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1.
Ethylene, Nitrate and Nitrite Interactions in the Promotion of Dark Germination of Common Purslane Seeds 总被引:1,自引:0,他引:1
Ethylene (10 µ11) caused about one-third of highlydark-dormant seeds of common purslane (Portulaca oleracea L.)to germinate in the dark. Attempts were made to increase germinationin the dark with nitrate and ethylene combinations. When applieddirectly to the seeds, KNO3 did not stimulate germination andKNO3 plus ethylene did not increase germination above that ofethylene alone. Pre-incubation of seeds in KNO3 for 4 to 7 dbefore the ethylene applications significantly increased germination.The effects of the KNO3 pre-incubation were additive at eachof four ethylene concentrations (0.1100 µ111).Potassium nitrate was effective only when ethylene followedthe KNO3 pre-incubation period. Potassium nitrite stimulatedabout 25 per cent of the seeds to germinate without a pre-incubationperiod and without ethylene. Also, ethylene plus KNO2 enhancedgermination above that achieved by either stimulus alone. Silvernitrate did not block the ethylene promotion of germination,but reversed the typical ethylene inhibition of seedling growthfollowing germination. The results support the views that nitrateexerted its effect via conversion to nitrite within the seedand that the rate of nitrate conversion may be a limiting factorin the dark germination of common purslane seeds. Ethylene mayfacilitate nitrite activity by increasing seed sensitivity tothe stimulus. Common purslane, Portulaca oleracea L., ethylene, nitrate, nitrite, germination, dormancy 相似文献
2.
Methanol Accumulation in Maturing Seeds 总被引:6,自引:2,他引:4
OBENDORF RALPH L.; KOCH JAMES L.; GORECKI RYSZARD J; AMABLE RICHARD A.; AVENI MARC T. 《Journal of experimental botany》1990,41(4):489-495
During in vitro growth and maturation of soybean seeds, cessationof embryo growth and dry weight accumulation occurred in thepresence of abundant C and N nutrients. Axis followed by cotyledontissues changed from green to yellow, and post-harvest germinationpotential declined if cultured after yellowing of axis tissues.A tissue specific accumulat;on of methanol occurred during thein vitro culture of immature seeds (i.e. initially 50 to 70mg fresh weight) to maturity in liquid medium. Methanol accumulatedto 3.0 g m3 or 50 µg seed1 in the medium,while methanol decreased from 37 to about 3.0 µg g1fresh weight in cotyledons. By contrast, axis tissues increased20-fold in methanol concentration to 90 µg g1 during20 d in culture. Ethanol was present only in trace amounts inaxis tissues and medium. Addition of exogenous methanol vapourto in situ grown seeds during precocious maturation decreasedsubsequent seedling vigour and germination with increasing levelsof exposure. Methanol accumulation in axis tissues during thegermination phase was not correlated with high temperature andtissue water content treatments which simulated pre-harvestdeterioration of seeds. However, the accumulation of methanolduring in vitro seed development and maturation in liquid culturemay contribute to reduced post-harvest germination performance. Key words: Soybean, Glycine max, seed maturation, in vitro, methanol 相似文献
3.
When a dark grown colony of Trichoderma viride is exposed towhite light for a short time, sporulation occurs only in thenarrow region of mycelia produced just prior to illumination.The action spectrum of this light effect was obtained for wavelengthsbelow 520 mµ using monochromatic irradiation of knownintensity having a band width of 10 mµ. The action spectrumshows 4 distinct peaks at 320, 380, 430 and 480 mµ. Thewavelengths at 320 and 380 mµ are most effective in photoinducedsporulation. The longer wavelengths, 430 and 480 mµ, areconsiderably less effective. The possibility that a carotenoid or a flavin compound may bea photoreceptor in this photoinduced sporulation is discussed. (Received January 4, 1969; ) 相似文献
4.
A method for isolating an f-type cytochrome (Chlorella cytochrome554) from Chlorella vulgaris var. viridis (CHODAT) utilizingN, N-diethylaminoethylcellulose is described. The spectrum ofreduced Chlorella cyt. 554 has absorption maxima at 554 mµ(-band), 524 mµ (ß-band), 417 mµ (SORETband), 352 mµ, 319 mµ and 277 mµ (proteinband). The oxidized form has absorption maxima at 554mµ530 mµ, (ß-band), 412 mµ (SORET band),360mµ 322 mµ and 275 mµ (protein band). Thespectral characteristics resembled other f-type cytochromes,e. g. in the high SORET to -extinction ratio (6.8) and an asymmetric-absorption band (especially at liquid N2 temperature) ; butcharacteristic differences were present. Mitochondria from whitelupine seedlings and sweet potato roots reduced Chlorella cyt.554. From the effects of antimycin A and 2-heptyl-4-hydroxyquinolineN-oxide it appears that Chlorella cyt. 554 was reduced sequentiallybefore cytochrome a+a3 and near the level of the cytochromesof the b type. Oxidation was slow using lupine mitochondriaand nil with sweet potato mitochondria. The oxidation-reductionpotential at pH 7.2 and 30? was 0.35 V. Ascorbate, cysteine,glutathione and Na2S2O4 readily reduced Chlorella cyt. 554.The cytochrome was not autoxidizable and was slowly oxidizedby excess potassium ferricyanide. The reduced form did not reactwith CO and was not adsorbed by IRC-50 or Cellex-P cation exchangers.
1 Temporary address until September 1961: Department of HorticulturalScience, University of California, Los Angeles 24, California,U. S. A.
2 Present address: Plant Industry Station, Pioneering ResearchLaboratory, Marketing Quality Research Division, AgriculturalMarketing Service, Beltsville, Maryland, U. S. A. (Received January 16, 1961; ) 相似文献
5.
Various photon doses (net number of photons per unit area perday), provided by varying both photon flux density and photoperiod,were applied to imbibing seeds of seven lots of four speciesof Compositae in various germination test regimes. In all fourspecies germination was dependent upon photon dose, the productof photon flux density and daily duration of exposure. The responsewas quantified by linear relations between the probit of percentagegermination and the logarithm of photon dose. In general, photonflux density and photoperiod only influenced the stimulationof germination by the low energy reaction indirectly (as factorsof daily photon dose), whereas there was a tendency for photoperiodto have a direct influence on the inhibition of germinationby the high irradiance reaction. Reducing the germination testtemperature from 25?C to 20?C and 15?C not only increased thedark germination of L. sativa L., but also broadened the photondose range at which full germination occurred by reducing theminimum value necessary for the germination of the most dormantseeds, and increasing the maximum value which failed to inhibitthe germination of any seeds. Differences between L. sativaand L. serriola L. in the response of germination to white lightwere only quantitative, rather than qualitative. The singlemost promotory dose for all four species was 3 ? 103mol m2 d1, although the inhibitory action of dosesup to 10 mol m d was generally only slight. Key words: Light, seed germination, seed dormancy, Compositae 相似文献
6.
The unicellular green alga Coccomyxa, a component of the lichenPeltigera aphthosa, liberated about 7.2mµg biotin permg dry weight of cells into the culture medium during a growthperiod of 1520 days. The corresponding figure for thefree-living alga Chlorella pyrenoidosa was 0.45mµg ofbiotin. Chromatographic analysis indicated that this was freebiotin and not a bound form of the vitamin. The biotin concentrationof rinsed Coccomyxa cells was 1.88mµg per mg dry weightof cells, of which less than 0.01mµg was extractable byhot water. Cells of Chlorella contained 0.16mµg of biotinper mg dry weight, of which 0.11mµg was extractable byhot water. The biotin content of Coccomyxa, which was about12 times that of Chlorella, is thus almost entirely in the boundform. The importance of biotin in the symbiotic interactionsbetween the alga and the fungus in Peltigera is discussed.
1Present address: University Department of Agriculture, Oxford,England.
2Present address: Institute of Marine Resources, Universityof California, La Jolla, California, U.S.A. 相似文献
7.
Spore discharge in Ascobolus crenulatus occurs both in the lightand in the dark. In a 12 h light: 12 h dark daily regime discharge-ratehas peaks in the dark periods, due apparently to light stimulationwith about half a day's interval between stimulus and response. Using a spore clock the course of discharge hasbeen followed for a single apothecium on changing from darknessto light. Exposure to light (500 lux) of wave-lengths around400, 440 and 460 mµ immediately causes puffing,whilst light of longer wave-length (504 and 580 mµ) hasno effect. Change from darkness to white light has no immediateeffect, but there is a delayed stimulation with a marked increasein discharge-rate 1014 h later. Simultaneous illuminationof an apothecium, which has been in darkness, by blue light(420 mµ, or 440 mµ, 500lux) and yellow light (580mµ, 500 lux) does not result in puffing. The yellow appearsto prevent the blue light from exerting its effects. 相似文献
8.
Immature Glycine max (L.) Merr. seeds initially at 5070mg fresh weight were successfully grown and matured in vitroin detached pods. Surface sterilized pods were floated in aliquid medium containing 5 per cent sucrose, minerals, and glutaminein 125 ml Erlenmeyer flasks and incubated at 25 °C under350400 µE m1 s1 white light. Seedswhich were matured in vitro increased tenfold in dry weight,were visually similar to commercial seeds of the same size,were tolerant to desiccation and germinated with normal seedlinggrowth. Excised pods transported dye from the pedicel to thegrowing seed within 120 min. Soya bean pod culture is a usefultechnique to study the influence of single or combinations ofchemical or environmental parameters on regulation of seed growth,seed maturation, and subsequent germination events without theconfounding interactions with the mother plant. Glycine max (L.) Merr., soya bean, pod culture, seed culture, seed growth, seed maturation, germination 相似文献
9.
1. The seeds ofNasturtium palustreDC. do not germinate, eitherin the light or darkness, at various constant temperatures,but require for their full germination a certain period of alow temperature (5°) applied immediately after light irradiation.These results indicate the existance of at least two processes,a light-dependent process and a low temperature-requiring process,in the initiation of germination ofNasturtiumseeds. Experimentalevidence indicated further that the light exposure causes twodifferent processes in the seed germination. 2. When a dark period at 23° was inserted between the lightirradiation and the low temperature treatment the germinationwas suppressed. The inhibitory effect of the inserted dark periodat 23° was eliminated by a short irradiation during thedarkness (light-break). 3. Prolonged exposure ofNasturtium seeds to any concentrationof gibberellin brought about no germination when exposure wasgiven in complete darkness. The germination was promoted onlywhen light irradiation was applied to the seeds. A short applicationof gibberellin at a fairly high concentration was, however,remarkably effective for the germination even in the darkness,and the germination was inhibited as the gibberellin applicationwas lengthened. It was considered that gibberellin could substitutefor the combined effect of light irradiation and low temperaturetreatment to induce the germination of Nasturtium seeds, andthat gibberellin was inhibitive toward the reactions followingthe above treatments which induced the germination (Received October 31, 1996; ) 相似文献
10.
Irradiation of spores of the fern Mohria caffrorum Sw. witheither red light (67.4 µW cm2) or far-red light(63.2 µW cm2) for a period of 24 h induced maximumlevels of germination. Brief irradiations with blue light (127.6µW cm2) administered before or after photoinductioncompletely nullified the effects of red or far-red light; however,with prolonged exposure to blue light, germination levels roseto near maximum. The similar effects of red and far-red lightin promoting spore germination makes the involvement of phytochromein this process questionable. Based on energy requirements,the promotive and inhibitory phases of blue light appear toinvolve independent modes of action. Mohria caffrorum, ferns, spore germination, photoinduction, phytochrome 相似文献
11.
- The effects of 3-(4'-chlorophenyl)-1, 1-dimethylurea (CMU)onthe fluorescence of photosynthetic pigments in vivo wereinvestigatedin blue-green, red and brown algae and in isolatedspinach chloroplasts.CMU caused an increase in steady statelevel of fluorescenceof chlorophyll a, but did not influencethe fluorescence ofphycobilins. The spectrum of the fluorescenceincrement hada peak at 685 m/µ and a shoulder at 730740mµ.These two bands probably arise from chlorophyll a(Cf684) belongingto pigment system II.
- On excitation of chlorophylla in a red alga, Porphyra yezoensis,a fluorescence band witha peak at 720 mµ was observedbesides a shoulder at 685mµ. The 720 m band is inferredto arise from chlorophylla (probably, Cf-1) in pigment systemI.
- On addition of CMUto the algal cells, the induction of fluorescencewas modifiedto take a simple time course. The induction wasobserved onlywith respect to the fluorescence of chlorophylla, but not inthe fluorescence of phycobilins. The spectrumof the "transient"fluorescence showed two emission bands ofchlorophyll a at 685mµ and 740 mµ, and was quitesimilar in form tothe spectrum of the CMU-caused increase insteady state fluorescence.
- These facts were interpreted in terms of the correlation offluorescence of chlorophyll a and the photochemical reactionsof photosynthesis
12.
Light-induced absorbance changes in the region around the redabsorption band of chlorophyll a were measured in cells andlamella fragments of Anacystis nidulans. In both materials,absorbance decreases were observed at 702 mµ and 682 mµ.(The pigments are designated as P700 and P680.) The nature ofP680 was investigated with special reference to its relationshipto P700. In the cells, light absorbed by chlorophyll a causedan absorbance decrease at 682 mµ; Simultaneous illuminationwith light absorbed by phycocyanin caused a partial recoveryof the absorbance decrease. Similar results were observed withthe light-induced absorbance change at 702 mµ. This indicatesthat P680 is also an electron carrier in the electron transportchain and occupies a place between the two photoreactions. Inlamella fragments, both the light-induced reversible absorbancechanges of P680 and P700 appeared in the presence of an electrondonor system; i.e., ascorbate and 2,6-dichlorophenolindophenolor N,N,N',N'-tetramethyl-l,4-phenylenediamine. The experimentsin which the oxidation-reduction potential of the reaction mediumwas changed showed that both P680 and P700 are one-electroncarriers, having a normal oxidation-reduction potential of 0.44v (assuming that the normal oxidation-reduction potential ofthe ferricyanide-ferrocyanide system is 0.409 v). A possibilitywas suggested that the absorbance change observed at 682 mµis another expression of the oxidation-reduction reaction ofP700). (Received October 30, 1968; ) 相似文献
13.
Effects of dehydration, storage temperature and humidificationon germination of Salix alba andS. matsudana seeds were studied.Newly released seeds showed 100% germination before and afterdehydration to 1112% moisture content. Germination ofthe high vigour lot (100% initial normal germination) was notaffected by dehydration to 6.7% moisture content but germinationdecreased with further dehydration to 4.3%. The lower vigourlot (75% initial normal germination) was more susceptible todehydration and germination decreased following dehydrationto 6.7% moisture content. Dry seeds of both species survivedimmersion in liquid nitrogen without loss of viability. Thegermination of seeds stored with 9% moisture content decreasedto 3540% in 5 months at -20°C or in 2 months at 5°C.However, at 25°C seeds entirely lost viability within 2weeks. Seeds showed improved performance when stored at -70°C> - 20°C > 5°C > 25°C and tolerated dehydrationto a moisture content in equilibrium with 15% relative humidity.Results suggest that they are orthodox in storage behaviouralthough they are short-lived. Humidification treatment of lowvigour seed lots resulted in a remarkable increase in germinationpercentage. Copyright 2000 Annals of Botany Company Salix alba, Salix matsudana, willow, seed storage behaviour, dehydration, humidification, cryopreservation 相似文献
14.
Cyclic 3',5'-adenosine monophosphate and sodium dibutyryl cyclic3',5'-adenosine monophosphate had no effect on dark-germinationof light-sensitive lettuce {Lacluca sativa L., var. Grand Rapids)seeds when given alone. Cyclic 3',5'-adenosine monophosphate,however, synergistically enhanced the 3 µ 105 Mgibberellic acid-induced germination, but showed no such effecton kinetin-stimulated germination. 5'-AMP, in contrast to cyclic3',5'-adenosine monophosphate, had no effect on gibberellicacidinduced germination. (Received August 8, 1971; ) 相似文献
15.
Effect of Water Potential and Temperature on the Germination of Four Species of African Savanna Trees 总被引:1,自引:0,他引:1
The germination responses of seeds from the African tree speciesColophospermum mopane, Combretum apiculatum, Acacia tortilisand Acacia karroo under varying regimes of temperature and waterstress (induced by incubation in PEG 8000) are reported Withthe exception of Combretum (at 0.14 and 0.29 MPa)and Colophospermum (at 0.29 MPa), incubation in PEG decreasedthe maximum achieved germination percentage (90100% forall species), but did not extend the germination lag (exceptin Combretum) or affect the time required to reach maximum germinationCombretum and Colophospermum were found to germinate under thewidest range of temperatures and water potentials, for example,as strongly negative as 1.0 MPa at 20 and 30 °C,respectively These seeds also showed greater or equivalent hypocotylelongation in PEG solutions creating potentials of 0.14,0.29 or 0.51 MPa when compared with seeds germinatedin water, indicating an additional stress adaptation Acaciaspecies showed progressive reduction in germination rates andradicle elongation in response to decreasing water potentialExperiments giving pre-imbibition treatments in water priorto transfer to PEG solutions showed that both Acacia speciesgerminated at approximately 90% if given such pre-treatmentand less than 10% if transferred directly to PEG It is concludedthat the most stress-adapted species studied are Colophospermummopane and Combretum apiculatum, a finding generally correlatedwith the growth habit of these trees Colophospermum mopane, Combretum apiculatum, Acacia tortilis, Acacia karroo, germination, water stress, Zimbabwe 相似文献
16.
Seed conditioning and germination in witchweed (Striga asiatica(L.) Kuntze) were temperature-dependent. With higher conditioningtemperatures, shorter conditioning time was required for germinationwith terminal dl-strigol (strigol) treatment at 30 °C. Maximumgermination (80100%) was obtained by conditioning inwater at 20, 25, 30 and 35 °C for 14, 7, 5 and 3 d, respectively,and terminally treating with 106 M strigol at 30 °C.Seeds conditioned in 108 M strigol instead of water germinatedmuch less with the same terminal strigol treatment. Generally,conditioning was slower when seeds were conditioned in strigolrather than water. The reduction in germination rate by pretreatmentin strigol or pretreatment at low temperatures could be overcomeby increasing the terminal strigol concentration in the germinationtest. Conditioned seeds did not germinate at 10 and 15 °Cwith a terminal 106 M strigol treatment but yielded closeto maximum germination at 25, 30 and 35 °C with the sameterminal strigol treatment. To obtain maximum germination, boththe minimum conditioning temperature and the minimum germinationtemperature for conditioned seeds were 20 °C. Factors suchas conditioning time, and strigol concentration and temperatureduring conditioning and/or germination determine whether seedsremain in the conditioning phase or shift to a germination phase. dl-Strigol, germination stimulation, parasitic plants, seed conditioning, seed germination, Striga asiatica, temperature, weed control 相似文献
17.
Over 50 per cent germination has been obtained from Elaeis guineensisform pisifera seeds stored in unaerated sterile distilled waterfor 6 months. The moisture levels of the seeds and excised embryoswere of the same order (2030 and 6070 per cent,respectively) as those of fully imbibed fresh seeds. The implicationsof an apparent lower oxygen requirement by seeds stored underwater as against germinating seeds are discussed in the contextof the successful storage. Elaeis guineensis, pisifera, germination, seed dormancy, embryo 相似文献
18.
Priming and accelerated ageing affect L-isoaspartyl methyltransferase activity in tomato (Lycopersicon esculentum Mill.) seed 总被引:1,自引:0,他引:1
Damage and degradation of cellular proteins is observed duringage-induced seed deterioration. L-Isoaspartyl protein methyltransferase(EC 2.1.1.77
[EC]
) is an enzyme hypothesized to play a role in limitingand repairing age-induced damage to proteins. Tomato (Lycopersiconesculentum Mill. New Yorker) seeds were assayedfor changes in L-isoaspartyl methyl-transferase activity duringaccelerated ageing and after osmotic priming. Accelerated ageingof seeds for 14 d at 45C and 100% relative humidityreduced germination from 94% to 71%, increased the mean timeof germination (MTG) from 2.4 to 5.8 d, and was accompaniedby a correlative decrease in L-isoaspartyl methyltransferaseactivity (r2=0.90). Aged and untreated seeds were primed for7 d at 20C in darkness using aerated solutions of 3% KNO3 orpolyethylene glycol 8000 (PEG) with equivalent osmotic potential(1.25 MPa). Priming with KNO3 decreased the MTG, butdid not improve germination percentage for untreated seeds.Priming did not affect L-isoaspartyl methyltransferase activityin untreated seeds, but restored activity in aged seeds primedin KNO3 to levels near that of untreated seeds. Priming withPEG did not effectively improve the MTG or increase L-isoaspartylmethyltransferase activity. During germination, L-isoaspartylmethyltransferase activity remained constant for 48 h post-imbibitionand then declined, suggesting that the enzyme was developmentallyregulated and inactivated or degraded as radicle emergence occurred. Key words: L-Isoaspartyl methyltransferase, protein repair, seed priming, accelerated ageing, Lycopersicon esculentum 相似文献
19.
Seed germination in Talinum triangulare as affected by photoperiod,with or without previous incubation in the dark in water at25 or 4 °C, was studied. The time course and quantity ofseed germination in photoperiods of 1 h and above were similarwith or without dark pretreatment, but the time to half maximumgermination was reduced from 12 days in non-dark pretreatedseeds to 4 days in seeds given 20 days in the dark at 25°C.A photoperiod of 0·25 h gave a lower rate and total germinationthan photoperiods of 1 h and above. Un-pretreated seeds required17 cycles of 24 h photoperiod for maximum germination as comparedwith 7 or less cycles if the seeds received more than 10 daysdark pretreatment at 25 °C. Both the rate and total germinationin light increased as the length of dark pretreatment at 25°C was increased from zero to 30 days. Incubation of theseeds in water in the dark at 4 °C for 5 to 30 days priorto illumination at 21 °C, reduced both the rate and quantityof seed germination in light as compared with those similarlyincubated in the dark at 25 °C. However, previous incubationin the dark for 30 days at 4 °C partially substituted forthe light requirement. The possible mechanism of breakage ofseed dormancy in Talinumis discussed in relation to these andother findings. Talinum triangulare (Jacq.), Willd, light, photoperiod, seed germination 相似文献
20.
Primary dormancy in tomato (Lycopersicon esculentum cv. Moneymaker): studies with the sitiens mutant
Intact wild-type tomato (Lycopersicon esculentum cv. Moneymaker)seeds do not complete germination to the same percentage orat the same speed as intact ABA-deficient sitiens (sitw) mutantseeds when seeds of both genotypes are imbibed on polyethyleneglycol (PEG) solutions of 0.3 to 1.5 MPa osmoticpotential. However, if the thicker testas of wild-type seedsare removed (stripped) from the micropyle without damaging theendosperm, both the percentage and speed of germination at lowexternal water potential are similar to that of sitw mutantseeds. Removing the micropylar end of the testa from sitw seedsdid not enhance either the speed or percentage of germinationon PEG solution. Despite similar germination percentage and speed between strippedwild-type seeds and either stripped or intact sitw seeds underosmotic stress, some differences in seed metabolism are evidentbetween genotypes. The activity of endo-ß-mannanasewas greater in the endosperm of sitw mutant seeds compared tothe endosperm of wild-type seeds when seeds were exposed toosmotic stress. Although 相似文献