bluuebunny/crossref_metadata_2025 huggingface dataset:
HEAVY METALS IN SOILS, VEGETATION DEVELOPMENT AND HEAVY METAL TOLERANCE IN PLANT POPULATIONS FROM METALLIFEROUS AREAS
Authors: SIMON ERIC
Published: May 2006

The development of vegetation (mainly the Violetum calaminariae Schwick.) in heavy metal‐contaminated areas depends on the metals mobility in soils and on metal availability for plants. Moreover, the ability of plant populations to evolve metal tolerance is one of the most important characters which determines the structure, density and development of the vegetation in such areas. In this work, metal mobility in soils and availability to plants in both calcareous and non‐calcareous situations were investigated in relation to the development of genetical heavy metal tolerance in plant populations.

In soils, exchangeable metals amounts are linearly related to total amounts. Availability of metals for plants depends on soil pH and on organic matter contents. High calcium content in soils reduced lead toxicity more than zinc toxicity and generally reduced metal uptake but some exceptions were found. The structure and the density of the vegetation colonizing calcareous and non‐calcareous places is related to the interaction between lead, zinc and exchangeable non‐toxic cations. A relationship between exchangeable Pb++/Ca++ in soils and the lead tolerance level of plant populations was found. The relation between exchangeable Zn++/Ca++ and zinc tolerance level was not satisfactory.
PROTON CO‐TRANSPORT OF ORGANIC SOLUTES BY PLANT CELLS
Authors: BAKER D. A.
Published: May 2006

I. SUMMARY

The possible role of proton co‐transport in the uptake of sugars and amino acids by plant cells is discussed. Evidence is presented for sodium or proton co‐transport of organic solutes in animal, bacterial and algal systems and this is discussed in relation to evidence for a similar mechanism operating in the cells of higher plants. It appears that in plant cells an electrogenic proton efflux pump generates a gradient of electrochemical potential for protons which provides energy for the movement of an organic solute‐proton‐carrier complex across the membrane. The large sugar transport associated with the loading of phloem sieve elements is postulated to be driven by a proton co‐transport system and the relation of this loading process to transport and subsequent unloading of the phloem is considered.
STUDIES ON THE NATURALLY OCCURRING GIBBERELLINS IN AONLA (EMBLICA OFFICINALIS GAERTN.) FRUIT
Authors: RAM SANT , RAO T. RAJA
Published: May 2006

The fruit of aonla (Emblica officinalis) remains at rest without growth for a period of 3 1/2 months after setting and resumes growth thereafter. Studies on endogenous gibberellin activity of the fruit and exogenous applications of gibberellin to the fruit at rest suggest that the inability of the fruit to resume growth immediately after setting is not due to gibberellin deficiency. The fruit, when making rapid growth following its rest, contained six gibberellin‐like factors active in the lettuce hypocotyl test. Five behaved like gibberellins A1, A3, A4, A7 and A9 in paper, thin‐layer and silicic acid: celite column chromatography.
GROWTH OF SUBTERRANEAN CLOVER IN RELATION TO THE FORMATION OF ENDOMYCORRHIZAS BY INTRODUCED AND INDIGENOUS FUNGI IN A FIELD SOIL
Authors: ABBOTT L. K. , ROBSON A. D.
Published: May 2006

Three vesicular arbuscular (VA) endophytes differed in their ability to increase the growth of subterranean clover when introduced into a freshly collected field soil. Four indigenous endophytes infected the roots in both the control and inoculated treatments. Two of the introduced endophytes, isolates of Glomus monosporus, differed in their ability to increase growth and phosphorus content of subterranean clover. These endophytes were both superior to the third introduced endophyte, G. fasciculatus.

Differences in the growth of subterranean clover when limited by phosphorus supply were related to the rate of mycorrhiza development. Inoculation of soil with the three introduced endophytes did not reduce initial infection by the four indigenous endophytes. Mycorrhizas formed by G. monosporus and G. fasciculatus were distinguished from those formed by indigenous endophytes on the basis of morphology.

Plants inoculated with isolates of G. monosporus had a greater proportion of their dry weight and phosphorus content in the tops than plants inoculated with G. fasciculatus or the control plants.
ELECTRON MICROSCOPY OF STRUCTURES ON THE ADAXIAL LEAF SURFACES OF CAMELINA SATIVA AND SPINACIA OLERACEA
Authors: LOVETT J. V. , JUNIPER B. E.
Published: May 2006

Observations of unidentified structures found on adaxial leaf surfaces of two plant species are reported. The observations were made at Bangor in 1977/78 and at Oxford in 1959. The structures are uncommon and, as yet to our knowledge, unreported in the literature.
HETEROCYST DIFFERENTIATION AND POLARITY IN CALOTHRIX
Authors: RAI A. K. , PANDEY K. D. , KASHYAP A. K.
Published: May 2006

When grown in a nitrogen‐free medium Calothrix brevissima West has a basal heterocyst followed by a filament of cells of decreasing size. In a nitrate medium, the alga does not form heterocysts but partial polarity, i.e. tapering of the filaments, remains. In contrast, polarity as well as heterocyst differentiation, is lost on growth in an ammonium medium and the frequent formation of false branches is observed. Following exhaustion of ammonia from the medium, differentiation of heterocysts, each with two distinct polar nodules, begins at semi‐regular intervals along the filaments. Polarity is regained following breakage of the filament adjacent to a heterocyst. The ways in which nutrient limitation and heterocyst differentiation patterns can lead to three different types of false branching in the same alga are discussed.
SUSCEPTIBILITY TO SHADE IN SEEDLINGS OF COLONIZING AND CLOSED TURF SPECIES
Authors: FENNER M.
Published: May 2006

The effect of shade on the growth of seedlings of a range of colonizing and closed turf species was investigated by means of a simple experiment. It was found that the colonizing species were, in general, more severely affected by shade than the closed turf species were, both in terms of percentage reduction in dry weight and in terms of percentage reduction in relative growth rate. The relevance of these results to the inability of colonizing species to establish in closed grasslands is discussed.
DIATOM AND POLLEN STUDIES OF A SEDIMENT PROFILE FROM MELYNLLYN, A MOUNTAIN TARN IN SNOWDONIA, NORTH WALES
Authors: WALKER ROSEMARY
Published: May 2006

Core samples taken from Late Devensian and Flandrian deposits at Melynllyn have been investigated. One profile was sampled at fairly close intervals for diatom and pollen analyses, and a series of radiocarbon dates was obtained. An absolute diatom counting method was used, which enabled the results to be expressed both in terms of annual diatom deposition and as percentages of the diatom sum. The diatom succession indicates that a change from alkaline to circumneutral conditions took place early in the Flandrian period. Diatoms characteristic of acidic, oligotrophic waters have been well established in the tarn from mid Flandrian times to the present day. Pollen analysis serves chiefly as a means of correlating the deposits with those from other sites in the Snowdonia region, although some features of the pollen diagrams are discussed. The data indicate that erosion was accelerated in the drainage basin of the tarn following the decline in Ulmus pollen percentages.
THE SYMPTOMS OF CALCIUM DEFICIENCY IN PLANTS
Authors: SIMON E. W.
Published: May 2006

As the symptoms of calcium deficiency develop in plants, there is often a stage in which the tissues are water‐soaked and one involving cell breakdown with loss of turgor (as in internal breakdown of apples). Eventually the tissue may become desiccated yielding a dry, more or less extensive area of necrosis. Two mechanisms are proposed. There is evidence that calcium deficiency renders membranes permeable which would account for a loss of turgor and permit cell fluids to invade intercellular spaces. An alternative situation may develop in soft, succulent fruits, the cells of which burst under hypotonic conditions in vitro. It is suggested that exogenous water may enter a fruit from the atmosphere or (in apple) through the phloem. Such exogenous water in the intercellular spaces of the fruit may cause cells to swell, so cracking the fruit or it may result in a bursting of the cells. A plea is made for further light microscope studies of the development of symptoms of calcium deficiency.
THE EFFECTS OF AIR POLLUTION ON PLANT GROWTH WITH SPECIAL REFERENCE TO SULPHUR DIOXIDE
Authors: CRITTENDEN P. D. , READ D. J.
Published: May 2006

Lolium perenne L. was grown in a sealed glass chamber force‐ventilated with ambient SO2‐polluted air and the yield compared with that of control plants grown in a second chamber receiving filtered air free of SO2 and suspended participates. Whole plant dry weight of L. perenne cv. S23 grown either on a nutrient‐rich sand culture or an unfertilized field soil was depressed by up to 36% in polluted air containing mean SO2 concentrations of less than 100 μg−3 in. When detailed growth analyses of S23 L. perenne in unfiltered air and of a clone of wild L. perenne previously reported to be resistant to SO2 pollution were compared, there were distinct differences between the two strains in response to SO2‐polluted air but both were less productive in the latter treatment.

Sulphur dioxide was strongly implicated as the factor responsible for the reduced dry‐matter production of plants raised in polluted air but there was a poor positive correlation between loss of yield and long term mean SO2 concentration within the unfiltered air chamber. The results are discussed with regard to probable mechanisms of growth inhibition and the possibility that experimental conditions cither enhanced or confounded the effect of SO2 pollution on plant growth.
TOLERANCE OF TREE ROOTS TO WATERLOGGING
Authors: COUTTS M. P. , PHILIPSON J. J.
Published: May 2006

A study is presented of the growth of rooted cuttings of Lodgepole pine and Sitka spruce into waterlogged soil. Lodgepole pine roots penetrated to depths of 20 cm at 10°C in soil devoid of oxygen, whereas Sitka spruce made only shallow growth into the water‐table. The growth rate of the pine roots decreased with depth below the water‐table and penetration was greater at 10 °C than at 20 °C. Large gas‐filled cavities were found in the stele of the pine roots that penetrated the water‐table but were absent from the spruce. When pine roots were allowed to grow into a water‐table for 2 cm. and were subsequently inundated to a depth of 10 cm, root tip survival was much better than where non‐acclimatized roots were flooded.

The results suggest that the deeper penetration of waterlogged soil by Lodgepole pine than Sitka spruce is due to internal oxygen transport in the pine roots; oxygen transport and other possible mechanisms for growth and survival of roots in waterlogged soil are discussed.
THE GROWTH AND NUTRIENT CONTENT OF FESTUCA VIVIPARA (L.) SM. PLANTLETS
Authors: HARMER R. , LEE J. A.
Published: May 2006

The nutrient content of Festuca vivipara (L.) Sm. plantlets from a site in the English Lake District were compared with that of seeds of the closely related species, F. ovina L. The almost linear increase in dry weight of plantlets throughout the growing season was associated with an increase in their mineral nutrient content derived from the parent plant. Their amino acid and soluble carbohydrate content also increased markedly with size. The relatively high levels of free amino acids and soluble carbohydrates in viable plant‐lets contrasts with the generally low levels of these compounds usually found in mature seed of grasses. Viable plantlets contained three to four times the nutrient content of F. ovina seeds resulting principally from the larger dry weight of the plantlets. The growth and survival of plantlets is discussed in relation to the success of vivipary as a method of reproduction in arctic‐alpine environments.
GROWTH OF ISOLATED EMBRYONIC AXES FROM DORMANT SEEDS OF HAZEL (CORYLUS AVELLANA L.)
Authors: JARVIS B. C. , WILSON D. A. , FOWLER M. W.
Published: May 2006

A medium of sucrose and inorganic salts permits development of isolated embryonic axes of hazel into leafy seedlings. Gibberellic acid stimulates the early growth of excised axes in this medium and with sucrose alone. In the longer term, GA3 leads to less root growth, increased shoot growth (but an overall reduction in seedling length) and a poor leaf development. Abscisic acid markedly inhibits extension of isolated axes irrespective of the presence of gibberellic acid.
DETECTION AND ESTIMATION OF POLYPHOSPHATE IN VESICULAR‐ARBUSCULAR MYCORRHIZAS
Authors: CALLOW J. A. , CAPACCIO L. C. M. , PARISH G. , TINKER P. B.
Published: May 2006

Polyphosphates have been extracted from onion roots infected with Glomus mosseae by the technique of phenol‐detergent extraction. The polyphosphate was separated from RNA and DNA and characterized by the technique of polyacrylamide gel electrophoresis. On gels stained with Toluidine Blue, the blue‐purple nucleic acid bands (β‐metachromatic) could be readily distinguished from the pink (γ‐metachromatic) polyphosphate band, which ran faster than tRNA, and was coincident with synthetic, marker polyphosphate of chain length 200 ±10. By excising stained gel bands, dry‐ashing and P determination, and by enzymic hydrolysis, the presence of condensed orthophosphate in this band has been confirmed. Polyphosphates could not be detected in uninfected roots and the content in infected roots increases several‐fold when plants are supplied with orthophosphate 24 h before extraction. By calculation it has been shown that the polyphosphate forms a substantial proportion (40%) of the total P present in the fungal component of mycorrhizal roots, and that this concentration is sufficient to support the proposed phosphorus translocation.
LIPID PHYSIOLOGY OF VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: COOPER KAREN M. , LOSEL DOROTHY M.
Published: May 2006

A microscopic and biochemical comparison was made of the distribution, quantity and composition of lipid in roots of onion, clover and ryegrass infected with the VA mycorrhizal fungus, Glomus mosseae, in uninfected roots and in the external mycelium from infected, aseptically grown onion roots. Abundant oil‐droplets were observed in the internal and external fungal mycelium, in the vesicles and chlamydospores, and adjacent to the appressoria at entry points. Mycorrhizal roots contained significantly more total lipid than uninfected roots. In estimations of separated lipid classes, the mycorrhizal roots consistently showed higher levels of triglyceride than non‐inycorrhizal roots. External mycelium contained high levels of neutral lipids, especially triglyceride, diglyceride and free fatty acids. Compared with uninfected roots, mycorrhizal onion roots contained higher levels of diphosphatidyl glycerol, phosphatidyl serine, phosphatidyl ethanolamine, phosphatidy) choline, phosphatidyl glycerol, phosphatidic acid and phosphatidyl inositol. With the exception of phosphatidyl inositol and phosphatidic acid, these were all prominent components of G. mosseae mycelium.
UNUSUAL REPRODUCTIVE STRUCTURES IN SYRINGODERMA ABYSSICOLA (S. & G.) LEVRING*
Authors: WALKER DAVID C. , HENRY ERIC C.
Published: May 2006

Reproductive structures of Syringoderma abyssicola (S. & G.) Levring are unique. They begin development as normal unilocular sporangia. However, the initial products of cytokinesis develop a cell wall, but not as in plurilocular sporangia. Some of these walled cells may in turn divide to produce a tetrad of naked flagellate cells. This is in contrast to other members of the Dictyotales, the order in which S. abyssicola is currently placed.
PHYSIOLOGICAL ECOLOGY OF THE MARINE ALGA ACROCYSTIS NANA
Authors: MNTANGI M. J. , FARRAR J. F.
Published: May 2006

Acrocystis nana is a tropical and subtropical red alga confined to areas of the shore emersed for between 3 and 9 h per tide. In the laboratory, it becomes unhealthy if immersed constantly but retains its original weight if dried for 3 h out of each 24 h and is aerated during the immersion period. Weight loss in various regimes in the light and in the dark is largely confined to material soluble in 0.1 N HC1 and is greatest from an 80% ethanol‐soluble fraction tentatively identified as floridoside. The thalli contain an extracellular sap with an ionic composition distinct from seawater. Results are discussed in relation to the zonation of A. nana on the shore and the concept of physiological buffering.
A RADIOCARBON‐DATED POLLEN DIAGRAM FROM VALLEY BOG, ON THE MOOR HOUSE NATIONAL NATURE RESERVE
Authors: CHAMBERS CARL
Published: May 2006

A radiocarbon‐dated pollen diagram from Valley Bog, situated in the upper reaches of Tees‐dale, is discussed. It provides evidence for a late alder expansion and the possibility of Mesolithic human activity on the Moor House National Nature Reserve. When compared with pollen diagrams from lowland County Durham there appears to be a delay in the elm decline at the high altitude. The elm decline is followed by a phase of Bronze Age deforestation which precedes a similar but more prolonged and pronounced Iron Age clearance.
PREPARATION OF PLANT MITOCHONDRIA USING GEL FILTRATION COLUMNS
Authors: HARLEY J. L. , BLACK M. K. , WEDDING R. T.
Published: May 2006

The possibility of preparing plant mitochondria using Sephadex or Bio‐gel columns was investigated. It is concluded that gel filtration is a feasible alternative to centrifugation with many plant materials. It has the advantage of providing preparations of higher O2 uptake rate per unit protein with similar or better ADP/O or respiratory control ratios than centrifugation. It is often also more rapid for routine preparation. Its disadvantage in particular is the dilution of the final suspension.
CARBOHYDRATE AND INOSITOL METABOLISM IN THE SEAGRASS, CYMODOCEA NODOSA
Authors: DREW EDWARD A.
Published: May 2006

Leaves of the seagrass Cymodocea nodosa contained more than 5% dry weight of both sucrose and an inositol, identified as 1‐chiro‐inositol. Sucrose was consumed during dark starvation at a rate suggesting it was a major respiratory substrate whereas the l‐chiro‐inositol content remained unaltered even after all the sucrose had been utilized. About 90% of photosyn‐thetically fixed carbon was incorporated into sucrose initially; some of this was converted into insoluble compounds during subsequent dark starvation. Glucose, fructose and the two inositol isomers, myo‐ and l‐chiro‐inositol, were also formed during photosynthesis. These inositols each accumulated about 1.2% of the fixed carbon and it was calculated that even this low rate of synthesis could account for at least 50% of new l‐chiro‐inositol required to maintain its concentration in new tissue. Myo‐inositol was not accumulated above a fraction of a percent dry weight and its active incorporation into insoluble material was demonstrated. Both inositols were synthesized to some extent from exogenously supplied glucose and sucrose but exogenous myo‐inositol initially accumulated as such within the tissues before incorporation into the insoluble fraction and none was converted to the l‐chiro isomer. It was concluded that 1‐chro‐inositol was synthesised from glucose rather than by epimerisation of myo‐inositol. l‐chiro‐inositol, which had no direct osmoregulatory role as its content neither increased at high salinities nor decreased at low salinities, appeared to be metabolic‐ally inert. Small quantities of muco‐inositol were also detected in Cymodocea. This too appeared to metabolically inert and both 1‐chiro‐inositol and muco‐inositol seemed to be byproducts of the cyclization of glucose to myo‐inositol.
THE EFFECTS OF ETHANOL ON ROOTING AND CARBOHYDRATE METABOLISM IN STEM CUTTINGS OF PHASEOLUS AUREUS ROXB.
Authors: MIDDLETON W. , JARVIS B. C. , BOOTH A.
Published: May 2006

The number of roots induced by indolebutyric acid (IBA)in cuttings of light‐grown seedlings of Phaseolus aureus Roxb. is greatly inhibited by high levels of ethanol. When supplied alone to cuttings of dark‐grown seedlings increasing concentrations of ethanol progressively reduce the number of roots. The ethanol is glycosylated, at least in part, to ethyl‐β‐glucoside which reaches concentrations several‐fold greater in cuttings of light‐grown seedlings compared to those of dark‐grown seedlings. In the hypocotyl of cuttings from light‐grown seedlings the glucoside constitutes 26% of the extracted sugar and 1100 μg/g fresh weight after a treatment of 18 h with 2 ml/1 ethanol.
THE BORON REQUIREMENT FOR ROOT DEVELOPMENT IN STEM CUTTINGS OF PHASEOL US AUREUS ROXB.
Authors: MIDDLETON W. , JARVIS B. C. , BOOTH A.
Published: May 2006

No roots develop in cuttings from light‐grown seedlings of Phaseolus aureus Roxb. without exogenous boron, irrespective of auxin pretreatment. Root numbers and lengths are severely restricted unless the supply of boron is optimal. When supplied in equal molarities, indole‐butyric acid (IBA) is far more effective than indoleacetic acid in promoting root number. Very small visible roots do develop on cuttings from dark‐grown seedlings in the absence of applied boron. The growth of such roots is promoted by boron although there is an inverse correlation between length and number. IBA is far less effective at increasing root number in cuttings of dark‐grown seedlings.
REGENERATION OF MERISTEMATIC ACTIVITY FOLLOWING DECAPITATION OF THE ROOT TIP OF VICIA FABA L.
Authors: FRANCIS DENNIS
Published: May 2006

The numbers of primordia and secondary roots present in the terminal 5 mm of roots of Vicia faba were scored over the 6‐day period following the removal of 2, 10 or 20 mm of the root tip and compared with the corresponding numbers found in 5‐mm long segments of intact roots which were 2–7, 10–15 and 20–25 mm basal to the tip of the meristem at the start of the experiment (C2 segments). 144 h following decapitation the numbers of laterals emerging from the apical 5 mm of each batch of decapitated roots were greater than those in the corresponding C2 segments, the greater number in this part of the former roots reflecting the emergence of secondary roots through the cut surface at the stump apex in addition to those emerging laterally. The time course for complete secondary root formation in the apices of each batch of decapitated roots was no different from that in the intact controls.

In contrast to the changes which took place at the root apex following the removal of 2 mm or more of tissue, the removal of the apical 0.5 mm of the root in addition to the cap resulted in regeneration of a meristem from the proliferating cells which remained behind at the time of decapitation. The latter type of regeneration was investigated by following the changes which took place in mitotic index, labelling index and the relative proportions of interphase nuclei with different amounts of DNA in the apical 2 mm of roots from which the apical 0.5 mm of the meristem had been removed over the 144 h period between decapitation and the resumption of normal root growth.
SEASONAL VARIATION OF GORSE (ULEX EUROPAEUS L) SURFACE WAX AND TRICHOMES
Authors: ZABKIEWICZ J. A. , GASKIN R. E.
Published: May 2006

A marked seasonal variation in wax production was observed by scanning electron microscopy and confirmed by extraction and weighing the wax. Contact angles of water droplets on films of this extracted wax also showed seasonal variation as well as differences between foliage of different ages. This suggests that the chemical composition of the wax could vary in a like manner. Trichome development patterns were less distinct, but there was some indication of progressive attrition with increasing tissue age.
VARIATION IN FOUR POPULATIONS OF SENECIO VISCOSUS L. AS REVEALED BY A CULTIVATION EXPERIMENT
Authors: AKEROYD J. R. , WARWICK S. I. , BRIGGS D.
Published: May 2006

From fruits of Senecio viscosus L., collected on three coastal shingle beaches and at one inland site, plants were grown in a garden trial, which revealed statistically significant differences between and within the four populations. Particularly distinctive were the early‐flowering dwarf plants raised from fruits collected from coastal shingle at Thorpeness.

Bagging of capitula indicated that S. viscosus is self‐compatible, although within‐family variances and the frequency of insect visits to the experiment suggest that outcrossing occurs. Further experiments and observations are necessary to establish the frequency of self‐ and cross‐fertilization in natural populations of the species.

The implications of the experiment, as regards the distribution and genecology of S. viscosus in Britain, are discussed, with special emphasis on the differences between coastal shingle populations.
NUMERICAL TAXONOMY OF SPECIES IN ALLIUM SUBGENUS MOLIUM
Authors: BADR A. , ELKINGTON T. T.
Published: May 2006

Numerical methods have been used to study the relationships between twenty‐two operational taxonomic units (O.T.U.'s) in Allium subgenus Molium Koch (Wendelbo). Data were obtained by investigating fifty‐five morphological and cytological characters and thirty‐one chemical characters, the latter being volatiles, mainly sulphides, derived from bulb tissue. The CLASP programme was used to produce a number of phenetic classifications firstly by hierarchical cluster analyses, the results being presented as dendrograms showing percentage similarities of O.T.U.'s and as minimum spanning trees (M.S.T.), and, secondly, by principal co‐ordinates analyses, the results being presented as vector plots. Three sets of classifications have been produced; the first employing the morphological and cytological characters on all twenty‐two O.T.U.'s, the second using chemical data on only fifteen O.T.U.'s and the third using all characters.

The O.T.U.'s have been divided into six major groups as follows: (a) A. cernuum; (b) A. triquetrum and A. paradoxum; (c) A. oreophilum and A. oreophilum cv. Zwanenburg; (d) A. erdelii; (e) A. zebdanense, A. roseum, A. roseum var. bulbiferum, A. subvillosum, A. neapolitanum, two subspecies of A. trifoliatum and A. subhirsutum; (f) A. moly, A. scorzonerifolium, A. geyeri, A. unifolium, A. fibrillum, A. acuminatum and A. dichlamydeum. These groups and their subgroups are discussed in the light of biosystematic studies, particularly the ability of taxa to cross with others. The phenetic classifications produced are also compared with the previous taxonomic arrangements of the subgenus.
EVOLUTIONARY ASPECTS OF WIND POLLINATION IN THE GENUS PLANTAGO (PLANTAGINACEAE)
Authors: PRIMACK RICHARD B.
Published: May 2006

The selective forces acting to maintain a copious production of uniformly sized pollen grains in wind‐pollinated plants were investigated among species in the genus Plantago and at the population level in P. lanceolata. The species with cleistogamous (closed) flowers produce far less pollen of more variable average diameters than the species with chasmogamous (open) flowers. Pollen grains of P. lanceolata captured by stigmas of female plants were smaller than a general sample of pollen collected from the anthers of perfect plants, indicating that large pollen grains are not as effective as small grains in wind dispersal. The rapid decrease in pollen density on the stigmas of P. lanceolata with increasing distances from the pollen sources suggests that plants of this self‐incompatible species must produce great amounts of pollen in order to pollinate nearby plants. The cost of this high pollen production associated with wind pollination can be seen in P. lanceolata in the increased production of reproductive tissue and larger seeds in female plants when compared with normal plants.
A NEW METHOD FOR THE PREPARATION OF CLAY‐RICH SEDIMENT SAMPLES FOR PALYNOLOGICAL INVESTIGATION
Authors: BATES C. D. , COXON P. , GIBBARD P. L.
Published: May 2006

The use of sodium pyrophosphate as an effective deflocculant for the removal of clay from sediment samples is described.

Tests on the action of the chemical on samples from a number of geographically and chronologically separated localities has shown almost complete removal of clay. No evidence from the tests suggests that pollen is attacked, preferentially destroyed or lost by this treatment.
SEASONAL PATTERNS OF FRUCTAN METABOLISM IN FORAGE GRASSES
Authors: POLLOCK C. J. , JONES T.
Published: May 2006

Summary

Fructan levels and mean molecular weights were measured throughout the year in leaves and stems of four forage grasses. In contrast to other studies, the major period of fructan synthesis in all varieties was autumn and winter, with maximal values in December. Extensive hydrolysis, accompanied by a decline in mean molecular weight, occurred between January and April. Fructan accumulation was maximal in periods when growth was restricted and the properties of the synthetic system are discussed in relation to the patterns of growth of temperate forage grasses.
CELL DEATH AS A FUNCTIONAL EVENT IN THE DEVELOPMENT OF THE LEAF INTERCELLULAR SPACES IN AVICENNIA MARINA (FORSSKÅL) VIERH
Authors: CHALAIN T. M. B. de , BERJAK P.
Published: May 2006

Summary

Examination of successive development stages of the leaf of Avicennia marina (Forsk.) Vierh has revealed that although a measure of early schizogeny occurs, formation of the major air spaces is by a process of lysigeny. A developmental sequence terminating in autolysis may be traced within cells forming a localized group, and the end products of the breakdown are identifiable as debris of a clearly cellular origin, which occurs within the newly created intercellular space.
THE ULTRASTRUCTURE OF POLLEN‐GRAIN DEVELOPMENT IN THE OLIVE (OLEA EUROPAEA). 1. PROTEINS IN THE PORE*
Authors: PACINI E. , JUNIPER B. E.
Published: May 2006

Summary

The olive tapetum is of the parietal type and the walk of the tapetal cells disappear at about the time as the microspore tetrads separate. As the intine starts to develop in the microspore the Golgi bodies are apparently active in discharging vesicles, and fibrillar PAS‐positive material starts to accumulate between an undulant plasmalemma and the intine. The plasmalemma then retracts from the pore zone and within the crescent‐shaped area thus formed accumulates what is believed to be a pectocellulosic wall much penetrated by invaginating tubules from the plasmalemma. After the first haploid mitosis more material forms between the plasmalemma and the pore apparently sealing off these invaginations. Fibrillar material thought to be protein first appears in the intercellular spaces between the tapetal cells and finally becomes concentrated over the outer surface of the pollen pore. This proteinaceous material does not accumulate if the cytoplasm of the pollen has degenerated prior to pore formation.
POLLINTATION ECOLOGY OF, AND HYBRIDIZATION BETWEEN, ORCHIS CORIOPHORA L. AND O. COLLINA SOL. EX RUSS. (ORCHID ACEAE) IN ISRAEL
Authors: DAFNI A. , IVRI Y.
Published: May 2006

Summary

The flower of Orchis coriophora L. contains free nectar in the spur and is very fragant; it attracts a large gallery of pollinators mainly Apis mellifera. The capsule production rate is about 90%

O. collina Sol. ex Russ. has empty spurs and is scentless; pollinators are scarce and capsule production rate is about 25%.

The species are sympatric in some habitats in Israel and create rare hybrids which seem to be the result of common pollinators.

It is suggested that each of the two species represents different pollination strategy in the genus. This view and the implications on self and cross pollination are discussed.
THE INFLUENCE OF SOIL pH ON THE EFFICIENCY OF VEICULAR‐ARBUSCULAR MYCORRHIZA
Authors: GRAW D.
Published: May 2006

Summary

Tagetes minuta and Guizotia abyssinica reacted differently to changes in soil pH and to fertilization with various phosphates in spite of inoculation with the same strain of Glomus macrocarpus. At pH 4.3, mycorrhizal Guizotia was unable to absorb P from all the compounds with the result that growth was severely inhibited by inoculation, whereas mycorrhizal Tagetes grew well at this pH in the presence of Ca(H2PO4)2. H2O, Ca5(PO4)3OH and AlPO4. Phosphorus uptake and growth of mycorrhizal Guizotia were improved at pH 5‐6 and surpassed the performance of non‐mycorrhizal plants at pH 6‐6. Growth of mycorrhizal Tagetes was reduced at pH 5.6 in the presence of Ca(H2PO4)2. H2O and Ca5(PO4)OH, but improved at pH 6.6 in all treatments with the exception of Ca5(PO4)3OH as P source.
FLORAL MORPHOLOGY AND POLLEN FLOW IN THE HETEROSTYLOUS SPECIES PULMONARIA OBSCURA DUMORT (BORAGINACEAE)
Authors: OLESEN JENS MOGENS
Published: May 2006

Summary

Pollen flow in the heterostylous species P. obscura was studied in two localities in Denmark. Various floral characters of the two morphs were measured, but differences were found only in height of stamens and stigma, and size of pollen. In studies with a scanning electron microscope (s.e.m.) pollen was discovered to have a continuous, equatorial girdle formed by the transverse furrows extending laterally from the ora. The stigmatic papillae were composed of a stalk with a many‐armed crown. The ratio of number of thrum to pin plants was approximately 1:1 fulfilling theoretical expectations. Six different Bombus spp. and a specimen of Psithyrus bohemicus were observed as visitors to P. obscura, which displays a range of adaptations to Bombus pollination. Thirty per cent of the Bombus specimens had corbicular pollen loads, which were almost 100% pure Pulmonaria pollen. Pollen flow was revealed by analysing the pollen loads on stigmas and proboscides. Both stigma types had more illegitimate pollen than expected on the basis of the ratio of production of the two pollen types. This could be caused by a high degree of intrafloral pollen flow. Since heterostyly does not apparently enhance the transport of legitimate pollen the adaptive role of the system is unclear.
REVERSAL OF THE CO2‐RESPONSES OF STOMATA BY FUSICOCCIN
Authors: Travis A. J. , Mansfield T. A.
Published: May 2006

Summary

The fungal toxin fusicoccin, which is known to stimulate stomatal opening, has been found to reverse the response of stomata to CO2. In the absence of fusicoccin, CO2 caused stomata to close, while in its presence, CO2 caused opening. This reversal of events was even more striking in epidermal malate levels. Three hundred and fifty μl l−1 CO2 normally suppressed malate formation, but in the presence of fusicoccin, amounts of malate were greater in 350 μl l−1 CO2 than in CO2‐free air.

These observations might be best explained if CO2 exerts two different effects on guard cells, one of which is normally obscured by the other. The familiar effect, that of stomatal closure in response to increases in CO2 concentration, is predominant, and it is suggested that this involves control of potassium ion uptake either through the activity of an electrogenic proton pump or through membrane permeability to K+. Fusicoccin has the effect of annulling this form of control by CO2, revealing an opposing response, namely a stimulation of opening by CO2. This could be due to a fixation of CO2 into malate, which is used as a counter ion for K+ in guard cells. There is, however, an enigma: the fact that (in the presence of fusicoccin) malate level is positively correlated with external CO2 supply suggests that the latter limits the rate of malate formation, yet incorporation of labelled CO2 can only account for about 1 % of the malate produced.
THE EFFECT OF NITRITE ON ROOT GROWTH OF BARLEY AND MAIZE
Authors: Lee R. B.
Published: May 2006

Summary

When sodium nitrite (1 mM) was added to a nitrate‐based nutrient solution, initially at pH 5, it had a small but consistently adverse effect on elongation of the seminal roots of barley and maize. In larger plants of maize, the length and dry wt of the nodal roots, and the dry wt of the shoots, were also decreased. The roots of both species were more sensitive to nitrite during growth under oxygen‐deficient conditions than when grown in solutions well supplied with air.

The concentration of nitrate in the roots of barley plants decreased when 1 to 3 mM nitrite was included in the nutrient solution.

It is suggested that nitrite toxicity is unlikely to be of importance in the survival of cereal roots in temporarily waterlogged soils save under the most abnormal circumstances.
STUDIES ON THE EFECTS OF LOW LEVELS OF SULPHUR DIOXIDE ON THE GROWTH OF LOLIUM PERENNE L.
Authors: BELL J. N. B. , RUTTER A. J. , RELTON J.
Published: May 2006

Summary

Lolium perenne L. cv. S23 was grown in Perspex chambers situated out of doors and ventilated with clean air or controlled levels of sulphur dioxide (SO2). Fumigations were carried out with [SO2] ranging from 43 to 423 μg m−3 for periods up to 194 days under both summer and winter conditions.

Concentrations as low as 43 μg m−3 for 173 days in winter and 106 μg m−3 for 194 days in summer could produce reductions in shoot dry wt but, in some experiments, similar or higher concentrations had no effect on growth. This difficulty in obtaining a clear dose/response relationship is possibly due to an interaction of environmental factors with the effects of the pollutants. In some of the experiments, growth was reduced in the absence of any detectable symptoms whereas, in other cases, the fumigated plants became chlorotic. There was some evidence for chronic SO2 injury being more severe on young plants.

SO2 acted primarily through a depression in net assimilation rate. No clear correlation was found between either chlorophyll content or total sulphur content of the fumigated plants and a reduction in any of the growth parameters investigated. The results are discussed in relation to those of other workers and their relevance to conditions in the field in the United Kingdom.
SENSITIVITY OF ROOTING AND TOLERANCE TO COPPER IN AGROSTIS TENUIS SIBTH.
Authors: NICHOLLS M. K. , McNEILLY T.
Published: May 2006

Summary

The rooting response of seven populations of Agrostis tenuis Sibth. to a range of copper concentrations in calcium nitrate solution is described. Variation in both index of tolerance and sensitivity of rooting to increased copper levels were found and shown to be phenotypically independent characters. It is suggested that rooting sensitivity to a range of copper concentrations provides a further measure of copper tolerance which is independent of the methods previously employed for assessing tolerance.
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: OWUSU‐BENNOAH E. , MOSSE BARBARA
Published: May 2006

Summary

Onions, lucerne and barley were inoculated with one of two endophytes placed below the seed in a replicated field trial. After 13 weeks shoot growth was increased by 77% (onion), 79% (lucerne) and 33% (barley) with one inoculum and by four‐, six‐fold and 30 % respectively with the other. Lucerne and onion benefitted most from inoculation in the sub plots with most available P whereas barley responses were confined to those with less available P.

The uninoculated plants reached approximately 45% infection from indigenous endophytes and the inoculated plants around 70%. Inoculation responses were not related to infection level. One introduced endophyte spored profusely and spread 22 cm from the point of inoculation, the other formed only few new spores; the indigenous fungi hardly sporulated at all. Spore production was little affected by host species or soil P level and was unrelated to percentage root infcetion.

The rationale of field inoculation is discussed with particular reference to amounts of inoculum required.
EFFECT OF MYCORRHIZAL FUNGI ON RECOVERY OF PHOSPHATE FERTILIZER FROM SOIL BY RYEGRASSPLANTS
Authors: Lpowell C.
Published: May 2006

Summary

Ryegrass plants were inoculated with Gigaspora margarita, Glomus tenuis or the indigenous mycorrhizal fungi and transplanted into pots containing four New Zealand hill country soils fertilized with finely ground superphosphate or one of five finely ground phosphate rocks. After seven harvests from Dunmore soil and four harvests from three other soils, Peru rock phosphate was the best fertilizer overall (an average of 24 % of applied fertilizer phosphate was recovered by plants) followed by superphosphate, Chatham Rise rock, Nauru Is. rock, Christmas Is. rock and Queensland rock (23, 15,4,4 and 2 % of the phosphate recovered respectively). The fertilizer value of superphosphate decreased rapidly over successive harvests in all soils, with slower decreases in the fertilizer value of Peru and Chatham rock phosphate. The values of Queensland, Nauru Is. and Christmas Is. rock phosphate were very low and largely unaffected by repeated harvesting. Mycorrhizal inoculation greatly influenced phosphate uptake from soil by plants. In 11 out of 28 soil‐fertilizer treatments, phosphate uptake by G. tenuis‐inoculated plants was increased significantly over plants inoculated with indigenous mycorrhizal fungi. The increased phosphate uptake following inoculation with efficient mycorrhizal fungi tended to decrease over successive harvests, as the available phosphate levels in soil were depleted.
ENHANCED CARBON TRANSFER BETWEEN ONIONS INFECTED WITH A VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGUS
Authors: HIRREL M. C. , GERDEMANN J. W.
Published: May 2006

Summary

Carbon (C) transfer between onion plants was enhanced by vesicular‐arbuscular mycorrhizas formed by the fungus, Glomus etunicatus. By applying pentachloronitrobenzene (PCNB) to hyphae, C translocation to the root was reduced but not eliminated indicating that two transfer processes may be involved; namely, cytoplasmic translocation within hyphae and mass flow along hyphal walls. Most of the transferred C remained in the roots; little or no C was translocated to the shoots. Therefore, it is uncertain whether C was released to the recipient plant or retained in fungal tissue.
SCANNING ELECTRON MICROSCOPY OF THE NITROGEN‐FIXING ACTINORHIZA OF MYRICA PENSYLVANICA L. (BAYBERRY)*
Authors: BENSON D. R. , GREENHUT V. A. , EVELEIGH D. E.
Published: May 2006

Summary

The nitrogen‐fixing root nodules of Myrica pensylvanica L. (bayberry) were shown to be inhabited by a filamentous micro‐organism typical of non‐leguminous root nodules (actinorhizal nodules) by scanning electron microscopy (s.e.m.). The micro‐organism was hyphal in young nodule areas and host cell infection was accomplished by cell wall penetration with subsequent proliferation of the micro‐organism. The penetration was often massive with hyphal entries recorded less than 1 μm apart. The smooth transition between host cell wall and endophyte hypha indicated some homology between their surfaces. The second stage of development of the endophyte was vesicular; club‐shaped vesicles arose as extensions of hyphal tips. The vesicles resembled similar structures from other non‐leguminous nitrogen‐fixing plants. X‐ray microanalysis of the nodules revealed the presence of crystalline deposits containing substantial calcium content packed within randomly distributed cortical cells. The crystals were typical of calcium oxalate, a common constituent in plant tissue.
OBSERVATIONS ON MEIOSIS IN THREE CYTOTYPES OF BETULA ALBA L.
Authors: BROWN IAN R. , AL‐DAWOODY DAWOOD
Published: May 2006

Summary

Meiosis was studied in three birch cytotypes; B. pendula 2n= 28, B. pubescens 2n= 56 and a type with the intermediate chromosome number 2n= 42. Meiosis was similar in B. pendula and B. pubescens and a similar range and frequency of abnormalities was found. In relation to both types there was strong circumstantial evidence that x= 7 rather than x= 14, which is commonly accepted. In addition it was also shown that in B. pubescens there exists means of producing aneuploid gametes.

Meiosis in 2n= 42 trees differed greatly from that in 2n= 28 and 2n= 56 trees. Many cells contained coalesced masses of chromatin and could not be analysed. Those that were studied showed a much greater frequency of abnormality than that found in the other two cytotypes. Surprisingly, around 50 % of analysable cells showed 21:21 distribution of chromosomes at metaphase II. Although the origin of these trees is unknown it is suggested that they are not triploids but hexaploids, i.e. x=n= 7.
THE BIOLOGY OF AMBROSIA TRIFIDA L.
Authors: Abul‐Fatih H.A. , Bazzaz F. A.
Published: May 2006

Summary

Ambrosia trifida L. is a fast growing annual colonizer of disturbed ground. When present it drastically reduces kinds, numbers and growth of other annuals. Its seedlings emerge before any other annual in early spring. We studied seed germination in relation to temperature, moisture, depth of sowing, and seedling emergence, survivorship and performance of mature plants in relation to time and depth of sowing and seed size.

Seeds germinated under a wide range of temperature (8 to 41°C) with an optimum between 10 to 24 °C. Further germination occurred after restratification suggesting germination polymorphism. The seeds also germinated under a wide range of soil moisture conditions (17 to 55 % dry wt) but highest germination occurred at 20 to 33 % soil moisture. Optimum depth of sowing was 2 cm; very little germination occurred very close to soil surface, and some occurred at the 16 cm depth. In the field seedlings emerged from shallow depths first and then from progressively deeper parts of the soil bank. There was positive correlation between seed size and maximum depth from which seeds of this species and those of five other associated annuals emerge. Time required for seedlings to emerge after germination was directly related to depth. Seedlings that emerged first had the highest probability of survival and those that emerged late suffered progressively higher mortality, irrespective of whether late emergence was caused by late germination or deep germination. Among the survivors that reached maturity, plant weight, height, and number of seeds per plant declined with delayed emergence. However, experimental manipulation showed that delayed emergence per se was not the cause of the mortality but rather competition with individuals which emerged earlier. Furthermore, delayed emergence of cohorts in separate plots did not significantly reduce plant height, weight and number of seeds per plant.

Thus in the field and within a patch there may be strong selection for early germination and emergence. However, this selection may be opposed by the unpredictability of the time of disturbance, the spatial patchiness of disturbance, and the longevity and induced dormancy of Ambrosia seeds. Compared to its associated annuals, A. trifida has the largest seeds and seedlings, the earliest germination and emergence and a very high photosynthetic rates. These properties give A. trifida a decisive advantage over the other species.
POLLEN INFLUX IN PEAT DEPOSITS: VALUES FROM RAISED BOGS IN THE SOMERSET LEVELS, SOUTH‐WESTERN ENGLAND
Authors: BECKETT S. C.
Published: May 2006

Summary

Pollen influx data from the Flandrian peat deposits of the Somerset Levels, south‐western England, are compared with other pollen influx data for peat and lake deposits. Peat deposits are found to have a much smaller annual recruitment of pollen than lake sediments. This difference is attributed to the absence of pollen contributed by inwash or stream inflow into a peat, particularly a raised bog peat, deposit.