摘要:

Celery seeds (Apium graveolensL.) given a germination induction period (3 days imbibition at 17°C in the light) could be prevented from germinating by up to 14 days subsequent exposure to high temperature (32°C), polyethylene glycol (PEG), abscisic acid (ABA) or dark (22°C). When the seeds were returned to 17°C in the light, germination occurred and, except for the high temperature treatment, was more rapid compared to seeds given a germination induction period only.Celery seeds incubated for 3 days at 17°C in the light and then air‐dried at 20°C germinated slowly when re‐sown at 17°C in the light, and achieved only 19% germination after 21 days. Exposing the seeds to high temperature, PEG, ABA or dark for up to 14 days before drying maintained seed viability and subsequent germination was faster. The longer treatment periods gave increased benefit, and PEG was the most effective treatment. It is suggested that the effectiveness of the treatments in inducing dehydration tolerance relates to their ability to inhibit germination possibly via their prevention of cell

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04519.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Transpiration, net photosynthesis and leaf conductance decreased when leaf water potential dropped below ‐0.30 MPa. Both transpiration and net photosynthesis rates were considerably reduced before the leaves were visibly wilted at ‐0.95 MPa. Consequently, visual symptoms are unlikely to provide a useful index for characterizing water deficits in cassava (Manihot esculentaCrantz cv. Llanera). Decreases in net photosynthesis closely followed decreases in transpiration and this suggests that stomatal closure controls both proces

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04520.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Betula papyriferaMarsh, seedlings adapted very poorly to flooding for up to 60 days. Responses to flooding included increased ethylene production; stomatal closure; leaf senescence; drastic inhibition of shoot growth, cambial growth, and root growth; decay of roots, and death of many seedlings. Flooding inhibited growth of leaves that formed prior to flooding, inhibited formation of new leaves, and induced abscission of old leaves. As a result of extensive leaf abscission, fewer leaves were present after flooding than before flooding was initiated. The drastic reduction in leaf area was associated with greatly decreased growth of the lower stem and roots. No evidence was found of adaptive morphological changes to flooding. The data indicate that intolerance ofB. papyriferaseedlings to flooding is an important barrier to regeneration of the species on sites subject to periodic inundation.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04521.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Depending on the species, coppicing (decapitation) may promote vigorous growth (Eucalyptus camaldulensisDehn), or cause rapid senescence and death (Eucalyptus obliquaL'Herit). In seedlings of the latter species, the presence of a small upwardly directed shoot on the decapitated stump prevents or delays decline. Coppiced seedlings ofE. camaldulensisandE. obliqua, with and without a remaining shoot, were analyzed for starch and soluble sugars (with the anthrone method), gibberellin‐like substances (GAs) and cytokinin‐like substances (by bioassay), and ethylene (by gas‐liquid chromatography) before and after decapitation.Levels of soluble sugars declined similarly in both varieties of eucalypts, and starch reserves appeared adequate for sprouting, and did not diminish following decapitation of the susceptible species.Decapitation did not markedly alter the relatively high amounts of GAs in roots and shoots ofE. obliqua, the susceptible species, although increased levels of Gas were observed in the stumps of seedlings left with 1 shoot after decapitation. The overall levels of GaS were relatively low in the roots and stems of the resistantE. camaldulensis, but higher in the shoots. Marked qualitative changes in GAs with decapitation were apparent in the shoots ofE. camaldulensis. A single major GA peak occurred prior to decapitation but afer decapitation several additional peaks of GA‐like activity appeared.Cytokinin‐like activity was initially low in all tissues, but increased dramatically in stump and shoot tissue following decapitation. Increases ranged from approximately 5‐fold (stump tissue of either species, minus‐shoot treatment) to approximately 40‐fold (shoot tissue of the resistantE. camaldulensisseedlings left with 1 shoot). In bothE. camaldulensisandE. obliquaethylene production increased to a peak 7 days after decapitation provided a shoot had been retained. This ethylene peak precedes a marked upturning of the retained shoot, and was not present in the stumps of totally decapitated seedlings. For totally decapitated seedlings ethylene evolution inE. obliqua(the susceptible species), but notE. camaldulensis(the resistant species), had ce

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04522.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Changes in abscisic acid and its metabolites were followed through two drought cycles inPseudotsuga menziesii(Mirb.) Franco seedlings to determine the metabolic pathway of the hormone and its relationship to branch (stomatal) conductance. Three year‐old, intact seedlings were water‐stressed, watered, and restressed over a period of 30 days. Water potential was sampled with a pressure chamber and branch conductance with a steady‐state porometer. Needle content of abscisic acid and 2‐trans‐abscisic acid and their saponifiable conjugates were quantified with gas‐liquid chromatography. The typical water potential threshold in branch conductance, decreasing abruptly at ‐2.0 MPa, corresponded to an increase in abscisic acid content of 240 ng g−1. The relationship between abscisic acid and water potential was not definitive, though the general trend was an increase in the hormone with intensifying stress until water potential was ‐5.0 MPa, when concentration sharply declined. No adjustment to stress was observed in the relationships, but stress during the second cycle progressed more slowly. A linear relationship between abscisic acid and its conjugate indicated the importance of the interconversion of the two compounds for storage and supply

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04523.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The activities of arginine decarboxylase (ADC; EC 4.1.1.19) and ornithine decarboxylase (ODC; EC 4.1.1.17) as well as polyamine content were examined inPhaseolus vulgarisL. cv. Taylor's Horticultural before and during anthesis, during fruit development and throughout vegetative growth. The specific activities of polyamine biosynthetic enzymes were highest in all rapidly growing tissues, e.g., root apices, hypocotyls, young internodes, young leaves, flower buds, young pods and pericarps. They were lowest in mature, non‐growing tissues. Similarly, the content of the major polyamines (putrescine, spermidine, spermine) is highest in rapidly growing tissues, and lowest in mature tissue. These correlations reinforce the growing connection between polyamines and rates of cell division and metabolic activity during both vegetative and reproductive developmen

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04524.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The endocellular distribution of calcium has been determined and Ca‐ATPase activity measured in subcellular fractions of various species: horse‐bean (Vicia fabaL., var. minor), barley (Hordeum vulgareL., var. Astrix), wheat (Triticum vulgareL., var. Hardy), lupine (Lupinus luteusL., var. Weiko III), oat (Avena sativaL. var. Zelma) which grow differently on calcareous media. The vacuolar calcium concentrations are below thermodynamic equilibrium with the medium for all plants. The deficit in vacuolar calcium is accentuated in plants which prefer calcareous soils. Membranes of such plants show weak affinity for calcium and also considerable Ca‐ATPase activity. It is suggested that low vacuolar concentration is a consequence of low cytoplasmic concentration. The role of Ca‐ATPases and the physicochemical properties of membranes in counteracting high external calcium is di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04525.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

A procedure is described for the induction of somatic embryos in the opium poppy.Papaver somniferumL. Callus was obtained from seedling hypocotyls on an agar solidified medium [Murashige and Skoog (1962) Physiol. Plant. 15: 473–497] containing 0.25 mg/l (1.2 μM) kinetin and 2.0 mg/l (10.7 μM) naphtalene acetic acid (NAA). Suspension cultures were initiated from callus using a liquid medium in which 2.0 mg/l (9.0 μM) 2,4‐dichlorophenoxyacetic acid was substituted for NAA. Meristemoids, spheres of closely packed cells, developed in suspensions and on the surface of a few callus cultures. Differentiation of meristemoids into somatic embryos was accomplished by removing growth regulators from the liquid medium. Embryoids appeared morphologically normal and similar to torpedo stage embryos, however, they possessed mature tracheary elements and laticifers in areas that should have contained only procambium. Whole plants have been obtained by placing embryos in the light on solid medium that also lacked growth regu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04526.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The development of SO42‐influx in roots and sulfur transport to shoots was followed in35S‐tracer experiments for sulfur‐deficient spring wheat (Triticum aestivumL. cv. Svenno) seedlings pretreated for various time periods (0–24 h) in nutrient solutions with SO42‐. Effects of the metabolic inhibitor 2,4‐dinitrophenol (DNP) and the protein synthesis inhibitor cycloheximide (CH) on SO42‐influx were also evaluated. The SO42‐influx appears feedback‐regulated by the internal sulfur level of the roots. Regulation may be achieved solely by a rapidly changed SO42‐carrier activity through an allosteric effect by the intracellular SO42‐concentration of the roots, followed first by induction of carrier synthesis and then by repression of carrier synthesis after transfer of the roots from SO42‐‐deficient nutrient solutions to solutions with SO42‐. A Hill plot of the partly sigmoidal relationship between SO42‐influx and intracellular sulfur concentration in the roots gave a Hill coefficient of ‐4.2, indicating negative cooperativity between a minimum number of four interacting allosteric binding sites for sulfur on each carrier entity. DNP‐experiments showed that SO42‐influx was mainly metabolic, especially after short pretreatment in SO42‐at an external SO42‐concentration of 0.1 mM. Pretreatment with CH rapidly prevented new SO42‐carriers from being formed. Long CH pretreatment (24 h) and different SO42‐pretreatments reduced SO42‐influx below the non‐metabolic level obtained by uptake experiments with DNP, indicating the existence of SO42‐carriers mediating passive SO42‐transport across the plasmalemma of the root cells. SO42‐influx was further decreased for the CH pretreated (24 h) plants by the presence of both CH and DNP in the experimental nutrient solution. This probably indicates the diffusive part of the non‐metabolic SO42‐influx in the present experiments. Finally, it is suggested that there is a feedback signal be

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04527.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Potato plants (Solanum tuberosumL. var. Russet Burbank) treated with 1 μl ethylene 1−1of air showed an inhibition of CO2assimilation by 18%. The inhibition occurred after 3 h of exposure to ethylene and was not mediated through closure of the stomata. The enrichment of the root zone with CO2almost completely abolished the ethylene inhibition of CO2assimilation which was apparently due to an increase in the intercellular concentration of CO2in leaves following enrichment. The effect of application of CO2to the root zone on ethylene inhibition of CO2assimilation seemed to last for a few days. Potato plants treated with aminoethoxyvinlglycine (AVG) showed an increase in fresh and dry weight as compared to non‐treated plants. Our results indicate that both CO2and AVG alter the effect of ethylene and promote growth in plants by inhibiting ethylene action and biosynthesis, respecti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1982.tb04528.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY