bluuebunny/crossref_metadata_2025_split huggingface dataset:
BIOLOGICAL EFFECTS OF A HERBICIDE ON A NITROGEN‐FIXING CYANOBACTERIUM (BLUE‐GREEN ALGA): AN ATTEMPT FOR INTRODUCING HERBICIDE‐RESISTANCE
Authors: VAISHAMPAYAN A. 
Published: May 2006

SummaryThe herbicide monuron [3‐(4‐chlorophenyl)‐1, 1‐dimethylurea] inhibits growth and heterocyst formation in the nitrogen‐fixing cynobacterium Nostoc muscorum. These inhibitory effects are glucose‐reversible in both N2 (nitrogen‐free) and NO3− media. A spontaneous mutant of this cyanobacterium, resistant to a dose of monuron normally applied to the rice‐fields of North India, has been isolated and preliminarily characterized as having no requirement for an organic carbon source for its normal physiology under monuron‐treated conditions. The behaviour of the mutant has been tentatively explained as resulting from a permeation mutation preventing monuron entry into N. muscorum.
A CHLOROPLAST AND OTHER ORGANELLES OF PHASEOLUSVULGARIS WITHIN A HYPHA OF COLLETOTRICHUMLINDEMUTHIANUM
Authors: O'CONNELL R. J. , BAILEY J. A. , RICHMOND D. V. 
Published: May 2006

SummaryIn the course of an ultrastructural study of the anthracnose pathogen (Colletotrichum lindemuthianum) infecting hypocotyls of a susceptible cultivar of French bean (Phaseolus vulgaris), a chloroplast and other plant organdies were observed within the cytoplasm of a fungal hypha.The chloroplast retained its morphological integrity and was not enclosed by an extra membrane derived from either plant or fungus. It is possible that the plant organelles entered the fungus through a rupture in the hyphal wail and plasmalemma that permitted cytoplasmic continuity between host and pathogen.
COLONIZATION OF THE ROOT SYSTEM OF SUBTERRANEAN CLOVER BY THREE SPECIES OF VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI
Authors: ABBOTT L. K. , ROBSON A. D. 
Published: May 2006

SummarySubterranean clover infected by Glomus fasciculatum was transplanted into soil containing propagules of two other species of vesicular‐arbuscular mycorrhizal fungi: Acaulospora laevis and Glomus tenue. Root temperatures were maintained at either 15 or 20 °C and the soil was either watered to 80% of field capacity for 3 weeks or left dry before the seedlings were transplanted. Glomus fasciculatum spread well from existing infection except when the soil contained a highly‐infective population of A. laevis. Infection by A. laevis was more rapid at 20 than at 15 °C and was greatly enhanced by pre‐wetting of soil. The lag phase in the development of infection was greater for G. tenue than it was for A. laevis. High values for the percentage of the root length infected by G. tenue were recorded only in plants in which infection by A. laevis did not develop rapidly. There was no effect of G. fasciculatum in the transplanted seedlings on the level of infection formed by A. laevis; at 20 °C the percentage root length infected by G. tenue was lower when plants had been infected by G. fasciculatum. Irrespective of species, the fungus which infected most rapidly in each case had the competitive advantage, probably due to its prior occupancy of the root.
MECHANISMS FAVOURING OUTBREEDING IN STRIGA HERMONTHICA [SCROPHULARIACEAE]
Authors: SAFA S. B. , JONES B. M. G. , MUSSELMAN L. J. 
Published: May 2006

SummarySelf‐incompatibility has been demonstrated in two samples of the parasitic flowering plant, Striga hermonthica, originating from Upper Volta and Sudan. Compatibility was determined by fluorescence microscopy of stigmatic preparations following controlled pollinations. Self incompatibility was associated with floral adaptations favouring pollination by long‐tongued insects such as butterflies. Outbreeding accounts for the variability of S. hermonthica, both in morphology and in host‐specificity. Genetic variation in host specificity imposes limits upon the effectiveness of the present methods of testing tropical cereals for resistance to S. hermonthica.
ECTOTYPIC DIFFERENTIATION IN POA ANNUA: WITHIN POPULATION VARIATION IN RESPONSE TO COMPETITION AND CUTTING
Authors: McNEILLY T. 
Published: May 2006

SummaryDry weight production of seed‐derived material of eight genotypes from each of two populations of Poa annua, one from an open and the other from a closed habitat, was compared as pure stands and in mixture with Lolium perenne cv. S23. Comparisons were made in a glasshouse experiment after 13 weeks growth, when uncut, and when cut to a height of 1.5 cm at 5, 7, 9, II and 13 weeks from planting‐ Significant differences were found between genotypes within both populations when cut in pure stands and in mixture with Lolium, and also in uncut stands in mixture with Lolium. When uncut and in pure stands inter‐genotypic differences were found only in the open population. Between population differences in within population variation were significant only when the populations were cut and in mixed stands, the open population being more variable. The closed population was significantly more variable when uncut and in mixed stands than in any other treatment combination, whilst the open population did not vary significantly with treatment. The occurrence of genetically‐based inter‐population differences in competitive ability in P. annua is confirmed.
PHOTOMORPHOGENIC REGULATION OF REPRODUCTIVE DEVELOPMENT IN GROUNDNUT AND THE SIGNIFICANCE OF NYCTINASTIC LEAF MOVEMENTS
Authors: KARVE A. D. , DESHMUKH A. K. , BHALERAO A. C. , DESHMUKH V. A. 
Published: May 2006

SummaryMany leguminous species are grown under relatively high plant population densities > 250000 plants ha−1. It is argued that these plants can tolerate high population densities because their nyctinastic leaf movements allow their aerial parts to receive directly the last light of the day, which increases the Pfr level in the plants before the onset of darkness, causing them to develop like unshaded plants. Measurements of irradiance above and below the canopy of a densely planted crop of groundnut (Arachis hypogaea fastigiata Waldron) showed that, during daytime, when the leaf laminae were horizontally orientated, only 10% of the incident light reached the ground, while after sunset, with the leaves in the vertical position, 70 to 90 % of the incident light could penetrate to the ground. Natural light, available to the plants after this time, was capable of inducing the straightening of hypocotyl hooks of dark‐germinated seedlings, a typical red light requiring photomorphogenic reaction. Laboratory experiments showed that groundnut plants, receiving daily 5 min red light immediately after the end of the photoperiod, developed significantly more branches and more reproductive organs than plants receiving 10 min far red light. The greater adaptability of two leguminous plants, bush bean (Phaseolus vulgaris L.) and groundnut, to high population density was demonstrated by comparing their performance with that of maize (Zea mays L.), okra (Abelmoschus esculentus Moench), safflower (Carthamus tinctorius L.) and sesame (Sesamum indicum L.) under a high and a low population density. Although crowding caused the plants of all six species to grow taller, with fewer branches and fewer reproductive organs, the harvest index of the two leguminous species remained unaffected by the population density, while that of the remaining four species was significantly reduced by the higher population density.
THE EFFECTS OF DESICCATION ON CONCENTRATIONS AND a/b RATIOS OF CHLOROPHYLL IN LEUCOBRYUM GLAUCUM AND THUIDIUM DELICATULUM
Authors: MARTIN C. E. , WARNER D. A. 
Published: May 2006

SummaryLeaves of shade plants typically have higher concentrations, and lower a/b ratios of chlorophyll than do leaves of sun plants. In poikilohydric mosses as in vascular plants, such differences in concentration have been interpreted either as adaptations which enhance light capture or, in the more exposed mosses, as degradation of chlorophyll owing to water stress. There were no significant correlations between degree of hydration and either concentration or a/b ratios of chlorophyll in tissues of Leucobryum glaucum (Hedw.) Angustt. ex Fr. and Thuidium delicatulum (Hedw.) B.S.G. exposed to increasing water stress. As these data do not support the latter hypothesis, it is concluded that the former explanation is probably valid.
A RELATIONSHIP BETWEEN PHYTOCHROME PHOTOEQUILIBRIUM AND GERMINATION OF SEEDS OF POA TRIVIALIS L. FROM CONTRASTING HABITATS
Authors: HILTON JANET R. , FROUD‐WILLIAMS R. J. , DIXON J. 
Published: May 2006

Summary Poa trivialis L, (rough meadow grass) is an indigenous grass weed of both arable and grassland situations. The effect of light quality on the germination of seed collected from both these habitats was compared. Seed from open, arable habitats germinated poorly when exposed to light giving a Pfr/P ratio similar to that of shade light. In contrast, germination of seed from closed, grassland habitats was much less inhibited indicating that seed germination behaviour may be adapted to the habitat in which the seed was matured. Differences in seed germination behaviour were also observed when seed was buried at various depths in soil under conditions where differences in light quality could be discounted. The results are discussed in relation to the ecological significance of different sensitivities to environmental factors known to influence germination behaviour.
PHOSPHATE UPTAKE BY GOODYERA REPENS IN RELATION TO MYCORRHIZAL INFECTION
Authors: ALEXANDER CLARE , ALEXANDER I. J. , HADLEY G. 
Published: May 2006

SummaryThe rate of P uptake per unit length of root of adult plants of the orchid Goodyera repens Br., infected with the mycorrhizal endophyte Rhizoctonia goodyerae‐repentis Constantin and Dufour, was up to 100 times greater than that of non‐mycorrhizal plants. When the active extramatrical mycelium was reduced by treatment with thiabendazole fungicide, the relative growth rate of mycorrhizal plants was reduced in low P conditions but not in P rich conditions. Rates of P uptake into fungicide‐treated plants were Jess than those of mycorrhizal plants at both P levels. Translocation of 32P from a point source to the plant via the extramatrical mycelium was demonstrated and could be inhibited by the application of thiabendazole. In a model system incorporating a perlite/Vermiculite substrate, translocation of 32P via the endophyte took place over distances up to 9 cm. The mycorrhiza of adult G. repens appears similar to other mycorrhizas in its ability to enhance growth and P uptake.
COMPETITION FOR INFECTION BETWEEN VESICULAR‐ARBUSCULAR MYCORRHIZAL FUNGI
Authors: Wilson J. M. 
Published: May 2006

SummaryThe competitive abilities of three VAM fungi were investigated. Various pairs of fungi were interacted and the amounts of infection produced by mixed and single inocula were compared. The outcome of the interactions varied according to the fungi involved. Aggressiveness appeared to be inversely related to infectivity. In the interactions examined, both Glomus fasciculatum (Thaxter sensu Gerdemann) Gerdemann & Trappe and Glomus tenue (Greenall) Hall were less aggressive than Gigaspora decipiens Hall and Abbott. No interaction occurred between Gl. fasciculatum and GL tenue. Except in the interaction between Gl. fascicidatum and Gi. decipiens, the total amount of infection formed by mixed inoculation was similar to that formed by single inoculation of the more infective fungus of the interacting pair. The outcome of the interactions were shown to be affected, in some circumstances, by inoculum frequency, time of harvest, most incubation of the inoculum, and the spatial distributions of the interacting propagules.
SELENIUM TOXICITY IN PERENNIAL RYEGRASS AND WHITE CLOVER
Authors: SMITH G. S. , WATKINSON J. H. 
Published: May 2006

SummaryShoot concentrations of Se associated with a 10% reduction in dry matter yield were established for perennial ryegrass (Loliumperenne L.) and white clover (Trifolium repens L.) grown in sand culture. Selenite– treated plants had lower shoot concentrations of Se than those treated with selenate; the critical toxic values associated with a 10% reduction in growth were 48 and 320μg Se g− 1 dry matter shoots for ryegrass plants, and 160 and 330μeg1 dry matter shoots for white clover plants, respectively. Differences in the mode of absorption of selenite and selenate, and in the distribution and chemical form of Se found in the plant after absorption, probably account for this disparity in toxicity. While both selenate and selenite increased the Se concentration in the tissues of the plants to high levels, a greater proportion of the absorbed Se was transported to the shoots of the selenate‐treated plants than of those treated with selenite. Increasing supplies of selenate were associated with a reduction in chlorophyll content. Contrary to the concept of a common uptake mechanism in the roots for selenate and sulphate, increasing supplies of selenate had a synergistic effect on S concentrations in the shoots rather than the expected antagonistic effect.
EFFECT OF PHOTOPERIOD AND WATER SUPPLY ON APICAL ABSCISSION OF LONG‐SHOOTS OF TILIA CORDATA MILL.
Authors: PIGOTT C. D. 
Published: May 2006

SummaryGrowth of long‐shoots of Tilia cordata Mill, is sympodial and indeterminate. Abscission of the apex occurs rapidly in short days. In natural conditions abscission occurs in a large proportion of shoots before, or shortly after, the summer solstice when daylength is 17 to 18 h. An experimental study shows that even in long days, if plants are pot‐bound and watered infrequently, apical abscission occurs within a few days of the buds opening. Transferring plants to a large volume of soil or watering frequently delays abscission for several weeks. On a high proportion of plants, which have been either exposed to short days, or deprived of water, defoliation in early or midsummer causes the buds to open, but by late summer buds on the majority of plants are dormant.
HABITAT REQUIREMENTS IN PRIMULA SPECIES
Authors: WHALE D. M. 
Published: May 2006

SummaryThe habitat requirements of Primula vulgaris Huds., P. veris L. and P. elatior (L.) Hill are discussed in terms of their tolerance to waterlogging, drought and shade. Hypotheses generated from this discussion are presented pictorialry and examined in the light of results from competition and field experiments. It is concluded that differences in tolerances to these factors are sufficient to account for the observed habitat requirements, but that the influence of grazing, in particular, can have a strong moderating influence. Grazing pressure varied between the natural habitat types of the species.
BIOCHEMICAL AND PHYSIOLOGICAL ASPECTS OF LEAF DEVELOPMENT IN COCOA (THEOBROMA CACAO L.)
Authors: ABO‐HAMED S. , COLLIN H. A. , HARDWICK K. 
Published: May 2006

SummaryThe export and translocation of radioactivity supplied as 14C‐auxin or as a 14C‐kinin to a donor leaf of cocoa was followed at different stages of the flush cycle to see whether there was any correlation between the pattern of movement of these growth promoters and apical bud activity. The auxin 3‐indole (1‐14C) acetic acid, (14C‐IAA), and the cytokinin, 6‐benzyI‐amino (8‐14C) purine, (14C‐BAP), were introduced into the plant by foliar feeding. Export of the radioactivity derived from the 14C‐IAA was predominantly basipetal at all stages of the flush cycle. Most of the tracer accumulated in the lower stem but there was a significantly high proportion in the older leaves. It appeared that the largest proportion of the radioactivity derived from 14C‐IAA was found in parts of the plant where growth, or possibly carbohydrate accumulation, was active. It is suggested that the movement of 14C‐IAA and its metabolites in cocoa may be largely determined by the direction of flow of the assimilate stream. The identity of the radioactive compounds exported from the donor leaf showed that some 80 % of the fed 14C‐IAA was metabolized to other indole compounds including indole aldehyde, indole aspartate and indole acetonitrile.When the 14C present in particular plant parts was expressed as a relative radioactivity ratio, this value, for the apical bud, declined throughout the flush cycle, being highest at bud break, indicating that the capacity of the bud to accumulate radioactivity derived from 14C‐IAA was greatest during the stages of leaf production.The distribution of radioactivity from 14C‐BAP indicated both acropetal and basipetal transport of cytokinin but accumulation of radioactivity occurred only in actively growing regions. Unlike 14C‐IAA, the 14C‐BAP exported from the leaf was not extensively metabolized and about 60% of the transported radioactivity was detected as 14C‐BAP and the remainder as conjugated 14C‐BAP. For this compound the relative radioactivity ratio in the bud was highest at dormancy break (F‐1), suggesting that cytokinin movement to the bud was related to the breaking of dormancy. The changes in pattern of transport of auxin and cytokinin throughout the cocoa plant were correlated with the stages of the flush cycle.
DIURNAL CHANGES IN WATER RELATIONS AND ABSCISIC ACID IN FIELD‐GROWN VITIS VINIFERA CULTIVARS
Authors: LOVEYS B. R. 
Published: May 2006

SummaryDiurnal changes in stomatal conductance and accompanying changes in the abscisic acid (ABA) content of expressed xylem sap were studied in unstressed grapevines (Vitis vinifera L. cvs Riesling and Silvaner) growing in the field in Adelaide, South Australia. Stomatal conductance increased rapidly during the early morning reaching a maximum in both cultivars at about 1000 h. Conductance during the latter part of the day was considerably reduced despite relatively mild environmental conditions.Quantitative analysis of ABA in untreated sap was carried out by high performance liquid chromatography (HPLC). The concentration of ABA in xylem sap varied from 1.5 × 10−4 mol m−3in the morning to 5 × 10−4 mol m−3in the late afternoon. Uptake of ABA from the xylem adequately accounted for diurnal changes in leaf ABA.Gas exchange analysis of detached field‐grown leaves showed that ABA, supplied via the transpiration stream, caused substantial reductions in stomatal conductance and assimilation when supplied at a concentration equivalent to that in xylem sap [5 × 10−4 mol m−3 (+) ABA]. The reduction in assimilation was entirely stomatal in origin.It is suggested that ABA uptake from the xylem causes partial stomatal closure during the afternoon and plays a key role in the control of stomatal conductance in field grown vines by optimizing the relationship between CO2 uptake and water loss.
THE EFFECT OF GROWTH REGULATORS, LIGHT AND TEMPERATURE ON FLAVOUR PRODUCTION IN CELERY TISSUE CULTURES
Authors: WATTS M. J. , GALPIN I. J. , COLLIN H. A. 
Published: May 2006

SummaryCell suspensions of celery (Apium graveolens L.) were subcultured on media containing a range of auxins and antiauxins to replace 2,4‐dichlorophenoxyacetic acid (2,4‐D). Where the cultures showed a low growth rate and became green, the cells and media contained flavour compounds, the phthalides (3‐butyl phthalide and sedanenolide) and other terpenoid compounds. Maximum secondary product synthesis and greening was in media which contained 3,5‐dichlorophenoxy‐acetic acid (3,5‐D). In order to stimulate flavour synthesis in cultures in a medium containing 2,4‐D, the cultures were exposed to different fight and temperature regimes for varying periods during their growth cycle. Although growth was reduced in darkness and at high (30 °C) and intermediate (20 °C) temperatures, no stimulation of phthalide and terpenoid synthesis occurred. However, when the cultures were maintained at 4 °C for the first 5 d of the growth cycle and then transferred to 25 °C, phthalides and other terpenoids, particularly limonene, were released into the medium. An analysis of aggregated and finely dispersed cells on a 2,4‐D medium showed the aggregates contained phthalides and terpenoids, but these were not present in the dispersed cells. It is suggested that the altered internal cell environment in the green, aggregated or temperature stressed cells contributed to the ability of the cells to synthesize secondary products.
CYTOGENETIC VARIATION IN THE BRITISH FLORA: ORIGINS AND SIGNIFICANCE
Authors: ELKINGTON T. T. 
Published: May 2006

SummaryCytogenetic variation in the British flora is discussed in relation to the taxonomy and evolution of species and to their distribution and past history. In polyploids there may be two or more cytotypes in Britain with different distributions and ecology, e.g. Empetrum nigrum and Hippocrepis comosa; alternatively only one cytotype is present in Britain, but it forms part of a wider polyploid pattern, the study of which may clarify past patterns of migration, e.g. Potentilla fruticosa and Sisyrinchium bermudiana. The study of polyploids may also have taxonomic significance, e.g. Cochlearia, Symphytum and Mentha. In some situations gene flow between polyploid levels takes place and may be in both directions. In other polyploid groups sexually sterile cytotypes may be maintained by vegetative reproduction, e.g. Ranunculus ficaria and Holcus mollis or by gametophytic apomixis. In some cases a polyploid and aneuploid series may be maintained in which all the components are fertile; this situation is discussed in relation to the genus Erophila. There has been considerable emphasis in the past in attempting to identify the genomic ancestors of allopolyploids; two British species, Spartina anglica and Senecio cambrensis are among the few examples of recent allopolyploids of known origin; in both cases formation has depended on the establishment of an introduced species as one parent.The significance of B chromosomes is discussed; although a range of British species contain B chromosomes it has only been possible to investigate their adaptive significance in one case. Interchanges exist in British species either in the heterozygous form, e.g. in Alopecurus species, where they can be identified by their meiotic consequences, or in the homozygous form, e.g. Epilobium sect. Epilobium species, where they can be identified by meiotic analysis of hybrids.The use of modern cytogenetic techniques including chromosome banding and in‐situ hybridization and the investigation of characteristics such as infra‐species variation in DNA amounts are discussed in relation to future cytogenetic investigations of the British flora.
THE EFFECT OF THE FUNGUS ATKINSONELLA HYPOXYLON (CLAVICIPITACEAE)ON THE REPRODUCTIVE SYSTEM AND DEMOGRAPHY OF THE GRASS DANTHONIA SPICATA
Authors: CLAY K. 
Published: May 2006

SummaryThe Balansiae (Clavicipitaceae, Ascomycetes) consists of five genera of fungi that parasitize grasses, sedges and rushes. Most or all species produce alkaloids that are toxic to mammalian and insect herbivores. Previous reports suggest that infected grasses are more vigorous than uninfected grasses and that the proportion of infected individuals is greater in older populations. In this study individual plants or genotypes of the grass Danthonia spicata (L.) Beauv. Infected by the fungus Atkinsonella hypoxylon (Peck) Diehl. were compared with uninfected genotypes from the same population. Danthonia spicata typically bears dimorphic chasmogamous and cleistogamous flowers but in the study population infected plants were partially sterilized, producing only cleistogamous flowers; uninfected plants produced chasmogamous and cleistogamous flowers. Two experimental comparisons were conducted by propagating infected and uninfected genotypes into clones, or ramets, which were then planted back into their native site. Infected ramets had higher survival and growth rates, but lower flower production, than uninfected ramets both in random field transects and in field competition studies between D. spicata and the grass Anthoxanthum odoratum L. The results indicate infected individuals have higher survival and growth rates but reduced fecundity compared to uninfected individuals.