bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE EFFECTS OF PHOTOPERIOD AND TREATMENT WITH GIBBERELLIC ACID ON THE CONCENTRATION OF SOLUBLE CARBOHYDRATES IN THE SHOOT APEX OF SPRING BARLEY
Authors: COTTRELL J. E. , DALE J. E. 
Published: May 2006

SummaryBarley plants (Hordeum vulgare L. cv. Clipper) were grown in controlled environment rooms for varying periods. The total soluble carbohydrate concentration was determined for stem apices over the period of early ear development using the p‐hydroxybenzoic acid hydrazide method.Concentration of soluble carbohydrates rose during the photoperiod and was lower in the apices of plants subjected to shade. It also increased as the ear enlarged, irrespective of photoperiod. In 8 h photoperiods plants initiated many more spikelets, but at a lower rate, compared to those grown in 16 h days. Apices of plants grown in 8 h days showed a lower relative growth rate, but despite this at the end of spikelet initiation concentration of soluble carbohydrates was about 30% higher than for apices from plants in 16 h photoperiods. Where plants were grown in 8 h high intensity light followed by 8 h low intensity light soluble carbohydrate content was slightly more than in the apices of plants kept throughout 16 h in high intensity light. Treatment of plants grown in 8 h photoperiods with gibberellic acid accelerated the rates of initiation and development of spikelets. Treatment caused a substantial but ephemeral increase in soluble carbohydrate content, although by the time that spikelet initiation ceased the concentration was similar in control and treated plants.It is concluded that total soluble carbohydrate concentration in the apex is not related to either rate of initiation or rate of development of spikelets. It is suggested that rate of utilisation of available soluble carbohydrate is subject to photoperiodic control and restricts growth and development of the ear.
TRANSPIRATION AND THE WATER RELATIONS OF FABA BEAN (VICIA FABA) INFECTED BY RUST (UROMYCES VICIAE‐FABAE)
Authors: TISSERA PREENI , AYRES P. G. 
Published: May 2006

SummaryTranspiration and the water relations of faba bean (Vicia faba L.) were studied in healthy tissues of plants infected by rust (Uromyces viciae‐fabae (Pers.) Shroet). Water relations measurements on infected plants were made either on uninfected, healthy halves of otherwise infected lower leaves or on wholly uninfected upper leaves and, thus, they excluded the direct influence of fungal tissues. Rust caused increased transpiration from infected tissues after sporulation but, even in well‐watered plants, infection of proximal halves lowered leaf water potentials and inhibited transpiration from distal regions of the same leaf. The normal relationship between leaf water potential and stomatal diffusion resistance was not affected in the uninfected distal part of the leaves. Relationships between soil water potential and leaf water potential were affected by rooting patterns. Increased transpiration caused by rust accelerated drying of the soil, and consequent lowering of leaf water potentials, when plants were grown singly in small unwatered pots.When healthy and rusted plants grew together in pairs in the same small unwatered pots of soil, and therefore at the same soil water potentials, healthy regions of proximally rusted leaves, and healthy leaves near the shoot apex of rusted plants, had lower leaf water potentials and were less turgid than comparable tissues of healthy plants. However, rust did not impair the ability of these same tissues to recover normal leaf water potentials and turgor when plants were rewatered.When healthy and rusted plants shared soil columns that allowed unrestricted downward growth of roots and soil was cooled to temperatures similar to those in the field, roots grew faster in well watered soil than in unwatered soil. Rust inhibited the growth of roots in the mid‐depth (mid soil water potential) region of unwatered soil columns. Although the pattern of water potentials and changes in turgor that developed in unwatered plants after 15 d was similar to that seen previously in unwatered plants grown in small pots, differences in root growth would probably give healthy plants and increasing advantage over rusted plants in water uptake during longer periods of drought.
THE EFFECT OF MYCORRHIZAL INFECTION ON THE RESPONSE OF BETULA PAPYRIFERA TO NICKEL AND COPPER
Authors: JONES MELANIE D. , HUTCHINSON THOMAS C. 
Published: May 2006

SummaryThe role of ectomycorrhizas in the metal tolerance of birch seedlings from Sudbury, Ontario was investigated. Betula papyrifera Marsh, is one of the few tree species able to survive in the copper‐ and nickel‐polluted area near Sudbury. Two types of birch seedlings were tested; those inoculated with Laccaria proxima (Boud.) Pat., Lactarius hibbardae Peck, Lactarius rufus (Scop, ex Fr.) Fries, or Scleroderma flavidum E. & E. isolates originating from the Sudbury area, and those which were not inoculated. Once the seedlings were infected, they were grown in sand culture containing 34 or 85 μM Ni, 32 or 63 Cu, or a control solution. At the low nickel concentration, the mycorrhizal plants, especially those infected with S. flavidum, grew significantly better than did non‐mycorrhizal plants. At the higher nickel concentration, S. flavidum‐infected seedlings weighed 86% of controls without nickel, while the other seedlings weighed only 52 to 61 % of control. The good growth of S. flavidum‐infected birch seedlings may have been due to retention of nickel in the mycorrhizas. These seedlings had the highest root nickel contents and the lowest stem nickel contents. At the high concentration of copper, growth of the mycorrhizal seedlings was significantly reduced compared with the non‐mycorrhizal seedlings. This reduction in growth of infected seedlings did not relate to an increase in the uptake or translocation of copper. Under the low copper treatment, infection with mycorrhizal fungi did not affect seedling growth. The potential role of iron and phosphorus in affecting host metal tolerance was investigated. Changes in the tissue concentrations of these elements did not relate to the effect of the fungi on metal tolerance.
TREATMENT OF THE STIGMA WITH AN EXTRACT OF A COMPATIBLE PISTIL OVERCOMES SELF‐INCOMPATIBILITY IN PETUNIA
Authors: SHARMA NEELAM , SHIVANNA K. R. 
Published: May 2006

SummaryTreatment of the stigma with an extract of a compatible pistil, just before pollination, was very effective in overcoming self‐incompatibility in Petunia hybrida Vilm. Progressive delay either in the application of the extract, or in pollination markedly reduced its efficacy in overcoming self‐incompatibility‐ The treatment seems to mask the self‐incompatibility recognition molecules of the pistil.
POLYPLOIDY AND HABITAT DIFFERENTIATION IN DESCHAMPSIA CESPITOSA
Authors: ROTHERA S. L. , DAVY A. J. 
Published: May 2006

SummaryThe chromosome numbers of 114 populations of the Deschampsia cespitosa (L.) Beauv. complex, widely distributed in the British Isles, were determined from root‐tip squash preparations. This revealed two widespread morphologically cryptic chromosomal races of seminiferous D. cespitosa (2n= 26, 52). The tetraploid is found throughout Britain; its range of habitats includes meadows, pastures, woodland, plantations, verges and waste ground. This is the first report of an extensive geographical distribution for tetraploid seminiferous D. cespitosa. The diploid appears to be mainly restricted to woodland, of mostly ancient, semi‐natural origin. Populations with both chromosome numbers are rare. The tetraploid is usually found where invasive colonization has clearly occurred.The closely related proliferous taxon, D. alpina (L.) Roem. & Schult., was tetraploid, in agreement with published data. The prolifery itself induces changes in floret morphology. The floral morphology and cytological data together suggest that sub‐specific rank is appropriate for this variant in British material.
GLUTAMATE METABOLISM IN INTACT SEEDLINGS AND SEEDLING SEGMENTS OF PEAS
Authors: MELCHER INGA M. 
Published: May 2006

SummaryGlutamate metabolism in intact cotyledons of pea seedlings (Pisum sativum L.) differs considerably from that in cotyledon slices. No decarboxylation of glutamate was found in intact cotyledons, whereas the decarboxylation in sliced cotyledons was so large that γ‐aminobutyric acid (γAbu) was by far the predominant metabolic product of glutamate. A number of mechanisms that could trigger glutamate decarboxylase activity are discussed.
PROTEIN CONTENTS OF SEED YIELDS OF FIELD‐GROWN SOYBEANS EXPOSED TO simulated ACIDIC RAIN: ASSESSMENT OF THE SENSITIVITIES OF FOUR CULTIVARS AND EFFECTS OF DURATION OF SIMULATED RAINFALL
Authors: EVANS LANCE S. , SARRANTONIO MARY J. , OWEN ELIZABETH M. 
Published: May 2006

SummaryAnalyses of seeds harvested from field‐grown soybeans (Glycine max Merrill) demonstrated that simulated acidic rainfalls can significantly decrease total protein contents. In an experiment conducted in 1983, seed yields of plants exposed twice weekly to long duration rainfalls showed no significant differences in seed protein contents among the acidity levels tested. In contrast, significant differences in protein contents were found for seed samples from the short duration, daily rainfalls. Seeds of plants exposed to simulated rain of pH 5.6 had average protein contents of 37.9% compared with a range between 30.6 and 32.1 % from plants exposed to lower pH values. Overall the protein contents of seeds of acidic rainfall treatments, expressed on a per plant basis, ranged from 23 to 34%. The results suggest that the response of soybean seed yields to acidity are affected by duration and frequency of simulated rainfalls. In the 1984 growing season, four commercial cultivars were tested under conditions of longer duration rainfalls, applied twice weekly. Significant treatment effects occurred only to the Amsoy cultivar and not to Asgrow, Corsoy or Hobbit. For the latter three cultivars the protein contents of samples were all relatively high (means were all between 35 and 39%). The relatively low protein content of Amsoy soybeans exposed to simulated rainfalls of pH 2.7 was apparently responsible for the statistical significance among treatments. These and previous results demonstrate that rainfall acidity can significantly affect protein contents of seeds of field‐grown soybeans and that effects on protein content are independent of changes in plant seed yields.
LEAF‐SURFACE PROPERTIES IN RELATION TO TOLERANCE OF SALT SPRAY IN FESTUCA RUBRAssp. LITORALIS (G. F. W. MEYER) AUQUIER
Authors: HUMPHREYS M. O. , KRAUS M. P. , WYN JONES R. G. 
Published: May 2006

SummaryLeaf‐surface properties were investigated in F. rubra ssp. litoralis (G. F. W. Meyer) Auquier cv. Hawk, which is tolerant of salt spray, and cv. Aberystwyth S.59, which is susceptible. Salt retention and leaf wettabilities were measured and leaf‐surface structure was observed using a scanning electron microscope. In both cultivars stomata were confined to adaxial leaf surfaces which were less wettable than abaxial surfaces probably because of ridging and wax deposits. Salt retention after spraying was much higher per unit dry weight in S.59 than in Hawk, although salt retention per unit of projected leaf area was similar in both cultivars. This was because leaves were folded about the midrib in Hawk but were much flatter in S.59. Folding reduced the exposure of adaxial leaf surfaces to salt spray. The adaptative significance of this is discussed together with its broader physiological implications.
PRODUCTION OF INDOLE‐3‐E THANOL AND INDOLE‐3‐A CETIC ACID BY THE MYCORRHIZAL FUNGUS OF OPHRYS LUTEA (ORCHID ACEAE)
Authors: BARROSO J. , NEVES H. CHAVES , PAIS M. S. 
Published: May 2006

SummaryThe GC/MS analysis of trimethylsilyl derivatives of extracts from the culture medium and from the mycelium of Ophrys lutea Cav., a mycorrhizal fungus grown in a liquid culture medium, revealed the ability of this fungus to synthesize indole‐3‐ethanol and indole‐3‐acetic acid.The identification of these compounds in the liquid medium and in the mycelial extracts suggested their transference from the fungus to the host during the establishment of mycorrhizas.
ULTRASTRUCTURAL STUDIES IN LICHENS
Authors: HONEGGER ROSMARIE 
Published: May 2006

SummaryThe cytology of the relationship between evolved lecanoralean lichen mycobionts and their trebouxioid photobionts were studied in the foliose Cetrelia olivetorum (Nyl.)Culb. & C. Culb., Platismatia glauca (L.)Culb. & C. Culb., and Parmelia tiliacea (Hoffm.)Ach., and in the fruticose Pseudevernia furfuracea (L.)Zopf (all Parmeliaceae) using SEM and partly TEM techniques. In freeze‐dried SEM preparations of all four species crystalline secondary metabolites of fungal origin were detected on the surface of the algal symbiont. Extracellular lichen products crystallized within and on the outermost surface layer of the cell wall which spreads from the mycobiont over the surface of the photobiont. This outermost wall layer revealed an irregularly tessellated pattern in freeze‐fracture preparations and was recognized as a very thin, electron‐dense layer in ultrathin sections. According to histochemical tests the surface layer of medullary hyphae and algal cells is largely composed of proteins and polyesters of fatty acids. Published data on the in vitro effects of phenolic lichen products on the metabolism of isolated, cultured photobionts are summarized, and possible roles of these secondary metabolites at the myobiont‐photobiont interface within the lichen thallus are discussed.
THE DEVELOPMENT AND ULTRASTRUCTURE OF ECTOMYCORRHIZAS
Authors: DUDDRIDGE J. A. 
Published: May 2006

SummaryThe effect of the presence of an exogenous carbon source in the synthesis medium on compatible and incompatible interactions between Suillus grevillei (Klotzsch) Sing, and a number of ectomycorrhizal hosts has been studied at the ultrastructural level. Comparisons are made with the results of the previous study in which carbohydrate was omitted. Observations suggest that the availability of an external source of carbon to the fungus upsets the balance of the symbiosis in favour of the fungal partner, even in compatible interactions, causing changes in the host cell wall and at the host‐fungus interface. The rate and degree of colonization of the root surface is also influenced by the presence of carbohydrate in the synthesis medium. These results suggest that any in vitro studies undertaken on compatibility and specificity in ectomycorrhizal associations should omit carbohydrate from the medium or use an aseptically synthesized donor host as the source of fungal inoculum.
WATER RELATIONS AND ULTRASOUND EMISSIONS OF PINUS SYLVESTRIS L. BEFORE, DURING AND AFTER A PERIOD OF WATER STRESS
Authors: PEÑA JOSÉ , GRACE JOHN 
Published: May 2006

SummaryUsing potted plants in a glasshouse, the relationship between ultrasound emission rate and water potential was investigated before, during and after a period of simulated drought. At the start of the experiment, just before budbreak, the plants emitted ultrasound pulses at rates of up to 25 c.p.m. During drought the rate increased to 60 c.p.m. Droughted plants displayed lower xylem density than the controls; and on this basis it was estimated that a third of the tracheids had emptied as a result of cavitation. On rewatering, the density of the xylem recovered and, after recovery, the plants that had been droughted failed to produce ultrasound emissions when water potential fell. By this time, the control plants, which had been well watered all the time, produced only a small number of ultrasound emissions when water potential fell.
INTERACTIVE EFFECTS OF CADMIUM, COPPER AND NICKEL ON THE GROWTH OF SITKA SPRUCE AND STUDIES OF METAL UPTAKE FROM NUTRIENT SOLUTIONS
Authors: BURTON K. W. , MORGAN E. , ROIG A. 
Published: May 2006

SummaryThe interactive effects of Cd, Cu, and Ni were studied in Sitka spruce [Picea sitchensis (Bong.) Carr] seedlings grown in nutrient solutions supplemented with combinations of these metals over three experiments of 3 × 3 × 3 factorial design. The results indicated that the toxic effects of Cd and Cu may be additive when both metals are present at concentrations which individually reduce yields, and that tree growth at several forestry sites in South Wales may be more severely affected than previously reported.Analysis of variance of the concentrations of the added metals in the plants showed that concentrations of Cd in both roots and shoots were significantly reduced by Cu treatments (P < 0.01) and that this effect was especially pronounced at the highest concentrations of Cd and Cu (significant Cd × Cu interaction, P < 0.01). Analysis of variance of the concentrations of the nutrients Zn, Mg, Mn, and Ca in roots and shoots showed that both Cd and Cu significantly (P < 0.01) reduced the concentrations of Mn, and also interactively affected these (P < 0.01). Concentrations of Mg in the shoots were also significantly reduced by Cu treatments.
PHOTOSYNTHESIS OF COTYLEDONS OF SOYBEAN SEEDLINGS
Authors: HARRIS MARGARET , MACKENDER RICHARD O. , SMITH DAVID L. 
Published: May 2006

SummaryThe rate of net photosynthesis in each of the foliar organs present on seedlings of Glycine max (L.) Merrill was measured by infrared gas analysis on the fourth day after sowing and every third day thereafter until 5 d after cotyledon abscission. Dark respiration rates for the whole seedling were also measured. Estimates of the daily net carbon assimilation were made using the sum of the net CO2 assimilatory rates for each foliar organ present and the dark respiration rate for the whole seedling. Rates of cotyledon photosynthesis were very low in comparison to the leaves, whether expressed per unit chlorophyll or unit area. Although the cotyledon contribution to seedling assimilation remained small throughout their lifetime, it was enough to balance seedling respiratory losses during days 7 to 10 prior to leaf expansion. Marked increases in the CO2 budget only occurred once primary leaf photosynthesis began on day 10. Net assimilation then increased rapidly as first, second and third trifoliate leaves expanded.
CARBOXYLATING ENZYMES OF SOYBEAN COTYLEDONS
Authors: HARRIS MARGARET , MACKENDER RICHARD O. , SMITH DAVID L. 
Published: May 2006

SummaryThe in vitro activities of ribulose‐1,5‐bisphosphate (RuBP) carboxylase and phosphoenol pyruvate (PEP) carboxylase enzymes extracted from soybean [Glycine max (L.) Merrill cv. Amsoy'71] cotyledons are correlated with cotyledon chlorophyll development. High levels of PEP carboxylase activity were found in the spongy mesophyll tissues of young cotyledons before greening occurred, but as the cotyledons developed, the activity of this enzyme fell rapidly and 13 d after sowing it had almost disappeared. RuBP carboxylase activity, in contrast, was concentrated in the palisade mesophyll and increased with chlorophyll content, reaching a peak on day 10. RuBP carboxylase activity then declined and by the onset of senescence was very low. In cotyledons whose senescence had been arrested by epicotyl removal, chlorophyll recovery was found to precede that of the activity of both carhoxylase enzymes. After a lag of 5 d, both enzymes showed increased activity in the palisade mesophyll, RuBP carboxylase activity being greater than that of PEP carboxylase.
CARBOHYDRATES IN ROOTS AND RHIZOMES OF PERENNIAL GRASSES
Authors: STEEN ELIEL , LARSSON KJELL 
Published: May 2006

SummaryRoots and rhizomes were sampled in a three‐year‐old grass ley during one year using a mesh bag method and soil coring. Samples, collected after different growth periods (1, 2, 3, 4, 5, 6 and 12 months) and at different times of the year, were analyzed for carbohydrates and Klason lignin. Throughout the year the rhizomes contained more non‐structural carbohydrates (20 to 40% of the organic matter) than the roots (1 to 8%). The non‐structural carbohydrate content varied over the year with a maximum in autumn and minimum in early spring and summer after the first grass cut. Fructan was the predominant constituent in this fraction. Structural carbohydrates and Klason lignin showed relatively small variations over the annual cycle. The ratio between structural carbohydrates and Klason lignin showed little variation with time but differed between roots (19) and rhizomes (2.5). The xylose content was higher in the roots than in the rhizomes. Only small changes occurred with time in the relative composition of the structural carbohydrates. This consistency in composition implies that there was a difference between subterranean and aerial parts. In the latter, ageing is characterized by increased lignification and systematic changes in structural carbohydrates owing to the formation of secondary cell walls.
YIELD TURGOR OF GROWING LEAVES OF BETULA AND ACER
Authors: TAYLOR GAIL , DAVIES W. J. 
Published: May 2006

SummaryLeaf growth of first year seedlings of silver birch (Betula pendula Roth.) and sycamore (Acer pseudoplatanus L.) was measured continuously using linear variable transducers (LVTDs) when shoots were enclosed in small Perspex chambers, in which temperature, vapour pressure deficit (VPD) and photon fiuence rate were all controlled. A new method was used to measure the yield turgor (Y) of growing leaves. The VPD of air in the chamber was altered so that transpiration rate was changed. Turgor pressures, measured using thermocouple psychrometers, and growth rates varied as a result of this treatment, and the relationship between leaf growth and turgor pressure (P) and the turgor pressure at which growth ceased (Y) could be measured within a very short time period using well‐watered plants.The value of Y was constant for illuminated and darkened leaves of both species, but Y was higher for sycamore leaves (Y= 0.250 MPa) compared with the value for birch leaves (K = 0.071 MPa).Cell wall extensibility (w, MPa−1 h−1) was calculated from the slope of the line relating turgor pressure to growth. For leaves of birch, there was a significant increase in m when leaves were illuminated (m, dark = 1.3 × 10−2 MPa−1 h−1; m, light = 46 × 10−2 MPa−1), similar in magnitude to the increase in wall extensibility measured previously by mechanical analysis of killed leaf tissue (WEX, the plasticity of tissue subjected to a uniaxial stress). No change in m was detected when darkened sycamore leaves were illuminated (m, dark = 4.2 × 10−2 MPa−1 h−1; m, light = 4.4 × 10−2 MPa−1 h−1).The results confirm earlier work on the factors controlling the diurnal patterns of leaf growth of these two species and suggest that leaf growth of birch is primarily limited by cell wall loosening but that the growth of sycamore leaves may be limited by leaf turgor.