bluuebunny/crossref_metadata_2025 huggingface dataset:
THE RESPONSE OF ACHILLEA MILLEFOLIUM L. (YARROW) TO SHADING
Authors: BOURDÔT G. W. , SAVILLE D. J. , FIELD R. J.
Published: May 2006

Summary

Growth analysis was used to assess the response of vegetative rosettes of Achillea millefolium L. (yarrow) to shading in the range of full daylight irradiance to a relative level of irradiance (r.l.i.) of 0–064. As functions of time, SLA, LWR, NAR and RGR showed more or less pronounced ontogenetic drifts which interacted with r.l.i. As functions of total dry weight, these interactions were greatly diminished. At dry weights from 1.53 to 4.0 g, the response of RGR to shading was characterized by a plateau between full daylight and approx. 0.40 r.l.i. owing to increases in SLA and LWR compensating for a reduction in NAR. Relative growth rate then fell steeply to a compensation point of O.o37 r.l.i. It was concluded that A. millefolium is considerably tolerant of shading and an ecological interpretation is given.
STUDIES ON THE BIOLOGY OF SENECIO VULGARIS L. SSP. DENTICULATUS (O. F. MUELL) P. D. SELL
Authors: KADEREIT JOACHIM W.
Published: May 2006

Summary

Experimental evidence and evidence obtained from herbarium material suggest a pronounced difference in the biology of Senecio vulgaris L. var. vulgaris and ssp. denticulatus (O. F. Muell.) P. D. Sell. Whilst var. vulgaris is a plant of ruderal habitats, which can complete its life cycle in a very short time and can be found flowering all year round, ssp. denticulatus is a winter annual with an Atlantic–Mediterranean–montane distribution, which is strictly coastal outside the Mediterranean. It shows strong seed dormancy, which seems to be regulated by one major gene, and requires substantially more time to complete its life cycle than var. vulgaris. There is also some evidence that the reproductive potential of ssp. denticulatus is smaller than that of var. vulgaris. It seems likely that the ruderal var. vulgaris evolved from forms similar to ssp. denticulatus.
THE EFFECTS OF FLUCTUATING CONCENTRATIONS OF SULPHUR DIOXIDE ON THE GROWTH OF PINUS SYLVESTRIS L. AND PICEA SITCHENSIS (BONG.) CARR
Authors: GARSED S. G. , RUTTER A. J.
Published: May 2006

Summary

Plants of Pinus sylvestris and Picea sitchensis, initially at the end of their third growing season, were grown for 2 years and 1 year, respectively, in regimes of fluctuating sulphur dioxide (SO2) concentration. The four fluctuating regimes had mean concentrations of about 100 μg m−3 and peak concentrations of either 300 to 400 μg m−3 or 750 to 900 μmg m−3,* combined with durations of high concentration which were either short (mean ∼ 5 h) and frequent, or long (mean ∼ 20 to 30 h) and infrequent. Their effects were compared with a constant concentration of about 100 μg m−3 and with clean air.

In the first year of treatment, effects on dry weight increment consisted of depressions in the root only, but marked chlorosis, necrosis and abscission of the leaves of Picea sitchensis were caused by SO2, while the leaves of Pinus sylvestris were hardly affected. By the end of the second year of treatment (Pinus sylvestris only) dry weight increase of the whole plant had been reduced by 14% in the constant concentration and in fluctuating regimes with peaks of short duration, and by 22% in regimes with peaks of long duration. All the SO2 treatments caused early fall of 3‐year‐old leaves during the second year of treatment of this species.

A comparison of the treatments with the characteristic regime of fluctuating concentration in those parts of Britain where the mean annual ground level concentration of SO2 is around 100 μg m−3, leads to the conclusion that the main effect of this regime is attributable to its mean, rather than its peak concentration.
AMINO ACID AND AMIDE METABOLISM IN THE HULLS AND SEEDS OF DEVELOPING FRUITS OF GARDEN PEA, PISUM SATIVUM
Authors: MURRAY D. R. , CORDOVA‐EDWARDS MARIA
Published: May 2006

Summary

Pea plants (Pisum sativum L. cv. Melbourne Market), each with a single developing pod, were pulse‐fed with [l4C]glutamine supplied through the cut stem. Hull and seed tissues were removed after a suitable interval (usually 24 h) and frozen for later analysis. The fruit received substantial label at all stages analysed (from 12 to 31 d after full blossom). Except at the youngest stage, most of the label recovered from the fruit was present in the seeds. The distribution of label in soluble metabolites of the hull, seedcoats, embryo sac liquid and embryo was determined by paper chromatography and radioautography. The results confirm that glutamine is utilized as a major source of carbon by pea embryos throughout their development.
AMINO ACID AND AMIDE METABOLISM IN THE HULLS AND SEEDS OF DEVELOPING FRUITS OF GARDEN PEA, PISUM SATIVUM II. ASPARAGINE
Authors: MURRAY D. R. , CORDOVA‐EDWARDS MARIA
Published: May 2006

Summary

Pea plants (Pisum sativum cv. Melbourne Market), each with a single developing pod, were pulse‐fed with [14C]asparagine supplied through the cut stem at stages ranging from 12 to 31 d after full blossom. The hull and seed tissues were removed after 24 h and frozen for later analysis. The hull retained a higher proportion of the total label in the fruit than the enclosed seeds until after 19 d, i.e. until the total nitrogen content of the hull had begun to decline. The distribution of label in soluble metabolites of the hull, seedcoats, embryo sac liquid and embryo was determined by paper chromatography and radioautography. The results confirm that the metabolism of asparagine is more rapid in the seedcoats than in the hull. In the youngest stages, label from the seedcoats is transmitted to the embryo sac mainly in forms other than asparagine, notably as glutamine, alanine and sucrose.
INFLUENCE OF VESICULAR–ARBUSCULAR MYCORRHIZA ON THE HYDRAULIC CONDUCTIVITY OF ROOTS OF TWO CITRUS ROOTSTOCKS
Authors: GRAHAM J. H. , SYVERTSEN J. P.
Published: May 2006

Summary

Carrizo citrange (CC) and sour orange (SO) seedlings were grown in a low phosphorus (P) sandy soil and either inoculated with Glomus intraradices Schenck & Smith or fertilized with soluble P. Mycorrhizal seedlings had nutritionally sufficient levels of leaf P, non‐mycorrhizal plants of similar size were P‐deficient. The root–shoot ratio of both rootstocks was reduced by mycorrhizal colonization, but root hydraulic conductivity per unit root length of mycorrhizal CC and SO was more than twice that of non‐mycorrhizal seedlings under well‐watered conditions. Mycorrhizal plants also had significantly higher transpiration rates when standardized on a root length basis, and greater transpiration appeared to be related to the increased conductivity of roots. Flow of water to roots via hyphae alone could not account for the greater water uptake by mycorrhizal roots. Apparently, mycorrhizal enchancement of P nutrition was primarily responsible for the greater conductivity of roots since no differences were found between root hydraulic conductivity of mycorrhizal and non‐mycorrhizal CC of equal P status under well‐watered conditions.
THE EFFECT OF ROOT DENSITY, INOCULUM PLACEMENT AND INFECTIVITY OF INOCULUM ON THE DEVELOPMENT OF VESICULAR–ARBUSCULAR MYCORRHIZAS
Authors: ABBOTT L. K. , ROBSON A. D.
Published: May 2006

Summary

We examined, in three glasshouse experiments, the development of vesicular‐arbuscular (VA) mycorrhizas formed by Glomus fasciculatum (Thaxter sensu. Gerd.) Gerd. & Trappe on Trifolium subtẽrraneum L. in relation to plant denser and inoculum quantity. The effect of inoculum placement on the formation of mycorrhizas on Medicago truncatula Gaertn. by another Glomus sp. was studied in a fourth experiment. More mycorrhizal root was formed by Glomus sp. when inoculum was dispersed throughout the soil than when it was localized either near the top or bottom of the pot. The absolute rate of mycorrhiza formation was initially more rapid with localized inoculum. However, a greater weight of mycorrhizal root was subsequently obtained with dispersed inoculum as roots continually intercepted propagules. Infection by G. fasciculatum spread deeper in one soil than in two others, perhaps reflecting differences in root growth and density associated with differences in phosphorus status of the soils for plant growth. The weight of roots which became infected increased with increasing plant density, but not when shoot growth was greatly decreased due to competition between plants. The relative rate of mycorrhizal infection remained unaffected by treatments in each experiment. When a low root density and a high inoculum level were combined, the amount of roots which became infected was greater than expected. These conditions favoured a longer exponential phase in the development of infection.
EFFECTS OF LIME, PHOSPHORUS, AND ADDITION OF VESICULAR–ARBUSCULAR (VA) MYCORRHIZAL FUNGI ON INDIGENOUS VA FUNGI AND ON GROWTH OF ALFALFA IN A MODERATELY ACIDIC SOIL
Authors: KUCEY R. M. N. , DIAB GAMAL ELDIN S.
Published: May 2006

Summary

The effects of inoculation with vesicular–arbuscular mycorrhizal (VAM) fungi on alfalfa (Medicago sativa L.) growth and phosphorus uptake were studied in a moderately acidic loess soil with four levels of added lime. Inoculation of alfalfa with VAM fungi from soils of pH 7.2 to 7.5 resulted in increased dry matter production at pH of 6.4 to 7.5, but not at pH of 5.4 to 6.1. Addition of lime and/or phosphorus always increased growth of alfalfa. Root colonization by indigenous mycorrhizal fungi was inhibited at the highest pH levels but root colonization by added fungi was stimulated at higher pH levels and inhibited at the lower pH levels.
THE DISTRIBUTION OF PERENNIAL RYEGRASS GENOTYPES IN SWARDS
Authors: McNEILLY T. , ROOSE M. L.
Published: May 2006

Summary

The number and spatial distribution of perennial ryegrass (Lolium perenne L.) genotypes in 4 pastures were estimated by sampling single tillers from points 5 cm apart on an 11 × 11 grid. Three electrophoretic loci were used initially to determine the genotype of each tiller.

Three 10‐year‐old sown swards contained at least 36–43 different genotypes per 0.25 m2 quadrat (10% of the number sown) while a 40‐year‐old pasture contained only 5 genotypes per 0.25 m2 quadrat. The cut sward had a greater proportion of its area occupied by a few large genotypes than the swards grazed by sheep or cattle.

The importance of age, management, and other factors influencing genotypic diversity in swards is discussed.
THE ECOLOGY OF SPECIES, FAMILIES AND COMMUNITIES OF THE CONTEMPORARY BRITISH FLORA
Authors: GRIME J. P.
Published: May 2006

Summary

It is argued that detailed studies of the functioning of populations cannot by themselves lead to an understanding of British vegetation. Several complementary lines of investigation are required to explore the role of past and present interactions between habitat templet and plant characteristics. Strategy concepts provide a framework in which to assemble information from such diverse fields of ecological research, and recent results suggest that the present ecologies of populations, species, families and communities remain strongly conditioned by patterns of ecological specialization which predate the development of the post glacial flora.
INTERNAL SPREAD OF FUNGI INOCULATED
Authors: BODDY LYNNE , RAYNER A. D. M.
Published: May 2006

Summary

The white‐rotting basidiomycetes Exidia glandulosa, Peniophora quercina, Phellinus ferreus, Schizopora paradoxa, Stereum gausapatum and Vuilleminia comedenswere inoculated into attached living branches of oak (Quercus robur). Patterns of establishment and spread varied in relation to species, time of inoculation and location with respect to branch order and proximity of experimental girdles. Peniophora quercina, Stereum gausapatum and V. comedens readily formed localized decay columns within 6 months, but apparently failed to extend further subsequently. The other fungi either failed to establish, or spread only for limited distances, E. glandulosa preferentially colonizing bark. Longitudinal spread was often markedly facilitated within the vicinity of a girdle, although radial and tangential spread were restricted. In several instances, individuals of Peniophora quercina, Stereum gausapatum and V. comedens became established naturally within the branches. Such individuals were invariably somatically incompatible with those inoculated, and further contrasted with the latter in giving rise to columns of considerable longitudinal and radial extent.
DOES AUXIN STIMULATE THE ELONGATION OF INTACT PLANT STEMS?
Authors: HALL J. L. , BRUMMELL D. A. , GILLESPIE JANE
Published: May 2006

Summary

Contradiction exists in the literature as to the effect of exogenous auxin on the growth of intact plants, and the assumed lack of such an effect has been used as evidence that auxin does not function in regulating growth through changes in concentration. Indole‐3‐acetic acid (IAA), applied in lanolin to the third internode of intact etiolated Pisum sativum L. cv. Alaska stems, rapidly and markedly stimulated elongation, to an extent similar to that observed in excised segments. This was a short‐term effect and did not alter the final stem size attained after 24 or 50 h. Decapitated plants responded more slowly to IAA application but, again, the final size attained was similar to that of the untreated controls. The results show that changes in auxin amounts cannot be ruled out in discussions of growth regulation.
COBALT REQUIREMENT FOR NODULE DEVELOPMENT AND FUNCTION IN LUPINUS ANGUSTIFOLIUS L.
Authors: RILEY IAN T. , DILWORTH M. J.
Published: May 2006

Summary

The cobalt requirement for nodule development and function in Lupinus angustifolius L. ev. Uniharvest was studied in a glasshouse using a range of cobalt applications. Nodule establishment was found to be limited only by severe cobalt limitation. Bacteroid content of the nodules was the main determinant of nodule function and thus plant performance. Leghaemoglobin synthesis appeared to be more sensitive to cobalt limitation but was a less significant determinant of acetylene reduction activity. The critical root cobalt level for the normal symbiosis was 500 ng Co g−1 d. wt but a level of 300 ng Co g−1 d. wt resulted in no yield loss since there was a compensatory increase in lateral nodulation.
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: HAYMAN D. S. , TAVARES M.
Published: May 2006

Summary

Nine vesicular‐arbuscular mycorrhizal endophytes were assessed for their infectivity and ability to improve the growth of alpine strawberry seedlings in sterilized, low‐phosphate soils (4 and 8 mg kg−1 NaHCO3‐soluble P), limed to different pHs. At pH 4, Glomus clarum greatly stimulated plant growth, but the other endophytes except Gigaspora margarita and Glomus fasciculatum‘E3’ had little or no effect. The most efficient endophytes at pH 5 were E3, Acaulospora laevis and G. clarum. The largest plants were those growing at pH 7 and inoculated with Glomus epigaeum; A. laevis and G. clarum were ineffective at this pH. The most effective endophytes at pH 6 and 7 were G. epigaeum, Glomus mosseae, E3, Glomus caledonium and Gigaspora heterogama, although results varied slightly between soils. Most endophytes infected well at all pHs, even where they did not enhance plant growth. In studies of this nature plant growth is affected by different pHs, soil P levels and the inoculum used. Nevertheless these data show clearly that different endophytes vary enormously in their symbiotic effectiveness at different soil pHs. The practical implications of these results are discussed.
HERMAPHRODITES AND SUBHERMAPHRODITES IN A REPUTEDLY DIOECIOUS PLANT,CIRSIUM ARVENSE(L.)SCOP.
Authors: KAY Q. O. N.
Published: May 2006

Summary

Cirsium arvense(L.) Scop. has been thought to be completely or almost completely dioecious, with clear morphological and functional differences between males that set an average number of less than 0.1 viable seeds per capitulum and females that produce no pollen. An investigation of three populations in southern Britain showed that 15 % of the clones with polleniferous ‘male’ flowers were in fact hermaphrodite, with high or fairly high seed yields (10 to 65 seeds per capitulum) and a further 11 % were subhermaphrodites with seed yields of 2 to 10 seeds per capitulum. The flowers and capitula of the hermaphrodites and subhermaphrodites closely resembled those of typical male clones at the flowering stage, but their fruiting capitula ranged from typically male to typically female in appearance. The mean size and weight of the seeds set on hermaphrodites and subhermaphrodites were similar to those of seeds set on females, and seed viability was high in most hermaphrodites and subhermaphrodites. Some hermaphrodites had higher seed yields per capitulum than the overall mean for females. Pollen output per flower was lower in hermaphrodites than in typical males, but pollen from hermaphrodites was fertile and gave high seed‐set when used to pollinate female flowers. Hermaphrodites were self‐fertile, although seed‐sets on selfing were relatively low. In the hermaphrodites, the pollen contribution relative to that of typical males ranged from 0.24 to 0.85, and the ovule contribution relative to that of pure females ranged from 0.13 to 1.29.
METABOLIC CHANGES IN MUSTARD PLANTS ASSOCIATED WITH MOLYBDENUM DEFICIENCY
Authors: CHATTERJEE C. , NAUTIYAL N. , AGARWALA S. C.
Published: May 2006

Summary

Mustard (Brassica campestris L. var. sarson Prain cv. T42) plants were grown in refined sand at graded levels of molybdenum ranging from acute deficiency (2 × 10−5 mg 1−1) to excess (2 mg 1−1). Visible deficiency symptoms appeared at 2 × 10−1 mg 1−1 or less molybdenum. Total dry matter and seed yield were maximal at 2 × 10 1−1 mg Mo 1−1. In leaves of the deficient plants there was depression in the concentrations of DNA and RNA, protein nitrogen and activities of nitrate reductase and cytochrome c oxidase but stimulation in the activities of acid phosphatase and ribonuclease and accumulation of phosphorus and nitrate nitrogen.
DIEL AND SEASONAL CHANGES IN THE CHLOROPLAST ULTRASTRUCTURE OFDESCHAMPSIA FLEXUOSA(L.) TRIN.
Authors: ARO E.‐M. , KORHONEN P. , RINTAMÄKI E. , MÄENPÄÄ P.
Published: May 2006

Summary

Chloroplast ultrastructure was studied during the season of main growth on leaves ofDeschampsia flexuosa(L.) Trin. collected from the wild in South Finland. Corresponding leaf segments were used for concurrent measurements of the O2evolution rate, chlorophyll (chl) content and chla/bratio. No significant diel variation was observed in the content or arrangement of grana thylakoids but fluctuation was evident in the volume of starch grains. The seasonal changes in thylakoid organization were more marked. At the beginning of June higher values than in typical sun species were recorded for the ratio of the length of appressed to non‐appressed thylakoid membranes (1.8), the average number of partitions per granum (9.5) and the grana area (31 % of the chloroplast area). All these parameters increased as the season progressed, especially after the middle of July. The chl content and chla/bratio decreased until the middle of August, but later in August, after rain, new leaves had a chl content and chla/bratio as high as at the beginning of June. In contrast, chloroplast ultrastructure remained typical for this late growth period. The highest photosynthetic capacity was measured during the two first weeks in June. At the beginning of July this capacity had decreased by 61%, and stayed low until the end of the experimental period. The changes in chloroplast ultrastructure are discussed in relation to the photosynthetic activity and the composition of the chlorophyll‐protein complexes in appressed and non‐appressed thylakoid membranes.
EFFECT OF GROWTH REGULATORS ON THE IN VITRO GERMINATION AND TUBE GROWTH OF MAIZE (ZEA MA YS L.) POLLEN FROM PLANTS RAISED UNDER SODIUM CHLORIDE SALINITY
Authors: DHINGRA H. R. , VARGHESE T. M.
Published: May 2006

Summary

Pollen grains, collected from maize plants raised under conditions of 0, 80, 120 and 160 meq l−1 salinity, were used to investigate the effect of various growth regulators on in vitro germination and tube growth. Indole‐3‐acetic acid had no effect on germination, irrespective of the source of pollen, whether derived from plants grown under saline or non saline conditions. However, its lower concentrations enhanced tube growth in pollen from salinized plants. Gibberellic acid at a concentration of 1 mg l−1 antagonized the depressive effects of 120 meq l−1 salinity on pollen germination. It stimulated tube growth of pollen from saline, as well as, non‐saline plants. However, pollen from salinized plants required a higher concentration of gibberellic acid. Benzylaminopurine ameliorated inhibitory effects of NaCl salinity both on germination and tube growth of pollen. Abscisic acid inhibited germination to a greater extent in pollen from nonsaline than saline plants; but stimulated tube growth in all cases. The present investigation suggests that pollen from salinized plants responds more to growth regulators than those from non‐salimzed plants.
ENZYMES OF AMMONIUM ASSIMILATION IN THE MYCORRHIZAL FUNGUS PEZIZELLA ERICAE READ
Authors: JOHN B. J. ST. , SMITH S. E. , NICHOLAS D. J. D. , SMITH F. A.
Published: May 2006

Summary

Growth of Pezizella ericae Read in solution culture with ammonium (NH4+) as the primary nitrogen source was accompanied by decrease in pH and ammonium concentration. Both glutamate dehydrogenase (GDH) and glutamine synthetase (GS) were involved in ammonium assimilation. Activities of these enzymes changed during the time course of the experiment (28 d). Maximum GDH activity [0.35 μol NAD(P)H oxidized min−1 mg protein−1] occurred when external NH4+ concentration was high (5 to 10 mM). Maximum GS activity (0.2 μol of γ‐glutamyl hydroxamate min−1 mg protein1) occurred when external NH4+ concentration was low (1 mM). L‐Methionine DL sulphoximine (MSX), a specific inhibitor of GS, inhibited uptake of 15NH4Cl in 13‐d‐old mycelium of P. ericae.

The nitrogen nutrition of the fungus and the host in the soil environment is discussed.
INTERACTION OF SUBSTRATE C:N RATIO AND OSMOTIC POTENTIAL ON GROWTH AND OSMOREGULATION OF FOUR FILAMENTOUS FUNGI
Authors: LUARD ELIZABETH J.
Published: May 2006

Summary

Variation in the carbon to nitrogen ratio in the range 10:1 to 1000:1 had only a small effect on the radial growth rate of four species of fungus on a basic nutrient agar medium. There was no obvious pattern to the differences observed, whether the nitrogen source was organic or inorganic or the medium osmotic potential high or low. The final fresh weight of the colonies was more sensitive to C: N ratio and was depressed by high C: N ratios by as much as 90 % in some treatments. Polyporus versicolor L. ex Fr. was the most efficient accumulator of biomass at C: N of 1000:1, but Penicillium chrysogenum Thorn had the highest mycelial N content. Colony yield did not show the same relationship to external osmotic potential as did the radial growth rate, and the ratio at which the maximum yield at each osmotic potential occurred varied with the different treatments.

Turgor potential was reduced by high C:N in the majority of treatments in Polyporus versicolor, Poria vincta (Berk.) Cke. and Phytophthora cinnamomi Rands but not at all in Penicillium chrysogenum. Water content increased with the C: N ratio and decreased with external osmotic potential in all the species except Phytophthora cinnamomi. There was no clear effect of C:N ratio on any of the hyphal solutes measured, that is Na+, K+, Cl−, proline or glycerol. Lower concentrations of the organic solutes were present in Phytophthora cinnamomi and Penicillium chrysogenum in these conditions than when KCl and Czapek‐Dox with yeast extract medium was used; turgor potential of Penicillium chrysogenum also was 50% lower. Sodium chloride was used to adjust the external osmotic potential and Na+ and Cl− were taken up in increasing amounts as the osmotic potential decreased in all species. Potassium concentrations were similar between species and treatments. The hyphal osmotic potentials, calculated from these solutes alone, were lower (more negative) than the values measured in Poria vincta grown at –1 MPa and Penicillium chrysogenum grown at – 10MPa, but very close to those for Phytophthora cinnamomi grown at – 2.5 MPa.
FUNGAL POPULATION AND COMMUNITY DEVELOPMENT IN CUT BEECH LOGS
Authors: COATES D. , RAYNER A. D. M.
Published: May 2006

Summary

Patterns of fungal colonization from the base of cut beech logs placed upright and partly buried in the ground at a mixed deciduous woodland site were fundamentally different from those from the aerial cut surface.

Principal colonists resulting in decay, and mostly arriving within three months, were the ascomycete Xylaria hypoxylon (L. ex Hooker) Greville and various rhizomorph/mycelial cord‐forming basidiomycetes, including Armillaria bulbosa (Barla) Kile & Watling, Phallus impudicus (L.) Pers., Phanerochaete velutina (DC ex Pers.) Parmasto and Tricholomopsis platyphylla (Pers. ex Fr.) Sing. Apart from A. bulbosa, these generally readily formed mycelial mats on the basal surface, between which somatic incompatibility reactions were often observed. Most frequent reactions occurred with X. hypoxylon which almost invariably produced numerous individuals in discrete decay columns. By contrast, lack of somatic incompatibility reactions between isolates of A. bulbosa indicated that a single extensive mycelial type occurred throughout the site. The occurrence of somatic incompatibility between isolates off. velutina from different logs indicated independent establishment, presumably via basidiospores, and this was consistent with the unusually late arrival of this species at the site. In no cases were numerous somatically incompatible individuals isolated from small volumes of wood lacking demarcation into discrete columns, as had been observed near the aerial cut surface.

Vertical penetration from the base was more rapid than from the aerial cut surface, with X. hypoxylon a major pioneer species, and there was no pronounced lag phase.
THE METABOLISM AND PHYSICAL STATE OF POLYPHOSPHATES IN ECTOMYCORRHIZAL FUNGI. A31P NUCLEAR MAGNETIC RESONANCE STUDY
Authors: MARTIN F. , MARCHAL J.‐P. , TIMINSKA A. , CANET D.
Published: May 2006

Summary

Phosphorus‐31 nuclear magnetic resonance spectroscopy was used to estimate the levels of polyphosphates and to probe their intracellular environment in the ectomycorrhizal fungi Cenococcum graniforme Ferd. & Wing, and Hebeloma crustuliniforme (Bull.) Quel. Polyphosphate content was a function of the growth phase and nitrogen content in the medium, lowest in rapidly growing mycelia, highest in older and N‐starved cultures. During phosphorus depletion the polyphosphate store was mobilized; degradation of the polymer was rapid in H. crustuliniforme, whereas it was slower in C. graniforme. This difference between the two fungi might be related to differences in the intracellular physical state of polyphosphates.

Measurements of nuclear magnetic relaxation parameters, such as resonance line widths and spin‐lattice relaxation times, T1, have been carried out in model systems and in intact mycelia with the aim of characterizing the physical state of polyphosphates. The intracellular T1 of inner P of polyphosphates was dramatically shorter than that in the culture medium. Polyphosphate relaxation may result from a combination of partial immobilization of the polymer by cellular components and interaction with paramagnetic ions.

On the basis of these data, it is suggested that polyphosphates exist in ectomycorrhizal fungi as aggregates with reduced correlation time. A more fluid state of polyphosphates in H. crustuliniforme than in C. graniforme might allow their rapid degradation by polyphosphates.
GROWTH AND MINERAL NUTRIENT STATUS IN PEANUT AND SORGHUM IN RESPONSE TO ACID PRECIPITATION AND ALUMINIUM
Authors: OWNBY JAMES D. , DEES LYNDON
Published: May 2006

Summary

The potential effects of acid rain on the availability of soil nutrients were examined by growing sorghum and peanut seedlings in a loamy sand/perlite mixture such that nutrient availability limited growth. Seedlings were watered with simulated acid precipitation at pH 5.5 (control), 4.5, 3.5, and 2.5 for 28 or 31 d. There was a significant increase in growth rate and plant dry weight for seedlings exposed to subambient (pH 2.5) watering regimes containing both SO42− and NO3− (6:1, mol/mol). When NO3− was omitted there was no enhancement of shoot growth, and root growth was approximately 50% of that in the control (pH 55) seedlings.

Peanut and sorghum seedlings were also grown in soil amended with AlCl3 to simulate conditions where acid precipitation depresses soil pH to the Al neutralization range. Under these conditions there was a complete cessation of growth which was attributed primarily to inhibition of uptake and translocation of Ca rather than accumulation of Al in plant tissues.

These experiments indicate that input of N but not S from acid precipitation may potentially benefit crop plants and forage grasses growing under low nutrient availability. Al mobilization in acidified soils may affect plant growth through the induction of Ca deficiency.
SEED MANGANESE CONTENT AND ITS RELATIONSHIP WITH THE GROWTH CHARACTERISTICS OF WHEAT CULTIVARS
Authors: SINGH DINESH KUMAR , BHARTI SUDHAKAR
Published: May 2006

Summary

Dry seeds of wheat (Triticum aestivum L.) subjected to electron spin resonance (ESR) spectroscopy show a characteristic sextet of Mn2+. Perchloric acid extracts of seeds also show a resolved hyperfine sextet of Mn2+. The Mna+ content of seeds show a direct linear relationship with the height of the wheat cultivars. The Mn2+ content of the seeds may be taken as a parameter to determine the height of the mature plant.
IMPROVED HYPHAL GROWTH OF TWO SPECIES OF VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI IN THE PRESENCE OF SUSPENSION‐CULTURED PLANT CELLS
Authors: CARR G. R. , HINKLEY M. A. , LE TACON F. , HEPPER C. M. , JONES M. G. K. , THOMAS E.
Published: May 2006

Summary

Conditions required for the combined culture of either Glomus caledonium (Nicol. &Gerd.) Trappe &Gerdemann or Glomus mosseae (Nicol. &Gerd.) Gerdemann &Trappe with suspension‐cultured plant cells have been investigated. Sucrose levels (0.05 to 0.5%, w/v) lower than those used for growth of plant cells were optimal for hyphal growth of both G. caledonium and G. mosseae. In vitro hyphal growth from chlamydospores of G. caledonium was stimulated by addition of cells of wheat (Triticum aestivum L. cv. Maris Butler), lucerne (Medicago sativa L. cv. Europ) and potato (Solanum tuberosum L. cv. Maris Piper). The presence of wheat cells similarly stimulated hyphal growth from chlamydospores of G. mosseae. Further tests on the effect of lucerne cells on G. caledonium indicated that a volatile substance was involved in the improvement of hyphal growth.
THE EFFECTS OF SOIL TEMPERATURE ON PLANT GROWTH, NODULATION AND NITROGEN FIXATION IN CASUARINA CUNNINGHAMIANA MIQ.
Authors: REDDELL PAUL , BOWEN G. D. , ROBSON A. D.
Published: May 2006

Summary

The effects of soil temperatures between 15 and 30°C on plant growth, nodulation and nitrogen fixation in seedlings of Casuarina cunninghamiana Miq. inoculated with Frankia from two different sources were examined. The optimum soil temperature for the growth of plants dependent on symbiotic nitrogen fixation was 25°C. Decreasing the soil temperature below 25°C markedly decreased plant growth that was reliant on symbiotically fixed nitrogen; effects on the growth of plants supplied with mineral nitrogen were much smaller. At 15°C there was no response in plant growth to inoculation after 148 d, whereas plants supplied with nitrogenous fertilizer were 10 times the weight of uninoculated plants.

Nodulation was delayed at 15 and 20°C with nodules formed at 15°C fixing no nitrogen in these studies. The production of fewer nodules at 20°C than at 25°C was partly compensated by the production of larger nodules. Nodule growth at 20 to 30°C was a prime determinant of nitrogen fixed, with the exception of one Frankia at 20°C.

The amount of nitrogen‐fixed g−1 nodule was the same for the two Frankia sources at 25 and 30°C, differences in effectiveness being due to nodule development. However, differences in the effectiveness of the two Frankia sources at 20°C were related to differences both in nodule development and in nitrogen‐fixing ability.

The absence of nitrogen fixation at 15°C would be expected to limit the natural distribution of Casuarina species reliant on symbiotically fixed nitrogen to areas where soil temperatures exceed 15°C for a major part of the potential growing season.
THE BIOLOGY OF MYCORRHIZA IN THE RICACEAE
Authors: BAJWA R. , READ D. J.
Published: May 2006

Summary

The ericoid mycorrhizal endophyte Hymenoscyphus ericae (Read) Korf &Kernan was grown both in pure culture and in mycorrhizal association with the host plant Vaccinium corymbosum L. on media containing peptides of differing chain length as sole nitrogen sources. The ability to utilize the peptide nitrogen was assessed in terms of growth of the fungus and of growth and nitrogen content of the plants.

The tripeptide, glutathione, and alanine units of 1–6 amino acid residues in length were all readily utilized by the endophyte, though assimilation was less rapid in the case of the longer chain lengths. Mycorrhizal seedlings showed significantly higher yields and had higher nitrogen contents than non‐mycorrhizal seedlings in almost all cases.

The physiological and ecological implications of these results are discussed.
THE BIOLOGY OF MYCORRHIZA IN THE ERICACEAE
Authors: BAJWA R. , ABUARGHUB S. , READ D. J.
Published: May 2006

Summary

The ability of the ericoid mycorrhizal endophyte to utilize a range of proteins as substrates for growth is assessed in liquid culture and in mycorrhizal association with host plants. Some aspects of proteolytic enzyme production are also investigated.

The fungus readily utilizes the soluble protein bovine serum albumin (BSA) as sole nitrogen and carbon source, and produces lower yields on less soluble plant and animal proteins. Maximum yields of endophyte on all substrates were obtained in the pH range 3 to 5. Infection provides a significant enhancement of plant growth on agar over this pH range on most of the proteins. Yields and nitrogen contents of mycorrhizal plants grown on cellulose sheets with BSA as sole N source were significantly higher than those of the uninfected controls, which were unable to use protein.

Using a chromogenic substrate it was shown that the pH optimum for enzyme activity is comparable with that for utilization of protein in pure culture and in mycorrhizal association. Non‐mycorrhizal plants produced negligible proteolytic activity.

The significance of these observations is discussed in relation to the nutrition of both host and fungus in the natural environment, and the broader ecological implications of the results are assessed.
PHOTOSENSITIVITY OF HYPOCOTYL HOOK OF CAESIUM‐TREATED TOMATO SEEDLINGS
Authors: KORDAN H. A.
Published: May 2006

Summary

Hypocotyls of etiolated caesium‐treated tomato seedlings were morphologically similar to, but shorter than, those of the etiolated water control seedlings. Chlorophyll development became manifest in the cotyledons of both the caesium‐treated and control seedlings when exposed to white or red light but brown discolouration, reduction in diameter, and subsequent deterioration of the hypocotyl hook were evident in the caesium‐treated seedlings exposed to white or red light. It is suggested that the hypocotyl hook is the primary site of caesium‐induced photosensitivity of tomato seedlings.
CHROMOPLASTS IN SOME CYCADS
Authors: WHATLEY J. M.
Published: May 2006

Summary

The ripe seeds of some species of cycads are red in colour and contain chromoplasts: those in seeds of Cycas revoluta Thurb. and Macrozamia lucida L. A. S. Johnson belong to the tubulous class of chromoplast whereas those of Zamia purpurea sp.nov. contain large globules, some packed thylakoids linked by electron‐dense bridges, and other unusual structures. The Zamia plastids do not fall clearly into any of the generally recognized chromoplast categories. Some features of the chromoplasts of cycads closely resemble those found in angiosperms; other features appear more typical of plastids in lower plants.
LOCALIZATION OF AMYLOSE AND AN AMYLOSE‐BINDING LIPOPROTEIN IN NEUROSPORA CRASSA HYPHAE BY CYTOCHEMISTRY AND IMMUNOELECTRON MICROSCOPY
Authors: VARKEY JACOB P. , NADAKAVUKAREN MATHEW J. , McCRACKEN DEREK A.
Published: May 2006

Summary

The presence of amylose was demonstrated in hyphal walls of Neurospora crassa Shen and Dodge by silver proteinate staining for carbohydrates and differential digestion with β‐amylase. The amylose was found to be localized in the innermost layer of the wall. Similarly, amylose‐precipitating factor (APF) was also found to be localized in the same wall layer using ferritin‐tagged antibodies to APF. Lipase‐digestion of the isolated hyphal wall resulted in considerable reduction of the silver grain deposition in the innermost wall layer, suggesting the removal of amylose from this layer. Because lipid‐free APF cannot bind to amylose, these observations indicate that APF and amylose in Neurospora are in a complexed form in the innermost layer of the hyphal wall as a structural component.
CARBON MOVEMENT BETWEEN HOST AND MYCORRHIZAL ENDOPHYTE DURING THE DEVELOPMENT OF THE ORCHID GOODYERA REPENS Br
Authors: ALEXANDER CLARE , HADLEY G.
Published: May 2006

Summary

Goodyera repens Br. was either grown from seed and infected with its natural mycorrhizal endophyte, Ceratobasidium cornigerum (Bourd.) Rogers, or obtained as natural mycorrhizal plants from the field. Insoluble [14C]carbohydrate was provided at a point source available only to the external mycorrhizal mycelium of protocorms, plantlets (up to 50 mg w wt) or plants. Protocorms and plantlets obtained 14C via their external mycelium but plants did not, even when stressed for carbon by being kept in darkness for two weeks. There was no enhancement of growth of mycorrhizal plants when a carbon source was present in the substrate over an eight‐week period. When 14CO2 was fed to plant shoots to monitor movement of carbon from plant to endophyte, there was no evidence of such movement over a 7 d period.

These results suggest that carbon moves only from fungus to orchid and that this movement ceases when the host reaches a certain stage of development. With respect to carbon, mature green plants of G. repens appear to be independent of their mycorrhizal association.
RELATIVE CHANGES IN LEVELS OF POLYAMINES AND ACTIVITIES OF THEIR BIOSYNTHETIC ENZYMES IN BARLEY INFECTED WITH THE POWDERY MILDEW FUNGUS, ERYSIPHE GRAMINIS D.C. ex MERAT f.sp. HORDEI MARCHAL
Authors: WALTERS D. R. , WILSON P. W. F. , SHUTTLETON M. A.
Published: May 2006

Summary

The concentrations of three amines (putrescine, spermidine and spermine) were much increased in first leaves of barley infected with powdery mildew, whilst the concentrations of putrescine and spermidine in roots of mildewed barley were significantly decreased. Although no significant change in the activities of three polyamine biosynthetic enzymes (ADC, arginine decarboxylase; ODC, ornithine decarboxylase; and SAMDC, S‐adenosyl methionine decarboxylase) could be detected in roots of mildewed barley, the activities of ADC, ODC and SAMDC were increased in infected first leaves. The significance of these alterations in polyamines and their biosynthetic enzymes in mildewed barley is discussed.
PHOTOSYNTHETIC RESPONSES TO LIGHT OF AUSTRALIAN AND CHILEAN SPECIES OFNOTHOFAGUSAND THEIR RELEVANCE TO THE RAINFOREST DYNAMICS
Authors: READ JENNIFER , HILL ROBERT S.
Published: May 2006

Summary

Photosynthetic responses to light have been examined in nine temperate rainforest species, includingNothofagusspecies from Australia and Chile, in order to correlate comparative light requirements with regeneration patterns and forest dynamics.Nothofagus gunnii(Hook. f.) Oerst. has the highest light requirements of the AustralianNothofagusspecies and this correlates with its failure to regenerate in closed forest.N. alpina(Poepp. et Endl.) Oerst. is the most shade‐tolerant of theNothofagusspecies examined in this study, and this result conforms with regeneration patterns observed in Chilean rainforest. The Australian species,N. cunninghamii(Hook.) Oerst. andN. moorei(F. Muell.) Krasser, and the Chilean species,N. obliqua(Mirbel) Oerst. andN. dombeyi(Mirbel) Oerst., have similar photosynthetic characteristics. Consequently, the comparative light requirements of theNothofagusspecies described here do not explain differences in the dynamics of rainforests dominated by these species. Differences in the regeneration characteristics of co‐occuring understorey and shade‐tolerant canopy species appear to be more important determinants of the dynamics of these forests.
EVIDENCE FOR A REVERSIBLE ACTION OF METHIONINE SULPHOXIMINE DURING GROWTH OF THE CYANOBACTERIUM, GLOEOTRICHIA GHOSEI SINGH
Authors: TIWARI D. N. , SINGH L. J. , MISHRA A. K.
Published: May 2006

Summary

Inhibition by l‐methionine‐dl‐sulphoximine (MSX) of growth, nitrate and ammonia uptake in Gloeotrichia ghosei Singh disappeared after a lag period of 6 to 8 d. The ability of the organism to resume growth or nitrogen uptake following a lag period was not due to decay of the inhibitor. Amino acids such as glutamine or methionine, which function as nitrogen sources, abolished the inhibitory action of MSX.
NITRATE REDUCTASE ACTIVITY IN SPHAGNUM FUSCUM IN RELATION TO WET DEPOSITION OF NITRATE FROM THE ATMOSPHERE
Authors: WOODIN S. , PRESS M. C. , LEE J. A.
Published: May 2006

Summary

Nitrate reductase activity has been measured in Sphagnum fuscum (Schimp.) Klinggr. growing on an ombrotrophic mire in subarctic Sweden, remote from urban and industrial sources of atmospheric pollution.

Perturbation experiments in the field demonstrated nitrate induction of nitrate reductase activity which was both rapid and concentration dependent. Cumulative nitrate reductase activity after repeated treatments with 1 mM nitrate declined with each successive treatment. It is suggested that this may be a result of intracellular ammonium accumulation. Nitrate reductase activity in plants subjected solely to wet and dry deposition from the atmosphere showed little diurnal change, and watering of Sphagnum fuscum hummocks with distilled water had no effect on the enzyme activity. Nitrate reductase activity was, however, shown to be induced by natural precipitation events, the cumulative induced activity being proportional to nitrate deposition.

The data suggest that the wet deposition of nitrate represents an important source of nitrogen for ombrotrophic Sphagnum species, and that there is a close coupling of the physiology of S. fuscum plants with their atmospheric environment. Such a relationship would be readily perturbed by atmospheric pollution.
DIRECT FOLIAR EFFECTS OF SIMULATED ACID RAIN
Authors: NEUFELD H. S. , JERNSTEDT J. A. , HAINES B. L.
Published: May 2006

Summary

The effects of foliar applications of simulated acid rain (pH 5–6, 4.0, 3.0 and 2.0) were observed for seedlings of four deciduous tree species native to the eastern United States, Liriodendron tulipifera L., Platanus occidentalis L., Liquidambar styracifiua L., and Robinia pseudo‐acacia L. Damage occurred only at pH 2.0. Liriodendron was least damaged, Platanus the most. For Liriodendron and Platanus, older leaves showed more damage than younger ones, whereas for Robinia the opposite was true. No age effect was noted for Liquidambar. Height growth was reduced at pH 20 in Platanus and Robinia, and less so in Liquidambar. Total biomass was significantly reduced at pH 2.0 for Platanus and Liquidambar, resulting mainly from reduction in stem and root biomass. Leaf biomass was not greatly affected in any of the species. Photosynthetic rates in Platanus were reduced after exposure to rain of pH 20, and were the result of changes in mesophyll conductance to CO2, as stomata! conductances were not affected. In Liquidambar, stomatal conductances to water vapour were lowered after exposure to rain of pH 2.0. Results show that under greenhouse conditions only rain of extremely low pH causes foliar damage and growth reductions. Lowered rates of photosynthesis in Platanus may have contributed to the observed reductions in growth.
HYPHAL PENETRATION OF BRASSICA (CRUCIFERAE) ROOTS BY A VESICULAR–ARBUSCULAR MYCORRHIZAL FUNGUS
Authors: GLENN M. G. , CHEW F. S. , WILLIAMS P. H.
Published: May 2006

Summary

In situ observations of a vesicular‐arbuscular mycorrhizai fungus Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe with roots of Brassica cultivars containing low and normal levels of glucosinolates (7 to 524 mg g−1fresh weight) revealed differences between fungal penetrations of all Brassica roots compared to compatible hosts. Hyphae penetrated older, thicker Brassica roots, failed to form arbuscules, and exhibited no post‐penetration stimulation of hyphal branching either internal or external to the roots. Some internal hyphae formed vesicles. Ultrastructural examination revealed that fungal hyphae penetrated Brassica roots intercellularly between dead cortical cells. Internal hyphae found near the healthy stele of the root lacked cytoplasm and had not penetrated the stele. Hyphae did not penetrate Brassica roots with healthy cortical cells; hyphae which contacted the surface of these cells became vacuolated and retracted their cytoplasm within a day. These observations indicate that functional mycorrhizas were not formed with Brassica roots, and that the level of glucosinolates in roots was not correlated with failure to establish symbiosis.
WOUND OCCLUSION AND DISCOLOURATION COLUMNS IN RED MAPLE
Authors: LEBEN CURT
Published: May 2006

Summary

Red maple (Acer rubrum L.) stems (15–25 cm diam. at breast height) were wounded in the autumn or spring with horizontal, 1‐cm wide chain‐saw cuts 4 to 6 cm deep and 10 to 16 cm long. Wound occlusion (VO, vertical occlusion, at the wound side), bark dieback (BD, failure of horizontal occlusion above and below the wound), and the length of discoloured wood columns (DWC) were recorded after two growing seasons. For 93 trees (one wound each), correlations between lengths of BD and DWC were not significantly different above and below the wound (r= 0.58 and 0.56, respectively), with DWC being 2 to 3 times the length of BD. Corresponding correlations between the VO rating and the length of DWC were 0.41 and 0.38 (no significant difference). Compared with wounds made in the autumn, wounds made in spring caused less BD, greater VO, and shorter DWC. It is suggested that hydrostatic pressure in the wood, which is positive in the spring and negative in the autumn, is a major determinant of the volume of DWC and hence of wood that is susceptible to decay.
LIGHT AND DRY STORAGE INFLUENCES ON THE RESPIRATION OF GERMINATING SEEDS OF FIVE SPECIES
Authors: HILTON J. R. , OWEN P. D.
Published: May 2006

Summary

In an attempt to study the influence of light on early metabolic events in seed germination, the rates of oxygen uptake of germinating seeds of five species were measured in relation to their germination response to light and to their loss of primary dormancy during dry storage. No significant effects of light on oxygen uptake prior to germination (i.e. prior to radicle protrusion) were detected. A difference m the initial rates of oxygen uptake prior to germination was observed when seeds were stored at low (8%) moisture contents suggesting that significant changes in their respiratory capacity occurred under these conditions.