摘要:

AbstractThe effects of uracil and its analogue 5‐nitrouracil on growth and flowering of tomato have been studied. A few drops (0.3 ml) of solutions containing 15, 30, 60, 90 and 150 μg of each prepared from a stock of 500 mg/I in glass redistilled water were applied per plant on 3–4 top leaves and the apex of one month old seedlings with 6–7 leaves. A second application double in volume of the same chemicals was made on the same plants a week later. The controls were given a distilled water treatment.Treatments with uracil and 5‐nitrouracil significantly increased the plant height and the fresh and dry weights of the shoot. Higher concentrations (500 mg/I) had no promotive effect. Although there had been a significant promotion of the leaf and stem growth, the root growth and the nodes were unaffected.Flowering was significantly hastened by both bases. Treatments with uracil also resulted in the formation of more flowers. Uracil and 5‐nitrouracil also caused significant increases in the total‐N of the leaf and the stem, and the effect on protein metabolism seems to be localised where they act as RNA metabolites. The presence of the nitro‐group in 5‐nitrouracil does not act as an additional source of nitrogen for protein metabolism as it did not have more promotive eff

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07317.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractSimultaneous cyclic variation in rates of both net photosynthesis and transpiration were induced in attached leaves of cotton and pepper plants under constant environmental conditions. The cyclic variations in photosynthesis and transpiration were found to be in phase, and the ratio net photosynthetic rate/transpiration rate remained constant over a wide range of gas exchange rates. A similar constancy of this ratio was also found as gas exchange rates declined following excision of a sunflower leaf, which was not initially cycling, in air. These results suggested that change in stomatal aperture was the only controlling factor involved and that it was affecting both processes proportionately. Visible loss of leaf turgur and measurable water stress developed in both pepper and cotton at peak exchange rates, but the gas exchange ratio remained constant.The failure of water stress and increased stomatal aperture to lower the gas exchange ratio suggested an absence of any significant leaf mesophyll resistance (r′m) to inward diffusion of CO2. The possibility that r′mwas low is discussed generally, and in relation to the use of chemical antitranspirants to raise the gas exchange ratio. Within the limits of the experiments, water stress apparently had no direct adverse effect on rates of net photosynthesis. The gas exchange ratio did not rise as exchange rates declined. Ultimately, at very low exchange rates, the ratio fell, declining to zero in cotton, but not in pepper. This decline was attributed to the onset of significant gas exchange through the cuticle, which was apparently less permeable to CO2than to water vapour. Positive net cuticular photosynthesis therefore probably does not occur in cotton. Except at very low exchange rates, the gas exchange ratio was higher in cotton than in pepper; it was similar in sunflower and cot

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07318.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractGel electrophoretic methods and equipment which were devised or modified for rapid and economic application to angiosperm tissues are described. Staining schedules are outlined that proved effective on a wide variety of tissues for elucidation of isoenzymes with the following activities; eslerase, peroxidase, catalase, leucine amino peptidase, phosphatase, amylase, and glutamic‐oxalacetic‐transaminase. Illustrative applications are discus

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07319.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractLong day photoperiod treatments given to Dancy and Clementine tangerines (Citrus reticulataBlanco.), the Mineola tangelo (C. parodisi Macf. × C. reticulata Blanco.) and the Rubideaux trifoliate (Poncirus trifoliata(L.) Raf.) produced 1.5 to 2.5 times the stem area, total linear growth and number of branches compared to short day treatments.Growing shoot tips were snbjected lo etectrophoretic analyses of tbe isoenzymic composition of esterases, teucine aminopeptidases, peroxidases and amylases. Differences were observed in the number and activity of the isoenzymes between the sbort and the long day treated plants of the threeCitrusspecies aiid Hnbideaux trifoliate orange. The possible significance of tbese differences is discnssed in relation to Ihe growth in response to the photoperiodic treatments

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07320.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstractthe contents of total phenolics in three parasitic angiosperms,Cuscutaspecies,Orobanche aegyptiacaandDendrophthoe falcataand their respective hosts, were colorimetrieally determined. A biochemical comparison was made of the phenolics on the basis of the ability of alcoholic extracts of the tissues to inhibit amylose phosphorylase invitro.High concentration of phenolics seemed to be a general feature of parasitic angiosperms. An increase in the concentration of the phenolics occurred in the tissues of infected hosts, in comparison with controls. the phenolics of Orobanche and mistletoe had inhibitory activity against amylose phosphorylase, but those of Cuscuta developed the inhibitory ability only when growing on hosts which themselves possessed inhibitory phenolics. the inhibitory activity of host phenolics was sometimes altered as a result of infection by parasite. Although the hosts often exerted some influence on the concentration and the inhibitory activity of phenolics in the parasites, there was no direct relationship between host and parasite phenolics. the sum of the phenolics in the tissues of parasite and the infected bost generally exceeded the phenolics in the tissues of the control host. The content of phenolics and their inhibitory activity did not appear to be directly related to the resistance of a host or to the extent of its susceptibility to parasite infection.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07321.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractDormancy was induced in lettuce seed by exposing to coumarin during imbibition. The level of dormancy which is imposed is dependent on the temperature during germination, coumarin being ineffective below 20°C. At 25°C there is marked interaction between coumarin and this temperature, and the response of the seed. It was shown by exposing treated seeds to temperature regimes involving periods at 25°C and 10°C. that the action of coumarin can be explained more readily by concluding that the events which are affected are cell elongation and division. There is also evidence that the coumarin is metabolised more rapidly at 25°C, and that the effectiveness of the coumarin in the experiments cited depends on its presence at the time when embryo growth is initiated. The mode of action of coumarin is unk

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07322.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe transport of oleanolic acid synthesized from14CO2in the individual leaves ofCalendula officinalisplants was investigated. It was proved that the rate and the direction of the transport depend on the stage of vegetation and the position of the leaf on the plant. The greatest transport rates of oleanolic acid were observed from the upper level leaves towards the inflorescence during the flowering period. The overblowing period was characterized by a slower migration of oleanolic acid from the leaf supplied with radioactive precursor. The migration was directed mainly to the root especially from the low level leaves. Using CH314COONa as precursor, it was established that the root is unable to synthesize oleanolic acid.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07323.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractEvidence is presented that the growth of cultured wheat roots is enhanced in closed culture systems not only by carbon dioxide but by a further and apparently very volatile product of root metabolism. The formation of this second growth‐stimulating substance is not considered to depend upon a reduction of oxygen tension in the culture system. Unlike ethanol the activity of the volatile promoter does not depend upon illumination of the cultures. The volatile promoter cannot be effectively absorbed by a number of gas absorbents. Attempts to demonstrate ethylene production by the roots have been unsuccessfu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07324.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe patterns of uptake of fluorescein‐labelled lysozyme (Fl‐lysozyme) by barley, maize, onion, tomato and vetch are similar as revealed by fluorescence microscopy. Penetration of the root cap and through the epidermis into the cortex increases with time of exposure and decreases with higher salt concentrations. In fact, one molar ethylammonium chloride can remove most of the absorbed protein from treated roots and the space observed to be stained by Fl‐lysozyme in this manner can be visualized as “free space”. Results with sterile and non‐sterile barley roots were indistinguishable. At low ionic strength, Fl‐lysozyme can penetrate cells and complex with nucleoli. Such cell protoplasts appear “coagulated”. Uptake results with fluoresceinper sewere unlike those with protein.The uptake of a much larger molecule, ferritin, is confined to the epidermis and root cell walls.Localized, absorbed protein and root growth inhibition by basic proteins have

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07325.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

AbstractThe photoperiodic responses ofBrassica campestrisL. cv. Ceres were investigated to determine the suitability of this plant for further studies on the spectral require ments for floral initiation. This is a long‐day plant, sensitive to one inductive photocycle on the fourth day from germination. The flowering response increased with the length and intensity of a single period of supplementary light used to extend an 8‐hour daylength and was greatest at 25°C. Application of nitrates retarded floral initiation by about two days under short day conditions, but did not affect the re sponse to one long day. Gibberellic acid induced earlier floral initiation under short day conditions.The photoperiodic response was little affected by omitting the main light period immediately before or after the supplementary light, as long as the intensity of supplementary light was greater than 5000 lux. Short interruptions (5–10 minutes) of a single 16‐hour dark period with high energy red or far‐red radiation did not promote flowering. When given continuously during a single 16‐hour dark period, far‐red radiation was more effective in flower promotion than an equal

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1968.tb07326.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY