bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recovery of kiwifruit vines from transient waterlogging of the root system
Authors: SMITH G. S. , JUDD M. J. , MILLER S. A. , BUWALDA J. G. 
Published: April 2006

summaryThe extent to which kiwifruit vines (Actinidia deliciosa var. deliciosa) recovered from transient waterlogging of the root system was determined under controlled conditions. Vines were waterlogged for periods varying from 1 to 7 days. The effects of decreasing concentrations of oxygen in the root zone on growth of the vine were rapid with substantial reductions occurring after being exposed to oxygen concentrations in the surrounding water of less than 0.125 mmol l1for as little as 1 day. There was no evidence of recovery of growth once aeration was restored to the roots, except for the appearance of new roots at the base of the stems of vines that had been waterlogged for less than 5 days. The quantity of new roots grown was inversely related to the time of waterlogging. Although new roots were also found on the control vines, the quantities involved were very much less than for the vines stressed for up to 4 days. No new roots were found for vines waterlogged for more than 4 days.The substantial loss of dry weight of roots of vines waterlogged for more than 3 days was due in part to a lack of growth and to a physical loss of root tissue. The loss of tissue resulted from the detachment of the cortex from the central stele through the dissolution of an entire layer of cortical cells which, in the control vines, were filled with starch. A microscopic examination of the cells of the root from waterlogged vines showed the cortical cells to be generally distorted with much of the intercellular material missing.The closure of the stomata within 2–3 h of the roots being waterlogged and the rapid desiccation of the leaves that followed the closure, was consistent with earlier findings with kiwifruit vines. Some recovery of stomata activity occurred for vines that had been waterlogged for less than 4 days once the oxygen supply to the root was restored. For vines that had their roots submerged for only 1 day, stomatal activity was fully restored 3 days after the vines were removed from the water. In contrast, there was no recovery of stomatal activity for vines that had been waterlogged for more than 3 days.A feature of stomatal behaviour that was not related to the effects of oxygen stress was the cyclic pattern which developed. Each cycle repeated itself every 4–6 days and consisted of a period of high stomatal conductance followed by a sharp decline to a much lower level. A highly significant negative relationship was found between the level of photosynthetically active radiation and stomatal behaviour.It was concluded that the speed with which the roots die and the associated damage to the leaves under anoxic conditions greatly limits the ability of kiwifruit vines to resume growth once oxygen supply to the root has been restored.
Long‐term exposure of Norway spruce,Picea abies(L.) Karst., to ozone in open top chambers
Authors: SUTINEN S. , SKÄRBY L. , WALLIN G. , SELLDÉN G. 
Published: April 2006

summaryOne clone of spruce,Picea abies(L.) Karst., was exposed to different concentrations of ozone in open‐top chambers for three seasons. The treatments were filtered air (CF), non‐filtered air (NF) and non‐filtered air + ozone (NF+). Changes in ultrastructure occurring in the 1985 flush of needles were followed for three years. Ultrastructural changes due to ozone first occurred in the chloroplasts. A decrease in length of the chloroplasts, an increase of the density of the stroma, an accumulation of ribosome‐like granules and a decrease in the size of starch grains, were observed. The second organelle to be affected was the microbody and the last the mitochondria. At this later stage the cytoplasm had also disintegrated. Structural changes always appeared first in the outer cell layer facing the sky. The changes then gradually advanced in the tissue towards the lower part of the needle. In the NF+ treatment changes were observed at the first sampling event in November, 1 month after the end of the first exposure period. At this time the needles were about 6 months old. In the NF treatment the same changes appeared when the needles were about 14 months old. No changes were observed in the CF treatment. Changes of the same type as those observed in the mesophyll tissue were also seen in stomatal and endodermal cells. In albuminous cells a general breakdown of the organelles was observed.
The effects of long‐term open‐air fumigation with SO2 on a field crop of broad bean (Vicia faba L.)
Authors: KROPFF M. J. 
Published: April 2006

summaryEffects of SO2 on growth and production of broad bean, observed in three open‐air fumigation experiments, were interpreted in terms of damage components with a mechanistic simulation model. The model consisted of an elementary model for crop growth, extended with submodels for the microclimate in the crop and with a submodel for uptake of SO2 by leaves and for effects on leaf photosynthesis.The major part of the observed reduction in total dry matter production could be explained by leaf injury observed in the oldest leaves of the fumigated plants at the end of the growing period. The effect consisted of dry matter loss through leaf abscission and a reduced growth rate at the end of the growth period due to reduction of the amount of absorbed radiation by the canopy. Direct effects of SO2 on leaf photosynthesis explained an extra 10% of the observed yield loss (losses ranged from 7 to 17% of control yield). This small effect was confirmed by field measurements which showed no detectable effects of SO2 on leaf and canopy photosynthesis. Increased leaf respiration, which was observed in the 1988 experiment, explained another 10% of the observed yield reduction.Total SO2‐sulphur uptake by the fumigated crop, which is an important component of dry deposition of SO2, was accurately simulated by the model.
Anther dehiscence in Lycopersicon esculentum
Authors: BONNER LYNDA J. , DICKINSON H. G. 
Published: April 2006

summaryWater tracers have been used to demonstrate the continued functioning of the anther filament during dehiscence in Lycopersicon esculentum Mill. Since Lycopersicon possesses neither nectar nor nectaries dehiscence cannot be related to sugar secretion, as has been demonstrated for other plants. The anthers seem structurally adapted for water conservation and the only transpirational loss of the flower appears to be through the petals. Transpiration from the anthers themselves thus appears not to be involved in regulating dehiscence. Anther opening is preceded by dehydration of the locule and circumstantial evidence indicates it to be an active process, with water being exported through the filaments to the petals along an osmotic gradient generated by starch/sugar interconversion. Measurement of water potential differentials between the petals and anthers points to the mechanism driving this export of water from the anthers. Interestingly, turgor pressure is maintained in the majority of the anther tissues until senescence, remaining remarkably constant against a background of dramatic changes in osmotic potential. These data, combined with the observation that the hydration level of the anthers falls only to 70% at senescence, indicates that dehiscence cannot primarily be a desiccatory process. Some domains within the anther do desiccate, but these are strictly localized. Thus, while hydration levels of living tissues remain independent of the environment, those observed to undergo protoplast degeneration and wall collapse exhibit environmentally‐linked hygroscopic absorption. Dehiscence thus emerges as an orchestrated programme of structural and physiological events leading to the desiccation of specific domains of the anthers. These findings are discussed in terms of current models for anther dehiscence in flowering plants.
Recent landscape history from a Co. Down lake deposit
Authors: HALL VALERIE A. 
Published: April 2006

summaryA radiocarbon‐dated pollen diagram from a lake deposit at a lowland site in Co. Down, Northern Ireland showed mixed agriculture had been continuous over much of the last two millennia. The introduction of cereal cultivation at between the 3rd and 5th centuries A.D. is earlier than usual at sites with heavy soils in Ireland. There was no palynological evidence to support the historical view that there had been substantial woodland clearance in the area during the 17th century. Landscape enclosure by hedges, starting in the 18th century, was detectable in the fossil pollen record. The pollen evidence for flax cultivation showed that this was relatively recent. Throughout the diagram the continual presence of Ulmus pollen demonstrated that, in contradiction of the historic view, the taxon was extant in the area throughout the period A.D. 600 to A.D. 1700.
Tansley Review No. 24 Why are atmospheric oxides of nitrogen usually phytotoxic and not alternative fertilizers?
Authors: WELLBURN ALAN R. 
Published: April 2006

SUMMARYAtmospheric pollution by the oxides of nitrogen, NO and NO2, can cause reductions in growth but rarely visible injury. This review considers their uptake into foliage, as well as their subsequent metabolism and physiology, and attempts to explain why these gases are often phytotoxic. The combined stresses of resisting cellular acidification, enhanced levels of nitrite (and ammonia), and the direct interference of the free radical ('N=O) with critical enzymes, reaction centres and regulatory mechanisms are thought to be the main reasons why oxides of nitrogen, especially NO, inhibit growth. If other air pollutants such as SO2are also present with NO or NO2then free radical‐induced injury, similar to that caused by O3alone, also occurs.CONTENTSSummary395I.Introduction396II.Uptake and cycling of oxides of nitrogen396III.Biochemical responses to NO and NO2405IV.Physiological responses to NO and NO2410V.Combinations of NO and NO2with other pollutants416VI.Recapitulation and beyond418Acknowledgements420References420
Seasonal changes in antioxidants in red spruce as affected by ozone
Authors: HAUSLADEN A. , MADAMANCHI N. R. , FELLOWS S. , ALSCHER R. G. , AMUNDSON R. G. 
Published: April 2006

SUMMARYTwo‐year‐old red spruce (Picea rubens Sarg.) seedlings were exposed to various levels of ozone, from 0.4 to 3 times ambient levels, in open‐top chambers in Ithaca, NY, USA. Exposures, which varied with changes in day length, were from 30 May to 16 December 1987 and 1 June to 1 December, 1988. During the second exposure period, ascorbic acid, total and oxidized glutathione, α‐tocopherol, and superoxide dismutase were measured in current and previous year's needles at monthly intervals from May to July, and at bi‐weekly intervals from September to December. Orthogonalized polynomials were used to model the response through time of each variable measured. A one‐way analysis of variance model was fitted to every regression coefficient in each polynomial model to test for ozone effects on seasonal patterns of antioxidant levels. Ozone influenced seasonal changes in total glutathione, the oxidized/total glutathione ratio, and α‐tocopherol in previous years's needles and α‐tocopherol and superoxide dismutase in current year's needles. Averaged over the whole growing season, the oxidized/total glutathione ratio and superoxide dismutase showed an ozone treatment effect in both age classes. Mean total glutathione content increased in previous year's needles, but was not influenced by ozone in current year's needles. Mean oxidized glutathione content was higher with ozone exposure in current year's needles, but not in previous year's needles. The role of antioxidants in cold hardiness and ozone detoxification is discussed.
The influence of acid mists on growth, dry matter partitioning, nutrient concentrations and mycorrhizal fruiting bodies in red spruce seedlings
Authors: DEANS J. D. , LEITH I. D. , SHEPPARD L. J. , CAPE J. N. , FOWLER D. , MURRAY M. B. , MASON P. A. 
Published: April 2006

SUMMARYTwo‐year‐old spruce (Picea rubens Sarg.) seedlings were exposed to acid mists containing equimolar ammonium sulphate and nitric acid giving treatments of pH 2.5, 3.0 and 5.0. Acid mist treatments were applied twice weekly from late July until early October, 1987, when the plants were harvested.There were no significant differences in biomass accumulation or in height growth between treatments, but marked differences in root morphology were found. Significantly larger amounts of coarse roots were produced in the pH 5.0 acid mist treatment and plants in the pH 3.0 treatment produced significantly greater amounts of fine roots. Plants receiving acid mists of pH 3.0 or less had a greater frequency of fine root branches along their coarse roots. Production of mycorrhizal fruiting bodies of Thelephora terrestris Ehrenb.: Fr. was significantly greater (P < 0.001) at pH 5.0 than in the other treatments.Plants in the pH 2.5 and 3.0 treatments contained larger concentrations of N, 1.54 and 1.12% and S, 0.52 and 0.28% respectively, than those receiving acid mist at pH 5.0, i.e. 1.00 and 0.21% respectively. However, the between treatment differences of tissue nutrient concentrations were small relative to the differences in inputs between treatments. Foliar S exceeded concentrations recommended for nursery stock by 50 and 150% at pH 3.0 and 2.5 respectively.
Effects of sulphur dioxide fumigation on Phleum pratense and vesicular‐arbuscular mycorrhizal fungi
Authors: CLAPPERTON M. JILL , REID DAVID M. , PARKINSON DENNIS 
Published: April 2006

SUMMARYTwo experiments were conducted using controlled environment SO2 fumigation chambers which allowed only the shoots of Phleum pratense to be fumigated. Experiment 1 examined the effect of SO2 fumigation on the ability of vesicular‐arbuscular (VA) mycorrhizal fungi to infect roots. Experiment 2 examined the effect of SO2 fumigation on the proliferation of VA mycorrhizas in the roots. There was a significant decrease in the amount of infection in the roots of plants exposed to SO2. Low concentrations (0.05‐0.07 μ 1−1) of SO2 affected the ability of VA mycorrhizal fungi to colonize and, also, to proliferate within roots. In both experiments, root colonization was the overriding factor affecting the number of tillers, leaf area, and shoot and root dry weights of infected plants. Increased VA mycorrhizal infection resulted in reductions in the plant growth parameters.
Population structure and dynamics in Suillus bovinus as indicated by spatial distribution of fungal clones
Authors: DAHLBERG ANDERS , STENLID JAN 
Published: April 2006

SUMMARYThe spatial distribution of clones in the ectomycorrhizal fungus Suillus bovinus (L. ex Fr.) O. Kuntze was studied from somatic incompatibility pairings of isolates in four Scots pine (Pinus sylvestris L.) stands with different forest history. A pattern of increasing clonal size, decreasing clonal number, and decreasing fruiting per unit area, was found with increased forest age and relatively little disturbance. Establishment by spores was important on disturbed sites, while mycelial spread increased in importance with decreased disturbance. The number of clones was found to be 800 ha−1 in younger forest stands and decreased to between 25–130 ha−1 in mature stands. At the same time the diameter of the area occupied by a single clone increased from 1–3 m to 30 m. Implications of the observations are discussed in terms of ecological strategies and population dynamics.
Drought acclimation and the morphology of mycorrhizal Rosa hybrida L. cv. ‘Ferdy’ is independent of leaf elemental content
Authors: HENDERSON JANET C. , DAVIES FRED T. 
Published: April 2006

SUMMARY Rosa hybrida L. cv. ‘Ferdy’ is a low maintenance landscape plant which is considered drought resistant. To determine the effects of endomycorrhizae on plant water relations and growth, rooted cuttings of uniform size were established in containers under moderately high P fertilization. Vesicular‐arbuscular (VA) mycorrhiza inoculated and noninoculated plants were placed under three water regimes: drought acclimated, non‐acclimated and later exposed to drought, or non‐stressed. Acclimated plants were conditioned by four 3‐d and three 4‐d drought cycles. Non‐acclimated plants received water daily prior to a single 4‐d drought cycles, and non‐stressed plants were watered daily throughout the study. Under water deficits, non‐acclimated plants had lower leaf water potentials (ΨL), transpiration rates (E) and stomatal conductances (g), than acclimated or non‐stressed plants. Non‐acclimated plants also had a greater leaf area, leaf number and shoot dry weight than acclimated plants, yet had a comparable leaf area ratio (LAR) and root‐shoot ratio. Mycorrhizal plants had a higher E, than non‐mycorrhizal plants, even though non‐mycorrhizal plants were of comparable biomass (leaf area, shoot and root dry weight and LAR). However, the root‐shoot ratio was greater with mycorrhizal plants which had fewer leaves (due to abscission), and lower cuticle and epicuticular wax weights than non‐mycorrhizal plants. There was no affect of VA mycorrhiza on leaf osmotic potential (Ψn) stomatal density, leaf cell density, leaf area, or macronutrient uptake. Acclimation of this low‐maintenance landscape rose cultivar to water deficits and the mechanism of drought avoidance via leaf abscission, were as beneficial to drought resistance as was mycorrhizal symbiosis.
Fine veins of dicotyledon leaves as sites for enrichment of solutes of the xylem sap
Authors: CANNY M. J. 
Published: April 2006

SUMMARYThe apoplastic tracer sulphorhodamine G (SR) was used as an indicator of the flumes, the sites where water left the apoplast and entered the symplast, in a selection of dicotyledon leaves. At these flumes the dye is deposited as crystals after a pulse of dye is fed to the transpiration stream, followed or not by a water chase. In contrast to wheat, the dicotyledons showed SR cystals inside the tracheary elements of the finest leaf veins. At short pulse times the crystals were in the stems of the branch‐trees of the fine veins, but after longer pulses, had moved to the vein termini. The dye solution was moving very slowly in the tracheary elements as it approached the ends of the branch‐trees, since the axial flow there is nearly balanced by radial leakage. These results are interpreted as evidence that most of the transpiration water enters the symplast in the vein sheaths of the fine veins, and that these veins are places where many of the natural solutes of the xylem sap will be enriched to quite high concentrations.
The metabolism and biological activity of ABA analogues in normal and flacca mutant tomato plants
Authors: LINFORTH R. S. T. , TAYLOR I. B. , DUCKHAM S. C. , AL‐NAIEB R. J. , BOWMAN W. R. , MARPLES B. A. 
Published: April 2006

SUMMARYThe metabolism of deuterium‐labelled analogues of ABA by normal and flacca mutant tomato plants was investigated. Comparison of the biological activity of ABA, ABA alcohol, ABA aldehyde and their 2‐trans isomers was made in both mutant and non‐mutant genotypes. While in normal plants ABA alcohol and ABA aldehyde were as effective as ABA in inducing stomatal closure, in the flacca mutants only ABA itself was biologically active. Both ABA alcohol and ABA aldehyde were converted to the inactive compound trans‐ ABA alcohol instead of ABA when fed to flacca plants. As trans‐ABA aldehyde was also readily converted to trans‐ABA alcohol by flacca plants, it was not possible to establish whether isomerization precedes reduction or vice versa in the synthesis of trans‐ABA alcohol from ABA aldehyde.
Effects of nutrient depletion on growth ofHolcus lanatusL. andFestuca ovinaL. and on the ability of their roots to absorb nitrogen at warm and cool temperatures
Authors: KACHI N. , RORISON I. H. 
Published: April 2006

SUMMARYTo examine the ecological relevance of slow growth for survival in unproductive environments, responses to nutrient depletion were compared between two ecologically contrasted grasses with reference to their ability to utilize a nutrient flush. Dry weight growth, ability of roots to absorb nitrogen and subsequent distribution between root and shoot were determined forHolcus lanatusL. andFestuca ovinaL. before and after subjecting them to nutrient depletion at warm and cool temperatures. Initially, the relative growth rates (RGR) ofH. lanatuswere much higher than those ofF. ovina, but after 21 days of nutrient depletion,F. ovinaattained higher RGR. During nutrient depletion,F. ovinamaintained higher shoot N concentrations thanH. lanatus, mainly due to lower rates of dry matter accumulation inF. ovina.Maintenance of N concentrations inF. ovinamay contribute to sustaining of the shoot activity under N‐depleted conditions. Nutrient depletion caused an increase in the proportion of N allocated to roots relative to shoots, butF. ovinaexhibited less plasticity thanH. lanatus.Following nutrient depletion, the ability of roots to absorb nitrate declined markedly inH. lanatusand to a much lesser extent inF. ovina.The ability to absorb ammonium was also reduced at warm temperatures, while at cool temperatures it was unchanged inH. lanatus, but increased inF. ovina.These results suggest thatF. ovinahas a greater potential to exploit ‘nutrient flushes’ thanH. lanatusunder unproductive conditions, especially at cool temperatures.
Physiological ecology of seed respiration in some tropical species
Authors: GARWOOD NANCY C. , LIGHTON JOHN R. B. 
Published: April 2006

SUMMARYWe examine the relationship of seed oxygen consumption rate (V̇o2) to seed moisture content, seed mass, and seed age in 22 ecologically diverse tropical species. These seeds vary greatly in moisture content, age, mass, mechanism of dormancy and length of viability. We quantify each relationship with a power equation, V̇o2=aXb, where X is the independent variable. Seed moisture content (MC) explains 80% of the variation in mass‐specific V̇O2 (ml O2 g−1 h−1) among seeds of all species, whereas seed mass explains < 1%. However, when seeds are reclassified as moist (> 28% MC) or dry (≤ 28% MC), seed mass explains 54% of the variation in mass‐specific V̇o2 (ml O2 g−1 h−1) within dry seeds, but no significant variation within moist seeds. In dry seeds, seed age explains only 27% of the variance in mass‐specific Vo2, although seed age and moisture content are negatively correlated. On a per seed basis, seed mass explains 54% of the variation in mass‐specific V̇o2 (ml O2 h−1 per seed) in dry seeds and 83 % of the variation in moist seeds: the exponents of the power function, 0.54 in dry seeds and 0.78 in moist seeds, are within the range reported for the allometric relationship of oxygen consumption and body size in animals and prokaryotes. We present a framework for future studies that recognizes seed respiration as an important, yet unstudied, component of tropical seed ecophysiology. We discuss the ecological significance of seed respiration in three groups of tropical species which differ in seed moisture content, mass, viability, and post‐dispersal moisture regimes: (1) shade‐intolerant pioneer species with small, dry, orthodox seeds; (2) seasonally dormant species; and (3) shade‐tolerant primary forest species with large, moist recalcitrant seeds.
Numerical taxonomy of the wild bananas (Musa)
Authors: SIMMONDS N. W. , WEATHERUP S. T. C. 
Published: April 2006

SUMMARYThe wild bananas (Musa) were described in numerical terms many years ago, well before ‘numerical taxonomy’ became popular. Those descriptions, slightly supplemented, are here subjected to analysis by modern methods. Principal co‐ordinate and clustering techniques give essentially similar results. Five groupings, rather than the four sections traditionally recognized, can be discerned. The fifth group contains five taxa previously included in section Musa (informally ‘Eumusa’) or of uncertain affinity. This group is only somewhat weakly distinguishable from section Australimusa. Several species previously regarded as of uncertain affinity seem to find ‘natural’ places. The results are by no means revolutionary but do encourage modest alteration of traditional views.