bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE MORPHOLOGY OF VEGETATIVE REGENERATION IN CALLUNA VULGARIS
Authors: MOHAMED B. F. , GIMINGHAM C. H. 
Published: May 2006

Summary Calluna vulgaris, in certain habitats, provides useful grazing for herbivores; management is generally by burning, with the aim of promoting vigorous production of young shoots by vegetative regeneration for the stem base. However, the capacity for such vegetative regeneration declines with age. The general morphology of the plant is described, with particular reference to the sequence of development in a single season's growth and to the stages in resumption of growth after overwintering. On this basis, an interpretation is given of the responses to grazing and burning, with evidence derived from detailed observation of treated plants and from transverse sections of stems. Light grazing at the periphery of the plant causes (i) the growth of a few of the uppermost short shoots into new long shoots, and (ii) the appearance of clusters of shoots from lower, woody, parts of the branches. Heavier or more sustained grazing emphasizes the second of these responses. Vegetative regeneration after burning is also of the second category, confined to undamaged positions near the base of the stem.The clusters of shoots appear at the points of origin of existing or former branches. The conclusion, derived both from morphological observations and from evidence of the deep‐seated origin of these new shoots, is that they are derived from persisting dormant buds on the close‐packed nodes just below the base of each long shoot. These nodes belonged to the overwintering end‐of‐season short shoot from which the long shoot developed.
AGEING IN PLANT EMBRYOS
Authors: BERJAK PATRICIA , VILLIERS T. A. 
Published: May 2006

SummaryAlthough no cell division was detected in the radicle during the first 24 hours of imbibition by the caryopses of Zea mays, fine structural changes showed the re‐establishment of a developmental pattern during this period. Such changes included mitochondrial differentiation, the appearance of dictyosomes and a complex system of ER, and the association of ribosomes to form polysome‐like structures. Association between ER and lysosome‐like bodies was seen during this stage, together with an intensification of the acid phosphatase reaction within the lysosomes. By the 48‐hour stage, easily‐separated, senescent cells had been produced and cell division had begun. Vesicles produced by the hypersecretory activity of the dictyosomes were either incorporated into the developing lysosomes or passed through the cell membrane to the wall. In the outermost cells the lysosomes finally ruptured and acid phosphatase activity became detectable in the ground cytoplasm. The development of the lysosomes and the hypersecretory activity of the dictyosomes are discussed as evidence of constructive changes implying genetic control of cellular senescence in the root cap.
EFFECTS OF SOME METABOLIC INHIBITORS AND TEMPERATURE ON ION‐STIMULATED STOMATAL OPENING IN DETACHED EPIDERMIS
Authors: WILLMER C. M. , MANSFIELD T. A. 
Published: May 2006

SummaryIon‐stimulated stomatal opening in isolated epidermis of Commelina commons is shown to be influenced by temperature in the manner expected for a process dependent on metabolism. The effects of three metabolic inhibitors on this stomatal opening in light and darkness and two concentrations of CO2 are reported. 3‐(3,4‐dichlorophenyl),I,I‐dimethylurea (DCMU) caused partial stomatal closure in light but this was reversed in CO2‐free conditions, suggesting that open chain photophosphorylation is not essential for stomatal opening in light. Salicylaldoxime suppressed the light‐stimulated component of stomatal opening and the effect was not reversed in CO2‐free conditions. This suggests that photosystem 1 or cyclic photophosphorylation supplied the energy for ion uptake in guard cells in light. Supporting evidence comes from the finding that 2,4‐dinitrophenol (DNP) also suppressed the light‐stimulated component of opening.In darkness, ion‐stimulated opening occurs, but to smaller apertures than in the light. This opening is insensitive to DNP treatment, suggesting that ATP from oxidative phosphorylation is not required. A possible interpretation of the results is that in darkness the energy for active transport into the guard cells is obtained from a direct linkage to the mitochondrial electron transport chain; the same could be true in light, with an additional linkage to electron transport in photosystem I. Lack of information on the movement of specific ions means that some doubt must remain about which ions are actively transported. A comparison of the behaviour of stomata on detached and attached epidermis suggests that care is required if data from this study are to be applied to the stomatal mechanism in intact Plants.
THE NATURE OF SEED DORMANCY AND GERMINATION IN THE SALT MARSH GRASS DISTICHLIS SPICATA
Authors: AMEN RALPH D. , CARTER GEORGE E. , KELLY RICHARD J. 
Published: May 2006

Summary Distichlis spicata, a salt marsh grass, sets dormant seeds which exhibit a low‐temperature, after‐ripening requirement. In addition to stratification, localized scarification and nitrate are effective agents in breaking dormancy and promoting seed germination. The pericarp and/or testa are impermeable to organic plant‐growth regulators, but not to water or inorganic salts. Gibberellic acid and kinetin are ineffective in breaking dormancy and do not affect germination. Abscisic acid, however, effectively inhibits stratified and scarified seeds. Dormancy and germination appear to be hormonally controlled.It is suggested that the endogenous inhibitor constitutes a block to nitrate reductase activity in the endosperm. Presumably the inhibitor blocks specific DNA transcription sites in the aleurone cells, but can be overcome by after‐ripening (inhibitor decay), abrasion (inhibitor leaching) or nitrate induction.
THE FINE STRUCTURE OF A PERITAPETAL MEMBRANE INVESTING THE MICROSPORANGIUM OF PINUS BANKSIANA
Authors: DICKINSON H. G. 
Published: May 2006

SummaryAn acetolysis‐resistant membrane develops around the microsporangium of Pinus banksiana while the pollen mother cells are undergoing meiosis. The formation of this membrane appears to involve the deposition and polymerization of sporopollenin precursors upon a primary layer believed to be lipid. The source of both these components is considered to be the tapetum and attention is drawn to the similarity in construction between this membrane and the tapetal orbicules. Possible functions of the membrane in the development and dispersal of the pollen are discussed.
STUDIES ON THE LIGNOTUBERS OF EUCALYPTUS OBLIQUA L'HERI.
Authors: CARRODUS B. B. , BLAKE T. J. 
Published: May 2006

SummaryThe anatomy of lignotubers of a eucalypt are examined and the distribution and amount of storage tissue discussed. The relative amounts of carbohydrates held in the lignotubers and adjacent root and stem are examined. It is concluded that the lignotuber is no more efficient than the root or stem as storage tissue, and that its prime function is probably related to the large number of buds it holds in a protected position.
THE EFFECTS OF SYCOPHAGA SYCOMORI L. ON THE STRUCTURE AND DEVELOPMENT OF THE SYNCONIA IN FICUS SYCOMORUS L. *
Authors: GALIL J. , DULBERGER R. , ROSEN D. 
Published: May 2006

SUMMARYThe anatomy of the syconia and flowers in the sycomore fig (Fiats sycomorus) has been studied. The developmental course of the ovules and pollen grains and their ultimate structure were found to be normal. No difference was detected between short‐ and long‐styled flowers. In the Mediterranean area, Sycophaga sycomori is the principal sycophilous wasp developing within the ovaries of the sycomore. The wasp inserts its egg into the embryo sac via the style. Inhabited but unfertilized syconia which do not contain plant embryos persist on the tree and continue to develop, while the unoccupied syconia drop within a few days. Inhabitation by the wasp has a decisive effect on the subsequent development of the syconia and flowers. Oviposition induces sclerification of the pericarp and proliferation of the nucellus, which serves as‘feeding’ tissue for the insect larva. Inhabitation by Sycophaga is indispensable for the maturation of the male flowers. Uninucleate pollen grains were the final stage attained in uninhabited syconia.
LIME CHLOROSIS AS A FACTOR IN SEEDLING ESTABLISHMENT ON CALCAREOUS SOILS
Authors: HUTCHINSON T. C. 
Published: May 2006

SUMMARYThe water relations of a number of species affected by lime‐chlorosis have been studied by following the development of leaf water deficits in detached leaves gravimetrically. It has been found, both for material collected in the field and for material raised under controlled laboratory conditions, that chlorotic leaves invariably lose water more rapidly than do green leaves of the same species. The rate of transpirational loss of individuals of a species is directly related to the degree of chlorosis they exhibit. Addition of iron chelate to soil in which a chlorosis‐susceptible plant grows alleviates the chlorosis and the rate of transpiration is also greatly reduced. The age of the material and intrinsic soil factors also influence rates and patterns of transpirational loss. Both the stomatal and cuticular phases of transpiration appear to be affected in chlorotic material, where the larger leaf water deficits may be due either to more rapid loss during the stomatal phase, coupled with later stomatal closure, or to more rapid cuticular loss, or both. The percentage of dry matter in chlorotic leaves is reduced compared with that in green leaves. The ecological significance of the overall findings is discussed in relation to the potential survival of species invading calcareous soils as seedlings. Such seedlings are very often subjected to annual droughts.
METABOLIC CHANGES OF POLYAMINES DURING THE GERMINATION OF PHASEOLUS VULGARIS
Authors: BAGNI N. 
Published: May 2006

SUMMARYThe distribution and changes in spermine and spermidine during the germination and seedling growth of bean (Phaseolus vulgaris) were investigated. The results show in vivo a substantial parallelism between RNA and protein changes and polyamine changes during germination. Spermine and spermidine diminish in the cotyledons and increase in the shoots especially the epicotyls. The data concerning in vitro cultures of isolated cotyledons and embryos show that there is a dc novo synthesis of spermine and spermidine in the seedlings particularly in the light. Although the greater part of the polyamines are translocated from cotyledons to embryo and afterwards into the different parts of the growing seedling, some is degraded. It is concluded that synthesis and translocation of such compounds during germination can be compared with an analogous pattern of RNA and protein changes.
PHOSPHATE ABSORPTION BY PLANTS FROM HABITATS OF DIFFERENT PHOSPHATE STATUS
Authors: NASSERY H. 
Published: May 2006

SUMMARYWhole plants of Urtica and Deschampsia of different phosphate status were used to study phosphate uptake. By contrast with excised roots, the attached roots of the plants showed differences both in the rate of uptake and their patterns of incorporation of phosphate. The rate of phosphate absorption from low concentrations was rather similar for the two species, but from high concentrations, Urtica absorbed at a greater rate. A greater proportion of the absorbed phosphate was incorporated into acid insoluble and acid soluble organic phosphate in Urtica than in Deschampsia. Urtica is more sensitive to phosphate concentration in its total growth rate relative shoot and root growth, and in total uptake than Deschampsia.
THE EFFECTS OF WATER STRESS ON NITROGEN‐FIXING ROOT NODULES
Authors: SPRENT JANET I. 
Published: May 2006

SummaryWhen the fresh weight of detached soybean nodules is reduced below 80% of its maximum (fully turgid) value, irreversible changes occur. Acetylene and nitrogen reducing activities cease, respiratory rates become very low and there are gross structural changes. Such nodules are probably shed by the plant.Reduction of water content down to 80% of the maximum fresh weight, leads to a proportionate slowing down of acetylene reduction, with a concomitant reduction in respiratory activity.
PLANT GROWTH RESPONSES TO VESICULAR‐ARBUSCULAR MYCORRHIZA
Authors: HAYMAN D. S. , MOSSE B. 
Published: May 2006

SummaryOnion and Coprosma plants were grown in a range of soils mostly containing very little available phosphate. Very large increases of shoot dry weight (up to eighteen‐fold with Coprosma and nineteen‐fold with onion) were obtained by adding phosphate. Similar increases (up to fifteen‐fold with Coprosma and twelve‐fold with onion) were obtained by mycorrhizal inoculation. The response to phosphate equalled or slightly exceeded the response to mycorrhiza, except in two soils rich in phosphate in which there was no response to either, and in one soil in which the mycorrhizal onion and Coprosma plants were twice as heavy as those given phosphate. The greatly increased growth from either treatment was associated with a large increase in the uptake of phosphorus. The probability of such growth responses, but not their size, was usually predictable in soils containing very little phosphorus soluble in CaCl2. In all soils with inoculum mycorrhizal infection was extensive. The sources of phosphorus available to mycorrhizal roots but not to non‐mycorrhizal roots differed in the various soils. In some inhibitory factors might make vesicular‐arbuscular mycorrhiza less effective in promoting the growth of the host plants.
PERFECT STATES OF RHIZOCTONIAS ASSOCIATED WITH ORCHIDS. II
Authors: WARCUP J. H. , TALBOT P. H. B. 
Published: May 2006

SummaryFurther Rhizoctonia isolates obtained from Australian orchids have been induced to fruit in culture. The perfect states thus obtained include Tulasnella allantospora Wakefield and Pearson, T. violea (Quélet) Bourdot and Galzin, and two new species, T. cruciata and Ceratobasidium sphaerosporum. The description of Tulasnella asymmetrica is emended.
ROUTINE ANALYSIS BY GAS–LIQUID CHROMATO‐GRAPHY OF SOLUBLE CARBOHYDRATES IN EXTRACTS OF PLANT TISSUES
Authors: HOLLIGAN M. 
Published: May 2006

SummaryThe general principle of gas–liquid chromatography, and the types of column packing and volatile derivative available for the analysis of carbohydrate are discussed. Techniques for the separation of soluble sugars from plant tissues as the trimethylsilyl and acetate derivatives are evaluated, with special refernce to the problems of resolution and peak identification. Finally, various aspects of quantitative gas–liquid chromatography are considered.
A METABOLIC THEORY OF FLOODING TOLERANCE: THE SIGNIFICANCE OF ENZYME DISTRIBUTION AND BEHAVIOUR
Authors: MCMANMON M. , CRAWFORD R. M. M. 
Published: May 2006

SummaryThe distribution and activity patterns of several enzymes of glycolytic and respiratory metabolism are considered in nineteen species of higher plants previously classified as tolerant or intolerant of experimental flooding. These results are combined with previous work on glycolysis, the inductive properties of alcohol dehydrogenase, and on tissue malic acid levels, to formulate a metabolic system of flooding tolerance. This system is based mainly on: (1) the control of glycolysis through the inductive and kinetic properties of alcohol dehydrogenase; and (2) a diversion from ethanol to malate accumulation, dependent upon the presence or absence of ‘malic’ enzyme.
THE LIFE‐CYCLE OF PLASMODIOPHORA BRASSICAE WORON. IN BRASSICA TISSUE CULTURES AND IN INTACT ROOTS
Authors: TOMMERUP INEZ C. , INGRAM D. S. 
Published: May 2006

SummaryThe life cycle of Plasmodiophora brassicae was studied in stained preparations of Brassica napus and B. rapa callus tissue cultures and clubbed roots. Resting spores germinated in situ in callus cells to produce naked protoplasts which underwent plasmogamy to form multinucleate primary plasmodia. Mitosis then occurred and was followed by cleavage of the plasmodia into zoosporangia containing uninucleate zoospores. The zoospores were released and fused in pairs (without karyogamy) and then penetrated living callus cells where growth and mitosis took place to give multinucleate secondary vegetative plasmodia. The vegetative plasmodial nuclei fused in pairs and then underwent meiosis immediately. This was followed by cleavage of the plasmodial cytoplasm to yield uninucleate, haploid resting spores. P. brassicae had a haploid chromosome number of five in both 2‐year‐old callus cells and in recently harvested club‐root tissues.
EFFECT OF CANE SUGAR ON THE UPTAKE OF CHLORIDE BY DISCS FROM CARROT ROOT
Authors: BRIGGS G. E. 
Published: May 2006

SummaryThe exosmosis and reabsorption of electrolytes by freshly cut discs is retarded by the presence of 0.2 M and 0.02 M cane sugar. The presence of cane sugar during pre‐treatment of freshly cut discs depresses the uptake of chloride when they are transferred to 0.01 M KCl; the presence during the uptake by discs pretreated in water causes an increase in the uptake of chloride; these effects are probably additive when the sugar is present during pre‐treatment and uptake.
A STUDY OF THE ROOT SYSTEM OF BARLEY
Authors: HACKETT C. , BARTLETT B. O. 
Published: May 2006

SummaryThe lengths of branched and unbranched axis, the density of branching, and the change in length of laterals along the axis (called the root profile) were determined on roots of Maris Badger and Proctor barley (Hordemn vulgare L.) grown in water culture under complete nutrient supply and deficiencies of potassium and phosphorus.The most striking observations were (a) 50–75% reductions in the length of unbranched axis caused by nutrient deficiency, (b) marked curvilinearity in the profile under all nutrient treatments, and (c) high dependency on the form of the profile on variety and nutrition.
NITROGENASE ACTIVITY IN WISCONSIN LAKES OF DIFFERING DEGREES OF EUTROPHICATION
Authors: STEWART W. D. P. , MAGUE T. , FITZGERALD G. P. , BURRIS R. H. 
Published: May 2006

SummaryNitrogen fixation in various Wisconsin lakes was compared using the C2H2 reduction technique. Rates of C2H2 reduction were unaffected by N2 when sufficient C2H2 was added to the gas phase. Thus in field studies the natural gas phase need not be removed before the addition of C2H2. C2H2 was reduced rapidly in eutrophic waters (Little Arbor Vitae Lake, Lake Mendota and southern Green Bay) but more slowly in oligotrophic waters (Crystal Lake, Trout Lake, Lake Mary and northern Green Bay). C2H2 reduction was greatest in the surface waters, was largely light‐dependent and showed a marked diurnal variation. There was also significant variation with area and with time, and in general acetylene reduction was detected only when heterocystous algae were present. The rate of nitrogen fixation in Lake Mendota, calculated on the basis of weekly measurements taken during most of the ice‐free season, was approximately 2.4 kg/ha/year.
CHANGE OF APPARENT WEIGHT OF PLANT TISSUES IN SOLUTION
Authors: BLYTH D. F. , BRIGGS G. E. 
Published: May 2006

SummaryIf there is any active transport of water between plasrnolysed cells of carrot root and the plasmolyticum the respiratory regulators potassium cyanide and methylene blue have a negligible effect on it. With 0.5 M KNO3 and 0.7 M cane sugar the changes in the apparent weight in the presence of these regulators relative to that in their absence is probably due to effects on the change of solutes in the tissue.
A POLLEN DIAGRAM FROM QUINCAN CRATER, NORTH‐EAST QUEENSLAND, AUSTRALIA
Authors: KERSHAW A. P. 
Published: May 2006

SummaryPollen analytical results from the organic sediments of Quincan Crater broadly confirm the sequence of vegetation changes indicated in a previous study at Lake Euramoo. Only the later stage of the transition from sclerophyll vegetation to ‘warm temperate’ rain forest, culminating about 6000 B.P., is represented at Quincan, but indicates that the change was most probably due to an increase in effective precipitation. Afterwards rain forest remained the principal vegetation type for 3000 or 4000 years but changed from the initial ‘warm temperate’ to a ‘subtropical’ kind probably as a result of an increase in temperature and possibly also of precipitation. At about 2000 B.P. the ‘subtropical’ rain forest assumed a ‘drier’ facies and there was a partial readvance of the sclerophyll vegetation.
ULTRASTRUCTURAL CHANGES IN CHLOROPLASTS OF PHASEOLUS VULGARIS DURING DEVELOPMENT UNDER CONDITIONS OF NUTRIENT DEFICIENCY
Authors: WHATLEY JEAN M. 
Published: May 2006

SummaryPlants of Phaseolus vulgaris were grown for a period of 4 weeks in nutrient solutions deficient in S, Mg, K, N, P and Fe, and compared with controls growing in complete nutrient solutions. At weekly intervals, tissue from all leaf groups fully expanded at the time of sampling was prepared for examination under the electron microscope. It was possible to examine chloroplast ultrastructure, firstly, during leaf development under each of the nutrient deficient conditions and, secondly, to compare the chloroplasts of similar leaf groups produced under different deficiency conditions. Although distinctive chloroplast types could be associated with conditions of Mg, K, N and Fe deficiency, chloroplasts from S and P deficient plants were variable in appearance. The chloroplast patterns produced were found to be consistent in palisade parenchyma tissue but in spongy mesophyll tissue cells frequently appeared plasmolysed and chloroplasts varied considerably in appearance. Particularly in the spongy mesophyll distinctive crystalline configurations were found within the chloroplasts.
PHYSIOLOGICAL‐ECOLOGY OF XANTHIUM STRUMARIUM LINN.
Authors: KAUL V. 
Published: May 2006

SummaryThere are various forms within the species which exhibit a differential seasonal behaviour. These have been designated as ‘monsoon’, ‘winter’, ‘winter‐summer’ and ‘summer’ forms. The life cycle of the ‘monsoon form’ starts under a high temperature regime and finishes under low temperature. The ‘winter’, ‘winter‐summer’, and the ‘summer’ forms grow in constant low temperature, an initial low temperature terminating in a high temperature and in constantly‐high temperature regimes respectively. The critical photoperiod for these forms ranges from 13 hours' duration to continuous light. The species does not grow at all in shaded localities. Many of the differentiating characters, however, become slightly less distinct when the different forms are raised together under a similar set of conditions in one or the other season, and this suggests that they originated from a common stock and evolved in response to environmental differences (as has been suggested for the various American species of Xanthium). The origin of the species with regard to its varying critical photoperiod has been discussed.
ENDOGENOUS STOMATAL MOVEMENTS IN TRADESCANTIA VIRGINIANA
Authors: MARTIN E. S. , MEIDNER H. 
Published: May 2006

SummaryThe stomata of Tradescantia virginiana undergo rhythmic changes in aperture in either continuous light or darkness. Whilst these changes persist for several days in continuous light, in darkness the rhythm damps after one cycle. In continuous light the rhythm was characterized by susceptibility to phase‐shift and by a period of approximately 24 hours. In continuous darkness the single opening cycle was also susceptible to phase‐shift depending upon the timing of the previous light treatment. Stomatal opening and closing in response to short light‐dark treatments could be superimposed upon the endogenous rhythm.