bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitivity of forest plant reproduction to long‐range transported air pollutants: the effects of wet deposited acidity and copper on reproduction of Populus tremuloides*
Authors: COX R. M. 
Published: April 2006

summaryFew, if any, studies have been carried out that examine and relate in vivo pollen germination following stimulated wet deposition of acidity and copper with various fruit and seed set parameters of trees. The methods used with inflorescences of a wind‐pollinated tree, Populus tremuloides Michx., are reported here. The responses of components of the reproductive system to rain simulants indicated significant (P < 005) overall response of in vivo pollen germination to pH. The combined data demonstrated a significant (P < 005) negative correlation between germination and pH. However, the response in the absence of copper showed no linear correlation because of a recovery at the lowest pH used (26). The effect of simulated rain at the time of pollination was shown to increase fruit abortion significantly. In addition, an overall significant negative correlation was found between fruit abortion and pH, but again in the absence of copper, fruit abortion recovered at the lowest pH (2–6). Seeds per fruit and percentage of placenta with full seeds were significantly reduced at pH 2–6 in the presence of 0–05 mg 1−1 Cu compared with the control. These two seed set parameters were also significantly intercorrelated (P < 0.01) with fruit abortion suggesting that lack of seed set may be the cause of the abortion. The significant correlation of both in vivo pollen germination and fruit abortion with pH, especially in the presence of copper, supports the view that inhibition of the pollen on the stigma by the simulated rain is responsible for the lack of seed set above the required threshold that prevents fruit abortion.
Fungal colonization of attached beech branches
Authors: CHAPELA I. H. , BODDY LYNNE 
Published: April 2006

summaryEarly colonizing fungal communities in beech branches exhibit a distinct spatial organization. Decay often begins in distal regions with stain‐associated fungi, which derive from latent propagules in the wood and bark, effecting the first stages of colonization. This characteristic assemblage is followed by a more combative group of wood‐rotting fungi, particularly Basidiomycotina. The resource at the front of colonization is partitioned between individuals of different species intermixed without clear delimitation. By contrast, the more combative Basidiomycotina which arrive later and displace the fungi in the colonization front usually occupy much larger spatial domains clearly delimited by interaction zone‐lines.
Fungal colonization of attached beech branches
Authors: CHAPELA I. H. , BODDY LYNNE 
Published: April 2006

summaryFungal colonization of healthy beech (Fogus sylvatica L.) branches was studied by sectioning branch lengths and drying the sections under controlled regimes. Maintaining water saturation prevented any fungal development in the wood, while active mycelium was isolated as soon as 14 days after the start of the drying period. Fungi developing in these sections were naturally established in healthy branches in the field and formed a floristically denned group, dominated by Hypoxylon fragiforme (Scop.) Kickx., H. nummularium Buill.: Fr., Nectria coccinea (Pers.: Fr.) Fr., and Coniophora putaena (Fr.) P. Karst., and also included coelomycete species. This group was obtained independently of position of the branch in the canopy, season of sampling over an 11 ‐month period, and site, sampling including four sites in south‐west Britain and one in the French Pyrenees. Several species in this group are specific or show a preference for beech as a host.Direct observations and isolation from sections with time indicated that whereas most species developed inwards from the bark, H. fragiforme and H. nummularium grew out from pockets within the wood. Each pocket contained a genetically different individual, as revealed by colony morphology and vegetative incompatibility tests.It was established that water content of the wood is the major determinant for the initial development of fungi in the xylem of beech, and that these early colonizers derive from inoculum latent in the healthy, living branches.
Vesicular–arbuscular mycorrhizas and the soil‐disturbance‐induced reduction of nutrient absorption in maize
Authors: FAIRCHILD G. L. , MILLER M. H. 
Published: April 2006

summaryIn previously reported studies, maize seedlings absorbed more phosphorus (P) from soil in a long‐term zero‐till system than from the same soil after disturbance. This partly resulted from greater vesicular‐arbuscular (VA) mycorrhizal infection in the undisturbed soil. In the study reported herein, a growth room experiment was conducted to determine how long a soil must remain undisturbed before subsequent disturbance will reduce P absorption. Starting with disturbed soil, maize was grown for 3‐week cycles. At the conclusion of each growth cycle, half of the pots were disturbed and replanted whereas the other half was replanted without disturbing. Over the three growth cycles, major increases in mycorrhizal infection in the plants in the undisturbed soil were observed concurrently with the increases in nutrient absorption.A significant increase in P absorption occurred in the first growth cycle on undisturbed soil and greater increases occurred after the second and third. At 21 d in the third growth cycle, plants grown in the undisturbed soil had almost twice the dry weight of plants grown in the disturbed and had higher concentrations of N, P, Mg, Cu and Zn in the shoots. Absorption of P between 14 and 21 d of the third growth cycle in the undisturbed soil was 10 times larger than that in the disturbed soil. Absorption of N, Mg, Cu and Zn was more than three times larger. In the third growth cycle, concentrations of N, P, Mg and Zn in the shoot and intensity of VA mycorrhizal infection were greater in the undisturbed soil as early as 14 d after planting. There was a concurrent and rapid increase in VA mycorrhizal infection and P absorption by maize over three growth cycles when an initially disturbed soil was left undisturbed. This rapid concurrent development, particularly starting from an initially disturbed soil, provides good evidence that soil disturbance reduces VA mycorrhizal infection and hence P absorption by maize.
Metabolic characteristics of akinetes of the cyanobacterium Fischerella muscicola
Authors: SINGH SURENDRA , KASHYAP A. K. 
Published: April 2006

summaryMature akinetes of Fischerella muscicola (Thuret) Gom. are shown to have a low rate of respiration and to lack photosynthetic pigments, photosynthetic O2‐evolving activity and the activities of the primary enzymes of inorganic nitrogen assimilation. The C/N ratio steadily increased during akinete differentiation and it is suggested that this increase results because, during akinete development, the loss of the activities of nitrogenase and glutamine synthetase precedes the loss of CO2 fixation.
The enhancement of anther culture efficiency in Brassica napus ssp. oleifera Metzg. (Sinsk.) using low doses of gamma irradiation
Authors: MACDONALD M. V. , HADWIGER M. A. , ASLAM F. N. , INGRAM D. S. 
Published: April 2006

summarySelected buds of Brassica napus ssp. oleifera Metzg. (Sinsk) cvs Ariana and Primor were treated with various doses of γ‐irradiation. When the anthers were removed and cultured, it was shown that low doses of γ‐irradiation greatly enhanced anther culture efficiency in both cultivars. When microspore culture techniques were used, however, embryogenesis was reduced by irradiation in all treatments. Some of the resulting embryoids developed directly into plantlets, whereas others developed abnormally and produced secondary embryoids. Plants were regenerated from both anther embryoids and secondary embryoids and, following diploidization, seed was obtained from these plants.
An in vitro bioassay for the stigmatic product of the self‐incompatibility gene in Papaver rhoeas L.
Authors: FRANKLIN‐TONG V. E. , LAWRENCE M. J. , FRANKLIN F. C. H. 
Published: April 2006

summaryThis paper reports the development of an in vitro bioassay for the somatic product of the self‐incompatibility gene in Papaver rhoeas L. As with in vivo pollinations, inhibition of pollen tube growth occurs only when the S‐alleles carried by the pollen are matched by those contained in the stigma used to make a print or from which the extract was obtained. Furthermore, these in vitro reactions appear to be quantitatively indistinguishable from those obtained with in vivo pollinations, so that the resolution of the assay allows the distinction between incompatible, half‐compatible and fully compatible reactions to be made on sight rather than by measurement and statistical analysis of pollen tube length.
Influence of ambient ammonium on net potassium uptake by decapitated maize seedlings
Authors: TOPA M. A. , JACKSON W. A. 
Published: April 2006

SUMMARYThe effects of ambient ammonium on potassium uptake and accumulation in xylem exudate were examined in 6‐d‐old decapitated maize (Zea mays L., ev. Pioneer 3369a) seedlings, Net uptake of both K+ and NH+4 was measured by solution depletion during a 5 h treatment period. [86Rb]K+ influx during a 10 min uptake period was also measured for some treatment combinations over the 5 h period. The presence of ambient 0.2 mM NH+4initially resulted in net efflux of K+ to solution containing 0.2 mM K+, as well as to K+‐free solutions. A transition from net K+ efflux to net K+ uptake occurred after 1.25–1.5 h in solutions containing 0.2 mM K+ and 0–2 mM NH+4. After the transition, the rate of K+ uptake was ∼ 50% of that found in the absence of ambient NH+4 [86Rb]K+ influx from 0.2 mM K+ was inhibited by 50% in the presence of 0.2 mM NH+4. Increasing ambient NH+4 to 2.0 mM increased the initial net efflux of K+ and delayed the time at which transition to net uptake occurred. The combined data indicate that the inhibitory effect of ambient NH+4 on net K+ uptake resulted from an initial but temporary enhancement of K+ efflux, and a constant inhibition of K+ influx. A reciprocal inhibition of net NH+4 uptake by K+ was not observed. Net NH+4 uptake initially was associated with K+ efflux, after which a transition to net H+ occurred. In the presence of NH+4, the transition from net K+ efflux to net K+ uptake, and the associated onset of net H+ efflux took place without measurable alterations in the rate of K+ accumulation in the xylem fluid. These results suggest spatially separate compartments for K+ efflux and xylem deposition.
The effects of removal of the root tip on lateral root distribution in adventitious roots of anion
Authors: LLORET P. G. , CASERO P. J. , NAVASCUÉS J. , PULGARÍN A. 
Published: April 2006

SUMMARYDistribution patterns of lateral roots (LRs) were analysed in intact (control) and decapitated adventitious roots (ARs) of Allium cepa L. Removal of the root tip caused: (1) The cessation of elongation of the AR. (2) An increase in the number of LRs per cm which developed on the AR. (3) Changes in the distribution of LRs along the mother root One aspect of the distribution modified by the decapitation was the suppression of an apical zone without LRs which was observed immediately behind the apex in intact roots. In decapitated ones by contrast accumulation of LRs was enhanced in this zone. Moreover, decapitation appeared responsible for successive LRs opposite the same xylem pole developing nearer each other than in intact roots. (4) Changes in the frequency and location of clumps of LRs. In decapitated roots 21.6%, of the total number of LRs were clumped. In intact ARs this figure was only 13.5%. Moreover, intact roots showed a tendency to LR clumping preferentially in their basal zone In contrast, clumps of LRs were noted indistinctly in both basal and distal zones of decapitated ARs. I his fact implies that removal of the root tip enhances the natural tendency toward clumping of LRs, chiefly in distal zones of the AR. Other aspects of the pattern remain unchanged after removing the root apex. Hence in decapitated as well as intact ARs there were two neighbouring xylem poles opposite which large number of LRs were produced, whereas the remaining ones were considerably less prolific. A further aspect which was not altered by the decapitation was the significantly high frequency of formation of neighbour LRs opposite adjacent xylem poles.
Evaluation of factors contributing to diurnal changes in O2 concentrations in floodwater of deepwater rice fields
Authors: SETTER T. L. , KUPKANCHANAKUL T. , WATERS I. , GREENWAY H. 
Published: April 2006

SUMMARYGlass chambers were used to isolate 0–75 m deep water columns in situ in deepwater rice fields in Thailand to evaluate the contribution by various factors to the pronounced diurnal changes in O2 concentrations in the floodwater Chambers filled with distilled water provided estimates of O2 flow from the air into the water, indicating the importance of eddy currents associated with wind action and evaporative cooling. Darkening the natural water gave estimates for O2 evolution due to photosynthesis, while comparisons between columns with and without rice distinguished between O2 evolution and consumption by the rice and the biomass other than rice respectively. Removal of the above water portions of the rice shoots showed the importance of the emergent portion of the canopy to O2 movement from the air into the aquatic part of the ecosystem. This flow may be associated with O2 flow through the lacunae and via air envelopes around the leaf, and with turbulence caused by swaying of the rice leaves in the wind.The changes in O2 concentration were analysed quantitatively using several simplifying assumptions. One major input was a net O2 flow from the air into the water, about half being due to a net flow across the air–water interface and the other half to flow associated with the rice plants. During the night, these flows were less than the O2 uptake by the biomass, hence O2 concentrations decreased. In the underwater portion of the rice stand, about 60 % of the O2 uptake was due to the rice and about 40% due to the biomass other than rice. During the day, the O2 requirements by respiration were more than compensated for by O2 evolution due to photosynthesis, resulting in increases in O2 concentration of the water.
The relationship between changes in photosynthesis and growth for radish plants fumigated with SO2 and O3
Authors: ATKINSON C. J. , ROBE S. V. , WINNER W. E. 
Published: April 2006

SUMMARYThe effects of possible ambient concentrations of SO2 and O3 on biomass production and gas exchange of radish (Raphanus sativus L, cv. Cherry Belle) are examined, the relationship between photosynthesis and growth is defined and the mechanisms behind pollutant induced changes in growth are elucidated.Ozone was shown to be considerably more phytotoxic than SO2. Fumigation at a concentration as low as 5 μmol O3 m−3 (0.12μl 1−1) produced ‘visible’ injury. No ‘visible’ injury symptoms were apparent with plants fumigated with SO2. The effect of fumigation with Oa at concentrations greater than 2.5 μmol m−3 (0.06 μl 1−1) was to reduce biomass production and alter carbon partitioning. This was not so for SO2, fumigated plants. Ozone‐fumigated plants showed a significant reduction in their photosynthetic efficiency (NAR) and despite an increase in LAR, RGR was still depressed below control values.The relationship between photosynthesis and biomass production for fumigated plants was examined and whole plant carbon acquisition was calculated from gas‐exchange measurements. On comparing calculated carbohydrate production with measured biomass accumulation, it was dear that changes in A were closely related to changes in growth.Light‐ and CO2‐response curves were used to determine maximum light‐saturated photosynthesis (Amax), incident quantum yield (QY) and carboxylation efficiency (d.A/de1), RuBP‐regeneration capacity (Jmax) respectively. The presence of SO2 over a concentration of 2.5–8.3 μmol m−3 (0.12–0.20 μl −1) enhanced Amax. QY and Jmax, However, dA/dc1, was reduced at all concentrations. This reduction was offset by an increase in Jmax. At the smallest O3 concentration (2.5 μmol m−3) Amax was stimulated and at the higher concentration severely reduced. Q Y was not negatively influenced by the presence of O3, but d.A/dc1 and Jmax were reduced, particularly as the dose increased.
The effect of nitric oxide fumigation at two CO2 concentrations on net photosynthesis and stomatal resistance of tomato (Lycopersicon lycopersicum L. cv. Abunda)
Authors: BRUGGINK G. T. , WOLTING H. G. , DASSEN J. H. A. , BUS V. G. M. 
Published: April 2006

SUMMARYNet photosynthesis of 5‐week‐old tomato plants (Lycopersicon lycopersicum L. cv. Abunda), was measured in clean air or with NO fumigation, for five consecutive days under simulated winter glasshouse conditions: temperature 22 °C, VPD 04 kPa, irradiance 30 W m−2 and daylength 8–9 h. NO concentrations applied were 0 or 1 μl 1−1 in combination with CO, concentrations of 350 or 1000 μl −1.A reduction in net photosynthesis due to NO became apparent on the third day of measurement. On the fifth day this reduction was 38%, of the control at 350 μl −1 CO2 and 24%, at 1000 μl −1 CO2. The increase in photosynthesis due to CO, enrichment was initially 40%; this effect was strongly reduced after 5 d in the presence of NO. Plants did not recover in the dark after the daily fumigation treatment, the level to which photosynthesis was reduced at the end of the day being the level at which it started the next day. The decrease in photosynthesis could not be explained by an increased stomatal resistance, and the plants did not show visible symptoms of injury. Practical implications of the results are discussed.
Competition between three species of Glomus used as spatially separated introduced and indigenous mycorrhizal inocula for leek (Allium porrum L.)
Authors: HEPPER CHRISTINE M. , AZCON‐AGUILAR CONCEPCION , ROSENDAHL S. , SEN R. 
Published: April 2006

SUMMARYThe ability of three vesicular‐arbuscular (VA) mycorrhizal fungi‐Glomus caledonium (Nicol, and Gerd.) Trappe and Gerd., Glomus sp. type E3 and Glomus mosseae (Nicol. and Schenck) Gerd. and Trappe ‐ to infect leek (Allium porrum L.), when used as spatially separated pairs of inocula was assessed by analysing the roots for the presence of diagnostic fungal enzymes alter separation of root proteins by gel electrophoresis. A difference in competitiveness was observed, such that Glomus sp. E3 was unable to infect a root system if either G. caledonium or G. mosseae were also present. When the latter two fungi were used as a pair of inocula, the one which had been placed to simulate an indigenous strain predominated in the root to the almost total exclusion of the one placed as an introduced inoculum. These results suggest that the successful establishment of VA mycorrhizal inocula in field soils will depend on the indigenous species present, the species being introduced and its placement in the soil. The use of diagnostic fungal isozyme analysis offers a method of monitoring the outcome of an inoculation programme by detecting the presence of the introduced species in the host roots.
Influence of glucosinolate content of Brassica (Cruciferae) roots on growth of vesicular–arbuscular mycorrhizal fungi
Authors: GLENN M. G. , CHEW F. S. , WILLIAMS P. H. 
Published: April 2006

SUMMARYWe tested the hypothesis that failure to establish symbiosis with vesicular‐arbuscular (VA) mycorrhizal fungi is correlated with glucosinolate concentrations in Brassica, a representative genus of the Capparales. Brassica campestris and B. napus cultivars (brassica) with a range of glucosinolate concentrations (7–524 μmol g1 f. wt in roots) were grown together with the VA mycorrhizal fungi Glomus mosseae and Gigaspora gigantea in agar. Fungal growth was observed in situ but fungi did not penetrate brassica roots. However, normal germ tube growth of the VA mycorrhizal fungi occurred near brassica roots when compatible hosts grew nearby. These compatible hosts developed normal mycorrhizal infections. These results suggest that brassica roots do not produce a diffusable inhibitor of VA mycorrhizal fungi, but lack a diffusable growth stimulus present near roots of compatible hosts.
Mycorrhizal associations of isolates of Sebacina vermifera
Authors: WARCUP J. H. 
Published: April 2006

SUMMARYIsolates of Sebacina vermifera Oberwinkler (Tremellaceae), identified by their teleomorphs, from orchid and non‐orchid hosts have been examined for their mycorrhizal associations. All isolates stimulated germination of seed of species of Microtis (Orchidaceae). Three isolates from ectomycorrhizal hosts formed ectomycorrhizas on Melaleuca uneinata R. Br. ex Alton I. and other ectomycorrhizal plants. None of the orchid isolates nor an isolate which was endophytic in Phyllanthus formed ectomycorrhizas but in addition to species of Micron's they stimulated germination of one or more species of Caladenia, Cyrtostylis or Glossodia but not other terrestrial orchids.Protocorms of Microtis developed at depth in soil in the presence but not the absence of ectomycorrhizal S. vermifera on M. uneinata. Young albino plants of Microtis rara R. Br. grew for 4 months in the presence of ectomycorrhizal S. vermifera with M. uneinata but mycorrhizal albino plants on their own all died, suggesting a possible tripartite mycorrhizal association.
Observations on growth rates and calcium carbonate deposition in the green alga Gongrosira
Authors: PENTECOST ALLAN 
Published: April 2006

SUMMARY In vivo growth rates of Gongrosira [probably G. incrustans (Reinsch) Schmidle], a cushion‐forming fresh‐water green alga (Chaetophorales) are reported for the first time. The annual radial growth rate averaged 0.42 mm in a mountain stream from northern England and was positively correlated with water temperature (r=+ 0.919, P < 005). The colonies were heavily incrusted with calcium carbonate (calcite). Photosynthetic activity probably promotes calcification between the closely packed basal filaments, but most of the precipitation appears to be abiogenic from supersaturated stream waters. Calcified Gongrosira bioherms are also described from a subtropical site in Mexico. The survival period for Gongrosira at the English site was approximately one year, and at both sites Gongrosira was a permanent and significant component of the epilithic algal flora.
The biological effects of gamma irradiation on secondary embryoids of Brassica napus ssp. oleifera (Metzg.) Sinsk., winter oilseed rape
Authors: MACDONALD MARY V. , NEWSHOLME D. M. , INGRAM D. S. 
Published: April 2006

SUMMARYThe effects of gamma irradiation on secondary embryoids of Brassica napus ssp. oleifera (Metzg.) Sinsk., winter oilseed rape, are reported. A kill curve was established, and the secondary embryoids were found to be more tolerant of high doses of irradiation than tissues of many other plant species. Secondary embryoids which had received less than 320 Gy retained their secondary embryogenic potential at subsequent subcultures, although their potential to develop into plantlets was greatly reduced. A haploid line from the cultivar Rapora was found to be more sensitive to gamma irradiation than a diploid line from the cultivar Primor. A number of regenerant plants have been established from irradiated embryoids and grown on to flowering.