bluuebunny/crossref_metadata_2025_split huggingface dataset:
HYBRIDS BETWEEN LOLIUM PERENNE AND FESTUCA PRATENSIS II. COMPARATIVE MORPHOLOGY
Authors: GYMER P. T. , WHITTINGTON W. J. 
Published: May 2006

SummaryMorphological evidence was found to support the belief that both natural and artificial hybrids between Lolium perenne and Festuca pratensis would fall into three classes, namely diploid, festucoid or loloid triploids. Natural diploids resembled diploids produced by artificial hybridization. Whereas natural festucoids resembled F1 festucoids, natural loloids on the other hand, perhaps due to selective or random survival in the pasture, showed some differences from both the F1 and back cross loloids.
THE RELATIONSHIP OF SOME POPULATIONS INVOLVING EUCALYPTUS CYPELLOCARPA AND E. GLOBULUS TO THE PROBLEM OF PHANTOM HYBRIDS
Authors: KIRKPATRICK J. B. , SIMMONS DIANNE , PARSONS R. F. 
Published: May 2006

SummaryA taxonomically anomalous population of eucalypts at Mallacoota, Victoria, is mapped and studied in detail. Measurements of adult and seedling morphology show the population to be intermediate between Eucalyptus globulus and E. cypellocarpa. However, on leaf terpenoid data the population is indistinguishable from E. cypellocarpa. The very restricted distribution of the population, and the high variability of its adult morphology suggest that it arose by hybridization between the two species named above. As the nearest stand of E. globulus is 6.4 km away, the population may represent a phantom hybrid stand. It is inferred from distribution data that E. globulus stands may have been present in the area before submergence by rising sea levels. If any pure E. globulus trees remained, a preponderance of E. cypellocarpa pollen may have prevented the continued production of more preponderant E. globulus progeny.
RADIOCARBON DATES AND VEGETATIONAL HISTORY OF THE BRITISH ISLES
Authors: SMITH A. G. , PILCHER J. R. 
Published: May 2006

SummaryRadiocarbon dates for a number of pollen analytic features marking important vegetational changes in the Post‐glacial of the British Isles are plotted in two figures (Figs. 2 and 3, summarized in Fig. 4). Despite the limitations of the radiocarbon method it becomes clear, where sufficient dates are available, that most of the vegetational developments of the earlier part of the Post‐glacial are diachronous. Some of these changes have been used as pollen zone boundaries. The elm decline appears synchronous, however, within the limits of the methods, and the final pine decline in Ireland, which is shown to be older than supposed by Jessen (1949), appears to be one of the least diachronous of the horizons examined. Marked differences in the dates of similar vegetational changes within a small area, and between upland and lowland, are pointed out.
A LATE‐ AND POST‐GLACIAL POLLEN DIAGRAM FROM CRANBERRY BOG, NEAR BEAMISH, COUNTY DURHAM
Authors: TURNER JUDITH , KERSHAW A. PETER 
Published: May 2006

SummaryCranberry Bog is a lowland moss which developed originally in a small shallow glacial hollow which contained open water during the late‐ and early post‐glacial. After a brief transition stage ombrogenous peat began to form and continued to do so throughout zone VI. An unusual feature of the bog is a well‐developed ‘Grenzhorizont’ which was not formed as a result of changes in climate. The late‐ and early post‐glacial vegetation of the area was transitional in character between that described from the Northumberland lowlands to the north and that described from the Yorkshire lowlands to the south, although it more closely resembles the former. Several unusual features of the pollen diagram, high birch frequencies throughout and low alder frequencies in zone VIII, are best understood in terms of a locally dominated pollen spectrum.
CHANGES IN THE CARBOHYDRATE COMPOSITION OF LEAVES OF TUSSILAGO FARFARA DURING INFECTION BY PUCCINIA POARUM
Authors: HOLLIGAN P. M. , CHEN C. , LEWIS D. H. 
Published: May 2006

SUMMARYLow molecular weight sugars and sugar alcohols, fructans of varying molecular weight and neutral sugars derived by acid hydrolysis from healthy leaves of Tussilago farfara and leaves infected by pyenial and aecial stages of Puccinia po arum have been identified and quantitatively analysed. At sites of infection, there are progressive increases in amounts of the fungal components, mannitol, arabitol and a mannose containing polymer, and of host fructans. Results are compared and contrasted with other host‐parasite combinations.
THE EFFECT OF RHIZOPHAGUS TENUIS MYCORRHIZAS ON RYEGRASS, COCKSFOOT AND SWEET VERNAL
Authors: CRUSH J. R. 
Published: May 2006

SUMMARYGrowth of ryegrass (Lolium perenne) in a soil extremely deficient in available phosphorus, depended on conversion of most of the root system into endomycorrhizas by Rhizophagus tenuis. A further growth increment could be obtained in infected plants by adding other nutrients, whereas uninfected plants responded only to phosphorus. Cocksfoot (Dactylis glomerata) and sweet vernal (Anthoxanthum odoratum) also relieved extreme phosphorus deficiency by symbiosis with Rhizophagus tenuis; but in slightly more fertile soil all three grasses grew better without the fungus. Then R. tenuis grew mainly in the rhizosphere of inoculated plants with much less penetration.
EFFECT OF ENDOGONE MYCORRHIZA ON PLANT GROWTH V. INFLUENCE OF INFECTION ON THE MULTIPLICATION OF VIRUSES IN TOMATO, PETUNIA AND STRAWBERRY
Authors: DAFT M. J. , OKUSANYA B. O. 
Published: May 2006

SUMMARYThe effects of mycorrhizal infection on the production of three viruses in three hosts were examined. In tomato, the multiplication of tomato aucuba mosaic virus was increased and the amount of potato virus × produced depended on the stage of the mycorrhizal development. The amount of extractable arabis mosaic virus from petunia and strawberry plants was greater from mycorrhizal than from non‐mycorrhizal plants. These results are attributed to the higher levels of phosphate contained in mycorrhizal plants, because enhanced virus production could also be achieved in non‐mycorrhizal plants given various levels of soluble phosphate. These results are discussed in relation to other three‐membered systems.
GROWTH AND NITROGEN FIXATION IN LUPINUS ARBOREUS AS AFFECTED BY SHADING AND WATER SUPPLY
Authors: SPRENT JANET I. 
Published: May 2006

SUMMARYThree experiments were carried out to investigate the effects of shading and water supply on growth and nitrogen fixation by young plants of Lupinus arboreus (up to 4 months old). Firstly, two light treatments, 20,000 and 6500 lux, were given under controlled environment conditions, and plants sampled weekly for 7 weeks. Secondly, four shading treatments (100%, 37%, 19% and 10% full daylight) were given to plants grown outside and samples taken after 4, 8 and 10 weeks. Thirdly, response to and recovery from moisture stress were investigated under controlled‐environment conditions.Results from the two shading experiments showed that L. arboreus responds to shade as a typical mesophyte. Growth (measured as dry weight) was proportional to the logarithm of relative irradiance. Roots were affected more than shoots and hence the shoot: root ratio rose with increased shading. Water content varied with age and shading, the responses differing amongst different parts of the plant. Photosynthetic efficiency increased with moderate shading but decreased, as did relative growth rate, at 10% full daylight. The compensation point was estimated to be 7–8% full daylight (approximately 70 J cm‐2 day‐1).Nodule number and weight were reduced by shading. There was a highly significant linear relationship between root and nodule dry weights, I g root tissue supporting 50 mg nodule tissue. Acetylene‐reducing activity per plant was also proportional to log relative irradiance and this was largely accounted for by the smaller amounts of nodule tissue formed under shade. Activity per milligram fresh weight was only slightly reduced by moderate shading and this probably resulted from increased vacuolation of the infected cells. Only severe shading (10% full daylight) had a marked effect on activity per milligram fresh weight. Nodule senescence was not observed under shade, since the amount of nodule tissue formed was in equilibrium with growth of other parts of the plant. N content was higher in shaded plants after 1 week, but the difference diminished with time until at 5 weeks the N content was the same in shaded and control plants.Response to and recovery from moisture stress were similar to those reported for other species. Seedlings were grown on the fine sand taken from forests where L. arboreus is planted in New Zealand. In this sand the change from sufficient water to severe deficit occurs over a very small range of water contents (1.0–0.5% DW). Shaded plants responded to similar levels of stress as unshaded plants. Water potentials of leaves measured with a pressure bomb were correlated with acetylene‐reducing activity of nodules.
SEASONAL GROWTH AND GROWTH RATE‐COLONY SIZE RELATIONSHIPS IN SIX SPECIES OF SAXICOLOUS LICHENS
Authors: ARMSTRONG R. A. 
Published: May 2006

SUMMARYThe pattern of seasonal growth and the relation of growth rate to colony size were studied in four foliose and two crustose species of saxicolous lichens. A new method of measuring growth was used whereby the advance of a sample of lobes along millimetres marked on the substrate was measured under a magnification of × 10. Three peaks of growth were found (in March, June and November) for the foliose species and a single peak (in May–August) for the crustose species. The peaks of growth corresponded approximately to peaks of rainfall. Growth rate in relation to increasing colony size fell in a smooth exponential curve when expressed on a cm2/cm2/unit time basis. This result is consistent with a linear radial rate for most of the thallus sizes for the six species. There is also evidence for an exponential increase in growth rate initially until about 1.5 cm thallus diameter in two of the species when the linear radial rate is achieved.
ONSET OF SEED DORMANCY IN AEGILOPS KOTSCHYI BOISS. AND ITS EXPERIMENTAL MODIFICATION
Authors: WURZBURGER JUDITH , KOLLER D. 
Published: May 2006

SUMMARYOnset of seed dormancy in caryopses of Aegilops kotschyi was investigated. Neither of the two caryopses in the spikelet was germinable until the fourth week after anthesis. After this, germinability of the upper caryopsis increased progressively while that of the lower one remained low. Drying by lyophilization improved germinability of the upper caryopsis, but only during the phase of increasing germinability. Excision of the upper floret at, or soon after anthesis, enhanced germinability of the remaining lower caryopsis. This response became progressively weaker as excision was delayed. The possibility is discussed that dormancy of the lower caryopsis depends on competition between the upper and lower caryopsis for an essential metabolite.
ACTIVE ACCUMULATION OF SODIUM BY ROOTS OF FIVE AQUATIC SPECIES
Authors: SHEPHERD U. H. , BOWLING D. J. F. 
Published: May 2006

SUMMARYThe accumulation of several major nutrient ions by the roots of some aquatic plants was investigated. Five species growing in freshwater lochs on the north coast of Scotland were studied. Electrical potential differences between root epidermal cells and the surrounding loch water were measured using micro‐electrodes. From these measurements, electrochemical potential gradients between the roots and the loch water were calculated, and also the driving forces on each ion. For each species investigated, the results indicate that sodium is actively accumulated by the roots. This contrasts with results of studies which provide evidence for a sodium efflux pump in plant cells. It is suggested that active accumulation of sodium is evident in plant roots when the external sodium concentration is low. The results showed that K+, Cl‐, and NO3‐ are actively accumulated; Ca++ and Mg++ appear to be in electrochemical equilibrium with the external medium.
CARBON DIOXIDE AND ETHYLENE EFFECTS IN THE CO‐ORDINATION BETWEEN THE POLLINATOR BLASTOPHAGA QUADRATICEPS AND THE SYCONIUM IN FICUS RELIGIOSA
Authors: GALIL J. , ZERONI M. , (BOGOSLAVSKY) D. BAR SHALOM 
Published: May 2006

SUMMARYThe multilateral inter‐relationships between figs and their pollinators contain ecophysiological elements in addition to morphological and behavioural co‐adaptations. The changes in the internal atmosphere of the ripening fig have a decisive effect on the activity of males and females of the pollinating wasp. During the early stages of the male phase of Ficus religiosa, the internal atmosphere of the fig consists of about 10% CO2, 10% O2 and some ethylene. The males of the pollinator, Blastopliaga quadraticeps, carry out their usual activities in perforating the walls of the galls and in fertilizing the females under these conditions while at the same time the females are inactivated. After perforation of the syconia wall by the males, the atmosphere within the fig becomes equilibrated with the external atmosphere. As a result, male wasps are inhibited, whereas the females become active, leave their galls, load pollen pockets with pollen and emerge from the fig. The differential response of male and female wasps to the changes in the composition of the internal atmosphere within the fig ensures the completion of the developmental cycle of both the pollinator and the fig. Differences in the behaviour of wasp pollinators of different Ficus spp. under normal conditions are regarded as adaptations to diversely composed internal atmospheres within male‐phase figs of the respective species.
GRAVITY AND THE DISTRIBUTION OF LEAF SHAPE IN THE TREES OF SASSAFRAS ALBIDUM
Authors: GHENT ARTHUR W. 
Published: May 2006

SUMMARYStudies of leaf distribution in the North American Sassafras albidum (Nutt.) Nées revealed marked excesses of lobed leaves, above random expectation, attached to the gravitationally lowermost three‐eighths of branches, although some leaves of the ovate, two‐lobed, and three‐lobed shapes were found in all attachment positions. Ovate leaves predominate along the upper surface, and at the base and apex of branches. Air‐dry weights of leaves of all three shapes proved significantly heavier at lower and mid‐branch attachment positions. Ovate leaves on secondary branchlets were shown to be significantly more lanceolate than those on primary branches. No consistent pattern of lobed‐leaf frequency relative to the concept of ‘juvenile’ and ‘mature’ foliage could be detected. The ‘thumb‐lobes’ of two‐lobed leaves were found to occur with significantly greater frequency on the apically directed, gravitationally lower edges of laterally‐attached leaves. Speculation on the possible role of starch grains or similar heavy‐bodied entities, as determinants of leaf‐lobing, is presented.
PLATE TECTONICS AND SOME ASPECTS OF PACIFIC PLANT GEOGRAPHY
Authors: WHITMORE T. C. 
Published: May 2006

SUMMARYThe new interpretation of the geological history of the west and south‐west Pacific, in the light of plate tectonic theory, is that the islands formerly lay much closer or in contact with each other and with the land masses which form the western rim of the Ocean. There have been massive increases in separation during the Tertiary because of ocean floor spreading. Plant distribution patterns in the region are re‐interpreted against this history. Old World Winteraceae (centred around the Coral Sea) and Ficus section Pharmacosycea (ranging east to New Caledonia) are considered in detail. Attention of geologists is drawn to enigmas of phytogeography whose interpretation await refinement of the geological reconstruction, namely the high endemism of New Caledonia and amphi‐Pacific plant genera of the lowland humid tropics.
TIMING ABSCISSION IN PHASEOLUS VULGARIS L. BY CONTROLLING ETHYLENE PRODUCTION AND SENSITIVITY TO ETHYLENE
Authors: JACKSON MICHAEL B. , HARTLEY CHRISTOPHER B. , OSBORNE DAPHNE J. 
Published: May 2006

SUMMARYAbscission in explants excised from the primary‐leaf petioles of dwarf bean (Phaseolus vulgaris L. cv. Canadian Wonder) is accelerated by removing the leaf‐blade 24 or 48 hours before the explants are cut. Deblading increases ethylene production before weakening of the abscission zone begins and the amount of ethylene produced is sufficient to promote abscission. Deblading also enhances the responsiveness of explants to ethylene and it is proposed that these two effects of deblading together account for the subsequent acceleration of abscission. If the auxin indol‐3‐yl acetic acid is applied to freshly debladed petiole stumps the responses to deblading do not occur.Explants from older plants abscind more slowly than those from younger plants and the difference can be related to the higher sensitivity to ethylene of younger explants, rather than to differences in their patterns of ethylene production. The nature of this sensitivity is briefly discussed.
PINOCYTOSIS, ATP‐ASE AND ION UPTAKE BY PLANT CELLS
Authors: BAKER D. A. , HALL J. L. 
Published: May 2006

SUMMARYThe possible role of membrane‐bound vesicles in the uptake of ions by plant cells is discussed. Evidence of compartmentation obtained from kinetic analyses of the influx and efflux of ions is considered in conjunction with the findings of biochemical and cytochemical studies of ATP‐ase activity and localization with reference to the possible role of this enzyme in ion uptake. A model is proposed for ion uptake, an important feature of which is the formation of pinocytotic vesicles at the plasmalemma. This model also incorporates the differential pattern of uptake observed at low (system 1) and high (system 2) external concentrations. The relationship of such mechanisms to long‐distance transport of ions is considered.
ENHANCEMENT OF NITRATE REDUCTASE ACTIVITY IN SENESCING KALE LEAF DISCS BY N,N‐DIMETHYLAMINO‐SUCCINAMIC ACID
Authors: KNYPL J. S. 
Published: May 2006

SUMMARYFreshly cut discs (385 mm2 total area) from mature leaves of kale (Brassica oleracea L. var. acephala) produced about 70 nmol NO‐2 when incubated with 0.02 M KNO3 for 3 hours. The amount of NO‐2 formed in the 3‐hour test was smaller when the discs were incubated on water for 24 hours before the test but it was much increased when the discs were incubated for 24 hours with KNO3, KNO3 plus N,N‐dimethylamino‐succinamic acid (B‐Nine) or B‐Nine alone. The effort of B‐Nine on increasing nitrate reductase activity was abolished by cycloheximide and unaffected by chloramphenicol. It is concluded that B‐Nine can induce the synthesis of nitrate reductase in the absence of light or of nitrate.
EFFECT OF ENDOGONE MYCORRHIZA ON PLANT GROWTH VI. INFLUENCE OF INFECTION ON THE ANATOMY AND REPRODUCTIVE DEVELOPMENT IN FOUR HOSTS
Authors: DAFT M. J. , OKUSANYA B. O. 
Published: May 2006

SUMMARYThe effect of Endogone infection on the stem anatomy and on the reproduction in tomato, maize, strawberry and petunia was examined. In tomato, petunia and maize plants, the infection increased the amount of vascular tissue. The lignification of the xylem was greater in mycorrhizal tomato and petunia plants and more vascular bundles were produced in the maize plants. Mycorrhizal infection stimulated flower production in petunia, the formation of fruit in strawberry and the development of pollen in maize.
THE SUPPLY OF PHOTOSYNTHETIC ASSIMILATES TO NODULES OF PISUM SATIVUM L. IN RELATION TO THE FIXATION OF NITROGEN
Authors: LAWRIE A. C. , WHEELER C. T. 
Published: May 2006

SUMMARYA marked correlation was found between the accumulation of labelled photosynthates in nodules and the rate of acetylene reduction during the growth cycle of pea plants in nitrogen‐free culture. Both the rate of acetylene reduction and this accumulation of labelled photosynthates were reduced when plants were darkened for different lengths of time and then fed 14CO2 immediately on return to the light, but, when plants were fed 14CO2 prior to darkening, photosynthates continued to accumulate in the nodules as nitrogenase activity declined.Micro‐autoradiography of active nodules indicated that the main site of accumulation of labelled photosynthates was the infected tissue. The main ‘sink’ appeared to be cells partially filled with bacteroids and little accumulation was observed in cells which were completely filled. By contrast, histochemical tests with tetrazolium salts suggested that the major sites of reduction were the cells which were totally occupied by bacteroids. The less densely filled cells showed much less reducing activity.The main sites of accumulation of labelled photosynthates do not apparently correspond with the sites of most active reduction and a substantial part of the photosynthates received by the nodules therefore appears not to be deployed in nitrogen fixation. It is suggested that nitrogen fixation is supported mainly by a rapid, undetected flux of photosynthates through metabolically active cells densely filled with bacteroids, which have largely ceased to multiply.
MODERN POLLEN RAIN STUDIES IN ICELAND
Authors: RYMER L. 
Published: May 2006

SUMMARYThe relationship between modern pollen rain and the floristic composition of vegetation was studied for six vegetation types in Iceland, viz. fell‐field, Rhacomitrium heath, grassland with dwarf‐shrub, dwarf‐shrub heath, mires within dwarf‐shrub heath, and a Salix herbacea‐ dominated slope. The results suggest that the vegetation types examined can be characterized, to some degree, by their modern pollen rain.
THE POLARITY OF AUXIN TRANSPORT IN INVERTED CUTTINGS
Authors: SHELDRAKE A. R. 
Published: May 2006

SummaryThe original, basipetal polarity of auxin transport persisted in the stems of inverted cuttings of Tagetes, tomato and tobacco in spite of the reversal of the relative positions of the roots and shoots. No significant acropetal auxin transport could be detected even after four months growth. These results indicate that the polarity of newly formed cells in secondarily thickening internodes is determined by the existing polarity of auxin transport within the tissues.
ON THE INHIBITION OF MESOCOTYL GROWTH BY ETHYLENE
Authors: MER C. L. 
Published: May 2006

SummaryOat seedlings have been treated with ethylene‐generating substances, (2‐chloroethyl)phos‐phonic acid (ethrel) and β‐hydroxyethylhydrazine (B‐OH), as well as with gaseous ethylene in an attempt to confirm the claim that mesocotyl growth can be stimulated by ethylene. The factorially arranged experiments included a standard exposure to light to permit evaluation of the light × ethylene interaction.Ethrel always inhibited growth and caused the malformations associated with ethylene treatment. In contrast, B‐OH brought about the ‘CO2 effect’; that is, mesocotyl growth was retarded at first but subsequently enhanced due to an increased number of cells having an unchanged final length, while the growth of the coleoptile was reduced. These plants showed no ethylene‐type distortions, however. As ethylene gas itself was invariably inhibitory it cannot be assigned any stimulatory properties at the concentrations used.One treatment combination (B‐OH with CO2) caused the death, selectively, of the tip cells of the coleoptile. Even without these cells, allegedly an essential part of the growth‐regulatory system of the seedling, a promotion of mesocotyl growth was observed.In the discussion support is deduced for the view that mesocotyl growth is not controlled by the tip of the coleoptile.