bluuebunny/crossref_metadata_2025_split huggingface dataset:
EFFECTS OF SOME GROWTH REGULATORS ON TILLER BUD ELONGATION IN CEREALS
Authors: JOHNSTON G. F. S. , JEFFCOAT B. 
Published: May 2006

SUMMARYThe effects of foliar and root applied 6‐benzylamino‐9‐(tetrahydropyran‐2‐yl)‐9H‐purine (PBA), 6‐benzylamino‐purine (BAP), indole‐3‐acetic acid (IAA) or gibberellic acid (GA3) on tiller bud growth were examined in cereal seedlings. Generally IAA and GA3 inhibited tiller bud growth whilst the synthetic cytokinins both markedly promoted growth. Some observations on stem and root growth were also recorded. The results are discussed with respect to the diversion of both assimilates and cytokinins and appear to favour the view that tiller bud development is controlled by a competition for assimilates with the roots and main shoot.
CARBOHYDRATE METABOLISM IN AGARICUS BISPORUS (LANGE) IMBACH.: METABOLISM OF [14C] LABELLED SUGARS BY SPOROPHORES AND MYCELIUM
Authors: HAMMOND J. B. W. , NICHOLS R. 
Published: May 2006

SUMMARYWhen growing sporophores and vegetative mycelium of Agahcus bisporus had been supplied with [14C] labelled hexoses for varying periods of time, the major compounds labelled in both forms were mannitol, trehalose, glutamate, alanine and an unidentified substance. Mannitol was strongly labelled after application of [14C] fructose but only weakly when [14C] glucose was supplied.The relative rates of oxidation by sporophores of labelled mannitol, trehalose, glucose and fructose were assessed by measuring 14CO2 production. Glucose and trehalose were the most rapidly oxidized substrates.Glucosephosphatase isomerase (E.C. 5.3.1.9) was extracted from sporophores and assayed. The conversion of glucose‐6‐phosphate to fructose‐6‐phosphate by the enzyme was competitively inhibited in vitro by 6‐phosphogluconate.The control of mannitol synthesis and the functions of mannitol and trehalose are discussed.
THE INFLUENCE OF STAGE OF HOST DEVELOPMENT ON VESICULAR‐ARBUSCULAR MYCORRHIZAE AND ENDOGONACEOUS SPORE POPULATION IN FIELD‐GROWN VEGETABLE CROPS I. SUMMER‐GROWN CROPS
Authors: SAIF S. R. 
Published: May 2006

SUMMARYThe pattern of mycorrhizal infection of roots of several fully grown vegetable crops showed three phases, a lag phase, a phase of rapid development and a constant phase. Twenty‐one days after sowing or transplanting, 0–24% of the roots were infected, but the proportion then increased rapidly to a more or less constant value of 55–92%. With musk melon (Cucurbita moschata L.), tomato (Lycopersicon esculentum Miller, Goed) and bringel (Solarium melongena L.), no constant phase was observed within the sampling period. During the first 4–8 weeks of crop growth, the Endogonaceous spore population of the soil decreased, but then increased to final harvest time. Three main types of endophytes were identified, two being members of Endogonaceae and one with very narrow, brown septate hyphae. The relationship between the different phases of mycorrhizal development, spore number in the soil and physiological changes in the host is discussed.
A CYTOLOGICAL ANALYSIS OF THE NOSTOC‐BRYOPHYTE RELATIONSHIP
Authors: DUCKETT J. G. , PRASAD A. K. S. K. , DAVIES D. A. , WALKER S. 
Published: May 2006

SUMMARYA comparative light and electron microscope study has been made of the Nostoc colonies within the thalli of Blasia pusilla and the three British species of Anthoceros, and also of the Nostoc isolated from each bryophyte. From their morphology in culture two taxa of Nostoc have been identified; N. sphaericum from Anthoceros punctatus, A. husnotii and A. laevis, and N. calcicola from other gatherings of Anthoceros laevis and Blasia. These findings support the notion that the algal‐bryophyte associations are none specific.Within bryophyte thalli, the Nostoc trichomes are closely packed and specific features cannot be recognized. Mucilaginous sheaths are much less extensive and there is no evidence that the alga thrive in mucilage produced by the adjacent bryophyte cells. Heterocyst frequencies as high as 50% in the bryophytic Nostoc spp. strikingly recall the Azolla, Gunnera and cycad‐blue‐green algal symbioses. Akinetes, readily produced in culture were only seen in the Nostoc from dormant Anthoceros. The absence of phycobilisomes and high heterocyst frequencies in the bryophytic Nostoc spp. corroborates physiological data that the algae receive organic carbon from their hosts which enable them to fix nitrogen heterotrophically.The Nostoc colonies in both Blasia and Anthoceros are extensively penetrated by multi‐cellular bryophytic filaments. Whereas in Anthoceros these comprise highly vacuolate, thin‐walled cells, which sometimes contain intracellular Nostoc trichomes, in Blasia the filaments are thick‐walled and often develop labyrinthine wall ingrowths. This transfer cell morphology may be interpreted as an adaptation facilitating interchange of metabolites between Blasia and Nostoc. Its absence in Anthoceros perhaps indicates a far less harmonious relationship or may be related to the higher nutrient status of the habitats where the Anthoceros spp. were collected.
PHYSIOLOGICAL STUDIES ON THE RELATIONSHIP BETWEEN ASCOPHYLLUM NODOSUM AND POLYSIPHONIA LANOSA
Authors: TURNER C. H. C. , EVANS L. V. 
Published: May 2006

SUMMARYTranslocation of 14C labelled products of photoassimilation within Ascophyllum nodosum tissue with or without epiphytic Polysiphonia lanosa was found not to occur. Aerial P. lanosa contains several water‐soluble sugars but only sodium mannoglycerate was radioactive following a 1h pulse in (14C) bicarbonate. Evidence is presented to show the presence of this compound in the rhizoids of P. lanosa and to demonstrate that its metabolism here differs from that in aerial parts of the plant. The ability of aerial parts of P. lanosa to utilize exogenously supplied (14C) glucose has been demonstrated.
THE RESPONSE OF LICHEN GROWTH TO ADDITIONS OF DISTILLED WATER, RAINWATER AND WATER FROM A ROCK SURFACE
Authors: ARMSTRONG R. A. 
Published: May 2006

SUMMARYThree lichen species were wetted in the field with distilled water, rainwater or water which had run off a rock surface, during July 1974 to February 1975. The radial growth rate of Parmelia glabratula spp. fuliginosa was not influenced by the wetting treatments. The radial growth rate of P. conspersa with the distilled water treatment was greater than the control, rainwater and runoff treatments. The radial growth rate of Physcia orbicularis was lower with rainwater and runoff treatments than the control and distilled water treatment. These results may be explained by the effect of wetting on the carbon balance of the lichens and by the influence of water chemistry.
PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS
Authors: KERSHAW K. A. 
Published: May 2006

SUMMARYThe rate of natural acclimation of net photosynthetic temperature optima in Peltigera canina var. praetextata has been examined intensively over a short time period. It has also been induced experimentally under controlled conditions in the laboratory: during an unusual pattern of weather conditions in early spring, the temperature optimum for net photosynthesis changed from approximately 5°C to 25°C and back down to 5°C. Concurrently maximum ambient field temperatures changed from 0°C up to 29°C and back down to 6°C over a 2 week period. Replicates of P. polydactyla collected in the field after being cold acclimated in April, showed an identical and immediate response when stored moist for 24 h at 25°C. In October experimental material with a net photosynthetic temperature optimum of 15°C showed a similarly rapid response when stored moist for 24 h at 5°C. However, temperature acclimation in Peltigera also appears to have a strong seasonal component, and low temperature acclimation cannot be induced experimentally during mid‐summer. Similarly high temperature acclimation cannot be induced in mid‐winter. The results are discussed in relation to temperature acclimation and winter hardening in higher plants, and it is suggested that the process of acclimation is particularly important to lichens enabling them to survive successfully in otherwise harsh environmental conditions.
PHYSIOLOGICAL–ENVIRONMENTAL INTERACTIONS IN LICHENS
Authors: KERSHAW K. A. , MACFARLANE J. D. , TYSIACZNY M. J. 
Published: May 2006

SUMMARYThe rapid decline of nitrogenase activity in Peltigera polydactyla and P. canina var. praetextata in the dark, to approximately 50% of its normal level in the light, is shown to be very temperature dependent and is not evident at temperatures of 15°C or less. An exogenous supply of 6% glucose, however, fails to eliminate the decline of activity. Nitrogenase activity in the dark is also completely dependent on aerobic conditions with zero rates being recorded after 1 min in the dark under a helium/acetylene atmosphere. Evidence is presented which shows the actual level of decline of nitrogenase activity in the dark has a seasonal component.The results are discussed in relation to oxidative phosphorylation and the availability of carbohydrates throughout the seasons. The ability of P. polydactyla and P. canina var. praetextata to maintain high levels of nitrogenase activity in the dark at temperatures of 15°C or less suggests that a large proportion of the nitrogen fixed by lichens with a blue‐green phycobiont in temperate and low arctic regions, is at night.
CYTOTYPE DIVERSITY IN A POPULATION OF BETULA ALBA L.
Authors: BROWN IAN R. , AL‐DAWOODY D. M. 
Published: May 2006

SUMMARYA cytological survey of two populations of Betula in Northeast Scotland revealed the existence of 2n= 28, 2n= 56, 2n= 42 cytotypes. In addition, putative mixoploids with mean somatic counts between 2n= 45 and 2n= 52 were found. The 2n= 42 and mixoploid trees are similar in morphology to the 2n= 56 trees and cannot be distinguished in the field. Seed from uncontrolled pollination of the 2n= 42 cytotypes produced seedlings with somatic counts ranging from 2n= 35 to 2n= 56 with 50% of seedlings being 2n= 42.
EFFECTS OF STEROIDAL ESTROGENS AND GIBBERELLIC ACID ON STEM ELONGATION IN TALL AND DWARF CULTIVARS OF PISUM SATIVUM
Authors: JONES THERESA K. , RODDICK† JAMES G. 
Published: May 2006

SUMMARYThe effects of exogenous estrone, estradiol‐17β and gibberellic acid (GA3) on stem elongation in tall (Alaska) and dwarf (Meteor) cultivars of Pisum sativum grown under red light and under natural illumination have been studied. Test compounds were formulated in a number of ways and applied by a variety of methods. GA3 elicited a characteristic response in almost all experiments, with elongation in the dwarf cultivar being stimulated to a greater extent (relative to the control) than in the tall cultivar, but no effects of steroidal estrogens were observed on any occasion. Nor was there evidence of any interaction between exogenous GA3 and estrone. The lack of effect of estrone did not appear explicable on the basis of seedling age and the claim that red light treatment is a prerequisite for estrone action was not substantiated. Two other dwarf pea cultivars viz. Feltham First and Little Marvel also responded to GA3, but not to estrone. The disparity between the lack of estrone effect on stem elongation reported here and the positive effect reported elsewhere in the literature is discussed.
FURTHER LOCALIZATION OF AUXIN TRANSPORT THROUGH INTERNODE SEGMENTS
Authors: WANGERMANN ELISABETH 
Published: May 2006

SUMMARYIn Vicia faba, phloem fibres are shown not to take part in the active polar transport of auxin which takes place exclusively through the vascular bundles of young internode segments. Though transport of auxin through parenchyma/fibre strips does not seem to be active, it is slightly polarized in favour of the basipetal direction.
TEMPERATURE REQUIREMENTS FOR GERMINATION OF DRY‐STORED, COLD‐STORED AND BURIED SEEDS OF SOLANUM DULCAMARA L.
Authors: ROBERTS H. A. , LOCKETT PATRICIA M. 
Published: May 2006

SUMMARYFreshly collected seeds of Solarium dulcamara L. germinated almost completely at daily alternating temperatures of 10/25°, 10/30° and 20/30°C but only 20% at constant 30°C, less than 10% at 25°C and not at all at 10°, 15° or 20°C. The only change in 12 months of dry storage was a decrease in capacity for germination at 25° and 30°C. Almost complete germination at these temperatures and also at 20°C was obtained by moistening with 300 ppm of a mixture of gibberellins A4 and A7 instead of water. When stored moist at 4°C for 1 month, germination at 25° and 30°C increased to 80% and there was a progressive increase in germination at lower temperatures during the first 3 months, alternating temperatures gave more than 90% germination. Similar changes occurred during winter in seeds buried 5 cm deep outdoors, and by mid‐April all the seeds had germinated in situ.
SEED PROTEIN HOMOLOGY AND ELUCIDATION OF SPECIES RELATIONSHIPS IN PHASEOLUS AND VIGNA SPECIES
Authors: SAHAI SUMAN , RANA R. S. 
Published: May 2006

SUMMARYElectrophoresis of seed proteins from Phaseolus and Vigna species was carried out on poly‐acrylamide gels with cationic and anionic systems. The species were grouped into seven clusters. On the basis of matrices of similarity index, keeping sixty as the minimum intra‐cluster similarity coefficient, a three‐dimensional model was constructed to represent the relationships amongst the clusters. Five Asiatic species including Phaseolus aureus, P. mungo, P. sublobatus, P. angularis and P. calcaratus formed a cluster which was separate from a cluster of American species. The Vigna species forming a third cluster showed greater affinity with the Asiatic Phaseolus species than with the American ones. P. aconitifolius, a form cultivated in India, and two American species, P. lunatus and P. lathyroides, were distinct between themselves and also from other species.
PRELIMINARY STUDIES ON SAPFLOW IN COCOS NUCIFERA L.
Authors: MILBURN JOHN A. , ZIMMERMANN MARTIN H. 
Published: May 2006

SUMMARYTechniques are described which enable the transport of phloem sap in the coconut to be studied with greater precision than previously. Factors governing the flow of sap include manipulation and damage to the tissue, which tend to reduce the flow, whilst the use of sharp knives to slice the phloem enhances exudation. A possible role for manipulation is proposed, but it does not seem essential for the induction of exudation. Phloem sap pressures have been measured directly up to about 7.6 bar, agreeing with those that might be expected from measurements of the osmotic pressure of the phloem sap and the water potential of the xylem sap.Very high rates of specific mass transfer (SMT) have been measured for phloem and sieve tubes, supporting earlier estimates on Arenga, and tentative measurements have been made of the hydraulic conductivity of Cocos sieve tubes. In general, the observations support the view that mass flow through the phloem may be driven osmotically, but the remarkable facility with which the solute content of the sieve tubes can be altered, will make proof difficult.Implications of the work in relation to the transmission of phloem‐borne pathogens are discussed.
SULPHUR DIOXIDE METABOLISM IN SOY‐BEAN, GLY CINE MAX VAR. BILOXI.
Authors: GARSED S. G. , READ D. J. 
Published: May 2006

SUMMARYFirst‐trifoliate leaves of soybeans Glycine max (L.) Merr. were exposed to 35SO2 in the light or dark, and the chemical distribution of the radioactivity in the source leaves and in the remainder of the plant was determined after 1.5 and 24 h. Only 34SO4 was found in leach‐ates in the light but substantial quantities of 35SO32‐ were present in the dark. Radioactivity was present in all fractions of the source leaves examined (insoluble, centrifuge pellet, soluble protein, chloroform‐soluble and water‐soluble). The main water‐soluble compounds labelled were sulphate > gluthathione > cysteine. Small quantities of sulphite were also recovered in the dark but not in the light. The ratio of soluble: insoluble radioactivity in the sink tissues was influenced more by leaf age than by light treatment. Sulphate, glutathione and cysteine were labelled in the petioles of the source leaves and 35SO4 was found in the nutrient solution after 1.5 h in both treatments. It is concluded that light is not necessary for the reduction of internal 35SO2 products. The results are discussed in relation to current knowledge of 35SO2 metabolism.
EFFECT OF HETEROGENEOUS OAT POPULATIONS ON THE EPIPHYTOTIC DEVELOPMENT OF VICTORIA BLIGHT*
Authors: AYANRU D. K. G. , BROWNING J. A. 
Published: May 2006

SUMMARYYield and yield components of glasshouse‐ and field‐grown mixtures (blends) of near isogenic, highly resistant (HR) and highly susceptible (HS) oat lines increased significantly more than increases attributable to increasing proportions of HR plants in the blends. Disease index (DI) and lodging index (LI) of field stands were highly positively correlated (r= 0.95), while both DI and LI also had high negative correlations with grain yield (r= ‐0.87, and ‐0.95, respectively). The percentage of diseased seedlings in greenhouse mixtures decreased significantly more than decreases due to decreasing proportions of HS plants. Glasshouse stands of HS seedlings developed significantly fewer roots than developed by HR seedlings, or by 1:1 mixture (plant/plant) of the two lines. Soil samples from the rhizosphere of field blends with 20%+ HR plants had significantly fewer Helminthosporium victoriae spores than those from samples with lower proportions. In both field and glasshouse experiments, alfalfa had no significant interaction with disease incidence or yield. The buffering of HS plants against Victoria blight incidence by HR plants in mixtures is suggested.
ATP AND NITROGENASE ACTIVITY IN NITROGEN‐FIXING HETEROCYSTOUS BLUE‐GREEN ALGAE
Authors: BOTTOMLEY P. J. , STEWART W. D. P. 
Published: May 2006

SUMMARYThe relationship between ATP and nitrogenase activity has been investigated using the obligate photoautotroph Anabaena cylindrica and Anabaenopsis circularis strain 6720, a photoautotroph which can also use exogenously supplied carbon. In the light photophosphorylation supports maximum observed rates of nitrogenase activity (0.60 and 1.2 μmoles C2H4 mg chl a−1 min−1 under aerobic and microaerobic conditions respectively). The ATP pools sustained under both conditions are similar at 160–200 μmoles mg chl a−1. Oxidative phosphorylation and substrate level phosphorylation are unimportant in supporting nitrogenase activity in the light. Cyclic photophosphorylation can supply all the necessary ATP provided fixed carbon compounds from photosynthetic CO2 fixation (Anabaena) or supplied exogenously (0.2%, w/v, fructose) (Anabaenopsis) are available. When the algae are placed in the dark nitrogenase activity declines. In Anabaenopsis, after an initial rapid drop, nitrogenase activity can be sustained in the presence of exogenous carbohydrate in the dark at up to 70% of the light rate under air, but not under anaerobic conditions. This decreased nitrogenase activity in the dark is not due to a lack of nitrogenase synthesis or of penetration of fixed carbon into the cells, but appears to be due to an inherent inability of dark metabolism to generate sufficient ATP and/or reductant for maximum nitrogenase activity. The ATP pool can be sustained at maximum levels when photophosphorylation, cyclic photophosphorylation, and oxidative phosphorylation operate individually, and to a lesser extent when substrate‐level phosphorylation operates. No consistent correlations were found between the ATP pool and nitrogenase activity, except under dark anaerobic conditions where there was a positive correlation. The data suggest either that the ATP pool which supports nitrogenase activity is distinct from that which supplies ATP for general filament metabolism, and/or that the supply of ATP is not the most critical short‐term factor in controlling nitrogenase activity in Anabaena and Anabaenopsis.
THE OXYGEN TENSION WITHIN LICHEN THALLI
Authors: MILLBANK J.W. 
Published: May 2006

SUMMARYA technique is described for estimating the internal pO2 of moisture saturated lichen thalli under conditions of known light intensity and temperature. The method is polarographic, using unprotected microelectrodes, with brief experimental periods.In lichens with the phycobiont forming a zone of the thallus (Peltigera canina, P. poly‐dactyla and P. aphthosa) the pO2 in the algal zone is normally slightly hypoaerobic rising to aerobic in bright sunny conditions, and becoming substantially hypoaerobic (pO2= 1–1.5 × 104 Pa) in darkness. The pO2 within external cephalodia of lichens which have them is more affected by light. P. aphthosa and Placopsis gelida were examined and showed large and abrupt responses to changes in light intensity, the pO2 ranging from 3 × 104 Pa to 104 Pa in Peltigera aphthosa; 2.1 × 104 Pa to 104 Pa in Placopsis gelida. The nitrogenase activity shown by these lichens is probably due to the high proportion of heterocysts, conferring some immunity to high pO2 conditions.
MITOSIS AND CELL PROLIFERATION IN LEMON FRUIT EXPLANTS INCUBATED ON ATTENUATED NUTRIENT SOLUTIONS
Authors: KORDAN H. A. 
Published: May 2006

SUMMARYExcised juice vesicle stalks from mature lemon fruits manifest mitotic activity and cell proliferation when incubated on attenuated nutrient solutions consisting maximally of two mineral salts and sucrose or minimally of sucrose alone. Neither cell proliferation nor mitotic activity become manifest in vesicle stalks incubated on glass‐distilled water alone or on mineral salts without sucrose. The findings presented here demonstrate that mitosis and cell proliferation can be activated in this tissue system on nutrient media far simpler in composition than any of those usually employed for higher plant cell or tissue cultures. Evidence is also presented here which suggests that cell wall deformation in the form of wall growth is required for the manifestation of mitotic activity in this tissue system.
A DIRECT TEST OF THE ABILITY OF VESICULAR‐ARBUSCULAR MYCORRHIZA TO HELP PLANTS TAKE UP FIXED SOIL PHOSPHATE
Authors: BARROW N.J. , MALAJCZUK N. , SHAW T.C. 
Published: May 2006

SUMMARYWhen phosphate is added to soil, it slowly becomes more firmly bound and less available to plants. This change is accelerated by high soil temperatures. The present results show that this effect extends to at least 80°C. Incubation of soil and phosphate at high temperatures was therefore used to provide treatments with firmly bound phosphate equivalent to that achieved after a much longer period of contact in the field. Responses to freshly added and to firmly held phosphate were then compared in the presence and in the absence of vesicular‐arbuscular (VA) mycorrhiza to test whether VA mycorrhiza improved the plant's access to firmly held phosphate.Incubation of soil and phosphate for 12 days at 70°C reduced the availability of the phosphate to about one fifth of that of freshly added phosphate. Inoculation with VA endophytes more than doubled availability of the phosphate to both Trifolium subterraneum and Allium cepa but the improvement was no bigger for firmly held phosphate than for freshly added phosphate.
VESICULAR‐ARBUSCULAR INFECTION AND SOIL PHOSPHORUS UTILIZATION IN LUPINUS SPP.
Authors: TRINICK M. J. 
Published: May 2006

SUMMARY Lupinus angustifolius, L. cosentinii and L. luteus were weakly infected (<10% of root length) with vesicular‐arbuscular endophytes and hence VA mycorrhizas were not considered of any value in their phosphorus uptake on the nutritionally poor sandy soils of Western Australia. Vesicles were present in approximately 30% of field plants and less often in the glasshouse. Arbuscules were observed on only one specimen of L. cosentinii in a restricted section of one lateral root. Infection was reduced further when soil moisture was high and by small additions of phosphorus to the soil. Under certain conditions, VA mycorrhizal infection in L. cosentinii was stimulated by the growth of red clover. ‘Proteoid’ ‐like rootlets were observed on lupins and these had specialized root‐soil surface properties that may be responsible for improved phosphorus uptake.