摘要:

AbstractThe role of abscisic acid in the regulation of senescence was investigated in detached tobacco leaves (Nicotiana rusticaL.). Leaves senesced in darkness showed a sharp rise in abscisic acid level in the early stage of aging, followed by a rapid decline later. The same trend was found when leaves were aged in light, but the rise in abscisic acid occurred four days later than in darkness. Senescence was slower in light than in darkness, while salt stress accelerated the processes. Leaves treated with kinetin which senesced in light and darkness, did not show an increase in abscisic acid. Application of kinetin led to a transformation from free to bound ABA. These results may indicate that ABA and cytokinin are involved in a trigger mechanism which regulates senescence; the stage at which this trigger is activated determines the rate of senescence.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03799.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractPure samples of the antheridiogen ofAnemia phyllitidis(AAn) were tested for their ability to affect the growth of dwarf corn (d5) and lettuce seedlings, and to influence α‐amylase production by barley half‐seeds. Stimulation of dwarf corn growth and barley amylase production was, on a molar basis, from 1/2 to 1/250 that given by GA3.In lettuce, AAnhad a synergistic effect with low levels of GA3; alone, AAnwas inhibitory or ineffective. Therefore, in addition to having a close chemical resemblance to gibberellin, AAninduces similar, but not identical physiological responses in flowering plants as well as f

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03800.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractZeatin and zeatinriboside were identified from the milk of matureCocos nuciferafruits. It would appear as if the two compounds are present in roughly equal proportions. Ethyl acetate extraction in a liquid‐liquid extractor at an alkaline pH (8.0) proved to be a very efficient method of extracting zeatinriboside. Partitioning with water‐saturatedn‐butanol proved to be the best way of extracting z

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03801.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effect of Ca2+and Mg2+on the rate of K+(Na+) uptake from different external concentrations ranging from 0 to 1 mM and in the absence and presence of a fixed concentration of Na+(K+) in the same range, was determined. The object was to examine to what degree the qualitatively well‐established action of the polyvalent cations on these processes could be understood quantitatively from a twofold starting‐point: in the first place the theory of carrier competition (Bange 1962, Acta Bot. Neerl. 11: 139–146) and secondly the hypothesis that polyvalent cations influence carrier site accessibility at the cell surface.It appears that along these lines a semi‐quantitative description of the phenomena observed is feasible. Possible causes of deviations are di

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03802.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractExcised stem sections from growing plants ofPopulus tremulaL. andPisum sativumL. including lateral buds were treated with indole‐3‐acetic acid in a phosphate buffer solution. In control sections the level of the abscisic acid‐like inhibitor decreased strongly during 24 h as did the level of the endogenous auxin. Exogenous indoleacetic acid counteracted the decrease in the inhibitor level to a considerable extent. Implications of this auxin effect in relation to apical dominance are disc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03803.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe carboxylation of ribulose‐1,5‐diphosphate was demonstratedin vitrowith extracts of ctiolated seedling roots. The presence of ribulose‐1,5‐diphosphate carboxylase was characterized in the subcellular fraction enriched in amyloplasts.Synthesis of chlorophyll, development of CO2fixation capacities and of Hill activity upon illumination have been studied with roots ofLens culinarisseedlings. The marked increases in CO2fixation with ribulose‐1,5‐diphosphate as the substrate and in Hill activity that occur after a lag phase seem to be related to cytological changes during the greeni

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03804.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe blue‐green algaFremyella diplosiphonDrouet can be grown in the dark on a medium consisting of mineral salts, glucose, and casein hydrolysate. A variety of organic substances was tested for effectiveness as a carbon or nitrogen source. The most effective individual compounds were glucose and citrulline, respectively. A daily irradiation of 5 min green light depresses the dark growth rate. The effect of green is reversible by brief irradiation with red light, and multiple photoreversibility was demonstrated.This green, red‐reversible effect on dark growth rate may be related to other photomorphogenic responses to brief irradiation with green and red in the Cyanophyta. A master photoreversible pigment similar to phytochrome is a possible photoreceptor for these effe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03805.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe adaptation of apple seedlings,Pyrus malusL., to localized nutrient stress was studied by measuring nitrogen uptake. Seedlings with split root systems were grown in nutrient solution. Various proportions of the roots were subjected to nutrient stress by placing some of the roots in water. The nitrogen uptake by stressed plants was measured under constant and varied lighting. Under optimum lighting it was found that if part of the root system was deprived of nitrogen, then the remainder partially compensated for this deficiency by increasing its uptake. This adaptation, however, was substantially reduced under low levels of lighting.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03806.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe phytochrome‐controlled dormancy of celery seeds (Apium graveolensL.) can be broken by exogenously applied growth regulators. Gibberellins, especially the mixture of GA4and GA7appeared to be the primary stimuli for germination of darkincubated seeds. However, concentrations less than 1 mMwere ineffective in replacing the light requirement in one celery cultivar (cv.Utah), and in another cultivar (cv.Lathom Blanching), concentrations above 1 mMwere insufficient. The addition of ethylenediaminetetraacetic acid (EDTA) to gibberellins, increased markedly their activity and reduced by several orders of magnitude the gibberellin concentrations needed to stimulate a light treatment. This synergistic activity is similar to the effect of benzyladenine (BA) or Succinic acid‐2,2‐dimethylhydrazide (SADH) when added to gibberellins. In a diverse plant system, the mixture of gibberellin with EDTA increased significantly the amount of reducing sugars released by embryoless barley

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03807.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractSunflower plants (7 weeks old) were transferred from a modified Hoagland solution to a N‐free nutrient medium and kept there for 7 days. Abscisic acid (ABA) was determined in several parts of the plants and in exudates collected from the roots of some of these plants.N‐deficiency considerably increased the ABA content of the leaves, especially the older ones, and also considerably increased the ABA content of the upper parts of the stem when compared to the control plants. In the roots and the exudates of these plants no ABA could be detected.After dissecting the stems the ABA content in the roots of the control plants with normal N supply dropped quickly, probably due to rapid metabolization. Judging by results obtained, it seems unlikely that the roots are responsible for the remarkable increase of the ABA content in the shoots caused by N‐defic

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03808.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY