bluuebunny/crossref_metadata_2025_split huggingface dataset:
CARBON SOURCE FOR DEVELOPING BOLLS IN NORMAL AND SUPEROKRA LEAF COTTON*
Authors: HORROCKS R. D. , KERBY T. A. , BUXTON D. R. 
Published: May 2006

SUMMARYNarrow‐row field experiments were conducted to investigate the importance of leaves near developing bolls as a source of assimilate in normal and superokra leaf cotton (Gossypium hirsutum L.) plants. A small plexiglass chamber was used to enclose individual leaves which were pulsed with 14CO2 for 5 min. Leaves were labelled when sink bolls were 10 days old. Despite much smaller leaves at each position (averaging 42% of normal leaf size) the superokra leaves exported similar amounts of 14C‐assimilate to the primary boll as did normal plant leaves. Primary sympodial bolls of superokra and normal leaf plants received 37 and 41% of their 14C‐assimilate from subtending leaves, respectively, 38% from the secondary sympodial leaf, and 28.2 and 21.5%, respectively, from the main stem leaf. Although the leaf subtending the boll of superokra plants was much smaller than the subtending normal leaf, the amount of assimilate provided to the boll was 88% of the normal leaf. The differences in assimilate export to a given boll may not be as important in causing fruit abortion in superokra cotton as expected from leaf size considerations.
CHANGES IN THE ETHANOL‐SOLUBLE CARBOHYDRATE COMPOSITION AND ACID INVERTASE IN INFECTED FIRST LEAF TISSUES SUSCEPTIBLE TO CROWN RUST OF OAT AND WHEAT STEM RUST
Authors: MITCHELL D. T. , FUNG A. K. , LEWIS D. H. 
Published: May 2006

SUMMARYMonosaccharides, sucrose and acyclic polyols in healthy and infected first leaves of oat and wheat susceptible to crown rust and stem rust respectively were quantitatively determined. In oat tissues heavily infected with crown rust (thirty‐four lesions/cm segment), sucrose and reducing sugars increased during flecking and then declined. During sporulation of wheat stem rust‐infected tissues, sucrose levels at an infection intensity of eight lesions/leaf were greater than those of comparable healthy tissues whereas, at a higher infection intensity (107 lesions/leaf), there was a slight decline in sucrose with increases in both fructose and glucose. Soluble sugars (combined sucrose, fructose and glucose) were greater in the ‘pustule area’ compared with ‘region adjacent’ on the same leaf of wheat. Activity of acid invertase in infected tissues is related to infection intensity in crown rust of oat. However, in wheat stem rust infected tissues, a stimulation of acid invertase only occurred during the appearance of definite type 4 lesions. At the sites of infection, there were increases in mannitol and arabitol during flecking and sporulation, and a direct correlation between acyclic polyol levels and numbers of erupted lesions/leaf.
ORIGIN OF THE QUIESCENT CENTRE IN ZEA MA YS
Authors: CLOWES F. A. L. 
Published: May 2006

SUMMARYEstablishment of the quiescent centre has been studied in embryogeny, in development of lateral root primordia and in roots regenerating after decapitation. In embryos a quiescent centre first appears just after the oblique root‐shoot axis becomes discernible, as soon as a cap meristem forms at the root pole and then again during the early stages of germination of seeds. In lateral primordia a quiescent centre also arises twice; once while the first set of cap initials, which are of endodermal origin, is functioning and then after they have ceased operating when new cap initials of pericyclic origin have replaced them. The first quiescent centre exists while the primordium is still embedded in the mother cortex, but the second can occur either before or after emergence from the mother root. In regenerating roots a quiescent centre establishes itself when a cap meristem becomes transiently distinct from the rest of the meristem by a difference in planes of cell growth and division. This happens before the meristem acquires the characteristic cell pattern of a normal grass root.These observations are discussed in relation to the reasons for the existence of quiescent centres to root meristems.
AGEING‐LINKED CHANGES IN PHOTOSYNTHETIC CAPACITY AND IN FRACTION I PROTEIN CONTENT OF THE FIRST LEAF OF PEA PISUM SATIVUM L.
Authors: GORDON K. H. J. , PEOPLES M. B. , MURRAY D. R. 
Published: May 2006

SUMMARYPea seedlings (Pisum sativum L. cv. Melbourne Market) were grown under light‐limited conditions (12 h photoperiod of 1 klx; 19°C) so that both the development and senescence of the first true leaf could be studied within a period of 4 weeks from the beginning of germination. Rapid cell expansion and synthesis of protein and chlorophyll occurred between days 8 to 12. Whereas photosynthetic O2 evolution and RuBP carboxylase both showed maximum values per leaf at 16 days, declining thereafter, that of NADH:glyoxylate reductase, a peroxisomal marker, occurred between 11 and 14 days and was decreasing by 16 days. Total leaf ribose‐5‐P isomerase activity increased two‐fold to a maximum at 14 days then fell sharply before 16 days. Dark O2 uptake by leaf slices and NADH oxidase activity showed extended maxima from the earliest stages to 20 and 16 days respectively. Soluble acid phosphatase also showed an extended period of maximum activity per leaf, from 12 to 21 days, then declined slowly.As a proportion of leaf soluble protein, Fraction I protein varied from 17% (day 8) to 41% (day 10), 57%(day 14), 76%(day 16) then to about 60% from day 21 onwards. Between 14 and 16 days the amount of Fraction I protein in the leaf continued to increase, although the amount of total soluble protein had begun to decline. Aminopeptidase (leucyl β‐naphthylamidase) activities per leaf also began to decline after 14 days. Since the maximum photosynthetic capacity of the leaf is not observed until 16 days, the data indicate the onset of leaf senescence prior to the completion of chloroplast development.
ANATOMY, HISTOCHEMISTRY AND CYTOLOGY OF DORMANT AND STRATIFIED APPLE EMBRYOS
Authors: DAWIDOWICZ‐GRZEGORZEWSKA ALINA , LEWAK ST. 
Published: May 2006

SUMMARYChanges in the anatomy and cytology of apple embryos isolated from seeds during after‐ripening (3‐month stratification at +4°C)were investigated. Structural changes differed in cotyledons and embryo axes. In cotyledons they were limited to stepwise differentiation of the vascular tissue, whereas the structural alterations in axes were related to starch accumulation. A general increase of starch up to the end of after‐ripening was noted after a temporary decrease during the first 10 days of stratification. Accumulation of starch during the third month of after‐ripening was restricted to the limit zone between the radicle and hypocotyl. Starch accumulation (followed by degradation) was localized in a zone corresponding to that in which cell elongation begins. The structural changes were correlated with the metabolic changes known to occur during the after‐ripening of apple seed.
A STUDY OF THE EXTRAFLORAL NECTARIES OF RICINUS COMMUNIS
Authors: BAKER D. A. , HALL J. L. , THORPE J. R. 
Published: May 2006

SUMMARYA study has been made of the fine structure and exudate composition of the extrafloral nectaries of Ricinus communis. Actively secreting glands were characterized by the presence of well‐developed swollen endoplasmic reticulum, numerous vesicles, ribosomes and mitochondria, and the occurrence of crystalline (protein) bodies in the nucleus and cytoplasm. Golgi bodies were not prominent. The gland exudate differed from the phloem exudate in a number of respects, particularly in the much lower levels of amino acids and phosphate and the presence of glucose and fructose. Plants with glands removed showed no difference in growth from the untreated controls. The findings are discussed in relation to the possible functions of extrafloral nectaries.
15N INCORPORATION AND GLUTAMINE SYNTHETASE INHIBITION STUDIES OF NITROGEN ASSIMILATION IN LEAVES OF THE NITROPHILE, DATURA STRAMONIUM L.
Authors: LEWIS O. A. M. , PROBYN T. A. 
Published: May 2006

SUMMARYThe N assimilation pathways in leaves of Datura stramonium L. have been investigated at low and high levels of xylem stream nitrate feeding by an 15N infiltration technique in the presence and absence of the glutamine synthetase inhibitor, methionine sulphoximine (MSO).In the absence of MSO, glutamate showed the highest 15N enrichment of any free amino compound at both feeding levels. At the high N feeding level, glutamine showed the highest accumulation of 15N at all stages of the time course, with secondary accumulation in glutamate. At the low N feeding level the reverse was true. These findings indicate the operation of both the glutamine synthetase‐GOGAT and glutamate dehydrogenase pathways in Datura leaves.In the presence of MSO intracellular pools of all the amino compounds, with the exception of glutamine and threonine, became rapidly drained. There was an almost complete restriction of the supply of newly reduced 15N to amino acid assimilation and it accumulated as ammonia. The large glutamine pool remaining contained no 15N enrichment, and was probably an extrachloroplastic storage pool not immediately available for amino acid synthesis. These experimental results indicate the almost exclusive role of the glutamine synthetase‐GOGAT pathway in the assimilation of newly reduced nitrate into amino acid metabolism in Datura leaves.
YIELD PERFORMANCE OF MIXTURES OF OATS AND BARLEY
Authors: BEBAWI F. F. , NAYLOR ROBERT E. L. 
Published: May 2006

SUMMARYFour experiments were conducted to compare the yield, and stability of yield of oats and barley grown separately and in an equiproportional mixture (w/w). The cultivars used were Maris Mink and Karin, chosen to synchronize, as far as possible, their maturity dates. In general, the mixtures marginally overyielded the more productive species but not significantly so. When barley was sown at half field density, grain yield did not drop. In contrast, the yield of oats was lower when plots were sown at lower density. Barley was generally more unstable in its yield than oats, which it outyielded on good sites but underyielded on poor sites. Mixtures were much more stable than barley, and almost as stable as oats, but were never the most stable type of plot.
THE GENECOLOGY OF LAWN WEEDS
Authors: WARWICK S. I. , BRIGGS D. 
Published: May 2006

SUMMARYAn examination of variation in Poo. annua L. provided evidence for population differentiation between two bowling greens and their adjacent flower beds. The bowling green populations consisted almost entirely of prostrate individuals, whereas the flower bed populations were more heterogeneous, containing both erect and prostrate growth forms.Family trials indicated that vegetative and floral erectness, and time from sowing to anthesis were under genetic control. Erect families came into flower significantly quicker than prostrate families. Moreover, there were significant differences, both between and within families, for each of the two growth forms in mean number of days from sowing to anthesis.An investigation was conducted using gel electrophoretic techniques to examine the genetic structure of these populations of P. annua, and to estimate the amount of natural out crossing. The esterase enzyme system was found to consist of multiple molecular forms. No apparent banding differences were found which distinguished erect and prostrate growth forms. Heterogeneity of banding patterns was discovered within both growth form groups, suggesting that each of the prostrate and erect growth forms consisted of more than one genotype. Evidence that the observed banding patterns were under genetic control was obtained from the examination of four families derived from selfed heterozygotes, which yielded segregating patterns within families.Both erect and prostrate growth forms, in the area under study, had the chromosome number 2n= 28.
THE ADAPTATION OF CALLUNA VULGARIS (L.) HULL TO CONTRASTING SOIL TYPES
Authors: MARKS R. H. , BANNISTER P. 
Published: May 2006

SUMMARYSamples of Calluna vulgaris were collected from several sites of contrasting soil type and the mineral status of plants and soils measured. Differences in the concentrations of several potentially toxic elements in these plants and soils occurred but the nitrogen, potassium and phosphorus concentrations, particularly in the plants, were similar. When cuttings of Calluna from each population were grown in all soil types, it was shown that these samples were adapted to the different soils. Two ways in which this species may be adapted to tolerate high concentrations of lead were noted.
AN INTERGLACIAL DEPOSIT AT SCANDAL BECK, N.W. ENGLAND
Authors: CARTER P. A. , JOHNSON G. A. L. , TURNER J. 
Published: May 2006

SUMMARYA lacustrine deposit with included peat was discovered beneath till at Scandal Beck, Cumbria. A pollen diagram from the organic layers has three pollen assemblage zones which cover the last part of an interglacial. It is argued that the deposit most probably dates from the Ipswichian.
UPPER CRITICAL LEVELS OF TOXIC ELEMENTS IN PLANTS
Authors: DAVIS R. D. , BECKETT P. H. T. 
Published: May 2006

SUMMARYThough the concentration of Cu, Ni or Zn in the tissue of young (five‐leaf) spring barley grown in a nutrient solution containing one of these elements varies considerably with the growing conditions, the minimum concentrations of Cu, Ni or Zn in plant tissue (Cu 19, Ni 12, Zn 210 ppm dry wt) necessary to cause toxic reactions are relatively independent of the growing conditions. The values for ryegrass S.23 are very similar (Cu 21, Ni 14, and Zn 221 ppm), as are the Cu values for lettuce, rape and what (21, 16 and 18 ppm respectively). At higher concentrations of these elements in plant tissue yield is reduced approximately in proportion to log (tissue concentration).The application of these observations to a procedure for monitoring environmental pollution, outlined in an earlier paper, is further developed.
TOLERANCE OF TREE ROOTS TO WATERLOGGING
Authors: COUTTS M. P. , PHILIPSON J. J. 
Published: May 2006

SUMMARYRooted cuttings of Sitka spruce and Lodgepole pine were grown in Perspex tubes of peat and the lower portion of the root systems was flooded, while either active or dormant, and at 6° and 15°C. Root survival was assessed after draining the tubes.Root elongation in both species stopped within a few days of flooding, during which the oxygen flux in the peat had declined to zero. Actively growing root tips were more susceptible to waterlogging than the region behind the tip and the latter region remained alive for up to 90 cm below the water‐table in certain treatments.Growing roots of pine were more tolerant to waterlogging than spruce, when assessed in terms of the survival of both the tip and the basal region of the root. By contrast, dormant roots of both species were so tolerant to waterlogging that the tips remained alive and rapid regrowth took place after the soil was drained.
FACTORS AFFECTING ABSCISSION IN SPIRODELA OLIGORHIZA (LEMNACEAE)
Authors: WITZTUM A. , KEREN O. 
Published: May 2006

SUMMARY0.1 M and 0.2 M sucrose do not induce abscission and significantly reduce abscission induced by ultraviolet radiation whereas higher concentrations (0.4 M) induce abscission even without UV radiation. The effect of different concentrations of sucrose on endogenous ABA levels and on ethylene release suggest that sucrose‐induced abscission occurs when ethylene release is accompanied by a rise in the endogenous ABA level. When plants are floated on low concentrations of ABA (0.1 ppm), they release a considerable amount of ethylene but do not abscise. On higher concentrations of ABA (10 ppm), they abscise, even though ethylene release is lower.
LIPID METABOLISM OF LEAVES OF POA PRATENSIS DURING INFECTION BY PUCCINIA POARUM
Authors: LÖSEL D. M. 
Published: May 2006

SUMMARYDuring the development of the uredial and telial stages of the rust, Puccinia poarum, on leaves of Poa pratensis, lipid accumulates in and around the infected tissues to a level more than double that of uninfected leaves. Microscopically, the infection on Poa differs from that on the alternate host, Tussilago furfara, in the less extensive development of fungal tissue, the much more frequent occurrence of haustoria and the greater amount and persistence of lipid globules in host cells. Urediosori contain significantly more triglyceride and sterols than healthy tissue and teliosori contain more neutral lipid of all classes. As on Tussilago. there was a rapid disappearance of chloropiast glycolipids and phosphatidyl glycerol in the early phases of growth on Poa, accompanied by increases in phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine, which are attributed primarily to synthesis of fungal membrane lipids.
METABOLIC POOLS IN THE SPADIX OF ARUM DURING FLORAL DEVELOPMENT
Authors: WEDDING RANDOLPH T. , BLACK M. KAY , HARLEY JOHN L. 
Published: May 2006

SUMMARYThe concentration of certain metabolic intermediates in the spadix of Arum has been determined over the complete period of floral development from the point at which the spathes are first visible in the leaf base to thermogenesis in the spadix. These intermediates include sucrose, glucose, fructose, pyruvate, alanine, citrate, α‐ketoglutarate, glutamate, glutamine, malate, aspartate and asparagine. Assays for these intermediates were supplemented by measurements of mitochondrial respiratory activity, soluble and protein‐bound flavins, thiamine and ethanol‐insoluble materials.These constituents and processes reveal four broad patterns of change indicating a complex system controlling floral development and thermogenesis. The clearest indication of a specific control seen is the correlation of low mitochondrial respiratory activity with low levels of soluble flavins, suggesting that lack of these cofactors limits the respiratory activity of young spadices.
THE EFFECT OF SIMAZINE ON THE GROWTH AND RESPIRATION OF A CELL SUSPENSION CULTURE OF CELERY
Authors: METCALF E. C. , COLLIN H. A. 
Published: May 2006

SUMMARYCelery cell suspension cultures, inoculated into liquid medium containing simazine and maintained for 3 weeks, showed little growth and low respiratory activity at concentrations of 1.0 and 10.0 mg 1−1 simazine but growth and respiration were normal with 0.01 and 0.1 mg 1−1 simazine. The addition of 1.0 or 10.0 mg 1−1 simazine to a cell culture caused an immediate stimulation of respiration rate; lower concentrations of simazine were ineffective. The initial high respiratory rate in 10 mg 1−1 simazine was not maintained and after 6 h the rate had declined to the level of the control. When the cells were incubated in 10 mg 1−1simazine for a longer period the rate declined to zero after 1 week, cell division was inhibited and the dry weight decreased. The initial high rate of respiration in simazine, followed by a decline, combined with the inhibition of growth and finally cell death suggested that the simazine may be acting as a respiratory uncoupler.
INDUCTION OF FLOWERING IN WILD LETTUCE (LACTUCA SERRIOLA L.)
Authors: PRINCE S. D. , MARKS M. K. , CARTER R. N. 
Published: May 2006

SUMMARYBoth seed and rosettes of Lactuca serriola L. are naturally vernalized during the winter. The response, measured by reduction in time required to flower, is greatest following vernalization of seed and declines with increasing age of the vegetative rosette. However, seedlings pass through a phase of minimum response to vernalization in the cotyledon stage (52% of seed response) after which it increases (73% at two‐leaf stage) before declining in older rosettes. The significance of the effect of stage of development at the start of vernalization is discussed in relation to control of phenology in the natural environment. Effects of photoperiod and temperature on induction of flowering are considered and comparison made with L. sativa.
INDUCTION OF WILTING BY MANNOSE IN SPINACH BEET LEAVES
Authors: HEROLD A. 
Published: May 2006

SUMMARYMannose, but not glucose, induces loss of turgor in whole plants, detached leaves and leaf discs of spinach beet. There is no comparable effect in leaves of tobacco and geranium. Supply of mannose to spinach beet discs causes an enhanced conductivity in the bathing medium after 8–10 h and this is associated with increased leakage of potassium ions over controls. After 24–36 h, water‐soaking is evidence of intercellular accumulation of water in the tissue. Previous work has established that mannose sequesters orthophosphate as mannose phosphate in leaves of spinach beet but not in those of tobacco and geranium, and the implied changes in cell membrane permeability are probably due to limited availability of Pi for ATP synthesis and turnover of phospholipid membrane components. The rate of cuticular transpiration may also be increased.
INOCULATION OF WHITE CLOVER AND RYEGRASS SEED WITH MYCORRHIZAL FUNGI
Authors: Ll. POWELL C. 
Published: May 2006

SummarySeeds of white clover and ryegrass were pelleted with soil heavily infested with the indigenous mycorrhizal fungi or efficient strains of Glomus tenuis and Gigaspora margarita and laid out on unsterilized pasture soils. Ryegrass plants inoculated with Glomus tenuis produced up to 48% more shoot growth than plants infected with the indigenous mycorrhizal fungi in Dunmore soil in glasshouse conditions. Similar inoculation of clover increased shoot growth by up to 91 % in Te Kuiti soil in the glasshouse and 37% in the field. Inoculation of clover with Gigaspora margarita increased dry matter of shoots by 79 % in Te Kuiti soil in the field.
ULTRASTRUCTURAL CYTOCHEMICAL DEMONSTRATION OF POLYSACCHARIDES AND PROTEINS WITHIN THE HOST‐ARBUSCULE INTERFACIAL MATRIX IN AN ENDOMYCORRHIZA
Authors: SCANNERINI S. , BONFANTE‐FASOLO P. 
Published: May 2006

SummaryThe host‐fungal arbuscule interfacial matrix in the VA mycorrhiza of Ornithogalum umbellatum L. has been studied at the ultrastructural level by various fixation methods, cytochemical techniques and by selective enzymic digestion. Evidence is produced that the interfacial matrix, though varying in size and infrastructure, irrespective of the arbuscule zone, constantly contains polysaccharides (mainly pectin and occasionally some cellulose) and proteins. Combined morphological and cytochemical results show that this structure is made up of wall material from the host cell.
CULTIVATION OF PINUS STROBUS ROOT‐HYPOCOTYL EXPLANTS FOR SYNTHESIS OF ECTOMYCORRHIZAE
Authors: ANDRE FORTIN J. , PICHE YVES 
Published: May 2006

SummaryDifferent conditions for the cultivation of Pinus strobus root‐hypocotyl explants were studied for the production of ectomycorrhizae in vitro. Moisture content of the culture medium used for growing seedlings before excision was critical and a low level of moisture during this period led to a slow and erratic growth of the explants. During short‐term experiments (6 weeks) no vitamins or inositol requirements could be detected but under the same conditions auxins improved growth significantly whereas kinetin did not. The optimum NAA concentration was about 2 × 10−7 M in the absence of exogenous kinetin. The requirement for a piece of hypocotyl might not be absolute because some evidence was obtained that auxin in the organic medium might, partially, replace it. Whereas virtually no growth took place with 5% sucrose in the organic medium, optimum concentration for root elongation was found to be between 11 and 15%. During the 2 first weeks following excision the rate of growth remained low (1.2 mm week−1) but between the 2nd and the 6th weeks it reached 6.3 mm week−1 before dropping back to 2.3 mm week1 between the 6th and the 10th weeks. Some typical ectomycorrhizae showing mantle and Hartig's net were obtained upon inoculation with ectomycorrhizal fungi, but more research is needed before the method can be recommended for general use in studies on the physiology of ectomycorrhizae.