摘要:

AbstractDuring the first eight weeks after setting young citrus fruits gradually lose their ability to abscise at the abscission zone between the stem and the pedicel; in fruits older than eight weeks abscission occurs at the calyx area. The activity of cellulase and polygalacturonase in the two abscission zones was markedly increased before and during abscission, and was localized mainly in the abscission zone. Ethylene accelerated the increase in enzymic activity after an 8‐ to 10‐h lag period; 2,4‐D delayed abscission and enzymic activity when applied during the first 24 h after excision. During this period 2,4‐D also partly suppressed the enhancing effect of ethylene. Early application of cyclo‐heximide inhibited the formation of the enzymes and thus abscission was delayed to a certain extent.Although there are some indications that the relationship between enzymic activity and abscission is a complex one, the data presented indicate that cellulase and polygalacturonase play a significant role in abscission of citrus fruits at various developmental stages. Both enzymes act almost simultaneously and are equally controlled by ethylene

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01845.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractPisumseedling andPastinacastorage roots contained high glutanrate dehydrogenase (GDH) activity in areas of reported rapid growth and high phytoctrome content. A similar distribution was observed for malate dehydrogenase. Freeze‐thawings of mitochondrial preparations fromPisumroots always resulted in increases of GDH specific activity; however, the observed increases were much larger with basal than apical sections. Both intact and freeze‐thawed mitochondrial preparations from seedling roots exhibited increases in GDH activity with time after isolation. In intact mitochondrial preparations from roots of etiolated seedlings, an increase in malate dehydrogenase activity was observed similar to that of GDH activity; however, no increased malate dehydrogenase activity was noted in preparations from light‐grown seedlings.IlluminatingPisumseedlings with far‐red light slowly increased GDH activity in roots over a period of two weeks. Since these observed increases were not due to direct exposure of roots to light, other factors were likely i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01846.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effect of various growth substances on regeneration and growth of bulblets on excised bulb scale segments ofHyacinthus orientalisL. cv. Pink Pearl was studied. Bulblet formation was promoted by the auxins IAA and IBA but was inhibited by NAA at high concentrations. IAA hardly affected bulblet weight, whereas IBA and NAA at high concentrations decreased it. Cytokinins had hardly any effect on bulblet regeneration and bulblet weight, Gibberellins inhibited both bulblet regeneration and bulblet weight; GA4+7acted much stronger than GA3. ABA and ethephon decreased bulblet regeneration and bulblet growth.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01847.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractA new method of inducing and maintaining a hypo‐gravity environment is described. Using this new technique (buoyancy compensation), the effect of reduced gravitational stress on dwarf marigolds (Tagetes patula) was studied. It was found that the specific activity of peroxidase was elevated significantly in gravity compensated seedlings. This effect, discovered with the buoyancy compensators, was confirmed with plants grown on traditional clinostat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01848.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe changing roles of the cotyledons and hypocotyl in the development of dark‐grownPhaseolus aureusseedlings are described. The effect of the cotyledons on total chlorophyll synthesis declined with age, but on a chlorophyll per gram fresh weight basis this was less pronounced. In five‐day‐old plants the hypocotyl was more effective than the cotyledons in increasing the chlorophyll level, and together their effect was less than additive. The promoting factors in the cotyledons were at a saturating level at this stage. The relationship between the effects of the two organs is discussed with particular reference to the components which they supply to the l

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01849.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe rate of ethylene production in the shoot tips of the apple cultivar ‘Ingrid Marie’ (Red motant) after succinic acid‐2,2‐dimethylhydrazide (SADH) treatment was investigated. The shoots were treated with SADH at 12.5, 25 or 50 mMin the months of June, July and August. The samples were analysed 7,15, 30 and 60 days after SADH spray.Ethylene production was considerably higher in the SADH‐treated shoots than in the untreated ones. Application of 12.5 or 25mMSADH late in June stimulated ethylene production 3‐fold, while 50 mMproduced a 5‐fold increase in ethylene production 7 days after spraying. There was a continuous decrease in ethylene production at the subsequent samplings. In untreated control shoots there was a slight increase. However, even 60 days after spraying the shoots treated with 50 mMhad higher ethylene production than the control shoots. The same relationship was found in the shoots treated in the months of July and August. A parallelism has been established between the rate of ethylene production and growth retardation, A residual effect of SADH treatment in earlier years was demonstrated and

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01850.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractSeedlings of the self‐fertilizing speciesLactuca scariolaL. grown continuously in 8 h days did not flower even one year from sowing. Seedlings grown in 16 h days uatil flower buds appeared 96 days after germination were either transferred to 8 h days or treated weekly with gibberellic acid (GA3), abscisic acid (ABA) or chlormequat (CCC) and retained, together with untreated control plants, in 16 h days. Each growth regulator caused characteristic morphological changes in the treated plants. All these plants flowered and produced seeds but the seeds showed distinct differences in weight, in their time to germination and in the seedlings which they produced. Germination and seedling characters depended on the light regime during germination as well as on the chemical applied to the parent plant and the rate of application. The parental treatment also affected the shape and size of the seedlings on a given day after germination, and certain treatments of the parent plant (transfer from long to short days and treatment with CCC in long days) advanced the flowering date of the seedlings. The gibberellin level in the seeds was raised, in increasing order, by treatment of the parent plant with 100 mg/1 GA3, transfer from long to short days, 10 mg/1 GA3, and 5000 mg/l CCC. It is suggested that the effect of day length on plant performance is mediated by the level of growth regelating substances within the plant and that the behaviour of seeds can be modified by the parental environment via the accumulation of different levels of certain growth factors in the seeds. A rise of one growth substance in the parent plant can result in the accumulation of a different one in the seed

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01851.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractHormonal extracts of cherry tomato fruits (Lycopersicon esculentumMill.) cv. Small Fry at different stages of fruit development and maturation were bioassayed for their auxin, gibberellin, cytokinin and growth inhibitor activities. In general, the levels of endogenous growth promoters were much higher in the young developing fruits than in the more mature fruits. Free cytokinin levels were highest in the first two weeks of development then declined rapidly. However, cytokinin activity in the ribotide fraction, after treatment with alkaline phosphatase, decreased during thefirst three weeks of development then increased rapidly over the following four weeks. Auxin levels increased during early development to reach a maximum in three‐week‐old fruits after anthesis. Gibberellin levels during the first two weeks of development were much lower than those of auxins and cytokinins, but then increased to reach a peak in the fourth week after anthesis.A growth inhibiting substance with Rf similar to that of abscisic acid was found in the acidic fraction of the fruit extracts. This inhibitor increased gradually during fruit growth and development and reached a peak at the age of five weeks which coincides with the green mature st

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01852.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIsoperoxidase A3from tobacco tissue culture,Nicotiana tabacamW‐38, apparently does not have a subunit structure. Its molecular weight is approximately 54,000.The oxidation of scopoletin appears to occur in more than a single step since a blue intermediate is first formed. This is followed by the production of the final yellow product. A plausible explanation for this observation is the coupling of free radicals generated by the primary enzyme catalyzed reactio

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01853.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe inhibitory effect of cordycepin (3′‐deoxyadenosine) on transcriptional processes has been used to follow the kinetics in the action of gibberellic acid on cell elongation in the coleoptiles from gamma‐planilets. It has been shown that, after a Sag period of 1 h, a high response to the phytohormone within a limited time is detec

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb01854.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY