bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROTEIN FORMATION IN DEVELOPING SOYBEAN (GLYCINE MAX L. MERR.) SEEDS AND ITS RESISTANCE TO WATER STRESS
Authors: DOVE LEWIS 
Published: May 2006

SUMMARYStorage protein synthesis in soybean (Glycine max L. Merr.) seeds is highly resistant to water stress. Seeds of plants deprived of adequate water for normal growth gained the same amount of storage protein as those of well‐watered controls. Cotyledons isolated from these plants synthesized storage protein when immersed in nutrient solution, or in water, or when stored in dry, sterile containers. These findings imply that a large non‐protein nitrogen reserve exists in seeds which is used to synthesize storage protein during development.
INFLUENCE OF VESICULAR‐ARBUSCULAR MYCORRHIZAE ON WATER MOVEMENT THROUGH BOUTELOUA GRACILIS (H.B.K.) LAG EX STEUD*
Authors: ALLEN MICHAEL F. 
Published: May 2006

SUMMARYRoot growth characteristics and water transport were compared between non‐mycorrhizal Bouteloua gracilis and vesicular–arbuscular mycorrhizal Bouteloua gracilis infected with Glomus fasciculatus. Mycorrhizal plants did not have significantly different leaf area or root length from non‐mycorrhizal plants, but did have significantly fewer and shorter root hairs. Mycorrhizal plants had 50% lower leaf resistance with no change in leaf or root water potentials; thus transpiration was increased 100% with a 50% reduction in whole‐plant, soil‐to‐root and root‐to‐leaf resistance. Assuming that the difference in water uptake was due to transport via the mycorrhizal hyphae, estimated fungus‐to‐root transport was 2.8 × 10−5 mg s−1 per hyphal entry point which compares favourably with evapotranspiration rates measured in other coenocytic fungi. Thus, one of the major factors causing increased water transport and reduced resistance to water through‐flow with mycorrhizal infection may be the increased surface area provided by the hyphae.
DEVELOPMENT OF MYCORRHIZAE, EXTRAMATRICAL MYCELIUM AND SCLEROTIA ON PINUS STROBUS SEEDLINGS
Authors: PICHÉ YVES , FORTIN J. ANDRE 
Published: May 2006

SUMMARYOn Pinus strobus seedlings cultured in growth pouches successful ectomycorrhiza formation took place upon inoculation with Pisolithus tinctorius, Cenococcum geophilum, Suillus granulatus, Suillus tomentosus, Paxillus involutus, Hebeloma cylindrosporum and Thelephora terrestris.Under the conditions used ectomycorrhizae formed within 2 weeks and some of them, P. tinctorius, P. involutus and T. terrestris, developed mantles and Hartig nets in less than 5 days. Mycelial strand formation took place around the root system of P. strobus 2 weeks after inoculation with P. tinctorius. Sampling on the 93rd day revealed no difference in ectomycorrhizal formation or the development of mycelial strands and sclerotia between root systems that were or were not illuminated. However, low light intensities on the aerial parts of the seedlings reduced the mycelial strands and sclerotia formation.Variation of nitrogen and phosphorus concentration added to the pouches were also studied. Increased concentrations of nitrogen, keeping phosphorus constant, led to greener seedlings and increased amount of ectomycorrhizal, mycelial strands and sclerotia. No sclerotia were formed in the complete absence of added nitrogen. Both the percentage of ectomycorrhizal short roots and the phosphorus contents of the seedlings increased in proportion to the amounts of nitrogen added.Increased concentrations of phosphorus, keeping nitrogen constant, led to a reduction in the percentage of ectomycorrhizal short roots without affecting the nitrogen content of the seedlings, the hyphal strands and sclerotia formation. The observations on the ontogeny of the sclerotia of P. tinctorius reported here for the first time fully support their identity as sclerotia.
A COMPARISON OF THE TOXICITY OF HEAVY METALS, USING ROOT ELONGATION OF RYE GRASS, LOLIUM PERENNE
Authors: WONG M. H. , BRADSHAW A. D. 
Published: May 2006

SUMMARYThe order of toxicity of different metals affecting root growth of seedlings of rye grass (Lolium perenne S24) was: copper > nickel > manganese > lead > cadmium > zinc > aluminium > mercury > chromium > iron. With the sole exception of manganese, these results confirm those of other studies and the order follows that of the stability of the metallic‐organic complexes. The results are of value in predicting the toxicity of heavy metals in plant growth on contaminated soils.
COMPETITION FOR POLLINATORS IN THE ECOLOGY OF CENTAUREA SCABIOSA L. AND CENTAUREA NIGRA L.
Authors: LACK ANDREW J. 
Published: May 2006

SUMMARYThe insects which visit Centaurea scabiosa and Centaur&#x030a;ea nigra feed mainly on nectar and are likely to visit more frequently the species which produces most nectar. Nectar was extracted from plants in field populations and from plants transplanted into the Botanic Garden, to determine diurnal pattern and total quantity and concentration of nectar produced over 24 h periods.Florets of both species open in the morning and secrete nectar fairly constantly through the first day of floret opening. C. scabiosa florets continue to secrete into the second day when more florets start to open, but C. nigra usually ceases to secrete nectar around 18.00 h on the first day. C. scabiosa at all times produced more nectar than C. nigra, and on average produced about four times as much. On Hod Hill plants of C. scabiosa produced slightly more nectar than those on the Devil's Ditch. There was no difference between different C. nigra populations. Different plants within each population differed considerably, one plant producing up to six times as much as another under fairly uniform conditions. Less nectar was secreted in cool weather or on a cloudy day than on a warm sunny day, and capitula on shaded shoots produced less than those in the sun. Capitula produced at the beginning and end of the flowering season appeared to secrete less than those produced in the middle. There was a large difference between years in some plants and plants studied in August 1977 produced more than those studied at any other time.
EFFECTS OF SIMULATED ACIDIC RAIN ON YIELDS OF FIELD‐GROWN CROPS
Authors: EVANS LANCE S. , LEWIN KEITH F. , CUNNINGHAM ELIZABETH A. , PATTI MITCHELL J. 
Published: May 2006

SUMMARYExperiments were performed to determine the effects of simulated acidic rainfall on yields of radish (Raphanus sativa L.), garden beet (Beta vulgaris L.), kidney bean (Phaseolus vulgaris L.), and alfalfa (Medicago sativa L.) grown under standard agronomic practices. The experimental design allowed the detection of statistically significant differences among means that differed from each other by less than 10 %. The plants were exposed to small additions of simulated rain at pH levels of 5.7, 4.0, 3.1 and 2.7. The spray‐to‐wet simulated rain applications were similar in volume to the median of all ambient rainfall showers. Some plants received no simulated rainfall and all were exposed to ambient rainfall at Brookhaven National Laboratory (Upton, N.Y), which had a mean weighted pH of 4.06 during the summer of 1980. Root mass of radish was not significantly affected by simulated acidic rainfall. The absence of a decrease in root yields in radish was coincident with an absence of visible foliar injury. Beet plants treated with simulated rain applications of pH 4.0, 3.1 and 2.7 showed significant decreases in yield compared with yields under both the ambient rainfall only and pH 5.7 simulated rain treatments. Root yields of beet exposed to simulated rain at pH 5.7, 4.0. 3.1 and 2.7 were 110, 79, 84 and 86% of those receiving ambient rainfall only. Foliar injury on beet was attributed to exposure both to simulated acidic rain of pH 4.0, 3.1 and 2.7 and to several consecutive ambient rainfalls which had an average pH of 3.9. This is the first experiment showing visible foliar injury due to either ambient rainfalls or simulated rain above pH 3.1 under agronomic conditions. With kidney bean, there were no significant differences among treatments of such parameters as number of seeds per plant, mass of seeds per plant and number of pods per plant. There were also no significant differences among treatments for fresh mass or dry mass of alfalfa hay. These studies suggest that no generalizations about crop sensitivity with regard to either plant portion harvested (e.g. roots, fruits, leaves) or taxonomic considerations can be made at the present time.
RESOURCE ALLOCATION ON DWARF SHOOTS OF BIRCH (BETULA PENDULA): REPRODUCTION AND LEAF GROWTH
Authors: TUOMI JUHA , NIEMELÄ PEKKA , MANNILA RAUNO 
Published: May 2006

SUMMARYA hypothesis that the female catkin and leaves on the same dwarf shoot of birch compete for the same limited resources of the bud during their development has been tested with Betula pendula. In all trees studied the mean length of leaves, both in May and July, was 15 to 20% lower on reproductive dwarf shoots with a female catkin than on non‐reproductive dwarf shoots of the same tree. However, there were no significant differences in leaf number or in bud development. The idea of plants as metapopulations and the cost of reproduction in trees are discussed.
GROWTH AND REPRODUCTIVE STRATEGIES OF TWO ANNUAL WEEDS AS AFFECTED BY SOIL NITROGEN AND DENSITY LEVELS
Authors: TRIVEDI S. , TRIPATHI R. S. 
Published: May 2006

SUMMARYThe growth and reproductive strategies of two weeds, Spergula arvensis L., a weed of croplands, and Plantago major L., a weed of wastelands and lawns, were studied in relation to two soil nitrogen and four population density levels. The dry matter yield under the various treatments revealed that S. arvensis is less sensitive to density increase than P. major. The dry matter allocation pattern with reference to reproductive allocation was, however, not appreciably modified by soil nitrogen or density levels in either of the species, though reproductive allocation was higher in S. arvensis than P. major. S. arvensis produced larger numbers of seeds in nitrogen‐rich soil while P. major did not. The results indicate that S. arvensis is more of an ‘r‐’ strategist and P. major is ‘K‐’ selected in the r‐K continuum. In the C‐S‐R strategy model (sensu Grime), P. major may be assigned a position more towards ‘C’ and S. arvensis more towards ‘R’.
INFLUENCE OF AGAR AND SUCROSE ON THE BEHAVIOUR OF DORMANT APPLE EMBRYOS CULTURED IN VITRO
Authors: BARTHE PH. , BULARD C. 
Published: May 2006

SUMMARYDormant as well as completely after‐ripened embryos of Pyrus malus L. var. Golden Delicious were cultured aseptically on media of different compositions. Distilled water was used as the simplest medium. The influence of the addition of agar (8 g 1−1), of mineral substances (macro‐and micro‐elements of the Heller's medium) and of sucrose (10 or 20 g 1−1) was studied. On the agar‐solidified media, three different modes of culture were used, depending upon the nature of the contact between the embryo and the medium. The criteria used to evaluate the depth of dormancy were the germination percentages and the progression in the greening of the cotyledons.Completely after‐ripened embryos behaved similarly on all the media used whatever the mode of culture. Dormant embryos behaved differently depending upon the composition of the medium and of the mode of culture. Dormancy was always deeper on agar‐solidified media than on liquid media and in the presence of sucrose than in its absence.In order to determine whether these differences in behaviour were due to quantitative differences in the leaching of free abscisic acid (ABA) into the medium, a two‐step culture method was introduced, using [14C]ABA. Dormant embryos were cultured first on water‐agar containing 10−5 M (±) [2‐14C]ABA (355 KBq μmol−1), then on one of the following media deprived of ABA: water‐sucrose‐agar, water‐agar, water.Observations during the first culture indicated that the amount of [14C]ABA absorbed was partially metabolized after only 2 days of uptake. During the course of the second culture, part of the original radioactivity of the embryos (4 days [14C]ABA uptake) was released into the medium. Leaching was much greater and lasted longer on water than on media solidified with agar: it does not depend upon the volume of the liquid used (3 or 15 ml). The presence of sucrose (20 g 1−1) in the agar medium does not modify the amounts of 14C‐radioactivity released. The main part of the radioactivity released in water and in water‐agar was shown to be ABA.
CYTOGENETICS OF GALINSOGA PARVIFLORA CAV. AND G. CILIATA (RAF.) BLAKE, AND THEIR NATURAL HYBRIDS (ASTERACEAE)
Authors: GOPINATHAN M. C. , BABU C. R. 
Published: May 2006

SUMMARYThe somatic and meiotic chromosomes of four natural populations of Galinsoga Ruiz & Pav. ‐ Population I (G. parviflora Cav.), Population II [G. ciliata (Raf.) Blake], Population III and Population IV have been analyzed. Our studies show that G. parviflora is a diploid (2n= 16); G. ciliata is a segmental allotetraploid (2n= 32); Population III is a triploid natural hybrid between G. parviflora and G. ciliata (3n= 24); and population IV is a putative introgressant between G. parviflora and the natural triploid hybrid (2n= 16). The meiotic chromosomes form eight bivalents and do not reveal any irregularities in G. parviflora which shows 100% pollen viability. During the meiosis of G. ciliata, however, 16 bivalents with occasional quadrivalents, anaphasic bridges and laggards are noticed, and pollen viability varies from 90 to 100%. In the triploid hybrids all the 24 chromosomes form univalents which are grouped into an unanalyzable chromosomal entanglement at metaphase I; consequently the per cent pollen viability is 0. The meiotic behaviour of chromosomes in introgressant is similar to that of G. parviflora, except for the high frequency of quadrivalents and laggards, and lesser pollen viability. The presence of inversion loops in G. ciliata and in Population IV imply that the parental species differ in chromosomal rearrangements.
POLYPLOIDY IN THE VICIA SATIVA AGGREGATE
Authors: LADIZINSKY G. , SHEFER Y. 
Published: May 2006

SUMMARYPolyploidy is rare in the genus Vicia and is absent in the Vicia sativa aggregate which is composed of types with 2n= 10, 2n= 12 and 2n= 14. Spontaneous amphidiploids were selected among 2n= 10 × 2n= 14 and 2n= 12 × 2n= 14 hybrid derivatives. Chromosome association at meiosis was mainly as bivalents in these amphidiploids; occasionally they were heteromorphic. The spontaneous amphidiploids were inferior to their diploid parental lines in growth rate, vigour and seed set over three generations. The behaviour of the spontaneous amphidiploids was compared with artificially induced autotetraploids. Meiosis in the autotetraploids was characterized by a lower number of associations per chromosome and small number of multivalents. The growth rate of the autotetraploids was retarded and seed set was lower in comparison with the diploid lines. The diploid and the autotetraploid lines could be easily separated from one another by the shape of their pollen grains; elliptical in the diploid plants and tetrahedral in the autotetraploids. No such modification of the pollen grains was observed in amphidiploids. The potential for polyploidy in Vicia sativa and possible reasons for its absence in that aggregate are discussed.
PHYSIOLOGY OF SALT EXCRETION IN THE MANGROVEAVICENNIA MARINA(FORSK.) VIERH
Authors: DRENNAN PHILIPPA , PAMMENTER N. W. 
Published: May 2006

SummaryDiurnal and long‐term excretion by leaves ofAvicennia marinaseedlings growing in aqueous culture was correlated with substrate salinity and transpiration. Excretion was greater in 100% than 50% seawater but the reverse was true for transpiration. The diurnal excretion pattern, with exudation minimal during the day and maximal during the night, showed a negative correlation with the daily transpiration pattern. The total amount of salt excreted, however, showed a positive correlation with the total amount of water transpired. Root and xylem sap salinities were linearly related to substrate salinity but leaf Na+increased to a maximum, indicating that control of leaf salt content is at the foliar, rather than the root level.
INDUCTION OF FLOWERING IN WILD LETTUCE (LACTUCA SERRIOLA L.)
Authors: PRINCE S. D. , MARKS M. K. 
Published: May 2006

SummaryA comparison of the phenology of plants grown from buried seeds recovered at monthly intervals with plants grown from non‐vernalized and from artificially vernalized seeds showed that seeds which germinate in the field before mid‐summer are hastened in their development and are therefore able to complete their life‐cycles before the end of the growing season whereas those which germinate after mid‐summer are devernalized and therefore remain vegetative until the following growing season. This appears to be the first time it has been suggested that devernalization might play an adaptive role in plants in the natural environment.
THE DEVELOPMENT OF ENDOMYCORRHIZAL ROOT SYSTEMS
Authors: BUWALDA J. G. , ROSS G. J. S. , STRIBLEY D. P. , TINKER P. B. 
Published: May 2006

SummaryWe have modelled the spread of vesicular‐arbuscular mycorrhizas (VAM) from localized inoculum in a developing root system by assuming that the rate of spread of infection at a particular time is proportional to the product of the length of root already infected and the fraction of the total root which is susceptible to infection at that time. An important parameter of the model is its asymptote n, the maximum fraction of the root system which becomes mycorrhizal. Our model is formally similar to the logistic equation for growth.An earlier model by Tinker (1975), which predicts that rate of spread of infection would be enhanced by increased density of roots L, (cm cm −3), was compared with ours, using results of experiments on wheat and clover sown at three densities. The new model fitted the data for spread of infection much better, especially that of young infections. The relative rates were generally little altered by total length of roots, Lt, but the absolute values for the two hosts differed widely. This suggests that infection spreads primarily along roots, rather than by random contact between roots and hyphae. This type of model may be useful for exploring the mechanisms by which environmental changes affect spread of vesicular‐arbuscular mycorrhizas.
INTERACTION OF LIGHT INTENSITY AND SOIL TEMPERATURE WITH PHOSPHORUS INHIBITION OF VESICULAR‐ARBUSCULAR MYCORRHIZA FORMATION
Authors: GRAHAM J. H. , LEONARD R. T. , MENGE J. A. 
Published: May 2006

SummaryThe interaction between light intensity and soil temperature with phosphorus inhibition of vesicular‐arbuscular mycorrhiza (VAM) formation in sudangrass (Sorghum vulgare, Pers.) was investigated in P‐deficient (0.5 mg P kg−1) sandy soil amended with 0 (OP), 15 (15P) and 30 (30P) mg P kg−1 soil as superphosphate. For seedlings inoculated with Glomus fasciculatus and grown at 100, 75, and 50% of glasshouse light intensity, the reduction in VAM formation by added soil P (15 P and 30P) was greatest at the lower light levels, whereas in the OP treatment, VAM formation was unaffected by a decrease in light intensity. Increases in root P concentration resulted from both soil P amendment and, in the 15P treatment, from a decrease in light intensity, and were associated with decreases in root membrane permeability and corresponding decreases in root exudation of amino acids and sugars. The reduction in sugar exudation in the 15P treatment at lower light intensity was paralleled by a decrease in root extract levels of sugars, but decreases in amino acid exudation could not be explained by changes in amino acid levels in root extracts. These results suggest that P inhibition of VAM formation is more severe at lower light intensities because of a decrease in membrane‐mediated exudation, although a reduction in sugar levels in root cells may also contribute to the observed decrease in exudation.When inoculated seedlings were grown at 25, 30, and 35°C soil temperatures, the reduction in VAM formation in the 15P and 30P treatments was overcome by increase in soil temperature. The increase in VAM formation by increased temperature in the 15P plants was associated with significant increases in root membrane permeability and exudation without a corresponding change in root P concentration. In the OP treatment, an increase in soil temperature increased VAM formation with little effect on root exudation, which suggested an effect of temperature on Glomus fasciculatus. Higher soil temperature may increase VAM formation through either a direct effect of temperature on the fungus or an indirect effect via an increase in leakage of root metabolites necessary for fungal activity, or both.
CHANGES IN ABSCISIC ACID LEVELS DURING AFTER‐RIPENING AND GERMINATION OF ACER PLATANOIDES L. SEEDS
Authors: TILLBERG E. , PINFIELD N. J. 
Published: May 2006

SUMMARYChanges in abscisic acid (ABA) levels during after‐ripening and germination of embryos of Acer platanoides have been studied by gas liquid chromatography. Inductive low temperature after‐ripening caused a very large decline in ABA content of the embryos over a 131‐day period, although small amounts remained even after this time. Reductions were also observed in control samples maintained at 17 °C but these were much smaller. During germination, following an inductive chilling treatment of 60 days, the levels of ABA in the embryos remained low throughout a 72 h incubation period. There was, however, a transient increase after 24 h, which was attributed to stress.The common concept that endogenous ABA plays a role in the regulation of dormancy seems valid for seeds of A. platanoides and the results are discussed in terms of the overall promotor/inhibitor balance within the seed. ABA, however, does not seem to be directly involved in regulation of the germination process.
THE INFLUENCE OF LIGHT INTENSITY AND ARTIFICALLY EXTENDED PHOTOPERIOD UPON INFECTION AND SPORULATION OF GLOMUS FASCICULATUS ON SUDAN GRASS AND ON ROOT EXUDATION OF SUDAN GRASS
Authors: FERGUSON J. J. , MENGE J. A. 
Published: May 2006

SUMMARYMycorrhizal inoculum of Glomus faciculatus, as measured by root infection and sporulation on sudan grass, increased with increasing light intensity. Compared to natural glasshouse daylight, spore numbers of G. fasciculatus also increased dramatically when mycorrhizal sudan grass was exposed to extended photoperiods with mercury vapour or metal halide lamps of high intensity. Results from both light experiments indicate that the level of sugars, but not amino acids, in root exudates from 2‐month‐old sudan grass plants was correlated with the spore production of G. fasciculatus. It appears that growing sudan grass at greater light intensities and under extended photoperiods will increase the quantity and quality of commercial G. fasciculatus inoculum.
AN ULTRASTRUCTURAL ANALYSIS OF THE DEVELOPMENT OF MYCORRHIZAS IN MONOTROPA HYPOPITYS L.
Authors: DUDDRIDGE J. A. , READ D. J. 
Published: May 2006

SUMMARYThe ultrastructural differentiation of mycorrhizas of the achlorophyllous plant Monotropa hypopitys was examined in relation to the stages of growth of the shoot. Plants were collected at regular intervals during the growing season and their roots were immediately excised and prepared for scanning and transmission electron microscopy. In addition to the presence of a fungal sheath and Hartig net of similar structure to those seen in ectomycorrhizas, the outer cortical cells frequently contain characteristic fungal intrusions. While not breaching the host cell wall, these intrusions stimulate its invagination. The resulting structures, analogous to the transfer cells found in regions of intensive solute mobilization and transport, are produced in greatest numbers during the period of most rapid shoot extension. The relationship between their structure and possible function is discussed. The structure of mycorrhizas in Monotropa hypopitys is sufficiently distinct from that of arbutoid mycorrhizas, to warrant the creation of a new category which we term ‘monotropoid’.