bluuebunny/crossref_metadata_2025_split huggingface dataset:
Do Striga hermonthica‐induced changes in soil matric potential cause the reduction in stomatal conductance and growth of infected maize plants?
Authors: TAYLOR A. , SEEL W. E. 
Published: March 2003

Maize (Zea mays L.) plants parasitized by the root hemi‐parasitic angiosperm, Striga hermonthica (Del.) Benth., consistently display a range of symptoms similar to those found in droughted plants. The mechanisms by which these changes occur are largely unknown. However, S. hermonthica has unusually high rates of transpiration, and stomata which are relatively insensitive to water deficit. Consequently, it has often been suggested that the parasite might cause a severe depletion of the available water in the host's rooting zone. To determine whether the lower stomatal conductance and retarded growth of infected plants could be a result of parasite‐induced water deficit, we have monitored the matric potential of the growth medium, water use, growth and stomatal conductance of infected vs. uninfected maize plants.Host plant height and stomatal conductance of parasitized plants were significantly lower than those of control plants from 31 or 37 d after planting (d.a.p.) respectively. However, there was no indication of an increase in the rate of water depletion in the rooting zone of infected plants until approx. 63 d into the parasitic association. In fact, from 39 until 59 d.a.p. infected plants used less water than uninfected control plants, probably the result of the plants having fewer expanded leaves during part of this period, combined with the lower stomatal conductance exhibited by the infected plants from day 37 onwards. Leaf RWC of infected plants was unchanged in comparison with that of uninfected plants, therefore the change in stomatal conductance was not a response to dehydration of the leaf tissue. Our results indicate that parasitism by S. hermonthica does not cause an increase in water uptake/use in the host until well after most of the symptoms of infection have become fully established. It is highly unlikely, therefore, that the observed effects on the host are primarily due to soil water deficit.
Impacts of increased nitrogen supply on high Arctic heath: the importance of bryophytes and phosphorus availability
Authors: Gordon C. , Wynn J. M. , Woodin S. J. 
Published: March 2003

Summary

• This study investigates effects of nitrogen and phosphorus on high Arctic heath vegetation, particularly bryophytes.

• Heath communities received factorial combinations of nitrogen (0, 10 and 50 kg ha−1 yr−1) and phosphorus (0 and 5 kg ha−1 yr−1) in five applications per growing season, for 8 yr.

• Nitrogen decreased lichen cover but did not affect cover of any other functional type. However, just 10 kg ha−1 yr−1 increased the proportion of physiologically active bryophte shoots, and decreased their nitrate assimilation capacity. Phosphorus had greater effects, and the combination of both nutrients altered species composition. Individual bryophyte species displayed contrasting responses to fertilization, suggesting that they should not be grouped as a single functional type.

• The ‘critical load’ of nitrogen for Arctic heath lies below 10 kg ha−1 yr−1. Nitrogen and phosphorus are colimiting in this sytem, so the critical load of nitrogen will be lower where phosphorus availability is greater. Responses of vegetation to any increase in net mineralisation due to soil warming will depend on the ratio in which nitrogen and phosphorus availabilities increase. The effects of nutrient enhancement are very persistent.
Nutrient economy of red pine is affected by interactions between Pisolithus tinctorius and other forest‐floor microbes
Authors: Koide Roger T. , Kabir Zahangir 
Published: March 2003

Summary

The influence of interactions between the mycorrhizal fungus, Pisolithus tinctorius
, and saprotrophic organisms on nutrient transfer to host red pine (
Pinus resinosa ) seedlings is presented here.
Red pine seedlings were grown axenically, and with P. tinctorius and forest‐floor microbes (both individually and in combination), in two experiments varying in nitrogen availability. Root and shoot growth, as well as tissue nitrogen and phosphorus content, were analyzed after harvesting.
At low nitrogen availability, forest‐floor microbes, but not P. tinctorius
, significantly reduced seedling nitrogen content. Moreover,
P. tinctorius
did not ameliorate this negative effect. However, seedling phosphorus content increased with forest‐floor microbes and
P. tinctorius
individually, and these combined to give an additive effect. Forest‐floor microbes and
P. tinctorius , individually, significantly increased seedling nitrogen and phosphorus contents at high nitrogen availability, interacting to give additive and synergistic effects on nitrogen and phosphorus content, respectively.
The effect of ectomycorrhizal fungi on host‐plant nutrition might depend strongly on the nutrient status of coexisting saprotrophic soil microbes. When nutrients are not limiting, their beneficial effects on host nutrition may be additive or synergistic.
Intracellular calcium oxalate crystal structure in Dracaena sanderiana
Authors: Pennisi Svoboda V. , McConnell Dennis B. , Gower Laurie B. , Kane Michael E. , Lucansky T. 
Published: March 2003

Summary

• The chemistry, crystallography and ultrastructure of intracellular calcium oxalate deposits in the angiosperm, Dracaena sanderiana are reported here.
• Crystalline deposits extracted from mature leaves and leaf primordia of D. sanderiana were studied by scanning electron microscopy and X‐ray powder diffractometry techniques, and compared with X‐ray standards for calcium monohydrate and calcium oxalate dihydrate.
• Intracellular calcium oxalate deposits were of two types; calcium oxalate monohydrate raphides or solitary calcium oxalate dihydrate crystals. Raphide‐containing cells exhibited lamellate sheaths around the chamber walls, mucilage‐like materials surrounding the developing crystal chambers, and paracrystalline bodies with closely spaced subunits within the chambers. The intracellular calcium oxalate dihydrate crystals usually displayed typical tetragonal‐dipyramidal morphology, but development of some unusual crystal faces occasionally occurred.
• Two intracellular hydrate forms of calcium oxalate (monohydrate and dihydrate) exist in D. sanderiana. The elaboration of crystal vacuoles derived from rough endoplasmic reticulum and modified crystals with energetically unfavourable faces suggest that precipitation of calcium oxalate dihydrate in D. sanderiana cells might be biologically controlled.
Ectomycorrhizal protection of Pinus sylvestris against copper toxicity
Authors: Van Tichelen Katia K. , Colpaert Jan V. , Vangronsveld Jaco 
Published: March 2003

Summary

Change in the copper (Cu) sensitivity of Pinus sylvestris
is presented, in response to the ectomycorrhizal fungi,
Suillus bovinus
and
Thelephora terrestris , common mycobionts on metal contaminated sites.
Seedlings grown under phosphorus (P) limitation were exposed to a range of Cu concentrations. Plant and fungal development, P nutrition, sorption of Cu on roots and external mycelia as well as transfer of Cu to shoots were assessed.
Root growth and P nutrition were severely inhibited in nonmycorrhizal pines at elevated Cu compared with mycorrhizal plants. Excess Cu had little effect on the development of mycorrhizal roots and mycelia. Thelephora terrestris
was less sensitive to Cu stress than
S. bovinus
. The extraradical mycelium of
S. bovinus
retained large amounts of Cu. However, binding of Cu in fungal tissue was not a prerequisite for low Cu sensitivity since
T. terrestris
absorbed considerably less Cu that
S. bovinus .
Both ectomycorrhizal fungi protect P. sylvestris against Cu toxicity; a benefit that was not due to a metal dilution effect. The mechanisms of mycorrhizal amelioration of Cu toxicity are probably diverse and species‐dependent.
Elevated CO2 increases sorghum biomass under drought conditions
Authors: Ottman M. J. , Kimball B. A. , Pinter P. J. , Wall G. W. , Vanderlip R. L. , Leavitt S. W. , LaMorte R. L. , Matthias A. D. , Brooks T. J. 
Published: March 2003

Summary

Atmospheric CO2 concentration is expected to increase by 50% near the middle of this century. The effects the free air CO2 enrichment (FACE) is presented here on growth and development of field‐grown grain sorghum (Sorghum bicolor) at ample (wet) and limiting (dry) levels of irrigation water at Maricopa, AZ, USA.
Daytime CO2 mole fractions were 561 and 368 µmol mol−1 for the FACE and control treatments, respectively. Irrigation plus precipitation averaged 1132 mm for the wet plots and 396 mm in the dry plots.
During the growing season, FACE increased biomass accumulation in the dry plots but the effects in the wet plots were inconsistent. At final harvest, FACE increased total yield from 999 to 1151 g m−2 in the dry plots and had no effect in the wet plots.
If atmospheric CO2 continues to increase, total sorghum yield is likely to be higher in the future in areas where water is limited.
Influence of coumarin on the net nitrate uptake in durum wheat
Authors: Abenavoli M. R. , De Santis C. , Sidari M. , Sorgonà A. , Badiani M. , Cacco G. 
Published: March 2003

Summary

The effects are reported here of coumarin, an allelopathic compound, on root anatomy and growth, nitrate uptake and translocation to the shoot, as well as respiration in Triticum durum (cv. Simeto) seedlings.
Wheat seedlings were grown in nitrogen‐free hydroponic culture; after 6 d, coumarin (at concentrations of 0, 25 µM, 0.1, 1, 2.5 and 5 mM) and/or nitrate (50 µM) were added to the nutrient solution.
Coumarin, in the range 25 µM–1 mM, decreased the relative growth rate of roots and increased the area of the root vessels. Within this concentration range, coumarin alone did not significantly affect net nitrate uptake. In seedlings exposed simultaneously to 100 µM coumarin and to 50 µM nitrate, the net nitrate uptake was significantly stimulated. In the presence of nitrate, even the lowest coumarin concentration tested significantly stimulated nitrate translocation from the root to the shoot.
The effects of low coumarin concentrations on root vessel size could explain this observation, though specific interactions between coumarin and systems regulating nitrate uptake and transport within the root cell cannot be excluded.
Signalling in the cereal aleurone: hormones, reactive oxygen and cell death
Authors: Fath Angelika , Bethke Paul C. , Belligni Maria V. , Spiegel Yoav N. , Jones Russell L. 
Published: March 2003

SummaryThe cereal aleurone is widely used as a model system to study hormonal signalling. Abscisic acid (ABA) and gibberellins (GAs) elicit distinct responses in aleurone cells, ranging from those occurring within minutes of hormone addition to those that require several hours or days to complete. Programmed cell death is an example of a response in aleurone layers that is hormonally regulated. GAs promote cell death and cells in intact aleurone layers begin to die 24 h after GA treatment, whereas cell death of aleurone protoplasts begins 4 d after GA treatment. ABA prevents aleurone cell death and addition of ABA to cells pretreated with GA can delay cell death. Aleurone cells do not follow the apoptotic route of programmed cell death. Cells treated with GA, but not ABA, develop large, acidic vacuoles containing a spectrum of hydrolases typical of lytic compartments. Enzymes that metabolize reactive oxygen species are also present in aleurone cells, but ascorbate peroxidase, catalase and superoxide dismutase become less abundant after treatment with GA; activity of these enzymes increases or remains unchanged in ABA‐treated cells. We propose a model whereby reactive oxygen species accumulate in GA‐treated cells and lead to peroxidation of membrane lipids and plasma membrane rupture.AbbreviationsRO, reactive oxygen species; HR, hypersensitive response; PSV, protein storage vacuole; PCD, programmed cell death; CAT, catalase; SOD, superoxide dismutase; APX, ascorbate peroxidase.
Phenology of roots and mycorrhiza in orchid species differing in phototrophic strategy
Authors: Rasmussen Hanne N. , Whigham Dennis F. 
Published: March 2003

Summary• The mycorrhiza of orchids represents an energy source that may replace or supplement photosynthesis. Dependency on mycotrophy in adult life stages would thus be expected to be inversely related to the prevalence of phototrophic structures.• The phenology of underground parts and mycorrhizal infection were monitored in five terrestrial species differing in leaf phenology (and thus in phototrophic strategy): Goodyera pubescens (evergreen), Tipularia discolor (wintergreen), Galearis spectabilis and Liparis lilifolia (summergreen) and Corallorhiza odontorhiza (chlorophyll deficient), growing sympatrically in a North American deciduous forest.• Mycorrhizal infection was extensive in T. discolor roots and C. odontorhiza rhizomes. Only the proximal part of roots was infected in G. pubescens, and mycorrhizal colonisation was patchy in roots and tubers of G. spectabilis and localized in the rhizome in L. lilifolia. Mycotrophic roots were long‐lived (1.5–3 yrs) determinate structures and mycorrhizal infection reached maximum intensity 2–6 months after development. Mycotrophy appeared to be active all year round in mature organs.• The phenology of mycotrophic roots and patterns of mycorrhizal infection were not related to the leafy season. The hypothesis that phototrophic and mycotrophic nutrition alternate through the seasons could not be confirmed.
Are xylem radial development and hydraulic conductivity in downwardly‐growing grapevine shoots influenced by perturbed auxin metabolism?
Authors: Lovisolo Claudio , Schubert Andrea , Sorce Carlo 
Published: March 2003

Summary

Downwardly‐growing grapevine shoots have smaller and more frequent vessels than upwardly‐growing ones and, as a consequence, a lower hydraulic conductivity. Here, grapevine ( Vitis vinifera L.) shoot growth orientation was manipulated to test whether downward shoot orientation negatively affects vessel growth in the apex via a shortage of water and nutrients.
The orientation of the central vine shoot portion was inverted by two consecutive 135° bends, resulting in double‐bent N‐shaped vines; the central downward shoot portion was of different lengths in the experimental treatments to induce increasing reductions of shoot conductivity. These treatments reduced shoot conductivity and water flow, but had no effects on vessel development and frequency in the apex.
In a second experiment, auxin concentration was assessed in shoots of upwardly‐ and downwardly‐growing plants. IAA concentration at the apical internodes was higher in downwardly‐oriented shoots than in shoots growing upwards. In addition, a higher density and a lower vessel diameter were observed in the lower, than the upper side, of the downwardly‐oriented shoot, suggesting increased accumulation of auxin in the lower side.
These results suggest that the downward orientation induces accumulation of auxin in the apex, which in turn affects the density and the size of the xylem vessels, causing reduction of hydraulic conductivity.
Plant growth and competition at elevated CO2: on winners, losers and functional groups
Authors: Poorter Hendrik , Navas Marie‐Laure 
Published: March 2003

SummaryThe effects of increased atmospheric CO2 concentrations on vegetative growth and competitive performance were evaluated, using five meta‐analyses. Paying special attention to functional groups, we analysed responses at three integration levels: carbon economy parameters, vegetative biomass of isolated plants, and growth in competition. CO2 effects on seed biomass and plant‐to‐plant variability were also studied. Underlying the growth stimulation is an increased unit leaf rate (ULR), especially for herbaceous dicots. This is mainly caused by an increase in the whole‐plant rate of photosynthesis. The increased ULR is accompanied by a decrease in specific leaf area. The net result of these and other changes is that relative growth rate is only marginally stimulated. The biomass enhancement ratio (BER) of individually grown plants varies substantially across experiments/species, and size variability in the experimental populations is a vital factor in this. Fast‐growing herbaceous C3 species respond more strongly than slow‐growing C3 herbs or C4 plants. CAM species and woody plants show intermediate responses. When grown in competition, C4 species show lowest responses to elevated CO2 at high nutrient conditions, whereas at low nutrient levels N2‐fixing dicots respond relatively strongly. No systematic differences were found between slow‐ and fast‐growing species. BER values obtained for isolated plants cannot be used to estimate BER of the same species grown in interspecific competition – the CO2 response of monocultures may be a better predictor.

Contents

Summary
175

I.
Introduction
176

II.
Materials and Methods
177

III.
Factors underlying the growth response
178

IV.
Variation in biomass enhancement ratio
181

V.
Functional groups of species
184

VI.
The response in a more natural environment
188

VII.
An outlook
192

VIII.
Conclusions
193

Acknowledgements
193

References
193

Appendices
196
Comparative analysis of Canadian, American and Swedish bankruptcy policy: why do governments legislate consumer debt?
Authors: McGregor Sue , Klingander Birgitta , Lown Jean 
Published: March 2003

AbstractComparative research in consumer bankruptcy law is scarce. After profiling bankruptcy statistics in each country, the paper compares bankruptcy laws in Canada, United States and Sweden across 20 criteria and then analyses the predominate ideology underlying each law: deviant behaviour modification, consumer protection or social safety net. There is obvious tension between ideologies in each country with the punitive, deviant behaviour modification paradigm the most pervasive across all three countries. There is much we can learn from a comparative policy analysis approach, leading to the conscious development of bankruptcy policy from discernible, declared ideologies. Seven areas for future research are proposed.
Consumer education: educational considerations and perspectives
Authors: Benn Jette 
Published: March 2003

AbstractThis paper examines questions concerning consumer education in relation to consumption and household management. It is based partly on literature studies and partly on a current pilot study, also on studies carried out in the classroom and developmental work in schools and on teacher training courses. The pilot study on consumer education is being carried out in Denmark and is funded by the Danish Ministry of Business Affairs. Another part of the study concerns a qualitative investigation of pupils’ understandings of consumption and its meaning in their lives, but this is not reported here. The key research questions relate to the way in which the young consumer is educated, both formally and informally, and what the possibilities and perspectives are for consumer education. Introductory research is discussed, followed by a presentation and discussion of key issues for consumer education, such as household management, consumption, home economics and education. Finally, three examples are described and discussed which demonstrate how the advocated principles of consumer education and empowerment can be put into practice. These examples are based on developmental work carried out in lower secondary schools and teacher training courses.
Foods produced using biotechnology: how does the law protect consumers?
Authors: Emirogˇlu Haluk 
Published: March 2003

AbstractThis paper addresses the following subjects: biotechnology and consumers, concern about risks, consumer acceptance, labelling of foods produced using biotechnology, the legal approach to consumer protection, and consumer protection policies relating to biotechnology products in the European Union, the United States, Turkey and global institutions such as the Convention for Biological Diversity (CBD) and the World Trade Organisation (WTO). It is likely that biotechnology will gain ground much more rapidly in the twenty‐first century than in the past. Despite rapid, detailed and precise advances in gene technology, its applications have not been the received with a great deal of consumer enthusiasm. Consumers have approached genetically modified foods with considerable apprehension and opposition. Consumer concerns about bioengineered food products focus on the questions of human health, environmental and social risks and benefits. The most important stages in the process of marketing new foods produced using biotechnology are to demonstrate user need and consumer acceptance. Generally, the technical complexity of biotechnology makes it difficult for consumers to understand details of the product and the specific attributes of biotechnology applications. Scientific uncertainty, the nature of consumer concerns and general reluctance to accept biotechnology products, increase the importance of consumer protection. Legal protection is a very important factor in the solution of new social problems related to technological advances. More specifically, consumer and environmental law support consumer protection related to foods produced with biotechnology. The basic principles of consumer law can be re‐formulated as consumer rights. Environmental law is a new phenomenon, but precautionary principles and public participation in decision‐making for environmental law are relevant to consumer protection relating to bioengineered food products.
Home economists’ perceptions of international development
Authors: McGregor Sue L.T. 
Published: March 2003

AbstractLittle is known about home economists’ perceptions of international development (ID). This paper offers some insights about this issue gained from an interpretative, thematic analysis of a very small sample of participants who attended the 1996 International Federation of Home Economics Congress. The analysis suggests inconsistencies in how home economists understand ID and what is seen to constitute ID activities, a lack of consensus about the meaning of development work, a lack of certainty about the difference between criticism and critique and concern for the imposition of western ideology on southern countries. Seven themes for future research are offered to help gain a better understanding of how home economists perceive ID including: (1) the role of participatory action research, critical theory, science and critical reflective practice in ID; (2) meanings attached to the concepts of international, development and economic growth; (3) the necessity of positioning an ID philosophy in practice, curricula, research and policy; and (4) perceptions of what constitutes development activities at home and abroad.
Adolescents’ brand sensitivity in apparel: influence of three socialization agents
Authors: Lachance Marie J. , Beaudoin Pierre , Robitaille Jean 
Published: March 2003

AbstractWearing clothes with prestigious brand names seems to be very important for adolescents. This phenomenon was studied in the context of consumer socialization by examining the influence of three socialization agents, namely parents, peers and TV, on the development of French Canadian adolescents’ brand sensitivity and their relative importance. Controlling for socio‐economic variables, multiple regression analyses were conducted separately for boys and for girls. For both genders, brand sensitivity is related to peer influence. Girls’ brand sensitivity is related to the importance fathers give to clothing brands. TV exposure is not related to adolescents’ brand sensitivity. For boys and girls, peers represent the most important predictor of this consumer socialization. The results are discussed in the light of social and economic pressures and family relationships.