bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECT OF MYCORRHIZAL FUNGI ON RECOVERY OF PHOSPHATE FERTILIZER FROM SOIL BY RYEGRASSPLANTS
Authors: Lpowell C. 
Published: May 2006

SummaryRyegrass plants were inoculated with Gigaspora margarita, Glomus tenuis or the indigenous mycorrhizal fungi and transplanted into pots containing four New Zealand hill country soils fertilized with finely ground superphosphate or one of five finely ground phosphate rocks. After seven harvests from Dunmore soil and four harvests from three other soils, Peru rock phosphate was the best fertilizer overall (an average of 24 % of applied fertilizer phosphate was recovered by plants) followed by superphosphate, Chatham Rise rock, Nauru Is. rock, Christmas Is. rock and Queensland rock (23, 15,4,4 and 2 % of the phosphate recovered respectively). The fertilizer value of superphosphate decreased rapidly over successive harvests in all soils, with slower decreases in the fertilizer value of Peru and Chatham rock phosphate. The values of Queensland, Nauru Is. and Christmas Is. rock phosphate were very low and largely unaffected by repeated harvesting. Mycorrhizal inoculation greatly influenced phosphate uptake from soil by plants. In 11 out of 28 soil‐fertilizer treatments, phosphate uptake by G. tenuis‐inoculated plants was increased significantly over plants inoculated with indigenous mycorrhizal fungi. The increased phosphate uptake following inoculation with efficient mycorrhizal fungi tended to decrease over successive harvests, as the available phosphate levels in soil were depleted.
ENHANCED CARBON TRANSFER BETWEEN ONIONS INFECTED WITH A VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGUS
Authors: HIRREL M. C. , GERDEMANN J. W. 
Published: May 2006

SummaryCarbon (C) transfer between onion plants was enhanced by vesicular‐arbuscular mycorrhizas formed by the fungus, Glomus etunicatus. By applying pentachloronitrobenzene (PCNB) to hyphae, C translocation to the root was reduced but not eliminated indicating that two transfer processes may be involved; namely, cytoplasmic translocation within hyphae and mass flow along hyphal walls. Most of the transferred C remained in the roots; little or no C was translocated to the shoots. Therefore, it is uncertain whether C was released to the recipient plant or retained in fungal tissue.
SCANNING ELECTRON MICROSCOPY OF THE NITROGEN‐FIXING ACTINORHIZA OF MYRICA PENSYLVANICA L. (BAYBERRY)*
Authors: BENSON D. R. , GREENHUT V. A. , EVELEIGH D. E. 
Published: May 2006

SummaryThe nitrogen‐fixing root nodules of Myrica pensylvanica L. (bayberry) were shown to be inhabited by a filamentous micro‐organism typical of non‐leguminous root nodules (actinorhizal nodules) by scanning electron microscopy (s.e.m.). The micro‐organism was hyphal in young nodule areas and host cell infection was accomplished by cell wall penetration with subsequent proliferation of the micro‐organism. The penetration was often massive with hyphal entries recorded less than 1 μm apart. The smooth transition between host cell wall and endophyte hypha indicated some homology between their surfaces. The second stage of development of the endophyte was vesicular; club‐shaped vesicles arose as extensions of hyphal tips. The vesicles resembled similar structures from other non‐leguminous nitrogen‐fixing plants. X‐ray microanalysis of the nodules revealed the presence of crystalline deposits containing substantial calcium content packed within randomly distributed cortical cells. The crystals were typical of calcium oxalate, a common constituent in plant tissue.
OBSERVATIONS ON MEIOSIS IN THREE CYTOTYPES OF BETULA ALBA L.
Authors: BROWN IAN R. , AL‐DAWOODY DAWOOD 
Published: May 2006

SummaryMeiosis was studied in three birch cytotypes; B. pendula 2n= 28, B. pubescens 2n= 56 and a type with the intermediate chromosome number 2n= 42. Meiosis was similar in B. pendula and B. pubescens and a similar range and frequency of abnormalities was found. In relation to both types there was strong circumstantial evidence that x= 7 rather than x= 14, which is commonly accepted. In addition it was also shown that in B. pubescens there exists means of producing aneuploid gametes.Meiosis in 2n= 42 trees differed greatly from that in 2n= 28 and 2n= 56 trees. Many cells contained coalesced masses of chromatin and could not be analysed. Those that were studied showed a much greater frequency of abnormality than that found in the other two cytotypes. Surprisingly, around 50 % of analysable cells showed 21:21 distribution of chromosomes at metaphase II. Although the origin of these trees is unknown it is suggested that they are not triploids but hexaploids, i.e. x=n= 7.
THE BIOLOGY OF AMBROSIA TRIFIDA L.
Authors: Abul‐Fatih H.A. , Bazzaz F. A. 
Published: May 2006

Summary Ambrosia trifida L. is a fast growing annual colonizer of disturbed ground. When present it drastically reduces kinds, numbers and growth of other annuals. Its seedlings emerge before any other annual in early spring. We studied seed germination in relation to temperature, moisture, depth of sowing, and seedling emergence, survivorship and performance of mature plants in relation to time and depth of sowing and seed size.Seeds germinated under a wide range of temperature (8 to 41°C) with an optimum between 10 to 24 °C. Further germination occurred after restratification suggesting germination polymorphism. The seeds also germinated under a wide range of soil moisture conditions (17 to 55 % dry wt) but highest germination occurred at 20 to 33 % soil moisture. Optimum depth of sowing was 2 cm; very little germination occurred very close to soil surface, and some occurred at the 16 cm depth. In the field seedlings emerged from shallow depths first and then from progressively deeper parts of the soil bank. There was positive correlation between seed size and maximum depth from which seeds of this species and those of five other associated annuals emerge. Time required for seedlings to emerge after germination was directly related to depth. Seedlings that emerged first had the highest probability of survival and those that emerged late suffered progressively higher mortality, irrespective of whether late emergence was caused by late germination or deep germination. Among the survivors that reached maturity, plant weight, height, and number of seeds per plant declined with delayed emergence. However, experimental manipulation showed that delayed emergence per se was not the cause of the mortality but rather competition with individuals which emerged earlier. Furthermore, delayed emergence of cohorts in separate plots did not significantly reduce plant height, weight and number of seeds per plant.Thus in the field and within a patch there may be strong selection for early germination and emergence. However, this selection may be opposed by the unpredictability of the time of disturbance, the spatial patchiness of disturbance, and the longevity and induced dormancy of Ambrosia seeds. Compared to its associated annuals, A. trifida has the largest seeds and seedlings, the earliest germination and emergence and a very high photosynthetic rates. These properties give A. trifida a decisive advantage over the other species.
POLLEN INFLUX IN PEAT DEPOSITS: VALUES FROM RAISED BOGS IN THE SOMERSET LEVELS, SOUTH‐WESTERN ENGLAND
Authors: BECKETT S. C. 
Published: May 2006

SummaryPollen influx data from the Flandrian peat deposits of the Somerset Levels, south‐western England, are compared with other pollen influx data for peat and lake deposits. Peat deposits are found to have a much smaller annual recruitment of pollen than lake sediments. This difference is attributed to the absence of pollen contributed by inwash or stream inflow into a peat, particularly a raised bog peat, deposit.
THE POSSIBLE ROLE OF MEMBRANE ELECTROPHORESIS IN THE POLAR TRANSPORT OF IAA AND OTHER SOLUTES IN PLANT TISSUES
Authors: Raven J. A. 
Published: May 2006

SummaryPolar transport of IAA in young higher plant shoot tissue requires an asymmetric distribution of membrane‐transport sites in the plasmalemma of the cells. The ‘chemiosmotic’ hypothesis of IAA transport requires that IAA‐ uniporters be largely on the basal side of the cells. It is suggested that the longitudinal gradient of electrical potential difference (PD, base positive to apex) which may result from activation of plasmalemma H+ efflux in the basal cells by transported IAA, may serve to maintain and reinforce this asymmetric distribution of carriers by the process of membrane electrophoresis of the carriers. The origin of this asymmetric distribution (and hence of polar IAA transport) may lie in electrical potential differences in maternal tissue around the developing embryo. Maintenance of polarity through seed dormancy may be related to gradients in cell‐wall fixed charges (and hence of electrical potential difference) along the shoot axis related to the uronate content of cell walls at different stages of cell development. The possibility of testing this hypothesis, and its relevance to other polar transport phenomena in plants, are briefly discussed.
EFFECTS OF BENZYLADENINE AND GIBBERELLIC ACID ON THE RESPONSES OF TOMATO PLANTS TO ANAEROBIC ROOT ENVIRONMENTS AND TO ETHYLENE
Authors: JACKSON M. B. , CAMPBELL D. JOAN 
Published: May 2006

SummaryBenzyladenine (BA) and gibberellic acid (GA) were applied together as a foliar spray to young tomato plants growing in pots of well drained soil, waterlogged soil or in nutrient solution supplied with air (aerobic), nitrogen gas (anaerobic), or ethylene (20 or 100 ul 1−1 in air) for up to 6 days.BA and GA (10 fig ml−1) lessened the inhibitory effects of waterlogging on stem elongation, transpiration and the increase of fresh and dry wt of the shoots. In absolute terms the promotion of shoot growth by BA and GA was greater in plants growing in non‐waterlogged than in waterlogged soil. Root growth was inhibited by BA and GA. The effect of waterlogging in promoting adventitious rooting at the base of the stem was reduced by BA and GA.Epinastic curvature by petioles was promoted by growing plants in waterlogged soil or anaerobic solution culture in association with an increase in the production of ethylene by the petioles. Applications of BA and of GA inhibited this epinastic growth but they did not lower the rate of ethylene production. However BA and GA diminished the effectiveness of ethylene as a stimulator of epinastic curvature.The application of ethylene to the roots inhibited the accumulation of dry wt by the root system and decreased slightly the growth promoting effects of BA and GA in the shoots.The inhibiting effect of waterlogging the root system on stem elongation could be offset if adventitious roots maintained in well aerated conditions were previously induced on the main stem above the primary roots. Epinastic curvature and ethylene production were not decreased by the presence of an adventitious root system. The extent to which applications of BA and GA may reflect the activity of endogenous hormones produced by aerobic roots is discussed.
THE OCCURRENCE OF MULTIPLE FRUITING LATERALS AT SINGLE NODES OF RASPBERRY CANES
Authors: JENNINGS D.L. 
Published: May 2006

SummaryRaspberry canes frequently have several buds at a node, but it was found that the ability of more than one to develop into a fruiting lateral was influenced by several genetic and non‐genetic factors. Cane diameter was important: a high diameter favoured the production of multiple laterals at a node but reduced the percentage of lateral‐bearing nodes. Consequently, overall lateral production remained nearly constant over a range of cane diameters. Cultivar Glen Clova and other genotypes with a high incidence of multiple laterals were used as donor parents of multiple lateral production in a breeding programme and were shown to transmit the character through genes acting in an essentially additive way. Genes affecting cane diameter contributed to these genetic differences but genotypes differed in their response to cane diameter variation. Gene L1 reduced the incidence of multiple laterals. Frost injuries checked the primary laterals and induced a very high incidence of multiple laterals; performance in a frost year may not be related to performance in other years.It is concluded that multiple laterals are a yield component of only limited value. Their potential for increasing yield is rarely fully realized because reduction in other yield components tends to be associated with their development except when cane diameters are very large.
HORMONAL REGULATION OF FLOWERING IN A SYMPODIAL ORCHID HYBRID DENDROBIUM LOUISAE
Authors: GOH C. J. 
Published: May 2006

SummaryThe growth habit, axillary bud differentiation and flowering behaviour in a sympodial orchid hybrid, Dendrobium Louisae cv. ‘Dark’ were studied. Flowering occurred only after termination of vegetative growth in the pseudobulb. Intermediate shoots with both vegetative and reproductive growth were produced when plants were placed in the shade. Decapitation did not stimulate floral initiation. In mature pseudobulbs, Cytokinin (benzyladenine) stimulated flowering. Gibberellic acid enhanced the cytokinin effect but was itself not effective. It is suggested that flowering in this orchid hybrid is regulated by growth substances, both qualitatively and quantitatively.
PROMOTION OF GERMINATION OF STELLARIA MEDIA SEEDS BY LIGHT FROM A GREEN SAFE LAMP
Authors: BASKIN J. M. , BASKIN C. C. 
Published: May 2006

SummarySeeds of Stellaria media (L.) Cyrill. given short exposures to light from a green safe lamp transmitting most of its energy in the 500 to 600 nm region of the spectrum germinated to a high percentage in darkness. The possibility is discussed that the small amount of blue light (400 to 500 nm) or the relatively large amount of yellow‐orange light (550 to 600 nm) transmitted by the safe lamp, rather than green light (500 to 550 nm) per se, may have stimulated germination. However, green light previously has been shown to stimulate seeds to germinate, and great caution should be exercised in treating as dark controls, seeds that have been exposed to light from a green safe lamp.
OXYGEN RELATIONS OF THE ROOT NODULES OF ALNUS RUBRA BONG.
Authors: WHEELER C. T. , GORDON J. C. , CHING TE MAY 
Published: May 2006

SummaryThe acetylene reducing activity of Alnus rubra nodules is maximal in 15 to 30% oxygen. Within the nodule, the large number and size of many of the intercellular spaces between the uninfected cells in the outer cortex facilitates the diffusion of air through the lenticeb to the infected cells in the mid‐cortex. Access of air to the infected cells, which are arranged in longitudinal bundles separated by one or more lines of starch‐containing uninfected cells and which run at an angle away from the stele towards the nodule apex, is restricted by the reduced number and size of air spaces in this region. The cytoplasm of the infected cells shows high activity of peroxidase and o‐diphenol oxidase, but the lack of correlation between the activity of these enzymes and nitrogenase activity suggests that they are not involved in the control of access of oxygen to the endophyte. It is suggested that one role of nodule peroxidase is the ignification of the infected cells associated with cellular senescence.
RESPONSES OF THREE CROP SPECIES TO VESICULAR‐ARBUSCULAR MYCORRHIZAL INFECTION ON ZINC‐ DEFICIENT INDIAN SOILS
Authors: SWAMINATHAN K. , VERMA B. C. 
Published: May 2006

SummaryMaize, wheat and potato plants were grown on three very zinc‐deficient Indian soils in a pot culture study; the treatments were inoculation of seed with the spores of the vesicular‐arbuscular (VA) mycorrhizal organism, Glomus macrocarpus, dressing with 65ZnSO4 to supply 10 p.p.m. Zn, or both with appropriate controls.Plants raised from inoculated seed usually exhibited root infection and were observed to assimilate significantly more Zn from the soil, than non‐mycorrhizal plants. For maize grown on Daurala soil, Zn application appeared to stimulate endomycorrhizal efficiency in collecting Zn for the host plant; for other crops and on other soils, fertilizer‐Zn did not improve plant uptake of Zn, and so it was concluded that mycorrhizal infection, by itself, could take care of the total Zn requirement of the higher symbiont.Yield responses closely followed the pattern of Zn uptake, with the exception that tuber production in the potato was unaffected by any of the treatments on all the soils. The starch contents of the tubers was, however, found to increase commensurately with the level of Zn in leaves.It is concluded that the observed mycorrhizal effect restricts itself to the more easily available fractions of Zn in deficient soils.The value of artificial inoculation with VA‐mycorrhizae under field conditions to upgrade nutrient‐deficient soils is discussed in the light of the above findings.
MID‐FLANDRIAN CHANGES IN VEGETATION ON MAINLAND ORKNEY
Authors: KEATINGE T. H. , DICKSON J. H. 
Published: May 2006

SummaryThe presence of birch‐hazel scrub with a rich ground flora of tall herbs and ferns in the mid‐Flandrian on Mainland, Orkney, suggested by Moar (1969), is supported, but no evidence was obtained for Pinus, Quercus, Alnus or other major forest trees as indigenous species. Evidence from lake muds and intertidal peat in the region of the Bay of Skaill suggests an increase in onshore wind speeds with the formation of the Bay of Skail and the beginning of sand‐blow c. 5000 B.P. The birch‐hazel scrub declined at this time and the remaining tall herb and fern vegetation was replaced by pasture within c. 200 years under the influence of neolithic man and his grazing animals. At c. 3400 B.P. a combination of increased oceanicity of climate and high grazing pressure appear to have led to the initiation of blanket peat formation on the hills. A contribution to the interpretation of 14C dates derived from marly sediments is included.
SOME UNUSUAL CHARACTERISTICS OF NITRATE REDUCTION IN ERYTHRINA SENEGALENSIS DC.
Authors: STEWART G. R. , OREBAMJO T. O. 
Published: May 2006

SummaryThe characteristics of nitrate reduction exhibited by the tropical leguminous tree Erythrina senegalensis differ in several respects from those of other higher plants. Nitrate reduction in this species can best be characterized as being a high activity‐low affinity system. High levels of nitrate reductase can be demonstrated using in vivo (50 to 278 μmol h−1 g fresh wt−1) or in vitro (360 μmol h−1 g fresh wt−1) assay procedures. The enzyme extracted from leaf tissue can utilize both NADH and NADPH as electron donors. The enzyme has a low affinity for nitrate, Kspp194 8 to 10 mM. The NADH and NADPH activities co‐chromatograph using several chromatographic procedures, suggesting a single molecular form of nitrate reductase is present.
COMPARISON OF THE ONION PLANT (ALLIUM CEPA) AND ONION TISSUE CULTURE
Authors: SELBY C. , GALPIN I. J. , COLLIN H. A. 
Published: May 2006

SummaryThe system for flavour production in the onion consists of the enzyme alliinase and the flavour precursors, the S‐alkyl‐L‐cysteine sulphoxides. Flavour production in the onion and in the callus were compared by looking at each part of the system in turn. Measurement of the specificity and Km values of the alliinase from onion bulb and callus showed the enzymes to be identical. The total amino acid level was lower in the callus tissue than onion bulb tissue and the composition was altered. However, this change in amino acid metabolism did not appear to affect the synthesis of the flavour precursors since addition of the important amino acids L‐cysteine and L‐valine to the medium did not lead to the production of an onion smell from the callus upon crushing. The most noticeable difference was in the composition of the flavour precursors. In the callus S‐methyl‐l‐cysteine sulphoxide was present at a low concentration while the major precursor of onion flavour S‐trans‐prop‐1‐enyl‐l‐cysteine sulphoxide, was absent altogether. It was suggested that the biosynthetic pathway for S‐trans‐prop‐1 ‐enyl‐l‐cysteine sulphoxide was not functioning in the callus.
SOME EFFECTS OF DAZOMET ON 0‐DIPHENOLOXIDASE ACTIVITY IN HOMOGENATES OF SOLANUM TUBEROSUM
Authors: VAUGHAN D. , ORD B. G. 
Published: May 2006

SummaryDazomet, a commercially available soil fumigant, inhibited 0‐diphenoloxidase activity in homogenates of potato tubers. This inhibition was prevented in the presence of sufficient quantities of Cu2+. Dazomet affected the V(max) of the enzyme reaction, but had no effect on the affinity of the enzyme for its substrate. Similar results were obtained using the Cu2+ chelating agent sodium diethyldithiocarbamate.
PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS
Authors: KERSHAW K. A. , MORRIS T. , TYSIACZNY M. J. , MacFARLANE J. D. 
Published: May 2006

SummaryThe occurrence of dark CO2 fixation in Peltigera cardna var. praetextata and Parmelia caperata is reported, with rates of 15 to 27 % and 10 to 12 % respectively of the equivalent light photo‐synthetic rate. The pattern of incorporation into oxaloacetate, malate, citrate, alanine and aspartate points to fixation via PEP and provides both anaplerotic replenishment of TCA cycle intermediates as well as active amino acid and protein synthesis in the dark.The environmental control of the rate of dark CO2 fixation by temperature, moisture and season is factorially examined and the potential role of dark CO2 fixation in the ecology of a lichen is briefly discussed.
ULTRASTRUCTURAL ASPECTS OF THE SYMBIOSIS BETWEEN ALGAL CHLOROPLASTS AND ELYSIA VIRIDIS
Authors: Hawes C. R. 
Published: May 2006

SummaryThe ultrastructure of chloroplasts in the frond of Codium fragile and in symbiotic association with the digestive cells of Elysia viridis is described. In the hepatopancreas the chloroplasts are always bounded by a host membrane and contaminant algal cytoplasm may be attached to the chloroplast envelope. The possibility that‘butterfly’shaped chloroplasts and chloroplasts with membranous baffles represent different forms of chloroplast division is discussed. The presence of non‐Codium chloroplasts in the digestive cells of E. viridis is reported.
Studies ON THE MECHANISM OF ACTION OF THE ANTIFUNGAL COMPOUND FALCARINDIOL
Authors: Garrod B. , Lea E. J. A. , Lewis B. G. 
Published: May 2006

SummaryThe mode of action of the polyacetylenic antifungal compound falcarindiol was explored. Chlamydospores of Mycocentrospora acerina removed falcarindiol from test solutions. Falcarindiol at 28 μg ml−1 burst bimolecular lipid membranes formed from lecithin or lecithin‐cholesterol and caused haemolysis in erythrocytes. At a concentration of 100 μg ml‐1 falcarindiol caused rapid electrolyte loss from both chlamydospores of M. acerina and discs of Doucus carota. Hyphal tips of M. acerina burst, and the internal structure of chlamydospores of M. acerina was altered by concentrations of 75 μg ml‐1 falcarindiol. The hypothesis is advanced that falcarindiol acts on the plasma membrane or affects some process needed for membrane function.
THE PERIHAUSTORIAL MEMBRANE IN HOP CELLS INFECTED BY PSEUDOPERONOSPORA HUMULI
Authors: Pares R. D. , Greenwood A. D. 
Published: May 2006

SummaryThe part of the host plasmalemma invaginated around the haustorium of Pseudoperonospora humuli was examined after staining with (a) Uranyl acetate followed by lead citrate and (b) a mixture of phosphotungstic acid and chromic acid. It was also examined by using a tilting and rotating goniometer stage.After staining with uranyl acetate and lead citrate the membrane could only be detected on about 45 % of the periphery of the haustorium transected in a section and only the outer dark component of the triplet unit membrane structure could be detected. The use of phosphotungstic acid‐chromic acid enabled the whole of the triplet membrane structure to be seen but did not enable the membrane to be detected over a greater percentage of the haustorium periphery than with the first procedure.The use of the goniometer stage resulted in the membrane being seen around 95 % of the periphery of the haustorium.