bluuebunny/crossref_metadata_2025_split huggingface dataset:
FRUIT BIOLOGY AND GERMINATION OF TWO TROPICAL POTAMOGETON SPECIES
Authors: SPENCE D. H. N. , MILBURN T. R. , NDAWULA‐SENYIMBA M. , ROBERTS E. 
Published: May 2006

SummaryThe drupes or achenes of Potamogeton schweinfurthii A. Benn. and P. richardi Solms. can float for long periods and germination only occurs naturally once the fruits have sunk. The factors controlling their floating, sinking and germination have been investigated. After brief reference to water depths at which these species occur in Uganda, fruit structure is described. The epicarp and mesocarp are initially green in both species and remain green in ripe, floating fruits of P. schweinfurthii. The sheathed embryo lies along the rim of the stony endocarp beneath a lid which can be detached by surgery.Of the factors relating to buoyancy and sinking in P. schweinfurthii, daylight compared with almost total darkness decreased the rate of discoloration of the green floating fruits, the rate at which the pericarp disintegrated and the rate of sinking. Measurements of respiratory oxygen uptake, net photosynthesis rates and density changes, in a series of unripe to just‐sunk fruits of P. richardi, suggest that this light‐dependence of floating fruits is connected with the maintenance of constant volume and density through gaseous relations within an intact cuticle. During prolonged darkness, fruit density increased at constant mass by shrinkage of the soft parts, caused by degenerative changes and absence of photosynthesis.Neither species germinated in the dark, compared with 100% of light‐stored, sunken fruits or with similarly stored fruit from which epicarp and mesocarp had been scraped. In the light, substantial germination also occurred in both freshly shed and older floating fruits after surgical exposure of the embryo. No after‐ripening period is required.Presumptive evidence was obtained for the promoting effect of red light on germination in P. schweinfurthii. Using a calibrated Schwarz thermopile and narrow‐band interference filters, the promoting effect of 0.05 J/cm2 of red light was established for P. richardi fruits with exposed embryos. Photoreversibility was established by similar doses of far‐red.These irradiation values are characteristic of the phytochrome system. Embryos within the intact stony endocarp require an irradiation of 8–10 J/cm2 (652 nm) for promotion and an equivalent dose of far‐red for reversal.These findings are discussed in relation to the ecology and distribution of the species.
POST‐POLLINATION PHENOMENA IN ORCHID FLOWERS
Authors: ARDITTI JOSEPH , FLICK BRIGITTA , JEFFREY DAVID 
Published: May 2006

SummaryApplications of ABA to Cymbidium flowers induce some, but not all, post‐pollination symptoms. Anthocyanin levels in sepals, petals, columns and labella are raised; flowers wilt; dorsal sepals become hooded; calli develop colouration while losing turgidity; columns do not swell, lose very little curvature; and stigmas do not close. Combinations of ABA and NAA induce all post‐pollination phenomena, but lower anthocyanin content than treatments with ABA only. ABA plus GA3 have effects which are similar to those of ABA alone, except that anthocyanin levels are reduced. The same is essentially true of ABA‐kinetin mixtures but intensities of the effects are different and with some concentration ratios, stigmatic closure also occurs. The effects of ABA and its interactions with GA3, kinetin or NAA are explained in terms of the roles these hormones may play in synthesis of nucleic acids and enzymes.
SOME GENETIC FACTORS AFFECTING FRUIT DEVELOPMENT IN RASPBERRIES
Authors: JENNINGS D. L. 
Published: May 2006

SummaryTwo diallel crosses between red raspberry parents were made and auxin applied to alternate fruits 7 days after pollination. In a diallel made in 1964 interaction effects between pollen and the maternal effect considerably influenced the set of pyrenes, but maternal effects predominated in a diallel made in 1965. Application of auxin in the first diallel reduced the interaction effects. It is postulated that the set of large pyrenes was largely determined by the interaction of physiological effects contributed by the male and female parents, but that maternal effects were so strong in the second diallel that variations in those of the male parent were less important. These factors were probably concerned with the arrest of flower growth and its subsequent recommencement following pollination. Auxin apparently affected late acting factors associated with seed tissues, but these were relatively unimportant for pyrene set. Self pollination improved the set of pyrenes in the first diallel, perhaps because the conditions were similar to those under which the varieties were originally selected. Maternal parents differed in the rate at which their fruits ripened, but the pollen parent also influenced the rate of ripening.
SOME CONSEQUENCES OF RASPBERRY POLLEN DILUTION FOR ITS GERMINATION AND FOR FRUIT DEVELOPMENT
Authors: JENNINGS D. L. , TOPHAM P. B. 
Published: May 2006

SummaryComparisons of pyrene set were made between raspberry flowers pollinated with undiluted pollen and others pollinated with pollen diluted with talc, or killed pollen. Pollen dilution reduced set but the reduction was not the same for all maternal parents. It also reduced the rate of fruit ripening, increased the proportion of pyrenes without seed content and reduced the tendency for abortive carpels to develop into small empty pyrenes. Observations of numbers of pollen grains germinating in the styles revealed differences attributable to the maternal parents, the pollen germinating poorest on the parent whose pyrene set was reduced most by pollen dilution. There were also maternal × paternal interaction effects on pollen germination. It is concluded that pollen germination was conditioned by growth substances provided partly by the grains themselves and partly by the styles of the seed parent, and that there were interactions between the two sources. Reduction in pollen concentration affected several aspects of early fruit development, but quantitative differences in the amount of pollen applied did not reduce the adverse effects of using diploid pollen. This suggests that such effects do not arise through direct action of the pollen on the maternal tissues.
LEAFLESS EUPHORBIA IN RAJASTHAN ROCKS
Authors: SEN D. N. , Sharma K. D. , Chawan D. D. 
Published: May 2006

SummaryStudies of attached and detached leaves of Euphorbia caducifolia, the latter collected from morphologically different plants, suggested that this species exhibited typical crassulacean features of acid metabolism. Fluctuations in acidity were found to be due mostly to the appearance and disappearance of malic acid in dark and light respectively. Deacidification also took place when leaves were kept in dark for a longer period. The TAN showed a fall when the leaves aged and were about to fall. A remarkable feature found in this species was the high percentage of total acids which ranged up to 8240 mg/100 g fresh weight of leaves, together with great differences in the constituents analysed. This suggests that morphological diversity is correlated with physiological diversity.
RESPIRATORY ENZYME SYSTEMS IN CULTURED CALLUS TISSUES
Authors: CHONG‐JIN GOH 
Published: May 2006

SummaryRespiratory enzymes of the glycolytic, pentose‐phosphate pathways and Krebs cycle were detected in cell‐free preparations from cultured callus tissues of potato and artichoke tubers. Some of the enzymes functioning in glycolytic or pentose‐phosphate pathways seemed to be associated with a particulate preparation.
A VIRESCENS MUTANT OF PHASEOLUS VULGARIS: PHOTOSYNTHESIS AND METABOLIC CHANGES DURING LEAF DEVELOPMENT
Authors: HEYES J. K. , DALE J. E. 
Published: May 2006

SummaryFixation of 14CO2, photophosphorylation, and protein, lipid and RNA composition have been compared for primary and trifoliate leaves of various ages of control and mutant plants.Except when old, leaves of control plants fix more CO2 than do those of the mutant, but the carboxylation pathways seem similar in the two plants. The level of Fraction I protein and that of ribulose diphosphate carboxylase activity are also similar, but lower in leaves of the mutant. Photophosphorylation per chloroplast mediated by photosystems I and II, tends to be slightly higher in the mutant, despite lower levels of chlorophyll in mutant plastids. Small differences in amount and composition of leaf lipids, but large differences in RNA content were found. Mutant leaves show a higher initial content of cytoplasmic ribosomal RNA than do controls; as leaves age this position is reversed. Chloroplast ribosomal RNA is initially similar, but continued synthesis is greater and more prolonged in the mutant.The significance of these data is discussed in relation to the nature of the mutation.
THE IDENTITY OF MENYANTHES MICROSPERMA N. SP. FOSS. FROM THE GORT INTERGLACIAL, IRELAND
Authors: WATTS W. A. 
Published: May 2006

Summary ‘Menyanthes microsperma’, an unknown seed from the Gort (Hoxnian) Interglacial deposit, Ireland, is a species of Nymphoides, probably the North American species N. cordata (Ell.) Fern.
THE OCCURRENCE AND SIGNIFICANCE OF AUXIN IN THE SUBSTRATA OF BRYOPHYTES
Authors: SHELDRAKE A. R. 
Published: May 2006

SummaryAuxin was detected in samples of substrata supporting bryophytes in a variety of locations in both Britain and Malaya. Activity occurred on chromatograms at zones corresponding to the Rf of indole acetic acid. The range of concentrations found, 0.4–10.4 μg/1, probably represents a two‐ to five‐fold underestimate due to losses during extraction and purification. The amounts of auxin in samples of soil on which bryophytes were not growing were within the same range. The importance of this environmental auxin for the induction of rhizoids in liverworts and for roots of higher plants is discussed.
THE ACCUMULATION OF 65ZN BY ROOT HOMOGENATES OF ZINC‐TOLERANT AND NON‐TOLERANT CLONES OF AGROSTIS TENUIS SIBTH.
Authors: TURNER R. G. , MARSHALL C. 
Published: May 2006

SummaryThe localization of 65Zn was examined in cell‐free systems extracted from the roots of clones of Agrostis tenuis in further investigations on the mechanism of heavy metal tolerance in this grass species. The cell wall fraction was a major site for zinc accumulation especially in a zinc‐tolerant clone where more zinc accumulated at this site than in non‐zinc‐tolerant clones. In the absence of the cell wall fraction or when its zinc‐binding potential had been reduced, other particulate cellular components accumulated large amounts of zinc. Zinc uptake by the cell wall occurred by the same process in all the clones studied. Uptake was very rapid and independent of temperature and pH, suggesting an exchange adsorption process. A basis for zinc tolerance in A. tenuis is briefly discussed.
SOME ASPECTS OF THE GROWTH OF MANGO (MANGIFERA INDICA L) LEAVES
Authors: TAYLOR F. J. 
Published: May 2006

SummaryQuantitative analyses for total methanol‐soluble material, methanol‐soluble carbohydrates, anthocyanin, chlorophyll, methanol‐insoluble nitrogen, saponifiable material, pectin, lignin, hemicellulose, and α‐cellulose were made at weekly intervals for the first 6 weeks of the growth of mango leaves. The results show that in the first 4 weeks, when the leaves contain anthocyanin, production of photosynthetic carbohydrates was low, and lignin and cuticle syntheses ‐were virtually absent. The increase in rigidity of the mango leaf between the second and fifth weeks was significantly correlated with an increase in the hemicellulose content of the leaf.
THE FIELD DISTRIBUTION OF INTERACTING STRAINS OF POLYPORUS SCHWEINITZII AND THEIR ORIGIN
Authors: BARRETT D. K. , USCUPLIC M. 
Published: May 2006

SummaryThe interaction phenomenon between cultures of Polyporus schweinitzii has been investigated and used to determine the natural distribution of different strains of this fungus in conifer plantations. The interaction behaviour of synthetic heterokaryons has shown that those derived from the pairing of completely unrelated basidiospores are those most likely to simulate the interaction potential of wild strains. The development of interacting strains from genetically complex polysporous mycelia is discussed.
CYTOLOGY AND POLLEN MORPHOLOGY OF NATURAL AND ARTIFICIAL TETRAPLOIDS IN THE LINUM PERENNE GROUP
Authors: OCKENDON D. J. 
Published: May 2006

SummaryArtificial tetraploids of the Linum perenne group closely resemble their diploid progenitors in macroscopic characters, but differ markedly in their pollen morphology. The pollen of the diploids invariably has three furrows, that of the natural tetraploids normally has six pores and that of the artificial tetraploids typically has six furrows. The pollen of the artificial tetraploids is particularly variable because of tendencies towards syncolpy and the asymmetrical arrangement of furrows. The artificial autotetraploids tend to have lower pollen fertilities and more meiotic irregularities than the artificial allotetraploids. None of the artificial tetraploids resembled the natural tetraploid L. perenne subsp. anglicum particularly closely, but its origin is discussed in the light of the available evidence.
STUDIES OF AUSTRAL BRACKEN (PTERIDIUM ESCULENTUM) IN THE VICINITY OF CANBERRA
Authors: CARTLEDGE O. , CARNAHAN J. A. 
Published: May 2006

SummaryAustral bracken (Pteridium esculentum) in the vicinity of Canberra is shown to behave differently from the European P. aquilinum. Studies of the morphology of the rhizomes suggest that the margins of austral bracken advance slowly and irregularly.Only two phases are recognizable in the austral bracken plant: the marginal phase and the central phase. The marginal phase is characterized by short fronds and rhizomes that are approximately parallel. The central phase generally has tall fronds, a dense rhizome system and rhizomes that lack the spatial orientation found at the margin.Sheep and cattle tracking and vigorous rhizomatous grasses may inhibit frond emergence. These factors in association with relatively low rainfall and poor soil may be responsible for the slow rate of expansion of bracken margins.
COMPARTMENTATION AND LOW TEMPERATURE FLUXES OF POTASSIUM IN MYCELIUM OF DENDRYPHIELLA SALINA
Authors: JENNINGS D. H. , AYNSLEY J. S. 
Published: May 2006

Summary Dendryphiella salina was grown at 21° C in two media, identical except that one contained potassium labelled with 42K. The cultures were transferred to 2° C, the fungus separated from the medium, the radioactive mycelium placed in the non‐radioactive medium and the efflux of 42K measured. Under these conditions the rate of dry weight increase is reduced by at least 75%. The fungus behaves as a multicompartment system with regard to potassium with at least 75% of the ion being in the slowest‐exchanging compartment. The efflux from this compartment into a medium containing 2.5 mM potassium is of the order of 0.14 p moles cm−2 sec−1, being at least doubled when 50 mM sodium is present. Addition of 10 mM calcium in the presence of sodium reduces the efflux to a value close to that obtained when sodium is absent.
THE EFFECTS OF PHOSPHORUS DEFICIENCY ON THE GROWTH OF EPILOBIUM MONTANUM L.
Authors: ATKINSON D. , DAVISON A. W. 
Published: May 2006

SummaryA study was made of the effects of altering the length and timing of a period of phosphorus deficiency on populations of Epilobium montanum L. The total amount of phosphorus per leaf increased with the length of time for which the element was supplied but the concentration of certain phosphorus fractions varied with both the length and timing of the deficiency. An initial period of deficiency before giving a phosphorus supply produced a drastic decrease in growth and prevented flowering. This appeared to be caused by non‐utilization of phosphorus rather than inhibition of uptake. All three populations were extremely plastic in their response to phosphorus; plants which had only 1 week with phosphorus produced stolons while those which had 2 weeks produced viable seed. This plasticity may partly account for the occurrence of the species in extreme environments and for its success as a weed. The main difference between the populations was not in phosphorus nutrition but in the relative proportion of seeds and stolons produced.
BACTERIAL PATHOGENS OF FRESHWATER BLUE‐GREEN ALGAE
Authors: DAFT M. J. , STEWART W. D. P. 
Published: May 2006

SummaryFour bacterial isolates have been obtained which cause lysis of laboratory cultures and natural populations of blue‐green algae. Over forty algal strains belonging to all orders of the blue‐green algae and including bloom‐forming species are susceptible. The bacteria also lyse certain gram‐positive and gram‐negative bacteria. The organisms are aerobic, gram‐negative rods, aflagellate, motile and pigmented with an absorption maximum of the pigments in methanol occurring at 435 nm and with shoulders at 460 nm and 415 nm. The guanine and cytosine in the DNA is within the range of 65–69± 1 M%. The organisms are identified tentatively as members of the Myxobacterales. Lysis of vegetative cells of the algae depends on the presence of growing bacteria, bacteria‐free filtrates alone being insufficient to cause lysis. Heterocysts are not lysed. The bacterial plaques resemble viral plaques in appearance. The lytic agents rapidly inhibit metabolic activity of the susceptible algae and may cause cell lysis within 2–10 hours. The isolates can be propagated readily in the absence of the host and are probably widely distributed in freshwater habitats.
SOME GENETIC FACTORS AFFECTING THE DEVELOPMENT OF ENDOCARP, ENDOSPERM AND EMBRYO IN RASPBERRIES
Authors: JENNINGS D. L. 
Published: May 2006

SummaryThe sizes and shapes of different parts of pyrenes obtained from two diallel crosses of raspberry were influenced both by maternal effects and by interaction effects involving maternal and genetic factors. The relative importance of these effects depended upon the environment in which the crosses were made. For a diallel made under field conditions interactions with maternal factors were large but considerably reduced by applying auxin to the developing fruits. For a diallel made in a glasshouse maternal effects were more important and maternal interaction effects less so. Application of auxin to the fruits reduced endosperm or embryo size in some crosses and increased it in others. It is postulated that these responses were related to the endogenous content of growth substances, negative responses indicating their presence in supra‐optimal concentration, and that variations in the responses provide clues to the physiological factors which govern successful pyrene development.
VARIATION IN EUCALYPTUS OBLIQUA L'HÉRIT
Authors: GREEN J. W. 
Published: May 2006

SummaryOpen‐pollinated seedling progenies of Eucalyptus obliqua grown in a uniform environment showed evidence of genetic variation among geographically different localities and among parent trees within localities. Locality variation did not appear habitat‐correlated, so no predictor of a superior locality for tree‐improvement purposes could be suggested, other than appearance of the trees; breeding strategy should include tree selection within localities. Several superior localities were indicated consistently but many showed marked fluctuations, suggesting the need for caution in interpreting seedling data.
SOME ASPECTS OF THE GROWTH OF MANGO (MANGIFERA INDICA L) LEAVES
Authors: TAYLOR F. J. 
Published: May 2006

SummaryYoung's modulus and tensile strength have been measured on mango leaves at weekly intervals up to the age of 35 days. Both increase with age, but there is a fall in the rate of increase of Young's modulus at 21 days. The relative plastic/elastic extension increased to a maximum at day 21. Prior to day 21, turgidity played an important role in the elasticity of the leaf, but not after that date. These changes are discussed in relation to the composition of the cell wall. Removing the cuticle and cell wall constituents sequentially showed that pectin was responsible for all the mechanical properties of the leaf up to day 14, when leaf expansion ceased. At day 35 the cuticle and the lignin together contributed about 80% to the tensile strength, and the cuticle alone about 70% to the Young's modulus.
INTERACTION EFFECTS OF GLUCOSE AND AUXINS IN ROOTING ETIOLATED STEM SEGMENTS OF SALIX TETRASPERMA
Authors: NANDA K. K. , JAIN M. K. 
Published: May 2006

SummaryEtiolated, 2·5 cm long stem segments of Salix tetrasperma did not root when cultured in agar even with 0·1% glucose, but rooted with 1·0% glucose in the medium. Rooting decreased with 2·0% and was completely inhibited by 5·0% glucose. Both IAA and IBA induced rooting when added to 0·1% glucose, the number of rooted segments decreasing with the concentration of IAA but increasing with that of IBA. Both auxins increased the number of roots when added to 1·0 and 2·0% glucose, the effect increasing with concentration except that 5·0 mg/1 IBA lowered the number as compared to 1·0 mg/1 added to 1·0% glucose. Auxins also induced rooting when added to 5·0% glucose, which alone inhibited it completely. The effect of auxins on the number of roots, however, decreased with the increasing concentration of glucose in the medium except with 5·0 mg/1 IAA which increased it. The results show that auxin effects on rooting are influenced by nutritional status of stem cuttings and that a proper balance of the two is necessary for this purpose.
THE MOVEMENT OF GROWTH REGULATORS AND HERBICIDES INTO THE SIEVE ELEMENTS OF WILLOW
Authors: FIELD R. J. , PEEL A. J. 
Published: May 2006

SummaryUsing an aphid technique to obtain samples of sieve element sap, the movement of certain growth regulators and herbicides, IAA, NAA, MCPA, 2,4‐D, 2,4,5‐T, MH, TCA and paraquat, into the sieve elements of bark strips and stem segments has been investigated.Two pathways were found to be operative in bark strips, a direct one from the free space, and an indirect one via the storage parenchyma. The compounds IAA and NAA, are extensively metabolized. The mobility of IAA into the sieve elements of bark strips and stem segments was considerably greater than that of its principal metabolite, IAA asp, though the latter could enter the sieve elements. The metabolites of NAA could not be detected in the sieve tube.The relative mobilities of the non‐metabolized compounds differed according to the pathway of transport. MCPA and 2, 4‐D were the most mobile on the direct pathway in bark strips, paraquat the least mobile. On the indirect pathway MH and MCPA were the most mobile, paraquat once again being the least mobile. Movement into the sieve elements from the bark of stem segments showed a reversal of the order of mobility found in strips. Here paraquat had the highest relative mobility, TCA the lowest.
PHOSPHATASE ACTIVITY OF INTACT YOUNG WHEAT ROOTS UNDER STERILE AND NONSTERILE CONDITIONS
Authors: RIDGE E. H. , ROVIRA A. D. 
Published: May 2006

SummaryIn assays of acid phosphatase activity with p‐nitrophenyl phosphate as substrate, the low activity found in fluids removed from around roots in liquid medium was not affected by the presence of micro‐organisms. Most phosphatase activity of intact seedling roots was associated with the root surface and was not increased by micro‐organisms in the rhizoplane; in some experiments activity was significantly reduced by soil micro‐organisms. Inoculation of roots with pure cultures of bacteria and a fungus known to have phosphatase activity did not increase this activity of the roots. These results are contrasted with those of other workers. Possible application to the soil situation is discussed.