypodermal cells was correlated with the number of zoospores encysting next to the cell, roots on which zoospores had encysted were stained with toluidine blue to quench most autofluorescence except that caused by lamellar suberin. Penetration of fluorescent long cells, nonfluorescent long cells, and nonfluorescent short cells was compared. Encystment of zoospores on the onion epidermis was more frequent adjacent to short cells of the hypodermis than could be expected for random encystment. More zoospores encysted next to short cells on heat-killed roots than on live roots. Encystment was more frequent over nonfluorescent long cells than over fluorescent long cells. Penetration by the fungus was more frequent into short cells and nonfluorescent long cells than into fluorescent long cells.
Alteration of ethylene synthesis in cucumber seedlings by triadimefon
Authors: Abbas S. , Fletcher R. A. , Murr D. P.
Published: September 2008

Etiolated cucumber seedlings grown from seeds pretreated with 5 μg∙mL−1triadimefon (1-(4-chlorophenoxy)-3,3 dimethyl-1-(1H-1,2,4-triazol-1-yl)-2-butanone) exhibited a marked reduction in both ethylene (C2H4) production and endogenous 1-aminocyclopropane-1-carboxylic acid (ACC) levels. Most of this reduction could be accounted for by a twofold drop in C2H4 production and fivefold drop in ACC content of root tissue. Roots of control seedlings efficiently converted exogenous ACC to C2H4, but the ability of triadimefon-treated roots to convert ACC to C2H4 was impaired. However, triadimefon-treated shoots and cotyledons were nearly twice as efficient in utilizing exogenous ACC and metabolizing it to C2H4 as control tissues.