bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship of soil fertility to suppression of the growth response of mycorrhizal big bluestem in non‐sterile soil
Authors: KITT D. GERSCHEFSKE , HETRICK B. A. DANIELS , WILSON G. W. T. 
Published: April 2006

SUMMARYWhen growth of vesicular‐arbuscular (VA) mycorrhizal and non‐mycorrhizal big bluestem was evaluated in 15 soils, three different growth response groups were evident. Group one, which included the prairie soils, displayed high mycorrhizal dependency as well as significant suppression of plant growth in non‐sterile soil. Group two showed no mycorrhizal dependency; however, plant growth was suppressed in nonsterile soil. The last group exhibited no mycorrhizal dependency or suppression in non‐sterile soil. Mycorrhizal dependency of big bluestem was not highly correlated with any individual soil parameter; however, concentrations of soil K, Ca, Cu, and Fe were used to successfully classify‘high’or‘low’mycorrhizal dependency. Suppression of plant growth in non‐sterile soil was also related to soil fertility. The magnitude of non‐sterile soil suppression was described by equations using soil Na, Zn, Mn, organic matter, Mg, and NH4. The mechanism of this suppression is still unclear; however, the nutrients which predict suppression may be related to the development of mycorrhizal symbosis or in demand by plants and other microbes, while those nutrients which predict mycorrhizal dependency may be related to those supplied to the plant by the symbiosis.
Salt tolerance in natural populations ofTrifolium repensL.
Authors: AB‐SHUKOR N. A. , KAY Q. O. N. , STEVENS D. P. , SKIBINSKI D. O. F. 
Published: April 2006

SUMMARYThe salt tolerances of plants from natural populations ofTrifolium repensL. (White Clover) growing in saline and non‐saline sites were compared by root growth tests at a range of NaCl concentrations. Plants from three salt‐marsh sites showed high or very high salt tolerance, with relatively vigorous root growth in 150–200 mM NaCl. Plants with two non‐saline inland sites showed little or no tolerance. A sea‐cliff population and plants of cv. Gwenda showed intermediate levels of tolerance at low salt concentrations. Halophytic maritime populations may‐provide material for the development of salt tolerant cultivars ofT. repens, a crop plant in which most existing cultivars are thought to be salt‐sensitive.
The responses of four Irish wetland tree species to raised soil water levels
Authors: IREMONGER S. F. , KELLY D. L. 
Published: April 2006

SUMMARYThe four most common tree species in Irish wetland woods are Alnus glutinosa (L.) Gaertn. (common alder), Betula pubescens Ehrh. (downy birch), Fraxinus excelsior L. (ash) and Salix cinerea ssp. oleifolia Macreight (Salix atrocinerea Brot., common sally). Seedlings of these species were subjected to different soil water levels (half saturated and surface saturated) in their second and third years of growth, and performance was compared to that in a free draining control treatment. All plants survived in the water treatments, except for over 50%, of the B. pubescens. Soil redox potentials indicated a gradient in the degree of hypoxia which seemed to reflect the order of tolerance of the species, as shown by measurements of relative growth and final dry weight. The observed differences in soil redox potentials may have been due to the oxidizing activity of the roots of tolerant species, which showed varying degrees of stem base hypertrophy and associated proliferation of lenticels. Species were affected by the waterlogging treatments in the order B. pubescens (most adversely affected) > A. glutinosa > F. excelsior > S. cinerea ssp. oleifolia.
The germination characteristics of seeds from Lychnis viscaria L. (Viscaria vulgaris Bernh.), Potentilla rupestris L. and Veronica spicata L.
Authors: WHITTINGTON W. J. , WILSON G. B. , HUMPHRIES R. N. 
Published: April 2006

SUMMARYThe effects of temperature, date of sowing and the presence or absence of light on the percentage germination by seeds of Lychnis viscaria L. (Viscaria vulgaris Bernh.), Potentilla rupestris L. and Veronica spicata L. were studied. It was found that both in controlled environments and in the open, the order of time‐to‐germination was the same, namely L. viscaria, V. spicata and finally, P. rupestris. The latter species required a temperature in excess of 10°C to germinate and V. spicata required light to germinate. A small (< 5%) number of V. spicata seeds did, on occasion, germinate in the dark and the seeds of this species whether fully imbibed or not, required a shorter period in the light than P. rupestris. Because the seeds used were stored and germinated under artificial conditions these findings can only serve as a first, but important, stage in understanding how the seeds germinate in nature.
Stomatal closure fully accounts for the inhibition of photosynthesis by abscisic acid
Authors: DOWNTON W. J. S. , LOVEYS B. R. , GRANT W. J. R. 
Published: April 2006

SUMMARYThe partial pressure of intercellular CO2 calculated from gas exchange data for abscisic acid‐treated leaves of grapevine (Vitis vinifera L.) and sunflower (Helianthus annuus L.) does not indicate the average intercellular CO2 of the leaf. The latter can be determined from chlorophyll fluorescence quenching information and accurately modelled from gas exchange data. Stomatal closure can fully account for previously assumed non‐stomatal inhibition of photosynthesis. Autoradiograms show that abscisic acid induces non‐uniform gas exchange over small areas of the leaf.
Ultrastructure of chloroplast membranes in leaves of maize and ryegrass as revealed by selective staining methods
Authors: LAWTON JUNE R. 
Published: April 2006

SUMMARYLeaves of Lolium multiflorum Lam. and Zen mays L. of different ages were prepared for TEM by a number of cytochemical methods. After post‐fixation in potassium ferricyanide with osmium tetroxide the peripheral reticulum in both mesophyll and bundle sheath chloroplasts of maize stain very clearly. Post‐fixation with uranyl acetate, copper and lead salts also stains the chloroplast envelope rather than the internal thylakoid system. Differences between the mesophyll and bundle sheath chloroplasts of maize and between those of ryegrass are revealed after post‐fixation in zinc iodide with osmium tetroxide. After post‐fixation in potassium iodide with osmium tetroxide the loculi stain less intensely than in zinc iodide. Malachite green added to glutaraldehyde at pH 70 enhances membrane staining in general and reveals large lipid drops in the stroma. At pH below 6–0 only the ‘A’ space is stained. The ‘A’ space and the loculus are stained when ethidium bromide is added to glutaraldehyde. The different reactions of the chloroplast membranes probably reflect differences in chemical composition.
Effect of inorganic phosphate, 3‐phosphoglycerate and glucose‐6‐phosphate on net starch synthesis by isolated chloroplasts of Codium fragile (Suringar) Hariot
Authors: WILLIAMS MICHAEL L. , COBB A. H. 
Published: April 2006

SUMMARYNet starch synthesis isolated chloroplasts of Codium fragile appears to be regulated in a similar manner to that of vascular plants. Exogenous 10 mol m−3 PGA stimulated net starch synthesis at 200 μmol m−2 s −1 (PPFD) by approx. 69%, whilst 10 mol m−3 P1 not only inhibited synthesis but also promoted net starch degradation. However, unlike vascular plant chloroplasts, 10 mol m−3 G6P was found to stimulate net starch synthesis by approx. 52% under the same conditions. This apparent difference in response to exogenous G6P is discussed in relation to the operation of the P1‐G6P translocator in chloroplasts of this species
Growth and nutrition of guayule (Parthenium argentatum) in a saline soil as influenced by vesicular–arbuscular mycorrhiza and phosphorus fertilization*
Authors: PFETFFER C. M. , BLOSS H. E. 
Published: April 2006

SUMMARYGrowth of guayule (Parthenium argentatum A. Gray) in a moderate and a highly saline‐sodie soil was increased by inoculation with Glomus intraradices Schenck & Smith. The growth of guayule plants was stimulated equally by the addition to the soil of either 100 μg g1 of phosphorus (P) or inoculum of G. intraradices.Mycorrhizal plants had increased concentrations of PO4 and decreased concentrations of Na in shoot tissues compared to non inoculated control plants. Addition of 100/μgg 1 of P to the soil increased the accumulation of PO4 in the shoot tissues and in most instances decrease accumulation of Cu, Zn, Na, K, and SO4. Concentrations of Na, K, and Cl and frequently Mn in the shoot tissues were increased while the concentrations of PO4 and SO4 in shoot tissues were generally decreased by the addition of NaCl to the soil.Addition of 100μgg 1 of P to the soil did not markedly affect the colonization of guayule roots by G. intraradices. The roots of mycorrhizal guayule grown in soil with NaCl added contained decreased numbers of arbuscules and vesicles. Addition of both P and NaCl to the soil reduced the formation of arbuscules and vesicles and reduced the occurrence of moderate and heavy levels of root colonization.
A new method for obtaining Anabaena‐free Azolla
Authors: LIN CHANG , WATANABE I. 
Published: April 2006

SUMMARY Anabaena azollae can be completely eliminated from megasporocarps of Azolla by the removal of the indusium and apical membrane after horizontally cutting the megaspore apparatus beneath the apical membrane. All subsequent sporelings of Azolla are free from Anabaena. These do not fix N and fail to survive on N2‐free media. They grow normally, however, in N2‐containing liquid medium or in a soil‐water system with small amounts of added N and eventually bear sporocarps. Anabaena is again absent in the new megasporocarps and sporelings of Azolla derived from the second generation of megaspores are likewise Anabaena‐free.
Mass allocation, moisture content, and dispersal capacity of wind‐dispersed tropical diaspores
Authors: AUGSPURGER C. K. 
Published: April 2006

SUMMARYAmong 34 wind‐dispersed tree species on Barro Colorado Island, Panama, the wet mass of diaspores ranges over six orders of magnitude, The seed mass as a percentage of diaspore mass (S/D) varies greatly among species from 14 to 94% with a mean value of 61% The mean percent moisture of diaspores is 10% no consistent differences occur between seed and non‐seed components of diaspores in percent moisture. Wing‐loading (weight/area) and hence dispersal capacity varies over one order of magnitude among these species and is correlated more highly with S/D than with percent moisture of diaspores. Compared to fruit diaspores, seed diaspores have less mass and a greater S/D, and are slightly more dehydrated. As a result, seed diaspores have lower wing‐loading and greater dispersal capacity than fruit diaspores. The morphological/aerodynamic features of a diaspore also have a significant effect on the mass variables. Overall, the type of diaspore (fruit or seed) is of major importance in explaining mass differences of diaspores among these wind‐dispersed species; morphological features and dehydration ability contribute secondarily.
Phragmites australis– A preliminary study of soil‐oxidizing sites and internal gas transport pathways
Authors: ARMSTRONG J. , ARMSTRONG W. 
Published: April 2006

SUMMARYThe possible pathways of oxygen transport within Phragmites australis and out into the soil were investigated by means of pressurized air flow, methylene‐blue dye and by anatomical studies.In most cases, gas was easily forced through the plants, thus demonstrating gas‐space connexion between aerial shoot, rhizomes and roots and a relatively low resistance to flow. Gas‐space connexions between the pith cavity and cortical aerenchyma in the rhizomes were also detected and were investigated anatomically they are present only in nodal regions just above the insertion of the pith diaphragm and take the form of radial channels through the stelar cylinder. Similar pathways in the culm connect the pith cavity with nodal lines of stomata and it is suggested that these regions may often form the major oxygen entry point to the rhizome‐root system.A failure to effect pressurized gas‐flow through some rhizomes led to the detection of secondary barriers to longitudinal gas‐flow. Seemingly a response to wounding, these are an impenetrable barrier to gases, to flooding, and probably also to microorganisms, and take the form of tylosoidal growths from and within regions of stellate‐and/or circumvascular‐parenchymas such as those of the nodal diaphragms. Stellate parenchymas of various sorts were found to be a common feature of the gas‐path in Phragmites and evidently they form an important component of the gas‐space system occurring within the nodal radial channels, the nodal diaghragms and, rather unusually, the root‐shoot junctions where they must confer a porosity which is higher than for most plants.As measured by methylene‐blue oxidation, oxygen release from underground parts was most rapid from young adventitious and secondary roots and particularly basal tufts of fine laterals. Zones of oxidation also occurred around the sprouting tips of horizontal and vertical rhizomes. Dormant tips showed very little oxidizing power, whilst the rhizomes themselves and the older parts of adventitious roots showed none. This was associated with cuticularization of the rhizome and hypodermal suberization and lignification; oxygen‐impermeable regions of the roots were also hyperdermally suberized and lignified.The findings are discussed in relation to the use of Phragmites in sewage‐treatment beds.
Comparative effects of the soil microflora on ectomycorrhizal inoculation of conifer seedlings
Authors: Mcafee B. J. , Fortin J. A. 
Published: April 2006

SUMMARYThe effects of vegetative inoculum of Laccaria bicolor (Maire) Orton, Pisolithus tinctorius (Pers.) Coker & Couch and Hebeloma cylindrosporum (Bull. & St. Am.) Quél. and addition of fine soil suspensions to jack pine (Pinus banksiana Lamb) and American larch [Larix larcina (DuRoi) K. Koch] seedlings were studied under controlled environmental conditions. Mixed inocula, composed of either (1) equal proportions of the above three mycobionts or (2) equal proportions of Laccaria and Hebeloma were also tested.Larch seedlings inoculated with L. bicolor formed significantly more mycorrhizas than did any of the other inoculum treatments. Untreated pine seedlings showed similar mycorrhiza development with L. bicolor and the two mixed inocula. On pine seedlings that received a fine soil suspension L. bicolor formed significantly more mycorrhizas than did other inocula.The addition of fine soil suspensions, containing biological propagules less than 45 μm, enhanced mycorrhiza formation and influenced shoot length and dry weight with some of the tested inocula, depending on the tree species. The competitive ability of the mycobionts in mixed inoculum was also affected by the soil suspensions.That P. tinctorius was not competitive in the mixed inoculum was attributed to its slower growth rate under the experimental conditions.
Nickel toxicity in mycorrhizal birch seedlings infected with Lactarius rufus or Scleroderma flavidum I. Effects on growth, photosynthesis, respiration and transpiration
Authors: JONES MELANIE D. , HUTCHINSON THOMAS C. 
Published: April 2006

SUMMARYGrowth, photosynthesis, transpiration and respiration were measured in birch (Betula papyrifera Marsh.) seedlings exposed to 85mUM nickel. The seedlings were inoculated with either Scleroderma flavidum E. & E., a fungus known from previous work to increase Ni tolerance, or Lactarius rufus (Scop, ex Fr.) Fr., another mycorrhizal associate, but one which did not increase Ni tolerance, or else they were not inoculated. Decreased water uptake per seedling was used as an indicator of the progression of Ni toxicity in the seedlings over 16 weeks. These measurements indicated that L. rufus provided some initial protection against Ni toxicity. However, water uptake in S. flavidum‐infected seedlings was least affected by Ni, and was significantly higher than that in L. rufus infected and uninoculated seedlings after week 10. Total dry weights of the S. flavidum‐infected seedlings were higher than those of other seedlings at weeks 12 and 21. Chitin analysis was used to determine the fungal component of root weight. The weight of S. flavidum tissue per root was significantly greater than that of L. rufus in both the Ni‐treated and control (non‐Ni‐treated) seedlings, and this amount increased with time. Lactarius rufus did not grow once the roots were exposed to Ni. Thus, the ability of S. flavidum to continue to grow following Ni exposure may be an important characteristic distinguishing between fungi which are ‘effective’ or ‘ineffective’ in enhancing metal tolerance. Nickel reduced photosynthetic rates in seedlings infected with S. flavidum relative to S. flavidum‐infected seedlings not treated with Ni, but did not have this effect in uninoculated seedlings. Respiration rates were not affected by metal treatment, or by mycorrhizal formation. Thus, S. flavidum increased Ni tolerance in the host, but not by preventing Ni‐induced reductions in photosynthetic rates or by affecting shoot respiration rates.
Growth responses and delayed winter hardening in Sitka spruce following summer exposure to ozone
Authors: LUCAS P. W. , COTTAM D. A. , SHEPPARD L. J. , FRANCIS B. J. 
Published: April 2006

SUMMARYTwo‐year‐old seedlings of Sitka spruce [Picea sitchensis(Bong) Cart.] were exposed to < 5, 70, 120 and 170 nl l−1O3for 7 h day−1in large ventilated glasshouses during the summer of 1986. Relative growth rates (RGR) were calculated at intervals throughout the summer and autumn using a non‐destructive technique in which measurements of stem height and diameter were used to estimate above‐ground biomass. No statistically significant effects of the ozone on growth were apparent during or after the period of fumigation, and growth of the seedlings had largely been completed by the end of August. The winter hardiness of these plants was subsequently tested on 10 November and 8 December by subjecting detached shoots to a range of carefully regulated freezing temperatures in controlled environment chambers. The results for the samples taken on the earlier date suggested that plants exposed to ozone were more sensitive to frost than the controls, and that this effect was dependent on the concentration of the pollutant. In the samples taken later, all the shoots appeared to have hardened equally to freezing temperatures in excess of about –20 °C. The results suggest that early autumn frosts might be damaging to Sitka spruce after exposure to high ozone concentrations in summer.
C4 plants as valuable model experimental systems for the study of photosynthesis
Authors: FURBANK ROBERT T. , FOYER CHRISTINE H. 
Published: April 2006

SUMMARYTwo decades have passed since the C4 cycle was first described. In this time, an increasingly large body of information has shown that the complexities of structure and metabolism associated with C4 photosynthesis may be successfully exploited to understand further the molecular biology, biochemistry and structure‐function relationships of photosynthetic cells.
The polyol pattern of fungi as influenced by the carbohydrate nutrient source
Authors: PFYFFER GABY E. , RAST DORA M. 
Published: April 2006

SUMMARY Penicillium (P.) italieum (1), Endothia parasitica (2), Agaricus bispours (3), Candida albicans (4), Mucor rouxii (5), Phycomyces (ph.) blakesleeanus (6) and Zygorhynchus moelleri (7) were cultivated in liquid media differing in the carbohydrate source and their free polyol (alditol) composition was established by gas‐liquid chromatography. Total polyol on a dry weight basis ranged from 4‐19% in (1)‐(4), and from 0·2‐2% in (5)‐(7). Species (l)‐(3) contained mannitol, in addition to erythritol, arabitol, and glycerol; the last two were also present in (4)‐(7), together with ribitol. Although the relative proportion of the constituents of the polyol fraction depended on the nutrient Sugar, the pattern of polyols generally remained constant. Notably, the mannitol precursor, fructose, did not induce synthesis of the hexitol in (4)‐(7) nor ribose that of ribitol in (1)‐(3).
Responses of lichens to salinity: concentration and time‐course relationships and variability among Californian species
Authors: NASH T. H. , LANGE O. L. 
Published: April 2006

SUMMARYSensitivity to salinity varied widely among 12 Californian lichen species occurring along a coastal to inland gradient, with the degree of sensitivity being approximately proportional to the distance from the coast where the species grew. For four of those species, it was found that net photosynthesis in three decreased with increasing sea‐salt concentrations, but in Dendrographa minor Darb. it was essentially unaffected. Time‐course studies with Pseudacyphellaria anomala Magn., a sensitivity species, demonstrated that a major decline in net photosynthesis occurred within an hour after submersion in a full strength sea‐salt solution and that the effect was partially reversible, but only up to 12 h after initiation of the treatment. For three sensitive species, an osmotic effect provided by treatment with sorbitol only partially explained the observed changes in gas exchange. Solutions of NaCl of equal osmotic value to full‐strength sea‐salt solutions decreased net photosynthesis more than full‐strength sea‐salt solutions alone. Because NaCl provides the principal ions in sea‐salt solutions, it is inferred that the observed ionic effects were principally due to these ions. Of the sensitive species Evernia prunastri (L.) Ach. was least sensitive to osmotic effects alone, but it was extremly sensitive to salinity.
Maintenance of morphological variation in a biotically patchy environment
Authors: EVANS R. C. , TURKINGTON R. 
Published: April 2006

SUMMARYThe relationship between morphological variability and biotic environmental heterogeneity was studied in a pasture population of Trifolium repens L. It had been argued that the unexpectedly high levels of variation in T. repens could be maintained by diversifying selection. The mosaic of neighbours (perennial grasses) with which T. repens co‐exists constitutes a prominent element of biotic patchiness that may lead to sorting among T. repens genotypes on the basis of neighbour‐specific compatibilities.A variation study was conducted on a set of 400 individuals of T. repens collected on a neighbour‐specific basis from a 43–year‐old pasture and grown for over 2 years under common garden conditions. Variation in a set of 12 morphological characters was assessed after 4 months and again after 27 months. After 4 months′ growth, a significant proportion of this variation was accounted for by the neighbour with which the individuals of T. repens had been growing in the pasture. The actual amount of variation accounted for, however, was low (6‐19%).When the same characters were assessed after 27 months, none of the neighbour‐specific differences in morphology were retained. It is concluded that the original results reflected developmental differences carried over from the pasture, and that diversifying selection is not of importance in the maintenance of morphological variation in this population.