bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal changes in the water balance of Douglas-fir (Pseudotsuga menziesii) seedlings grown under different light intensities
Authors: Drew Allan P. , Ferrell William K.
Published: November 2007

The water relations of germinant seedlings of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) grown outdoors under 9, 44, and 100% full light were analyzed during the summer, autumn, and winter seasons. Empirical regression models, based on the relationship plant water potential = f(soil water potential, leaf conductance), were determined for selected light treatment – season combinations. Plant water potential is higher during active summer shoot growth than after elongation growth has ceased in the autumn owing to earlier stomatal closure in response to soil drought in summer compared with a more abrupt closure at a lower plant water potential in the autumn.For all light treatments, leaf conductance declined in the winter independent of plant water potential and simultaneously with the onset of subfreezing air temperatures. During the first winter, water potential of seedlings was higher than during the previous summer or autumn over a wide range of equivalent soil water potentials.Seedlings grown under low light intensity are less drought resistant and have lower plant water potential than those grown under full light regardless of soil moisture status.
Ultrastructure of laticifers in redifferentiated organs on callus from Papaver somniferum (Papaveraceae)
Authors: Nessler Craig L. , Mahlberg Paul G.
Published: November 2007

Callus was initiated from seedling hypocotyls and mature stems of Papaver somniferum and maintained in culture. The ultrastructure of callus cells resembled parenchyma of intact plants, their most conspicuous feature being a large central vacuole. Meristemoids were formed at random on the surface of calli transferred to the appropriate medium. In cross section, meristemoids appeared as an inner meristematic region surrounded by several layers of concentrically arranged cells. Cells of meristemoids were smaller, more densely cytoplasmic, and more compactly arranged compared with callus. Roots and shoots induced to form from callus possessed cells that were morphologically and developmentally similar to laticifers in intact plants. Laticifers in redifferentiated organs, like those in intact plants, contained numerous capped vesicles that are apparently derived from stacked endoplasmic reticulum. Cell wall perforations between adjacent laticifer elements in redifferentiated organs developed by the gradual, simultaneous thinning of walls at the perforation sites.
Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv. Dramatic (Compositae). I. Development and morphology
Authors: Vermeer Janet , Peterson R. L.
Published: November 2007

Floral apices of Chrysanthemum morifolium cv. Dramatic form glandular trichomes on the receptacle in interfloret positions and on the corolla tube above the constriction subtended by the ovary. The glandular trichomes in both positions are initiated by the enlargement of single epidermal cells followed by a single anticlinal division and a series of periclinal divisions resulting in a 10-celled biseriate structure. Receptacular trichomes develop while florets are being initiated on the flanks of the floral apex and by the time petal primordia are initiated these trichomes are mature. Glandular trichomes on the corolla tube are initiated on peripheral florets while florets are still being initiated in a centripetal direction. Each glandular trichome has a cuticular covering beneath which secreted materials accumulate, thereby distending the cuticle. A large pore eventually forms in the cuticle and presumably allows the escape of secreted substances.
Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv. Dramatic (Compositae). II. Ultrastructure and histochemistry
Authors: Vermeer Janet , Peterson R. L.
Published: November 2007

Glandular trichomes on the inflorescence of Chrysanthemum morifolium cv. Dramatic are initiated from a single epidermal cell outgrowth and develop through an anticlinal division and a series of periclinal divisions to form a biseriate multicellular structure. Cells of the young trichome contain a large nucleus with prominent nucleoli and few small cellular organelles. Prior to the secretory stage, numerous ribosomes, polyribosomes, and dictyosomes are present in a dense cytoplasm but most of the dictyosomes are lost as secretion commences. Plastids in the stalk cells senesce but in a different manner than those in the upper tiers of secretory cells. Lipoidal substances form in the degenerating plastids. Cell wall ingrowths and the deposition of a flocculent material in the primary cell wall characterize secretory hairs. In very old hairs cellular lysis takes place with mitochondria being the last cellular organelle to remain intact. The secreted material, which collects in a subcuticular space, appears to be a terpenoid. The function of this material is not known.
Growth of bean cells in suspension culture in the presence of NaCl and protein-stabilizing factors
Authors: Gale J. , Boll W. G.
Published: November 2007

Sensitivity of Phaseolus vulgaris to NaCl was much lower in cell suspension than in whole plant cultures. At levels of −4 bars, growth (dry weight accumulation) was decreased by about 40% during the first 9 days. Growth of whole plants was decreased 70% by −2 bars NaCl. There was a small but not statistically significant stimulation of cell culture growth at levels of NaCl between −0.5 and −1.0 bars. (These values are in addition to the −3.5 bars of the standard culture solution itself.)Growth of cells in the control medium stopped at the end of 10 days but continued in the salinized cultures, reaching the level of the controls at about day 13. After six passages in saline medium, there was no evidence of increased tolerance to salt. Sensitivity increased, although subsequent growth in nonsaline medium was not affected.This system was used for assaying the effect of various antioxidants, vitamins, hormones, and amino acids on salt damage at the cellular level. At the concentrations assayed, these materials had either no effect or were toxic.
Ultrastructure of wilt syndrome caused by Verticillium dahliae. VI. Interpretive problems in the study of vessel coatings and tyloses
Authors: Robb Jane , Smith A. , Brisson J. D. , Busch Lloyd
Published: November 2007

When leaves of Verticillium dahliae infected chrysanthemums and sunflowers show symptoms, many of the xylem vessels in the petioles are occluded by tyloses or, partially, by vessel coating materials. Four different cytological techniques are used to study these occluding structures: (1) SEM observation of bulk material fixed in glutaraldehyde and OsO4; (2) TEM observation of thin, monitored cross sections fixed in glutaraldehyde and stained and stabilized with FeCl3; (3) TEM observation of bulk material fixed in glutaraldehyde–acrolein and OsO4; (4) SEM observation of bulk material fixed in glutaraldehyde and stabilized with FeCl3. Three different kinds of coating materials are described: (1) smooth coating (type 1), (2) fibrillar coating (type 2), and (3) bubbly coating (type 3). A possible fourth type of coating is tentatively described as irregular coating (type 4). It is concluded that accurate identification of tyloses and coating materials is impossible with currently used techniques. The interpretational problems encountered at the various levels of microscopy (i.e., LM, SEM, and TEM) are summarized.
Another conidial state for a species of Chaetosphaeria
Authors: Barr Margaret E. , Crane J. L.
Published: November 2007

Chaetosphaeria aspergilloides sp.nov. is described and illustrated from material collected in Mexico. The conidial state of this species belongs to the genus Cuslingophora.
Erratum: Light and electron microscope studies on cell wall breakdown in American elm xylem tissues infected with Dutch elm disease
Authors: Ouellette G. B.
Published: November 2007

On page 2678, the section beginning on line 31 of the left-hand column should read "Such a mass (Fig. 58) is bound by a thin band of fibrillar-like material, apparently continuous at times with similar material within the mass (Fig. 58B, broken arrow); at one end (point a), it is abutted by material characteristic of intercellular spaces, and at the other (point b), it seems to encroach on the primary wall of the adjacent cell (Fig. 58A). Some of the masses may show signs of cleavage demarcated by bands of less opaque material sometimes continuous with the denser outer material (Fig. 60)."
Papilla response of barley epidermal cells caused by Erysiphe graminis: rate and method of deposition determined by microcinematography and transmission electron microscopy
Authors: Zeyen Richard J. , Bushnel W. R.
Published: November 2007

Papillae were deposited in barley epidermal cells directly beneath appressoria of Erysiphe graminis f. sp. hordei and appeared as hemispherical, internal wall appositions. The papilla response began shortly after the formation of a rapidly moving cytoplasmic aggregate beneath the appressorium. As documented in coleoptile tissue by time-lapse light microcinematography, the papillae grew rapidly for 20–30 min after becoming visible, their radii increasing by 0.1 μm/min. For small papillae, deposition continued for about 30 min; for larger papillae, deposition continued for 120–180 min. Results with transmission electron microscopy on leaf epidermal cells suggested that papilla deposition by host cytoplasmic aggregates can be divided into four sequential stages: (i) the deposition of osmiophilic (lipidic) materials, (ii) the deposition and partial compaction of nonosmiophilic, amorphous material (probably insoluble polysaccharides), (iii) compaction of nonosmiophilic, amorphous material, and (iv) the incorporation of osmiophilic material into the host wall and into the compacted nonosmiophilic, amorphous material. At maturity, the papillae are hardened, electron-opaque wall appositions that may be effective in preventing fungal penetration and development. Failure of papillae to prevent fungal penetration and development may be related to the inability of the epidermal cells to complete the entire sequence of events in papilla deposition before attempted fungal penetration.
Gradient analysis of bryophytes in Jasper National Park, Alberta
Authors: Lee Thomas D. , La Roi George H.
Published: November 2007

Patterns of bryophyte community characteristics, including absolute cover and alpha diversity, and the response patterns of important bryophyte species are described in relation to complex gradients of elevation and moisture in the Canadian Rocky Mountains east of the Continental Divide. Thirty stands including grasslands, wetlands, forests, rock outcrops, and tundra were quantitatively sampled for bryophytes using 50 10 × 100 cm quadrats in larger 10 × 50 m macroplots. Direct gradient analysis, using elevation as the first axis and synthetic moisture index derived from moisture indicator values of vascular species as the second axis, was used to depict the similarity relationships among stands and the response patterns of bryophyte communities and species. Bryophyte community cover is low in xeric sites and high in mesic and hygric sites, reaching a maximum of 70% in Pieea engelmannii – Abies lasioearpa forests of the subalpine zone. Bryophyte species richness of stands is positively correlated with the number of substratum types per stand; on the most abundant substratum per stand, it is positively correlated with elevation. Habitat breadth and overlap were measured for important species. Most species habitats are narrow along the moisture gradient and broad along the elevation gradient. Species with similar habitats are usually different in their substratum affinities, but notable exceptions occur.
Antiviral activity of Boerhaavia diffusa root extract and the physical properties of the virus inhibitor
Authors: Verma H. N. , Awasthi L. P.
Published: November 2007

The aqueous extract of air-dried roots of Boerhaavia diffusa shows broad-spectrum antiviral activity and no phytoxic effects. Infection by four viruses was completely prevented, at treated and nontreated sites, when the extract was applied on two basal leaves of host plants 24 h prior to virus inoculation. This inhibition was completely reversed by the application of actinomycin D on treated leaves within 6 h of extract treatment and partially reversed within 18 h. The crude extract from resistant leaves contained an inhibitor of virus infection.The inhibitor in the root extract was partially active up to a dilution of 1:500, was completely inactivated at 95 °C for 10 min, and survived at room temperature for 20 days. The expression of inhibitory activity was prevented when the treated plants were exposed to temperatures beyond 35 °C. The inhibitory principle in the extract was nondialyzable and insoluble in organic solvents, viz., petroleum ether, solvent ether, chloroform, and benzene. It was adsorbed by animal charcoal, wood charcoal, and celite, and was precipitated by ammonium sulphate (90%), ethanol (50%), and cold trichloroacetic acid (10%). The inhibitor was not sedimented at 120 000 × g for 120 min. Further characterization is being done for positive identification of the inhibitor.
Further analytical and experimental studies on the shoot apex of Helianthus annuus: variable activity in the central zone
Authors: Davis E. L. , Rennie Patricia , Steeves Taylor A.
Published: November 2007

The cytologically distinctive central zone of the vegetative shoot apex of Helianthus annuus L. cv. Peredovic has a mitotic frequency considerably lower than that of the surrounding peripheral zone in intact plants. Apices excised and grown in culture for 5 days before being supplied with [H3]thymidine reveal a correspondingly low level of DNA synthesis in the central zone when autoradiographed. In similarly cultured apices, mitotic activity in the central zone is less than that recorded for intact plants. Labelling immediately after excision of the apex indicates that the central zone cells are activated by the operation and quiescence returns during the following 5 days. This activation is confirmed by mitotic counts 2 days after excision. The removal of only two young leaves from the apical buds of otherwise intact plants results in a comparable stimulation of mitotic activity in the central zone. These observations cast doubt upon the significance of mitotic activity in living shoot apices when these have been exposed for observation by removal of leaves. They also raise questions about the validity of labelling techniques which involve the partial dissection of the shoot apex.
Flower cold hardiness: a potential determinant of the flowering sequence exhibited by bog ericads
Authors: Reader R. J.
Published: November 2007

In laboratory freezing trials, cold hardiness of six types of bog ericad flowers differed significantly (i.e., Chamaedaphne calyculata > Andromeda glaucophylla > Kalmia polifolia > Vaccinium myrtilloides > Ledum groenlandicum > Vaccinium macrocarpon) at air temperatures between −4 and −10 °C but not at temperatures above −2 °C. At the Luther Marsh bog in southern Ontario, low temperatures (−3 to −7 °C) would select against May flowering by the least cold hardy ericads. Availability of pollinators, on the other hand, would encourage May flowering by the most cold hardy species. Presumably, competition for insect pollinators has promoted the diversification of bog ericad flowering peaks, while air temperature, in conjunction with flower cold hardiness, determined the order in which flowering peaks were reached.
Structures of the motile cells of Coelomomyces psorophorae and function of the zygote in encystment on a host
Authors: Travland Linda B.
Published: November 2007

Coelomomyces psorophorae is an aquatic fungus in the order Blastocladiales. Its motile zoospores and zygote transmit this pathogen to its copepod and mosquito larval hosts, respectively. In copepods, the fungal mycelium gives rise to isogametes, which fuse to form zygotes.The fine structure of the motile cells: zoospore, isogamete, and zygote, is reported. Morphology is compared with spore structure of other fungi in the order, and a model is proposed for a blastocladialian parasitic spore type. Features of this parasitic spore include close mitochondrial–nuclear contact, asymmetrical nucleus, internal axoneme, vestigial kinetosome lacking, and presence of adhesion vesicles.Encystment of zygotes on the cuticle of larvae of the mosquito Culiseta inornata appears to involve secretion of the contents of adhesion vesicles. Subsequent events include cell wall formation and dedifferentiation of specialized zygote structures.
Germination and decreased growth of Kochia scoparia in relation to its autoallelopathy
Authors: Lodhi M. A. K.
Published: November 2007

The autotoxic properties of Kochia scoparia phytotoxins on its germination and on radicle and seedling growth were studied. Inhibition of seed germination, a commonly known allelopathic phenomenon, did not occur and seeds reached close to 100% germination within 24 h when tested against different phytotoxins isolated from Kochia leaves regardless of the concentrations applied. Similarly, the radicle length of Kochia seeds measured was not significantly affected. However, when radicles were allowed to grow for an extended period of time in various concentrations of isolated phytotoxins, their length was significantly reduced in almost all cases. Such autotoxic growth retardation patterns were more pronounced in 10-day-old seedlings. It appears that Kochia phytotoxins do not inhibit germination but retard growth later, which also supports the high density but drastically reduced growth of Kochia in its 2nd year of revegetation in the field. The autotoxins isolated and identified from Kochia leaves were phenolics and flavanoids.
An analysis of the effects of gibberellic acid on the leaflet structure of dwarf cultivars of pea (Pisum sativum)
Authors: Israelstam G. F. , Davis Erica
Published: November 2007

The effects of gibberellic acid (GA3) on the penultimate leaflets of dwarf and normal cultivars of pea were investigated. In control plants, the leaflets of the dwarf were heavier, thicker, and had a smaller surface area than the normal. Epidermal and palisade cells of the dwarf were longer than those of the normal cultivar and the dwarf had longer spongy mesophyll cells and more layers of spongy mesophyll than the normal, with fewer intercellular spaces.Application of GA3 to dwarf plants increased leaflet surface area and length of epidermal cells, while leaflet weight and thickness and the number of layers of spongy mesophyll cells decreased. No significant changes in the leaflet of the normal cultivar were induced by GA3.The overall effect of GA3 application to the dwarf cultivar was to induce a degree of differentiation in the penultimate leaflets such that they tended to resemble more closely those of the normal cultivar.
La végétation forestière du cap Saint-Jacques, île de Montréal, Québec
Authors: Bouchard André
Published: November 2007

As part of a study of the forest vegetation of the Island of Montreal, 10 stands of deciduous hardwoods of Cap Saint-Jacques were sampled with the quarter method. Indirect ordinations indicate that the floristic organization of these urban forests is mainly due to surficial deposits and moisture regime in addition to the types and the intensity of disturbances.
Satureja gilliesii, a poikilohydric shrub from the Chilean mediterranean vegetation
Authors: Montenegro Gloria , Hoffmann Alicia J. , Aljaro Maria Ester , Hoffmann Adriana E.
Published: November 2007

Satureja gilliesii is a small shrub, representative of the Chilean mediterranean vegetation found on arid slopes and on partially degraded soils. It has two types of branches: dolichoblasts with winter leaves and brachyblasts with smaller spring leaves. The leaves are mesophytic and no stomatal control is detectable. Dolichoblast leaves are shed at the beginning of drought but the brachyblast leaves that have become dry and brownish remain attached to the plant. Even while the plant undergoes a severe water stress, these leaves survive throughout the drought period in a state of marked dehydration. After the first winter rain, they become turgid and regain a green color. Thus, S. gilliesii shows a poikilohydric behavior such as that described for some angiosperms.
Pithoascus intermedins from seeds of Vaccinium angustifolium
Authors: Gourley C. O. , Nickerson N. L.
Published: November 2007

Pithoascus intermedius was isolated for the first time from seeds of lowbush blueberry, Vaccinium angustifolium. The low rate of germination of infected seeds suggested that the fungus may have been pathogenic on the host.
Developmental anatomy of the achene in Cannabis
Authors: Prakash N. , Bohm Lesley R. , Maze Jack
Published: November 2007

Anatomy of the achene is studied in four varieties of Cannabis sativa (sativa, spontanea, indica, and kafiristanica) at different stages of its development from the ovary. The nucellus undergoes extensive curvature soon after fertilization so that the campylotropous ovule assumes an ana-amphitropous form. The endosperm is nuclear and shows a permanently coenocytic haustorial caecum. The embryo, when mature, is curved and dicotyledonous and occupies most of the space in the seed. The cotyledons enclose a set of well formed plumular leaves. Stored food is present in cells of both the radicle and the cotyledons and also in one to several layers (depending on position) of the endosperm. The seed coat has little or no protective role in the propagule but chloroplasts are formed in it soon after the globular embryo stage. In the pericarp, it is the endocarp layer that undergoes the most striking transformation; the cells show gross enlargement and extensive cell wall modification and thickening. The layer which lies immediately above the endocarp as well as the epicarp also show wall thickening but no significant increase in cell size. A careful comparison at identical stages among the four varieties reveals no significant difference is achene development.
Alleles of the incompatibility factors of Typhula ishikariensis
Authors: Bruehl G. W. , Machtmes R.
Published: November 2007

We identified 16allelesof the A and 17of the B incompatibility factors within 18 dikaryons of T. ishikariensis, a tetrapolar basidiomycete. A 1:1 ratio of alleles of the A and B incompatibility factors was previously reported for T. idahoensis and for T. incarnata.
Fungal populations from forest soils in southern Quebec
Authors: Widden Paul
Published: November 2007

The fungal populations of four forest soils in southern Quebec were studied, using the soil-washing technique. Although the four forests were located on the same basal materials, the effects of planting different tree species were reflected by changes in the chemical properties of the soils. Of the fungi isolated from these soils, Gliocladium roseum, Paecilomyces carneus, P. fumosoroseus, Gliomastix murorum, Penicillium implication, P. spinulosum, P. thomii, Trichoderma hamatum, and two unidentified Trichoderma species preferred the more neutral, deciduous forest soils. However, Chrysosporium pannorum, Penicillium janthinellum, P. simplicissimum, Trichoderma viride, T. polysporum, and another unidentified Trichoderma preferred the more acidic coniferous forest soils. For other species of fungi no differences between populations in the four sites could be detected. It is concluded that a clearer understanding of the ecology of these fungi requires a more detailed analysis of the influence of seasonal and spatial changes in their physical and chemical environment on their population densities.
Lipids in Sphagnum mosses of various ages
Authors: Karunen Pirjo , Mikola Heikki , Linko Reino , Euranto Erkki K.
Published: November 2007

The lipid content in the annual increments of different ages (1 to 5 years) of Sphagnum fuscum (Schimp.) Klinggr., S. angustifolium (Russow) C. Jens., and S. papillosum Lindb. has been determined by thin-layer chromatography. It was highest in the youngest portion of the moss shoot, ranging from 4.8 to 5.2% of the dry weight and decreased with increasing age to about 40–60% of the original value.The main lipid fractions of the youngest section, the capitulum, of the S. fuscum shoot were steryl and wax esters, triglycerides, and more polar lipids and accounted for 0.4, 0.3, and 3.5%, respectively, of the dry weight. The amounts of these lipids were found to decrease during senescence at independent rates.
Chemosystematic studies in the genus Pinus. III. The leaf oil terpene composition of lodgepole pine from the Yukon Territory
Authors: Rudloff E. von , Nyland E.
Published: November 2007

The leaf terpenes of 95 lodgepole pines from the Yukon and Northwest Territories, as well as those of 30 typical shore pines from more southerly locations, were analyzed by gas–liquid chromatography. The terpene patterns of the northern trees were compared with the known patterns of lodgepole pine from the Rocky Mountains (types B and C) and that of the shore pine (type A). Many trees from northern locations (including nunataqs that were refugia during the last ice age) had the type A terpene pattern of the shore pine and a few had the rare type C or intermediate (A–B, B–C) patterns. The implications for further lodgepole pine population studies by means of leaf oil terpenes analysis are discussed.
Flower-visitors, nectar production, and inflorescence size of Asclepias syriaca
Authors: Willson M. F. , Bertin R. I.
Published: November 2007

Spatial and temporal variation in insect visitation rates are analyzed with respect to nectar production and inflorescence size of Asclepias syriaca L., the common milkweed. Nectar sugar production peaked in the afternoon and evening but this trend was not paralleled by visitations of native insects (either vectors or thieves). The main pollinia vectors were noctuid moths at night and honey bees (Apis mellifera) in the afternoon. Vector visitation rates were highest at the beginning (native species) or middle (total vectors) of the blooming season, declining markedly toward the end, probably as a result of decreasing frequencies of A. syriaca flowers. Large inflorescences attracted more vectors and more thieves and a higher proportion of all visits were made by vectors but the species composition of visitors did not usually change with inflorescence size. We discuss the possibility that honey bees may provide major 'new' selection pressures on floral display, nectar production patterns, and flowering phenology in the common milkweed.
Preliminary studies of the physiological ecology of Umbilicaria lichens
Authors: Larson D. W.
Published: November 2007

Lichens which grow as clones or large anastomosing mats are often hard to handle experimentally because of the difficulty in defining an individual plant. Lichens in the Umbilicariaceae, however, are normally monophyllous and thus may be more convenient experimental material for the study of physiological ecology. In this study, the response of five species of Umbilicaria to a variety of experimental treatments is examined to determine the suitability of using such plants as an experimental system in physiological ecology, when using the ‘discrete sampling’ method of infrared gas analysis. The treatments used included the time-course response of net CO2 exchange following resaturation, the effect of ventilation, the response to the concentration of CO2, the response to irradiance, and the response to a low temperature pretreatment. The species could be considered suitable if steady-state rates of gas exchange extend over a period of several hours, if rates of CO2 exchange were not influenced by ventilation, if rates of CO2 exchange were independent of CO2 concentration over at least a 100 ppm range, if the plants could be stored for periods of time up to 1 month without significant alteration of their response to environmental conditions, and if the equipment used enabled light-saturated rates of net CO2 exchange to be obtained.The results showed that (1) steady-state rates of gas exchange exist from 1 to 10 h in U. vellea and U. papulosa and from 1 to 20 h in U. mammulala, U. muhlenbergii, and U. deusta,(2) none of the species has ventilation-dependent rates of fixation, (3) all species show no limitation of CO2 exchange at CO2 concentration between 200 and 350 ppm, (4) only U. vellea shows altered CO2 exchange after 1 month of dry- or wet-frozen storage at −25 °C, and (5) U. deusta is not light saturated using the growth and incubation chamber facilities that have been constructed. Umbilicaria species thus appear to be suitable as experimental material for further use in physiological ecology.
A new species of Stemphylium parasitic on Smilacina stellata
Authors: Reifschneider Francisco J. B.
Published: November 2007

A new species of Stemphylium Wallr, is described and illustrated. This species, Stemphylium arnyi, is pathogenic on Smilacina stellata and it is the only Stemphylium species reported on this host.
Duration of hardening and cold hardiness in winter wheat
Authors: Roberts D. W. A.
Published: November 2007

Experiments in which winter wheat plants were exposed to two different controlled hardening-temperature regimes (constant 3 °C, and 5.5 °C (day): 3.5 °C (night)) for long periods (up to 15 weeks) indicate that cold hardiness changes with time.The cold hardiness in plants grown from seed at 3 °C drops rapidly immediately after moistening and reaches a minimum 2–3 weeks later. Hardiness then begins to increase and reaches a maximum that lasts approximately from the 7th to the 11th week of growth after which it slowly declines.The patterns of change in cold hardiness during growth at 3 °C, and 5.5 °C:3.5 °C were almost synchronous if hardiness was plotted against duration of hardening, but were not synchronous if hardiness was plotted against stage of development as measured by the number of leaves produced. A somewhat similar result was obtained if plants grown for 3 weeks at 21 °C before hardening were compared with plants grown from dry seeds under the same hardening conditions. These experiments show that duration of hardening is more important in determining the level of cold resistance and the ability of wheat to retain its cold resistance than is stage of development, as measured by the number of leaves produced at the time cold resistance is measured.When plants seeded outdoors in mid-September were transferred at various dates (0–30 weeks after seeding) during the fall or winter to standardized hardening conditions in a growth cabinet for 0–15 weeks before freezing, their cold resistance changed in a way that suggests that plants in the field undergo the same pattern of changes in cold resistance as plants reared continuously in a growth chamber. This result suggests that the long exposure to hardening temperatures is one of the reasons why wheat in the field has less cold resistance in late winter than in autumn. Loss of carbohydrate reserves during winter may be an additional reason for this phenomenon.Under both growth cabinet and field conditions, increasing cold hardiness coincided with vernalization. Maximum cold hardiness was retained for several weeks after the completion of vernalization. These results suggest that the development of the maximum level of cold resistance may be related to the vernalization process.
Bud development in Larix occidentalis. II. Cone differentiation and early development
Authors: Owens John N. , Molder Marje
Published: November 2007

The time and method of cone-bud differentiation and the phenology of cone-bud development were studied in 10- to 20-year-old trees growing outside their natural range and three 50-year-old trees growing within their natural range.Both pollen-cone and seed-cone buds of western larch (Larix occidentalis Nutt.) normally differentiated on short shoots that were at least 1 year old. Pollen-cone buds were commonly on proximal nonvigorous, often pendant vegetative long shoots in lower regions of the crown, whereas seed-cone buds were usually found on distal short shoots on vigorous but less pendant vegetative long shoots in upper regions of the crown.All potential cone buds were indistinguishable from potential vegetative short shoot buds during bud-scale initiation. In early June, when vegetative short shoots had begun to initiate leaves, cone-bud apices entered a period of differentiation during which time the mitotic frequency of the apices greatly increased followed by a marked increase in apical size. During differentiation, pollen-cone apices did not initiate any basal foliar organs and a short stalk resulted at the base of the cone, whereas seed-cone apices initiated a few basal foliar primordia before bract initiation began. Microsporophyll initiation began during the last half of June and initiation occurred rapidly until the end of July. Micros porangial development occurred from August to late October when fully developed pollen-cone buds became dormant. Pollen mother cells began meiosis before dormancy and overwintered at the diffuse stage. Bract initiation began about the end of June, was rapid until mid-August, then continued more slowly until seed-cone buds became dormant in late October. Ovuliferous scales were initiated acropetally from mid-August until dormancy. Cone-bud differentiation occurred at about the end of the period of vegetative lateral long shoot elongation at all locations.
Terrestrial bryophytes as indicators of fluoride emission from a phosphorus plant, Long Harbour, Newfoundland, Canada
Authors: Roberts B. A. , Thompson L. K. , Sidhu S. S.
Published: November 2007

A study of the effects of fluoride emissions (HF, SiF4) on certain species of bryophytes was carried out in the vicinity of an industrial plant producing elemental phosphorus at Long Harbour, Nfld. Damage symptoms varied from mild phyllid chlorosis (yellowing) to severe browning of up to 95% of the phyllids. Polytrichum commune Hedw. was the main bryophyte species used in the survey. Random collections from 45 sample sites were analysed for total fluoride. The fluoride concentrations in phyllid tissue ranged from a high of 6066 ppm (dry weight) at a distance of 1 km northeast of the emission source to 44 ppm (dry weight) 1 1.7 km northeast of the emission source in the direction of the prevailing wind. Control samples were obtained from similar sites in areas far removed from the industrial plant and contained, on average, 11.3 ppm (dry weight). The concentration of fluoride in the bryophyte phyllid tissue was inversely correlated with distance from the emission source, in the direction of the prevailing wind. The severity of acropetal scorching was found to be correlated with the concentration of fluoride in the bryophyte phyllid tissue, and in addition, samples high in fluoride had fewer sporophytes. Fluoride concentrations in bryophyte tissue are compared with concentrations of fluoride in the needles of balsam fir, Abies halsamea L., in four damage zones, and also with available and total fluoride in soil humus and concentrations of fluoride in air. The total area affected by fluoride emissions was increased using bryophytes as the pollution indicator species, especially in areas far from the industrial plant.
Cleared-pistil and thick-sectioning techniques for detecting aposporous apomixis in grasses
Authors: Young B. A. , Sherwood R. T. , Bashaw E. C.
Published: November 2007

Two techniques were evaluated for detecting sexual and aposporous embryo sacs in an apomictic grass. Pistils of Cenchrus ciliaris L. were fixed in formalin – acetic acid – alcohol (FAA), cleared in methyl salicylate, and examined in toto by interference contrast microscopy. The same pistils were then embedded in plastic, sectioned, and studied by conventional microscopy. The two methods yielded identical interpretations of embryo sac morphology. The cleared-pistil technique was simple and required about 1/10 the time of the sectioning method.
Growth response of inoculated peas (Pisum sativum) to combined nitrogen
Authors: Mahon John D. , Child Jeffrey J.
Published: November 2007

Pea plants (Pisum sativum L. cv. Trapper) were inoculated and grown in controlled-environment chambers at two irradiance levels. Shoot and root dry weights and nitrogen contents, total leaf and stipule areas, and rates of C2H2 reduction were determined during growth in different treatments of NH4NO3 addition. Although overall growth increased with irradiance, the growth responses to combined nitrogen addition were similar at both light levels. Two phases of early vegetative growth were identified by their different responses to combined nitrogen. During the first phase, low levels of NH4NO3 greatly increased the relative growth rate, the growth per unit leaf area, and the percentage of nitrogen in the tissues. This indicated a period of nitrogen stress which lasted only until the 3rd week. Over the next 2 weeks, combined nitrogen increased the relative growth rates to a lesser extent, primarily through an increased partitioning of assimilates to shoot development. This distribution effect was rapidly reversible on changing nutrient conditions. The early stimulation of leaf area development by addition of combined nitrogen during these two growth phases resulted in greater capacity for symbiotic fixation after NH4NO3 was removed.
The genus Leucophleps (Basidiomycotina, Leucogastrales)
Authors: Fogel Robert
Published: November 2007

Leucophleps and Leucogaster are not related to the other genera traditionally placed in the Melanogastrales and have been placed in a new order Leucogastrales, with a single family, Leucogastraceae. The genus Leucophleps is described on a worldwide basis. Four species are included: L. magnata Harkness.L. aculeatispora sp.nov., L. levispora (Mattirolo) comb, nov., and L. spinispora nom.nov. Leucophleps clelandii, L. foveolala, L. Candida, L. citrina, and L. odorata are excluded.
Analyse biostatistique du développement cellulaire du tube pollinique, au cours de la gamétogenèse mâle expérimentale du Juniperus communis (Cupressacées)
Authors: Duhoux E. , Macdonald P. D. M.
Published: November 2007

Male gametogenesis in gymnosperms proceeds through a series of well-defined stages, the time spent in each stage being variable. Pollen grains of Juniperus communis L. were allowed to develop in vitro and the numbers of pollen tubes in each stage of development were noted at subsequent times. A biostatistical analysis yields estimates of the mean durations of the stages, the rate of formation of the male gametes, and an upper bound on the rate of mortality, parameters which are virtually impossible to measure directly. The analysis allows a quantitative comparison of development rates in two different culture media.
A rapid method for isolation of mesophyll protoplasts
Authors: Nagata Toshiyuki , Ishii Shigetaka
Published: November 2007

Pectolyase Y23, a new maceration enzyme from Aspergillus japonicus, combined with Cellulase Onozuka R10 liberated protoplasts from tobacco mesophyll in less than 25 min. The protoplasts divided to form cell colonies. This combination of enzymes also liberated protoplasts from mesophyll of rice and oat. The enhanced macerating activity of Pectolyase Y23 was found to be due not only to the high activity of pectin lyase and polygalacturonase, but also to a factor which stimulated maceration.
Lasiostictis reassessed
Authors: DiCosmo Frank
Published: November 2007

Lasiostictis fimbriata is described. The ascal tips from ascomata rehydrated in 2% KOH solution or distilled water and mounted in Melzer's reagent showed no amyloid reaction, and the ascospores bear gelatinous sheaths. On the basis of these new observations, L. fimbriata should be referred to the Rhytismataceae.
Development of a vesicular-arbuscular mycorrhiza in bean roots
Authors: Holley J. D. , Peterson R. L.
Published: November 2007

The ontogeny of the mycorrhizal association of a Glomus species in bean roots was studied. Electron-dense particles adjacent to external hyphae bind iron, as shown by X-ray microprobe analysis, when roots are fixed with glutaraldehyde – ferric chloride. This material is thought to be phenolic in nature. External spores, each with a subtending hyphal stalk, ranged in colour from hyaline to black. Intercellular hyphae, which are initially densely cytoplasmic, become progressively more vacuolate, with some vacuoles containing electron-dense particles. These hyphae form peg-like projections which cause the cell wall to be stretched inwards. Penetration into the inner cortex is followed by the formation of a simple haustorial trunk which dichotomizes successively until fine hyphae fill the cell. The endophyte is at first enclosed by a wall layer but the finer branches are covered only with an extrahaustorial matrix and cortical cell plasma membrane. Cortical cell cytoplasm changes in response to the fungus. Most arbuscules show some evidence of collapse or degeneration in the fine branches. Degeneration within the endophyte follows a pattern; initially the cytoplasm loses its well-defined appearance and small vacuoles develop. These small vacuoles then fuse to form larger vacuoles until the cytoplasm is reduced to a thin dense band around the periphery. The hyphae then collapse and coagulate into successively larger clumps, until only a dense residual mass remains in the cell. A membrane encloses the developing hyphal clumps and the cortical cytoplasm degenerates as clumping advances. No cell wall matrix is seen around the clumped endophyte.
Carbon balance in relation to drying in four epiphytic mosses growing in different vertical ranges
Authors: Tobiessen Peter L. , Slack Nancy G. , Mott Keith A.
Published: November 2007

The response of photosynthesis and respiration to drying was measured in four species of epiphytic mosses, Ulota crispa (Hedw.) Brid., Neckera pennata Hedw., Anomodon rugellii (C. Mull.) Keissl., and Plagiomnium cuspidatum (Hedw.) T. Kop., from habitats along a desiccation gradient. There was little difference among the mosses in these responses. The relationship of water content to water potential did differ among the mosses, with Plagiomnium, the facultative epiphyte, showing a typical response of more mesic species and the other three showing a more xeric response, i.e., water potential does not begin to fall steeply until a lower water content is reached in Ulota, Neckera, and Anomodon. Both photosynthesis and respiration in all four moss species were quite sensitive to moderate water stress.
Geosmithia gen. nov. for Penicillium lavendulum and related species
Authors: Pitt John I.
Published: November 2007

Geosmithia Pitt is erected to accommodate species, previously placed in Penicillium, with the following combination of characters: colonies with conidia in colors other than grey–blue or grey–green, penicilli with all elements roughened, and with both phialides and conidia cylindroidal. Geosmithia lavendula (Raper & Fennell) Pitt, G. putterillii (Thom) Pitt, G. namyslowskii (Zaleski) Pitt, G. cylindrospora (G. Smith) Pitt, G. argillacea (Stolk, Evans & Nilsson) Pitt, and G. emersonii (Stolk) Pitt are described as new combinations; G. swiftii is a new species for the anamorphic state of Talaromyces bacillisporus (Swift) C. R. Benjamin. A key is provided.
A comparison of the storage protein (globulin) of eight species of Cucurbitaceae
Authors: O'Kennedy Brendan T. , Reilly Charles C. , Titus John S. , Splittstoesser Walter E.
Published: November 2007

The percentage of globulin from cotyledons of dormant seeds of eight species of the Cucurbitaceae family was similar. After 4 days of germination, the globulin fraction decreased with a concomitant increase in the water-soluble protein fraction. Small changes in total protein occurred. Sodium dodecyl sulfate – polyacrylamide gel electrophoresis showed that the globulins of the eight species were composed of high molecular weight proteins which were different. The subunit arrangement of the globulin suggests a tetramer structure with a molecular weight greater than 200 000. After4 days of germination, a heat-stable, water-soluble protein was produced from the globulin. When this protein was reduced with β-mercaptoethanol, followed by electrophoresis, two peptides with molecular weights of 18 500 and 20 000 were produced in each species. It was concluded that all of the globulins have the same basic structure in different subunit arrangements.
Vascular plant vegetation of the Southern Circumpolar Region in relation to antarctic, alpine, and arctic vegetation
Authors: Bliss L. C.
Published: November 2007

Classification of southern circumpolar vegetation has been based upon a system quite different than that used for alpine and arctic vegetation. Although the flora and in part the physiognomy of the vegetation is quite different in the Southern Circumpolar Region, it is felt that a more uniform classification system is needed.This paper subdivides the vegetation of the southern polar region into a Subantarctic and an Antarctic Biome. The former includes closed forest, scrub fern bush, maritime and montane tussock grassland. The Antarctic Biome includes tundra-like closed vegetation, cushion plant open fellfield, and the grass-herb fellfield, moss and lichen communities of the Antarctic Continent and adjacent islands.
Ultrastructure et représentation spatiale du manteau fongique des ectomycorhizes
Authors: Strullu D. G.
Published: November 2007

A study of mycorrhizas of Douglas fir (Pseudotsuga menziesii Mirb.) by light and electron microscopy has allowed us to show the organization of the mantle. A three-dimensional structure of the fungal mantle is proposed. The outer plectenchyma is characterized by free hyphae; these hyphae are devoid of cytoplasmic contents. The inner plectenchyma shows closely interwoven hyphae; the fungal cells have a living aspect and a glycogen-rich cytoplasm.
Bioassay of the seasonal ability of water from a eutrophic Alberta lake to promote selective growth of strains of Anabaena flos-aquae and other blue-green algae
Authors: Schanz Ferdinand , Allen E. Dale , Gorham Paul R.
Published: November 2007

Significant differences were observed in the capacity of samples of filtered, unautoclaved water from Hastings Lake, Alta., to support growth of two strains of Anabaena flos-aquae (A-l 13-9q2, NRC-445-i), a strain of Aphanizomenon flos-aquae (NRC-568), and a culture of Anabaena sub-cylindrica isolated from Hastings Lake when tested by a 2-week, 1-L standard bioassay in aerated hydrometer cylinders at 20 °C with photosynthetically active radiation (400–700 nm) of 60 μE m−2 s−1. Growth was measured by two independent methods, optical density at 750 nm and mean filament length × mean filament number, and analyzed by fitting logistic curves to the data for comparisons of yields, lag phases, and growth rates. Anabaena A-113-9q2 grew best in spring and fall, poorest in summer, and the growth was always much lower than the controls in ASM-1-TR minus nitrogen (NO3) medium. The results support the hypothesis that nutrient variability in the water column contributes to the selection and growth of dominant species and strains and is one of the factors (along with buoyancy and other concentrating mechanisms) which cause observed successional changes and localized differences in composition of bloom-forming populations and scums. Inhibitors along with nutrient deficiencies may have caused the low biomass densities supported by the lake water. Buoyancy can best account for the 10-fold higher biomass densities observed for heavy bloom-forming populations collected from the top 0.25 m of the water column of Hastings Lake.
Miscellaneous microfungi III
Authors: Raj T. R. Nag
Published: November 2007

Bothrodiscus obscura (Peck) comb.nov., Hyalotiella americana (Speg.) comb.nov., Mastigosporium graminum (Karst.) comb, nov., and Pestalosphaeria austroamericana sp.nov. with a Pestalotiopsis anamorph are described.