bluuebunny/crossref_metadata_2025 huggingface dataset:
INHIBITION OF RESPIRATION, GERMINATION, AND GROWTH BY SUBSTANCES ARISING DURING THE DECOMPOSITION OF CERTAIN PLANT RESIDUES IN THE SOIL
Authors: Patrick Z. A. , Koch L. W.
Published: August 2008

Substances capable of markedly inhibiting the respiration, germination, and growth of tobacco seedlings were obtained after residues from timothy, corn, rye, or tobacco plants had been allowed to decompose under appropriate conditions in the soil. Bio-assay tests, based on manometric methods, made it possible to determine some of the conditions under which the decomposition gave rise to phytotoxic by-products and to obtain rapidly an accurate measure of the degree of their toxicity. Among the factors influencing the production of the toxic products, the species and stage of maturity of plant material added, the water content and pH of the soil, and length of decomposition period seemed most important. Substances capable of reducing the respiration of tobacco seedlings by 50 to 90% were consistently obtained when any of the abovementioned plant residues had been decomposing for 15 to 25 days under conditions of high soil moisture and when the pH of the soil solution was below 5.5 throughout this period. Timothy gave rise to substances possessing the highest toxic activity, followed by corn, then rye, and finally tobacco. Aqueous extracts of unamended soil or of macerated plant tissues prepared either before decomposition had taken place or when decomposition was inhibited by autoclaving the soil were not toxic.The toxic substances, obtained by water extraction, exhibited an inhibiting effect on respiration of tobacco seedlings after an exposure of less than one hour and also induced darkening and necrosis of root cells. Some extracts affected the cells of the apical meristem most severely while others affected only the cells of the elongation region.While the toxic substances have not been identified, they were relatively nonspecific in their action, affecting tobacco, timothy, and barley in approximately the same manner and in many instances possessed also antifungal activity. They were soluble in water, insoluble in petroleum ether, stable in acid, and most active in the pH range 4.5 to 5.8. They were precipitated by alkali and the activity was markedly reduced when readjusted to the acid range. They were also heat stable and did not lose their activity in storage at 1°–3 °C. provided they were covered by a layer of toluene.Because of their rapid production and the marked injurious effects exerted on various plants it is believed that these toxins may perform a significant role in the field as the primary cause of some root rots and in predisposing plants to attack by organisms not normally regarded as pathogenic.
GROWTH AND MORPHOGENESIS IN THE CANADIAN FOREST SPECIES: III. THE TIME SCALE OF MORPHOGENESIS AT THE STEM APEX OF PINUS RESINOSA AIT.
Authors: Duff G. H. , Nolan Norah J.
Published: August 2008

The main shoot apex of P. resinosa is found to comprise four groups of meristematic cells constituting four generative centers by which the parts of the winter terminal bud are laid down. These are the superficial initiating cells, the group or zone of subapical mother cells, the zone of pith mother cells, and the flanking cells.The superficial primordia of the terminal winter bud pass the winter as secondary lateral budlets on the flanks of the main bud axis. Those of the leaf-bearing short shoots do not normally differentiate leaves until the following spring. Neither do those which develop into lateral long shoots. The fertile budlets, on the contrary, produce cones in the late summer and autumn. The female cone enters the winter with no tissue differentiation of the cone body. This takes place very slowly but prominently in the course of the winter. The male inflorescence is well advanced in the autumn and winter progress is relatively slight.The natural control of morphogenesis at the shoot apex including the fitful seeding habit of P. resinosa is considered in the light of the growth timetable. To explain its mechanism, a working hypothesis involving production, consumption, and concentration of auxins is advanced as a preliminary to future work.
PHOSPHATE METABOLISM IN LEAVES: I. IDENTIFICATION OF SOME PHOSPHORYLATED COMPOUNDS IN WHEAT LEAVES
Authors: Runeckles V. C.
Published: August 2008

The phosphorylated compounds present in wheat leaves have been investigated following their extraction from leaf tissue supplied with radioactive orthophosphate (P32). In addition to several glycolytic and photosynthetic intermediates, the compounds identified include the phospholipid constituents, phosphorylcholine, phosphorylethanolamine, and their L-α-glyceryl esters.Alkyl phosphates have been shown to appear as artifacts in extracts obtained by using alcohols as killing agents. A mechanism for their synthesis is discussed, together with their importance in the interpretation of data on the dynamics of phosphate metabolism in vivo.
THE EFFECT OF VARIOUS METHODS OF BREAKING RESISTANCE ON STEM RUST REACTION AND CONTENT OF SOLUBLE CARBOHYDRATE AND NITROGEN IN WHEAT LEAVES
Authors: Forsyth F. R. , Samborski D. J.
Published: August 2008

The resistance of Khapli wheat to a number of races of stem rust, Puccinia graminis (Pers.) f. sp. tritici (Erikss. and Henn.), was broken after treatment with maleic hydrazide, DDT, detaching the leaves, and "searing" (heat treatment at the base of the leaf). In addition, the reaction of several other varieties to a number of races of stem rust was altered from resistant to susceptible by detaching and searing.DDT and searing caused marked increases in carbohydrate and soluble nitrogen levels, while maleic hydrazide caused smaller increases. There were no differences in carbohydrate levels, and only a slight difference in soluble nitrogen, between plants kept at 65° and 75° F., the temperatures at which McMurachy is respectively resistant and susceptible to rust. Insoluble nitrogen decreased after searing and DDT at rates approximately equal to those of the control. Insoluble nitrogen decreased at a faster rate in leaves kept at 75° F. than at 65° F. It remained fairly constant in leaves treated with maleic hydrazide.The data support the concept that substrate availability is of major importance in rust development.
CULTURAL CHARACTERS AS A GUIDE TO THE TAXONOMY AND PHYLOGENY OF THE POLYPORACEAE
Authors: Nobles Mildred K.
Published: August 2008

A study of the cultures of 252 species of the Polyporaceae provides evidence that the family is composed of two major groups: a primitive group consisting of species that produce no extracellular oxidase and, if heterothallic, show the bipolar type of interfertility; and a more advanced group made up of species that produce extracellular oxidase and, if heterothallic, show the tetrapolar type of interfertility in species whose hyphae are regularly nodose-septate or simple-septate, and the bipolar type of interfertility in species with hyphae simple-septate in the advancing zone and nodose-septate elsewhere. Within these major groups, groups of species, alike in hyphal and basidiospore characters, appear to be related and may represent taxa of generic or higher rank. An annotated key is presented, in which these groups of species are segregated in order of the increasing complexity of their hyphal components. The evaluation of the groups as taxonomic entities and of their arrangement in the key as a system of classification for the Polyporaceae requires a correlated study of sporophores and cultures. For the present, the species constituting each group, with relevant synonymy, are listed for the consideration of students of the family.
CYTOTAXONOMIC STUDIES ON RUMEX SECTION AXILLARES
Authors: Sarkar Nina Marie
Published: August 2008

The present investigation covers only the North American species of Rumex subgenus Rumex (Lapathum) section Axillares. A review was made of all the previous taxonomical and cytological work done in this group. All the species of the section Axillares were morphologically studied and their natural distribution plotted on maps. The distributional data were derived from about 3000 herbarium specimens gathered from various herbaria in the United States and Canada. Chromosome numbers of 17 taxa of the section Axillares were determined. The three subsections were found to comprise a polyploid series, the monotypic subsection Venosi with 2n = 40, R. verticillatus of the subsection Verticillati with 2n = 60, and all but two of the species studied in the subsection Salicifolii with 2n = 20; the two exceptions were R. mexicanus and R. utahensis, both with 2n = 40. Meiosis was studied in the species of the subsection Salicifolii only. Both the diploid and the tetraploid species showed essentially normal meiotic behavior. Pollen fertility was also very high in all the species. A number of intra- and inter-specific hybridizations were made between the taxa in the subsection Salicifolii, involving both the diploid and the tetraploid species. The resulting diploid (diploid × diploid), triploid (diploid × tetraploid), and tetraploid (tetraploid × tetraploid) F1 hybrids were both morphologically and cytologically studied. Morphologically almost all the diploid and tetraploid hybrids were intermediate between the two parents. The triploid hybrids showed more similarity to the tetraploid species involved in the cross, Meiosis in all the diploid hybrids was essentially normal with 10 bivalents. However, there was a significant decrease in chiasma frequency as compared with the parent species. This was postulated to be due to cryptic structural hybridity. There were three different categories of pollen fertility, ranging from low to very high, which were not correlated with any meiotic irregularities. All the diploid hybrids were fertile and set abundant seeds. Meiosis in the triploid hybrids was very irregular with mostly 10 bivalents and 10 univalents at metaphase I. Anaphases were also irregular, resulting in numerous micronuclei. All the triploid hybrids were sterile and set only a few undeveloped seeds. Meiosis in the tetraploid hybrid studied was also irregular with mostly 9 bivalents and 22 univalents. It was thus postulated that both the tetraploid species are allotetraploids with one genome in common between them and that this genome is essentially the same one shared by the diploid species so far cytologically studied. The tetraploid hybrids were completely sterile and did not set any seed. From the cytogenetic data, the diploid species studied were shown to be very closely interrelated. However, no taxonomic revision was undertaken owing to lack of more complete data involving all the species comprising the group.
THE GENUS PROROCENTRUM EHRENBERG. MORPHODYNAMICS, PROTOPLASMATIC STRUCTURES, AND TAXONOMY
Authors: Bursa Adam
Published: August 2008

The morphodynamics of Prorocentrum species have been studied comparatively in cultures and in plankton. Plankton populations show little morphological variation. In cultures a variety of forms, often similar to other species of Prorocentrum which have been described from distant seas, are found. Morphological variation in Prorocentrum species depends upon various life phases, individual features of the clones, and various types of the cysts. Formation of morphological aberrants is also affected by aging of cultures. All protoplasmatic structures, including the cell membrane, possess their own particular features, changing in the course of the life cycle. Since both physiological and morphodynamic metabolisms are inseparable in their activities, it is useful to complete taxonomic diagnoses with physiological observations. Five new species are described: Prorocentrum cordiformis, Prorocentrum pomoideum, Prorocentrum pyrenoideum, Prorocentrum redfieldi, and Prorocentrum levanlinoides. Morphodynamics in Prorocentrum micans and Prorocentrum scutellum was also studied. Most of the observations were made in vivo. Specific morphological differences in form and structure of protoplasmatic organelles were demonstrated in each species concerned. An attempt was made also to base taxonomic diagnoses upon the apical tooth, trichocysts, and membrane structure.
STUDIES ON FERTILITY AND LATE BLIGHT RESISTANCE IN SOLANUM BULBOCASTANUM DUN. IN MEXICO
Authors: Graham K. M. , Niederhauser J. S. , Servin Leopoldo
Published: August 2008

Solanum balbocastanum Dun. was collected extensively throughout its range in Mexico and Guatemala. Experimental self- and cross-pollinations showed that the species is highly self-sterile and consists of cross-sterile and cross-fertile individuals. Self-sterility may be due to the presence of incompatibility factors or to triploidy. Authentic hybrids were produced between S. bulbocastanum and S. trifidum Correll, and between S. bulbocastanum and S. pinnatisectum Dun.After inoculation with race 1.2.3.4 of Phytophthora infestans three types of reaction were observed among 1148 seedlings of S. bulbocastanum: immunity with no perceptible lesions, resistance expressed by non-sporulating lesions of the hypersensitive type, and susceptibility indicated by large sporulating necrotic lesions. Seedlings resistant to an isolate of race 1.2.3.4 of Canadian origin did not always show the same level of resistance to a Mexican isolate of the same race. Varying degrees of field resistance were observed among seedling plants, while tuber-propagated plants were generally field immune. Solanum bulbocastanum is considered a mixture of resistant and susceptible genotypes.
FINE STRUCTURE IN CELLS OF PEA AND WHEAT EMBRYOS
Authors: Setterfield G. , Stern H. , Johnston F. B.
Published: August 2008

To provide a basis for relating biochemical findings on isolated cell fractions to cytological structure in situ, embryos of pea and wheat were fixed with osmic acid, sectioned, and observed in phase-contrast and electron microscopes. The nuclei of all cells were similar, showing nuclear membranes, chromosomes, and prominent nucleoli. The cytoplasm contained highly developed structure which presumably reflected the incipient growth condition of the cells. Several cytoplasmic components were common to both embryos: small dense granules, endoplasmic reticulum, mitochondria, presumed proplastids, amyloplasts, irregular bodies, plasma membranes, and plasmodesmata. The small dense granules, presumably ribonucleoprotein particles, occurred profusely, both free and in association with extensively developed endoplasmic reticulum. These particles are probably responsible for the microsomal fractions obtainable from embryos and seedlings. The mitochondria were usually relatively small (0.25−0.5 μ diameter) although groups of very long (5 μ) ones were occasionally found. Bodies resembling mitochondria in size and shape, but lacking cristae, were present and represent either immature mitochondria or proplastids. Reserve material occurred as starch in structurally complex amyloplasts and possibly as protein in the irregular bodies. In addition to these structures cells of the wheat embryos remote from the meristems contained prominent cytoplasmic bodies classified as "dense" and "thick-walled". The dense bodies probably represent stored lipids while the significance of the thick-walled bodies, which showed a variety of forms, is unknown.
ACHILLEA MILLEFOLIUM COMPLEX IN CANADA AND PORTIONS OF THE UNITED STATES
Authors: Mulligan Gerald A. , Bassett I. John
Published: August 2008

The chromosome numbers of plants of the Achillea millefolium complex from 27 locations in North America are reported. The levels of polyploidy found are correlated with diameters of the pollen grains. Measurements of pollen grains from more than 300 herbarium specimens are used as an indication of the occurrence of tetraploid and hexaploid species of Achillea in Canada. The results of some crossing experiments are also reported. It is concluded that the common Achillea of North America is tetraploid and is the native A. lanulosa Nutt. It extends from the Pacific to the Atlantic coasts, as far south as California in the west and Pennsylvania in the east, and to northern Canada and Alaska. Another native species, hexaploid Achillea borealis Bong., extends along the Pacific coast from southern California to the Aleutian Islands and along the northern shorelines of Alaska and Canada. A Eurasiatic hexaploid, A. millefolium L. s. str., has been sparingly introduced into Newfoundland, Prince Edward Island, Nova Scotia, and perhaps elsewhere along the Atlantic seaboard. In eastern Canada a male-sterile purple-flowered hexaploid also occurs. This hexaploid escapes from cultivation and forms localized patches. It undoubtedly has been selected from the Eurasiatic A. millefolium L. s str.
CHROMOSOME NUMBERS OF CANADIAN WEEDS. II
Authors: Mulligan Gerald A.
Published: August 2008

The chromosome numbers of 38 Canadian weeds are reported and the significance of some of these numbers is discussed. Counts obtained on material of Iva xanthifolia L., 2n = 36, Erysimum hieraciifolium L., 2n = 48, and Nepeta cataria L., 2n = 34, differ from those obtained by previous workers. The chromosome numbers of the following species have not previously been reported: Rumex transitorius Rech. f., 2n = 20; R. triangulivalvis (Danser) Rech. f., 2n = 20; R. verticillatus L., 2n = 60.
CORRELATIONS AFFECTING REGENERATION AND REACTIVATION IN SPLACHNUM AMPULLACEUM (L.) HEDW.
Authors: MacQuarrie Ian G. , von Maltzahn Kraft E.
Published: August 2008

Correlations affecting restitutional behavior in the gametophore are examined. In short stem segments a direct relationship is found between the length of the segment and the number of regenerates; in longer segments this relationship disappears. No such correlation exists between leaf size and number of regenerates per leaf. The presence of leaves increases regeneration from the stem; the stem inhibits regeneration from the leaf.Isolation and not wounding is shown to be the most important factor in leaf regeneration.The apex of the gametophore inhibits both regeneration from the base of the gametophore and bud reactivation. These apical dominance effects can be replaced by the application of indoleacetic acid (IAA) to the tips of decapitated plants. Similar concentrations of IAA and γ-phenylbutyric acid (PBA) inhibit regeneration from both isolated stems and leaves; at lower concentrations some promotion is found with IAA, none with PBA. Shorter exposure of leaves to these compounds results in reversible inhibition, or even an increase in regeneration. IAA and PBA do not counteract each other in their effects.Leaves isolated from intact and decapitated plants show differences in regenerative behavior when treated with IAA. This indicates that IAA could be involved in the inhibition or regeneration from attached leaves.It is concluded that IAA is not the primary factor in the control of correlative inhibition of restitution in the gametophore.
CYTOGENETICS OF SOLID STEM IN COMMON WHEAT: I. MONOSOMICF2ANALYSIS OF THE VARIETY S-615
Authors: Larson Ruby I.
Published: August 2008

The F2lines of monosomics of Chinese Spring by S-615 were compared with normal F2lines for stem solidness. The solid stem index of each plant was determined by totalling index numbers (ranging from 1 for thin-walled, hollow, to 5 for completely solid) assigned to cross sections of the culm at seven designated points. As both the normal and monosomic lines showed a continuous distribution of this index, the factorial analysis was not too reliable. The normal F2gave an estimated difference between the parents of at least four genes; the monosomic XIII F2, which was more solid than the normal, gave a difference of three genes.Quantitative differences between monosomic F2lines and the normal indicated that chromosomes II, XIII, and XX, comprising homoeologous group 2, tend to make the culm hollow. Chromosomes XIX and XXI also inhibit pith development. Of these five chromosomes, XIII has a gene for hollow culm in Chinese Spring only; XIX, XX, and XXI, which are in the D genome, are effective in both S-615 and Chinese Spring, and II is inconclusive. Chromosome VIII in Chinese Spring promotes pith production. The chromosomes of S-615 bearing genes for solid stem were not identified by this method, as a monosomic F2analysis does not reveal recessives present only in the variety being tested.
STUDIES ON SLIME ACCUMULATIONS IN PULP AND PAPER MILLS: II. PHYSIOLOGICAL STUDIES OF PHIALOPHORA FASTIGIATA AND P. RICHARDSIAE
Authors: Brewer D.
Published: August 2008

Physiological studies of six isolates of Phialophora fastigiata and two isolates of P. richardsiae from pulp mills have been made to determine conditions for growth. Isolates of P. fastigiata grew from at about 3 °C to 30–35 °C, with optimum conditions at 20 to 25 °C and pH 4 to 9. The temperatures for P. richardsiae were somewhat higher. No vitamins were required by P. fastigiata in a basal glucose mineral medium with ammonium tartrate. Ability to metabolize 11 carbohydrates as monosaccharides and oligosaccharides, but not D-arabinose, has been demonstrated. Likewise 16 sources of nitrogen as ammonia, nitrate, and various amino acids, but not cysteine, were utilized unequally. The differences between isolates of P. fastigiata from the same slime were as great as between isolates from different mills.
A NOTE ON SPOROGENESES IN DIPCADI SEROTINUM (L.) MEDIC.
Authors: Chennaveeraiah M. S. , Mahabale T. S.
Published: August 2008

Distinguished from the rest of the genera of the Scilloideae, Dipcadi is characterized by tuberous scapigerous herbs with racemed flowers, cylindric perianth of six erect segments, the outer recurved from about the middle and the inner at the tips only, included stamens and a short capsule which is broad, tridymous, loculicidal, and many-seeded. The genus is insufficiently known both cytologically and embryologically. The present paper gives an account of micro- and mega-sporogenesis in a plant of D. serotinum. This taxon, with a diploid chromosome number of eight and with all chromosomes having satellites and all apparently taking part in nucleolar organization, has other features of interest such as meiotic irregularities, abnormal megaspore tetrads, and polyspory. These have been recorded here and explanations are given as far as possible.
ON THE GENERA MORMOLYCA FENZL AND CYRTOGLOTTIS SCHLTR.
Authors: Garay Leslie A. , Wirth Michael
Published: August 2008

The generic limits of Mormolyca Fenzl are extended to include Cyrtoglottis Schltr., on the basis of intermediate species. A previously misunderstood species, Maxillaria galeata Scheidw., is included in the genus Mormolyca, and the relationship of this genus to the rest of the Maxillaria-alliance is discussed. One new species, Mormolyca polyphylla, is described, and a synopsis of the genus is presented.
AN APPARATUS FOR THE GROWTH OF FUNGI ON MEDIA OF CONSTANT COMPOSITION
Authors: Loughheed T. C.
Published: August 2008

An apparatus is described for growing fungi on media of defined and constant composition. The fungus grows as a surface mat on a porous, inert membrane supported on the surface of a liquid medium. A continuous flow of the medium is maintained through the growth cell to ensure its constant composition.
STUDIES OF THE METABOLIC RELATIONS OF ALLANTOIN IN WHEAT
Authors: Krupka R. M. , Towers G. H. N.
Published: August 2008

Changes in the allantoin and allantoic acid content of germinating seedlings and aging leaves of wheat were followed. The results of experiments on photosynthetic assimilation of C14O2 and the feeding of glycine-C14 and glyoxylate-C14 indicate that in wheat seedlings the root is probably an important site of allantoin synthesis. Glycine-C14 was found to be a better precursor of allantoin-C14 than glyoxylate-C14. Allantoin-C14 was not synthesized from urea-C14. A scheme for allantoin synthesis which is based on these results is outlined.
CYTOTAXONOMIC STUDIES IN THE GENUS ANEMONE
Authors: Heimburger Margaret
Published: August 2008

Chromosome morphology has been described in 20 species of Anemone s. lat. (Anemone s. str. 15 species, Pulsatilla 3, Hepatica 2). Two series, one based on 8 chromosomes and the other on 7, are present, in each of which two patterns can be recognized when an orderly arrangement of the chromosomes has been made. In the 8-chromosome series, the distinctions are based on differences in the arm ratio of chromosome IV, namely ratios of about 1:2 versus 1:1.4–1.8. Species in the first group include A. palmata, 2n = 16; A. parviflora, 2n = 16; A. caroliniana, 2n = 16; A. silvestris, 2n = 16; A. virginiana–riparia–cylindrica complex, (all 2n = 16); A. quinquefolia, 2n = 32; and species in the second group are A. pavonina, 2n = 16; A. coronaria, 2n = 16; A. hupehensis, 2n = 16; A. rivularis, 2n = 16; A. rupicola, 2n = 16; Pulsatilla pratensis, 2n = 16; P. nuttalliana ssp., 2n = 16; and P. occidentalis, 2n = 16. A. multifida, 2n = 32, has one chromosome set in each of the above groups. The 7-chromosome series falls into two groups on the basis of a combination of characters. Group one: long arms of chromosome I shorter than those of the longest chromosomes, long arms of chromosome II longer than those of the third pair, and arm ratios in chromosome II of 1.4–1.6. Group two: long arms of chromosome I longer than those of all others, long arms of chromosome II shorter than any of the others, arm ratios in chromosome II < 1:1.4. Species in the first group are Anemone canadensis, 2n = 14; A. richardsonii, 2n = 14; and A. fasciculata, 2n = 14; and in the second group, Hepatica americana, 2n = 14; and H. acutiloba, 2n = 14. Anemone multifida and A. quinquefolia are recognized as allotetraploids. The cytological results are discussed in relation to current classification.
AN ANATOMICAL STUDY OF THE SUBTERRANEAN ORGANS OF EUPHORBIA ESULA IN RELATION TO ITS CONTROL
Authors: Bakshi Trilochan S. , Coupland Robert T.
Published: August 2008

Young roots of Euphorbia esula exhibit a structure similar to that of a typical dicotyledonous species. In older roots, wood comprises as much as two-thirds of the total tissues. Cork is several layers thick, and lenticels are of open type. Pericyclic meristem forms a continuous ring any part of which may give rise to lateral organs. The primordia of lateral roots and shoots cannot be distinguished morphologically from each other until they have emerged from the parent organ. In the case of stems the lateral buds originate endogenously from the internodes but exogenously at the nodes. The subterranean organs of the species are supplied with simple, nonarticulated, and branched laticifers. Almost all parenchyma cells including the laticifers are filled with starch grains. The significance of these anatomical features with respect to the control of the species is discussed.
NOTES ON EXOBASIDIUM
Authors: Savile D. B. O.
Published: August 2008

The biology, taxonomy, and host relationship of Exobasidium are discussed. A key, detailed descriptions, and host records are given for Exobasidium vaccinii Wor., E. vaccinii var. arctostaphyli (Harkn.) comb, nov., E. burtii Zeller, E. decolorans Harkn., E. canadense sp. nov., E. cordilleranum sp. nov., E. cordilleranum var. minor var. nov., E. vaccinii-uliginosi Boud., E. vaccinii-uliginosi var. phyllodoces var. nov., E. dimorphosporum sp. nov., and E. empetri Ito & Otani. Evidence is presented to support the derivation of Empetrum from Ericaceae.
SNOW MOLD INFECTION OF ALFALFA, GRASSES, AND WINTER WHEAT BY SEVERAL FUNGI UNDER ARTIFICIAL CONDITIONS
Authors: Cormack M. W. , Lebeau J. B.
Published: August 2008

Snow mold infection by an unidentified low-temperature basidiomycete and Typhula spp. developed best under artificial conditions when inoculated plants in pots were incubated for 2 months at 2 °C with 80 to 90% R.H. in the special cabinets described or with other covering. A saturated atmosphere was detrimental to mycelial growth and infection. Freezing temperatures and complete host dormancy were not required but greenhouse-grown plants benefited from prior conditioning for 2 weeks at 2° to 5 °C with light for 8 hours daily. The reactions of alfalfa varieties, creeping red fescue, Kentucky bluegrass, red top, timothy, and winter wheat to the low-temperature basidiomycete were similar to those previously observed in the field. T. idahoensis Remsb. caused moderate to severe damage and T. itoana Imai caused slight to moderate damage to the grasses and winter wheat. Typhula sp. from alfalfa was highly virulent to that host. The low-temperature basidiomycete was the only snow mold organism tested that synthesized HCN in culture or in the plant tissues.Sclerolinia borealis Bub. & Vleug. caused slight damage to winter wheat and grasses after 3 months at 2 °C but did not develop well under any of the conditions employed.
THE GERMINATION OF LIGHT-SENSITIVE SEEDS OF TYPHA LATIFOLIA L.
Authors: Sifton H. B.
Published: August 2008

Germination in Typha lalifolia L. is strongly favored by white light and by low oxygen concentration. Microscopic study shows that the effect is on the aleurone grains, whose colloids are so affected that they attract and hold water more strongly, and the resultant swelling ruptures the seed coat. The swelling of the grains was observed under various sets of conditions. Its progress is described and has a bearing on current theories with respect to these structures. The process of vacuolation in the cells was also studied. On it light has no apparent effect, but it is notably stimulated under conditions of vigorous, aerobic respiration. In some samples of seed, where the tendency to vacuolate is especially strong, atmospheric pressure of oxygen strengthens vacuolation to an extent that will compensate for its depressing effect on swelling of the grains, and satisfactory germination follows. In other samples this is not so. Under very low light intensity, rather wide alternations of temperature promote germination. This was found to be due to promotion of vacuolation. Respiration studies show slow respiration and a low respiratory quotient at the low temperature. It is suggested that this allows a clearing away, during the time at low temperature, of the products of respiration, thus allowing, when the higher temperature is resumed, the vigorous respiratory activity that makes for vigorous vacuolation.
EFFECT OF BENZIMIDAZOLE AND NICKEL ON THE CHLOROPHYLL METABOLISM OF DETACHED LEAVES OF KHAPLI WHEAT
Authors: Wang Dalton , Waygood E. R.
Published: August 2008

Studies have been made on the effect of benzimidazole and nickel on the chlorophyll metabolism of detached etiolated and green leaves of Khapli wheat. It was found that benzimidazole stimulated the formation of chlorophyll and protects the latter from rapid destruction. The protective effect was most prominent in treated leaves in the dark. The effect of nickel ion differs from benzimidazole only in respect to its inhibition of chlorophyll formation. Evidence obtained indicates that the destruction of chlorophyll in light and in dark are probably two independent processes.
NOTES ON FUNGI FROM NORTHERN CANADA: IV. TRICHOLOMATACEAE
Authors: Bigelow Howard E.
Published: August 2008

Among the many fungi collected in northern Canada by government biological survey parties are agarics belonging to the Tricholomataceae. Over 100 collections were examined in this study. Twelve genera and 33 species are represented. The records of these species in northern Canada are of value in determining the limits of distribution.Myxomphalia is raised to generic rank. The following new combinations are proposed: Clitocybe luteovitellina, C. posti, C. septentrionlis, C. umbellifera, Lepista irina, Myxomphalia maura.
THE RELATION OF BARK MOISTURE TO THE DEVELOPMENT OF CANKER DISEASES CAUSED BY NATIVE, FACULTATIVE PARASITES: 2. FUSARIUM CANKER ON BLACK COTTONWOOD
Authors: Bier John E.
Published: August 2008

A close correlation was found to exist between the development of a bark canker in nursery-grown Populus trichocarpa Torrey and Gray, caused by Fusarium lateritium Nees., and the moisture content of the living bark. When bark moisture was expressed as a percentage of the amount of water required to saturate the sample under experimental conditions, relative turgidities of 80% or more inhibited canker development which, however, occurred normally at lower percentages. Studies of the epidemiology of Fusarium canker in the nursery afforded evidence in support of the limiting effect of bark moisture on canker development. Thus during the dormant season of 1957–58, the monthly average temperature was higher than the minimum temperature for the growth of F. lateritium on potato dextrose agar, and the relative turgidity did not reach the inhibiting value of 80%. Cankers continued to develop throughout this period. During the growing season while temperatures were still more favorable for fungus development, no extension of cankers occurred in the nursery trees, apparently because, during the growing period, the relative turgidity was in excess of 80%. Canker development was prevented during the winter by placing dormant cuttings in water, which likewise increased the moisture content of the bark above the 80% level.During the dormant season the bark of field-grown black cottonwoods maintained relative turgidity values of approximately 80% or higher and the disease could not be found on these trees.
A TISSUE-AUTORADIOGRAPHIC STUDY OF THE TRANSLOCATION OF C14-LABELLED SUGARS IN THE STEMS OF YOUNG SOYBEAN PLANTS
Authors: Perkins Harold J. , Nelson C. D. , Gorham Paul R.
Published: August 2008

Autoradiography was used to determine the tissues involved in the downward translocation of C14-labelled photosynthate and of C14-labelled glucose, fructose, or sucrose introduced into soybean plants through the cut petiole of a primary leaf. Sections of lyophilized, paraffin-embedded tissue were autoradiographed in such a way as to prevent significant movement of water-soluble compounds. Cross sections, 10 μ thick, were taken from petiole and stem at various distances from the primary node. In 5 to 10 minutes, the bulk of the C14 from photosynthate or from sugars that were introduced through the cut petiole was concentrated in and around the vascular tissues. These tissues were located on the same side of the stem as the petiole through which the C14 had entered. Within these tissues the bulk of the C14 was concentrated in some columns of cells with little or no C14 in others. The C14 of photosynthate was localized in the phloem while that of sucrose introduced through the cut petiole was concentrated predominantly in the pith and in the adjacent xylem. The C14 of fructose or glucose was localized mainly in the xylem. This comparative study has demonstrated that all translocation need not take place in the phloem, but some may take place in such tissues as the pith and xylem.
NOMENCLATURE OF DRECHSLERA AND BIPOLARIS, GRASS PARASITES SEGREGATED FROM ‘HELMINTHOSPORIUM’
Authors: Shoemaker R. A.
Published: August 2008

As a result of a taxonomic study of some graminicolous fungi classed in ‘Helminthosporium’ the following conclusions concerning their nomenclature were reached. The original spelling of Helmisporium Link validated by S. F. Gray in 1821 is taken up instead of the illegitimate orthographic variant ‘Helminthosporium’ Link ex Pers. Helmisporium is restricted to the generic type and its chiefly lignicolous allies, all of which form conidia both apically and laterally on the conidiophores. The graminicolous species form conidia apically and a new apex is formed by subterminal growth. Sixteen species with cylindric conidia that germinate from all cells are included in Drechslera Ito. The lectotype, D. tritici-vulgaris (Nisikado) Ito, is designated and D. arundinis (Lév.) Ito is excluded. The generic name Bipolaris is proposed for the other major group of graminicolous species. These, like the holotype (basionym H. maydis Nisikado), form fusoid phragmospores that exhibit bipolar germination.
INHERITANCE OF THE TYPE OF SOLID STEM IN GOLDEN BALL (TRITICUM DURUM): I. EARLY GENERATIONS OF A HYBRID WITH RESCUE (T. AESTIVUM)
Authors: Larson Ruby I.
Published: August 2008

In a population of one thousand F2 plants of the hybrid between Rescue, a solid-stemmed variety of Triticum aestivum L. emend. Thell., and Golden Ball, a solid-stemmed variety of T. durum Desf., the more solid top internode of Golden Ball was associated with a dense spike and with durum-like morphology. Rigid selection failed to produce an F1 line with a top internode as solid as that of Golden Ball combined with the morphological characters of T. aestivum. This was probably because the D genome present in Rescue but absent from Golden Ball tends to inhibit pith production in the top internode. Some increase in solidness was attained in two F1 lines, and some lines had pith patterns different from that of either parent. This was probably due to segregation of genes in the A and B genomes.Segregates with stems less solid than those of either parent appeared in the F2 generation and some fairly hollow, dwarf F1 lines were established. Hollowness was probably caused by a combination of aneuploidy for chromosomes of the D genome and segregation of genes in the A and B genomes. These less solid lines varied more in pith content from plant to plant than did Rescue and the more solid F4 lines; Golden Ball varied least.
THE TIME FACTOR IN THE DECOMPOSITION OF CONIFEROUS LEAF LITTER
Authors: Kendrick W. Bryce
Published: August 2008

A method is described for determining the duration of the various stages in the decomposition of coniferous leaf litter on mor sites. Knowledge of the time required for the decay process in different species would allow useful comparisons to be made of their inherent mor-forming tendencies.
THE BOTANY OF SOMERSET ISLAND, DISTRICT OF FRANKLIN
Authors: Savile D. B. O.
Published: August 2008

The geology, physiography, general appearance, climate and weather, and history of exploration of Somerset I. are discussed briefly. The principal habitats and the areas visited are described. Data are presented on prevailing winter wind directions on Somerset I. and Boothia Pen., drawn from observations on residual snowbanks and plant growth. A few phenological data are presented, which supply further evidence that spring development at low arctic sites lags behind that at both subarctic and high arctic sites. Annotated lists are given of the fungi (28 species) and vascular plants (90 species) collected. Among the fungi Puccinia helicalis sp. nov. on Pedicularis capitata, and Doassansia nearctica sp. nov. on Ranunculus hyperboreus are described; and Exobasidium warmingii, intermediate between Exobasidium and Kordyana, is made the type of Arcticomyces gen. nov. Thirty-two species of vascular plants are added to the recorded flora of the island.
CYTOGENETIC STUDIES IN AMARANTHUS: II. NATURAL INTERSPECIFIC HYBRIDIZATION BETWEEN AMARANTHUS DUBIUS AND A. SPINOSUS
Authors: Grant William F.
Published: August 2008

Spontaneous triploid hybrids (2n = 49) were discovered between Amaranthus spinosus L. (2n = 34), a diploid species, and A. dubius Mart. ex Thellung (2n = 64) which was found to be a tetraploid. Meiosis in the hybrids was irregular and 15 univalents were most frequently found along with the bivalents pairing apparently allosyndetically (15 I's + 17 II's = 2n = 49) at metaphase I. Univalents were excluded from the telophase nuclei in both meiotic divisions resulting in supernumerary microspores and in a reduction in the mean size of the microspores. Consequently, the triploids were largely sterile and the few undersized seeds produced failed to germinate. Seed weight, seed volume, stomatal size, and pollen grain size were proportional to chromosome number in the parents only, not in their hybrids. Since A. dubius exhibits typical bivalent behavior in synapsis, it is considered to be an allotetraploid in which A. spinosus has been one progenitor. It is suggested that the diploid A. quitensis H. B. K. (2n = 32) might be the other progenitor, but from chromosome number relationships and morphological considerations more than two species may be involved. As a result of the high sterility of the triploids, gene exchange between the parental species must be of a very limited nature.
BIOSYNTHESIS OF PUNGENIN FROM C14-LABELLED COMPOUNDS BY COLORADO SPRUCE
Authors: Neish A. C.
Published: August 2008

A number of C14-labelled compounds were fed to detached leafy twigs of Colorado spruce (Picea pungens Engelm.), and after a metabolic period of 24 hours the pungenin was isolated and the specified activities of the glucose moiety and the aglycone (3,4-dihydroxyacetophenone) were determined. In some instances the aglycone was degraded further to determine the C14in the methyl and carbonyl carbons separately.Caffeic acid and L-phenylalanine were the best precursors of the aglycone; cinnamic acid, p-coumaric acid, phenyllactic acid, and shikimic acid were quite good. Sodium acetate was a poor precursor, and was converted to glucose more readily than to the aglycone. Compounds found to be very poor precursors include tyrosine, 3,4-dihydroxyphenylalanine, 3-hydroxytyramine, phenylacetic acid, mandelic acid, p-hydroxyphenylpyruvic acid, p-hydroxyphenyllactic acid, p-hydroxybenzoic acid, and protocatechuic acid. Cinnamic acid-α-C14gave 3,4-dihydroxyacetophenone labelled chiefly in the methyl group, while cinnamic acid-β-C14, L-phenylalanine-β-C14, p-coumaric acid-β-C14, and caffeic acid-β-C14formed 3,4-dihydroxyacetophenone labelled mainly in the carbonyl carbon. It appears that a phenylethanoid compound is formed by a process involving the loss of the terminal carbon of a phenylpropanoid compound.3,4-Dihydroxyacetophenone-carbonyl-C14was fed to spruce twigs bearing new terminal growth; up to 20% was converted to pungenin but most of it formed unidentified compounds. It was a poor precursor of lignin, compared with cinnamic acid, and a poor precursor of glutamic acid, relative to acetate.
EVIDENCE FOR DIFFERENT KINDS OF CONCURRENT TRANSLOCATION OF PHOTOSYNTHETICALLY ASSIMILATED C14 IN THE SOYBEAN
Authors: Nelson C. D. , Perkins Harold J. , Gorham Paul R.
Published: August 2008

When the primary leaf of a soybean plant was allowed to carry on photosynthesis in C14O2, a small amount of labelled carbon was translocated downward into the root at a velocity of at least 5040 cm per hour. This velocity was 50 times greater than the velocity at which sucrose was translocated in the phloem. The rapidly translocated C14 was not moved as carbon dioxide. When the time of translocation was increased from 30 seconds to 10 minutes there was an increase in C14 content of the root without any increase in C14 content of the lowest part of the stem. Part of the C14 was translocated through a steam-girdled stem, but under these conditions there was no accumulation in the root. This indicates that the rapid translocation of C14 occurred in both living and dead tissues of the stem. These results were correlated with the localization of C14 in tissue autoradiographs of cross sections of the stem to show that there were at least three pathways of downward translocation: (a) a slow translocation in the phloem, (b) a rapid translocation in the xylem, and (c) a rapid translocation in either the cortex, the phloem, or the pith.
ENZYMIC ACTIVITIES OF SUBCELLULAR PARTICLES FROM LEAVES: IV. PHOTOSYNTHETIC PHOSPHORYLATION AND PHOTOSYNTHESIS BY ISOLATED CHLOROPLASTS FROM PEA LEAVES
Authors: Smillie R. M. , Krotkov G.
Published: August 2008

Chloroplasts were isolated in 0.35 M NaCl from green pea leaves. Such preparations formed ATP photosyathetically from AMP or ADP and inorganic phosphate. The conditions and cofactors of this reaction were studied. The rates of photosynthetic phosphorylation by isolated pea chloroplasts were compared with photosynthetic phosphorylation by spinach chloroplasts and with photosynthesis by intact pea leaves. The isolated pea chloroplasts also photosynthetically fixed carbon dioxide. The possible roles of chloroplasts and mitochondria in cellular phosphorylations are discussed.
CLAVICEPS FROM ZIZANIA
Authors: Pantidou Maria E.
Published: August 2008

The nomenclatorial status of the species of Claviceps occurring on Zizania has been uncertain for several years because although its perfect state has been known since 1915 it has been imperfectly described and placed in the wrong genus. A detailed description of this fungus is presented and a new combination for this species is proposed.
HISTOLOGICAL STUDY ON CROWN BUD ROT OF ALFALFA
Authors: Hawn E. J.
Published: August 2008

Microscopic examination of stained sections made from alfalfa crown buds artificially inoculated with typical crown bud isolates of Rhizoctonia solani Kühn, Fusarium avenaceum (Fr.) Sacc., Fusarium acuminatum (Ell. & Ev.) Wr., and Ascochyta imperfecta Peck indicates their respective abilities to cause crown bud rot under conditions similar to those found in the field. Identifiable portions of these fungi are shown and their growth within the host tissue is described.
STUDIES ON THE WESTERN WOOD-ROTTING FUNGUS PORIA ZONATA BRES.
Authors: Gilbertson L.
Published: August 2008

Poria zonata Bres., a wood-rotting fungus known only from the western United States and British Columbia, is reported to be widely distributed within that area on recently fallen trees of Abies grandis, A. concolor, A. lasiocarpa, Larix occidentalis, Pseudotsuga menziesii, and Tsuga heterophylla. A description of the sporophores of the fungus, its cultural characteristics, and the white pocket rot caused by it are given.
EPIDEMIOLOGY STUDIES ON THE SEPTORIA DISEASE OF OATS
Authors: Clark R. V. , Zillinsky F. J.
Published: August 2008

Ascospores were found to be the principal cause of primary infection in the disease of oats caused by Leptosphaeria avenaria f. sp. avenaria. Macrospores produced in the leaf lesions on oat plants were responsible for the secondary spread of the fungus and the subsequent development of the black stem phase of the disease. Viable ascospores were present throughout the growing season and provided the means for widespread development of the disease. The purpose of the microspores is not clearly understood but they would appear to be of little importance in the initiation and subsequent spread of the disease. Seed-borne infection was found to be of no importance in the epidemiology of this disease.