bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photosynthesis and nutrient‐use efficiency of barley in response to low arbuscular mycorrhizal colonization and addition of phosphorus
Authors: FAY P. , MITCHELL D. T. , OSBORNE B. A. 
Published: April 2006

summaryThe effects of arbuscular mycorrhizal infection by Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe on growth and photosynthesis of barley (Hordeum vulgare L. cv. Manitou) were investigated in sand culture at five levels of calcium phosphate (50, 100, 200, 400 and 800 mg P kg−1). Mycorrhizal infection was low and varied with P supply, declining from 3.3% at 50 mg P kg−1 to 1.5% at the highest P concentration. In general, there were small differences in biomass between mycorrhizal (+AM) and non‐mycorrhizal (‐AM) barley but a significant reduction in dry mass of senesced leaves occurred in the +AM plants. Leaf P concentrations increased with P application, but did not differ between + AM and ‐AM plants. Although there were no differences in dry mass between + AM and ‐AM plants at 50 mg P kg−1, it was at this lowest P supply that +AM plants had higher rates of photosynthesis and greater P‐use and N‐use efficiencies. The mycorrhizal enhancement of maximum photosynthetic rate at the lowest P level was associated with a higher stomatal conductance, but was not related to increased leaf P or to changes in photon yield or the ratio of variable (FV) to maximum (FM) chlorophyll fluorescence.
Effects of Ascochyta caulina on photosynthesis of leaves of Chenopodium album
Authors: KEMPENAAR C. , HORSTEN P. J. F. M. , SCHEEPENS P. C. 
Published: April 2006

summaryThe effect of leaf necrosis caused by Ascochyta caulina (P. Karst.) v.d. Aa & v Kest. on photosynthesis of leaves of Chenopodium album L. was studied in growth chambers. Fully expanded leaves of young plants were sprayed with a suspension of pycnidiospores, or with a spore‐free control solution. Subsequently, leaves were exposed to high humidity for 6, 18, or 24 h to promote different levels of necrosis. Individual leaves were assessed for proportion of necrotic leaf area and net photosynthetic rate (npr) 3, 4 and 7 d after treatment. The npr of leaves decreased with increasing proportion of necrotic leaf area. The relationship between the two was linear in five of six regression analyses carried out. The observed linearity indicates that necrotic leaf tissue hardly affected the surrounding healthy leaf tissue. The proportion of necrotic leaf area that caused a npr of zero was on average 0.4, ranging from 0.2 to 0.5.
Catechin, proanthocyanidin and lignin contents of loblolly pine (Pinus taeda) needles after chronic exposure to ozone
Authors: BOOKER FITZGERALD L. , ANTTONEN SEIJA , HEAGLE ALLEN S. 
Published: April 2006

summaryConcentrations of soluble and bound phenolic compounds were measured in needles of 3‐yr‐old loblolly pine (Pinus taedaL.) trees exposed from May to November 1993 to a range of ozone (O3) concentrations in open‐top field chambers, The treatments were charcoal‐filtered air (CF). non‐filtered air (NF), and NF air with O2added at 1.5 times (NF 1.5) and 2(1 times (NF 2.0) the ambient O., concentration for 12 h daily. Average daily (0800–2000 hours) O3concentrations in the CF. NF. NF 1.5 and NF 20 treatments were. 29. 47, 76 and 98 nl 1−1. respectively, for the 140 d treatment period. At the end of the treatment period, total phenolic and proanthocyanidin concentrations in the previous year's needles were 25–29% higher in the NF 2.0 treatment compared with the lower O3treatments. Catechin concentration increased in the previous year's needles by as much as 81 % between the NF 2.0 treatment and the lower O3treatments. Catechin is an effective antioxidant, and elevated levels might confer some protection against O3injury. No significant differences in total phenolics and proanthocyanidins in the previous year's needles were detected among the remaining treatments, or among any O3treatment for the current year's needles. Lignin content in needles of both years was not significantly affected by O3exposure. Chances in the phenolic content of older needles in response to elevated O3could alter plant‐pathogen interactions and slow down microbiol decomposition, which could contribute to a decline in site soil quality.
The effects of different ozone exposures on three contrasting populations of Plantago major
Authors: PEARSON S. , DAVISON A. W. , REILING K. , ASHENDEN T. , OLLERENSHAW J. H. 
Published: April 2006

summary Plantago major grows throughout Britain in a range of ozone climates. Because populations have been shown to differ in ozone resistance, the aim of the experiment was to compare the reaction of populations from contrasting ozone climates to different types of ozone exposure. Three populations were grown under controlled conditions in five different ozone treatments (including controls for 10 wk. Development, growth, stomatal conductance and seed production were recorded. Populations were from the south coast of England (Lullington), near a mountain summit (Great Dun Fell) and lowland Scotland (Bush). Ozone treatments were: charcoal and Purafil filtered air (CF); 35 nl l−1 for 24 h every day: 70 nl l−1 h for 7 h everyday: CF then three episodes each week of 70 nl l−1 for 7 h; and 35 nl l−1 continuously plus three 7 h episodes each week of 70 nl l−1.The different ozone treatments resulted in different responses in each population. Ozone promoted senescence in the Great Dun Fell population but not in the others; it reduced root growth more in the Lullington population than in the others but those from Lullington and Great Dun Fell maintained seed production to a much greater extent than the Bush population. The reproductive effort (number of seeds g−1 of vegetative weight) actually increased in ozone in the Lullington and Great Dun Fell populations. It is suggested that this might he a general stress response rather than being specifically related to ozone. Effects on stomatal conductance were similar to those previously reported and the converse of effects on seed production.The relative responses of the populations varied according to the ozone treatment. Continuous exposure to 35 n1 l−l reduced leaf size only in the Great Dun Fell population, but seed output was reduced in the Bush population. In some cases, giving 3–d episodes of 70 n1 l−1 had a greater effect than giving the dose every day but the effects varied with the population. This greater effect was considered to be a result of the time it takes for a plant to develop maximum anti‐oxidant defence, which is lost when the ozone decreases after the episode. A plant exposed to episodes might have to re‐induce defence with each exposure.Although it is reported frequently that ozone favours allocation of resources to the shoot over the root, it is concluded that this is an over‐simplification of the response. Even within a species there is a complex suite of responses that varies with the population and with ozone exposure. Describing a population as resistant or sensitive is also an over‐simplification.
Effects of emissions from copper‐nickel smelters on the frost hardiness of Finns sylvestris needles in the subarctic region
Authors: SUTINEN MARJA‐LIISA , RAITIO HANNU , NIVALA VESA , OLLIKAINEN RISTO , RITARI AULIS 
Published: April 2006

summaryIt has been proposed that freezing injuries play an important role in the forest decline phenomenon. In this study, the effect of emissions from the copper‐nickel smelters in Monchegorsk and Nikel‐Zapolyarnyi in the Kola Peninsula, south‐west Russia, on seasonal changes in the frost hardiness of Pinus sylvestris L. needles were studied. The frost hardiness of current‐year needles during autumn, winter, spring and early summer in 1991–1993 was estimated by the electrolyte leakage method and by visual estimation of the proportion of damaged needles at nine sites in Finnish Lapland, at five sites in the vicinity of Monchegorsk and at two sites in Norway, in the vicinity of Nikel. The foliar S, Cu, and Ni concentrations also analysed. There were no significant differences at any time of the year between the frost hardiness of pine needles at the sites in Norway and Finnish Lapland. However, in the winter, the degree of visual damage at −45 °C, the temperature close to the lowest recorded temperature in this area, was slightly higher at the sites near to Nikel than at the sites in Finnish Lapland. In the Kola Peninsula the frost hardiness was consistently lower at the sites located 10 km to the south and 36 km to the south‐west of Monchegorsk than at the other sites (48–110 km to the south‐west). The differences were greatest in early June, 1991, when frost hardiness was −2 °C and −8°C at the sites closest to Monchegorsk. At the same time, the frost hardiness at the other sites was e.−20 °C. There were slight differences between years, but the trends were the same. A clearly increasing gradient in the S, Cu and Ni concentrations was observed on moving towards the emission point source at Monchegorsk. Highly elevated concentrations were found within 40 km of the smelter. The results suggest that air pollutants from the copper‐nickel smelter have predisposed the pines to freezing injuries, rhus contributing to forest decline in the Kola Peninsula.
The metabolism of fructans in roots ofCichorium intybusduring growth, storage and forcing
Authors: VAN DEN ENDE WIM , MINTIENS ANNEMIEKE , SPELEERS HILDE , ONUOHA AMABILIS A. , VAN LAERE ANDRÉ 
Published: April 2006

summaryDuring the 1993 growing season samples from field‐grown roots of chicory(Cicborium intybusL. var.folinsumev. Flash) were analysed by ion‐exchange HPLC (Dionex). We measured the concentrations (μmol g−1f. wt) of glucose, frurtose, sucrose, 1‐kestosc and 1,1 nystose. The concentrations of the higher fructans were relative (units g−1f. wt). The data showed a significant increase in the concentration of fructans with a high degree of polymerization (DP) during July, August und September and a decrease of the glucose concentration. The Concentrations of sucrose, fructose and oligomeric fructans remained roughly constant over the same period. However, in early October, important changes occurred over a very short period. These changes included: (1) a significant increase in fructose concentration; (2) an increase in the concentration of fructans with a low DP; (3) a decrease in fructans with a high DP; (4) an appearance of alternative peaks (probably representing fructans without terminal glucose); and (5) an increase in sucrose concentration. These changes werenotaffected by a short‐day treatment starting on 6 September. Forcing of the roots for endive production was accompanied by further breakdown, mainly of the larger fructans. Activity of SST (sucrose: sucrose fructosyl transferase) decreased slowly throughout the growing season lo essentially disappear by October. Neutral invertase activity increased more gradually. SST activity decreased very rapidly during cold storage and forcing.
Effects of sulphur dioxide and ozone on lichen colonization of conifers in the Liphook Forest Fumigation Project
Authors: BATES J. W. , MCNEE P. J. , MCLEOD A. R. 
Published: April 2006

summaryIn the Liphook Forest Fumigation Project the conifersPicea abies(L.)Karst.,P, sitchensis(Bong‐) Carr. andPinus sylvestrisL. were grown from the seedling stage and subjected, by open‐air fumigation, to three regimes of SO2(ambient, 4 ppb (parts in 109by volume); low, 12 ppb; high, 20 ppb) and two regimes of O3(ambient, 25 ppb; high, 30 ppb) in factorial combination, between 1987 and 1990. We determined the abundance of three lichens,Evernia prunastri(L.) Ach.,Hypogymnia physodes(L.) Nyl. andLecanora canizaeoidesNyl. ex Crombie, which colonized the trunks and branches of the saplings, at the end of the experiment between May‐July 1991. All three species showed a marked preference forP. abiesand were scarcest onP, sylvestriswhich had the most acidic hark.E. prunastriwas the rarest of the three lichens and only colonized plots exposed to ambient SO2(4 ppb). Diminutive thalli ofH. physodeswere relatively numerous in the ambient SO2, plots, much scarcer in those receiving low SO2(12 ppb) and rare in those with high SO2(20 ppbl. Coverage byL. conizaeoideswasverylow in the ambient SO2, plots but appreciable in the low and high SO2treatment plots. The results indicate directly beneficial effect of SO2onL. conizaeoidescolonization rather than an indirect benefit through competitor release. The O3treatment (1.3 times ambient during Spring‐Autumn) did not influence the abundance of the lichens. All three lichen species appeared to be more sensitive (positive and negative effects) to SO2, than mapping studies have suggested. Possible reasons for the high SO2‐sensitivity of the lichens are discussed. These include the high acidity of conifer bark and the fact that growth from diaspores and development of immature thalli is involved rather than survival of established populations.
Stomatal uptake of SO2, NOx and O3 by spruce crowns (Picea abies) and canopy damage in Central Europe
Authors: SLOVIK STEFAN , SIEGMUND ALFRED , FÜHRER HANS‐WERNER , HEBER ULRICH 
Published: April 2006

summaryThe stomatal uptake of SO2, NO2 and O3 by Norway spruce canopies (Picea abies (L.) Karst.) has been integrated at six sites in central Germany (Königstein in the Taunus mountains. Witzenhausen, Grebenau, Frankenberg, Fürth in the Odenwald mountains and Biebergemünd in the Spessart mountains), Results are based on 788000 half‐hourly available sets of field data on air pollution and site meteorology measured since 1984 (45 site years). Data on stomatal water conductance are available from statistical response functions obtained in the field at all times of day and seasons of the year. From this, stomatal conductance was calculated fur different atmospheric tract gases. Statistical response functions are presented which allow the separate estimation of annual stomatal net uptake of trace gases in the field if only (i) measured annual means of SO2, NO2, and O3, pollution and (ii) the length of the trunk growth period (defined by temperature) are known. The following specific annual doses of stomatal trace‐gas net uptake in the field (μmol m−2total needle surface d−1annual trunk growth period/(nPa Pa−1) annual mean of trace gas concentration) are obtained; SO2: (0.157 ± 0.011) μmol m−2d−1/(nPa SO2, Pa−1), NOx: (0.4774 ± 0.034) μmol m−2d−1/(nPa NO2 Pa−1), O3: (0.474 ± 0.034) μmol m−2d−1/(nPa O3 Pa−1). There is an apparent NO2, compensation point at 7 nPa Pa−1in the field if NOx (=NO2, + NO) fluxes are integrated; the individual NO2, compensation point equals c 3.2 nPa Pa−1. Additionally, a statistical response function is presented, which estimates actual stomatal water transpiration rates in the field on the basis of measured water vapour pressure differences. VPD (mPa Pa−1). Complex canopy effects were calculated on the basis of available data using an effective leaf area which is 0×32 times the morphological leaf area index. Results are consistent (i) with available water balance data, (ii) with observed SO2‐dependent sulphate accumulation rates in spruce needles and (iii) with observed epicuticular SO2, deposition rates. Pollution data are compared with observed damage of spruce canopies in the field. There was a statistically significant correlation between observed damage to spruce canopies.
Identification of pollen components regulating pollination‐specific responses in the stigmatic papillae of Brassica oleracea
Authors: ELLEMAN C. J. , DICKINSON H. G. 
Published: April 2006

summaryWhen components of the mature pollen grain of Brassica oleracea are applied to the cuticularised surfaces of the stigmatic papilla, a number of changes can take place in the architecture of the subjacent cell wall. Treatment of the papillar surface with isolated pollen coating evokes a rapid and extensive expansion of the outer of the two stigmatic wall layers. This response occurs within 4 h but is restricted to those regions where no callose is formed and where the coating exhibits a characteristic increase in electron opacity. This study establishes that the coating alone is responsible for initiating the expansion of the outer wall, which is considered to be an essential step preceding penetration of the stigma surface by the pollen tube. Vesicle‐like inclusions, some staining intensely, occasionally occur in regions of the wall expanded by isolated coating, sometimes fusing to form a subcuticular ‘boundary layer’. These structures are not observed under compatible grains in vivo and their presence is regarded as artefaetual. However, close examination of the plasma membrane at sites beneath areas of expanded cell wall reveals membrane‐bound structures resembling the vesicles being generated by the cytoplasm and moving into the apoplast. These data indicate that signals from the coating initiate the loosening of the wall matrix by stimulating an unusual form of localized secretion which appears to be an essential prerequisite for stigmatic penetration.Isolated pollen coating contaminated with fragments of the grain itself engender a very different response, including the formation of densely‐staining vesicles accompanied by extensive accumulations of callose; wall expansion never occurs under these circumstances. Self‐pollinations in B. oleracea are frequently accompanied by the synthesis of stigmatic callose, the presence of which has, in the past, been interpreted as forming a structural barrier to incompatible pollen tubes. However, callose elicited both by self‐pollinations and coating supplemented by killed grains is independent of protein synthesis and occurs in the presence of the phosphatase inhibitor, okadaic acid. Since both these inhibitors also overcome self‐incompatibility (SI) in B. oleracea, these data strongly suggest that callose synthesis is unrelated to the operation of SI, and it is proposed that callose, when formed, is elicited by molecules released from the necrotic pollen protoplast. Interestingly, isolated pollen coating of self‐ and cross‐genotypes does not readily elicit callose.The significance of these changes in the stigmatic wall is discussed in the perspective of current views on pollination and self‐incompatibility in Brassica.
The effects of dry O3, SO2 and NO2 on reconstituted epicuticular wax tubules
Authors: JETTER REINHARD , RIEDERER MARKUS , LENDZIAN KLAUS J. 
Published: April 2006

summaryEpicuticular wax tubules were reconstituted in vitro by recrystallizing nonacosan‐10‐ol from the soluble cuticular lipids of Picea pungens Engelm. on a glass support. Fumigation of these preparations for 100 h with dry O3 (1.8 %), SO2 (100%) or for 1500 h with NO2 (0.1 %) did not change their composition or crystal habit. Exposure of reconstituted wax tubules to 1 % of dry NO2 yielded planar crystals of nonacosan‐10‐one after 100 h. Further exposure (264 h) resulted in the complete degradation of aggregates and the formation of nonadecanoic and eicosanoic acids. The same oxidation steps and the accompanying changes of crystal shapes could be induced by fumigation of nonacosan‐10‐ol tubules with 100% of dry NO2 for 0.25–1 hand for 2 h, respectively. The oxidation of nonacosan‐10‐ol depended on the doses applied. At ambient concentrations, equivalent doses would accumulate only over thousands of years. Oxidative transformations alone can therefore not account for the in vivo degradation of wax tubules on conifer needles.
Variation in seed production and germinability in common reed (Phragmites australis) in Britain and France with respect to climate
Authors: McKEE JUNO , RICHARDS A. J. 
Published: April 2006

summaryNorthern populations of Phragmites australis (Cav.) Trin. ex Steud. (common reed) often flower so late that the ability to produce viable seeds before winter dieback can be limited. If climate changes as predicted, the reed may become able to set seed further north in its range. This would have implications for the ability of reed to colonize new sites as well as for the distribution of animals which eat reed seeds in winter.A survey of 34 British populations in 1993 and 1994 showed that seed production is highly variable between sites, ranging from 0 to 100%. Southern and western populations tended to show the highest seed sets, although some southern populations were infertile and some northern sites set seed. Average seed weight tended to be higher in sites which showed good seed set. Seeds from sites with high average seed weight tended to germinate more readily.The seed‐setting capability of populations was successfully associated with climatic conditions at the time of flowering. However, seed weight was not found to relate to climate, but depended on seed production and overall plant height. Logistic regression modelling indicated that the best seed sets should occur in P. australis when: (i) August rainfall is low; (ii) the combined rainfalls of September and October are high; and (iii) the combined temperatures of these months are high. The model accounts for approximately one third of the variation in observed seed sets between sites, indicating that other, unmeasured, factors might also play a part in determining seed set in P. australis.At three northern populations which were studied in more detail, a number of genotypes coexisted, and legitimate pollen germination and pollen‐tube growth was observed in each case. As no seed set occurred in two of these, self‐incompatibility cannot explain poor seed setting.
The differential effects of cell wall‐associated phenolics, cell walls, and cytosolic phenolics of host and non‐host roots on the growth of two species of AM fungi
Authors: DOUDS D. D. , NAGAHASHI G. , ABNEY G. D. 
Published: April 2006

summaryExperiments were conducted to test the hypothesis that cellular compounds, especially wall‐associated compounds, released during emergence of secondary roots, stimulate the growth of arbuscular mycorrhizal (AM) fungi. Purified cell walls, crude cell‐wall extracts, crude cytoplasmic extracts, and phenolic compounds previously identified as cell wall‐associated, from Ri T‐DNA‐transformed roots of host (Daucus carota L.) and non‐host (Beta vulgaris L.) were incorporated into growth medium and tested for their effects upon growth of the AM fungi Gigaspora gigantea (Nicol. & Gerd.) Gerdemann and Trappe and Gigaspora margarita Becker and Hall. Purified cell walls of both plants had little effect on G. gigantea but non‐host cell walls inhibited the growth of G. margarita. Ferulic acid, a major constituent of non‐host root, depressed the growth of both fungi. Nothing tested which was unique to the non‐host root affected hyphal growth to the point that contact would be prohibited. Caffeic acid, found in D. carota cytoplasm, also depressed growth of both fungi. Para‐hydroxybenzoic acid, a constituent of D. carota roots, stimulated growth of G. margarita hyphae, but did not affect hyphal growth of G. gigantea. Vanillic acid, unique to D. carota root cell‐wall extracts, stimulated hyphal growth and branching of both fungi, and should increase the probability of contact between fungus and host root.