摘要:

SUMMARYThe apical section (18 mm long) of a decapitated (1 mm removed)Avenacoleoptile does not curve geotropically in water nor in a gibberellic acid solution.Gibberellic acid stimulates the geotropic curvature of similar sections carried out in indoleacetic and naphthylacetic acid solutions of a suboptimal concentration for the geotropism, but it inhibits the curvature if indoleacetic acid is supplied in a supraoptimal concentration. The inhibition requires much more gibberellic acid than is needed for the promotion.These results, together with data and suggestions from the literature, motivate an investigation into the possibility of a competitive synergism between gibberellic acid and auxins in the process of auxin transport.The regeneration of the physiological tip is not accelerated by gibberellic acid, but the geotropic curvature, made possible by the auxin production in the new tip, is increased.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00051.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYQuantitative data are presented of a study of a combined height‐pH gradient in a primary dune slack at Schiermonnikoog. A transect of 10 × 4 m was floristically and ecologically analysed per sq m. Species number was taken as a measure of species diversity and was found to be related to range of pH and height: highest diversities occurred in the middle range of the gradient. This confirms a general rule described by Odum. Species‐area relation in the transect fits into the Preston model, the slope index being slightly under the theoretical equilibrium value 0,27. Ordination and classification of quadrats on a basis of information index I showed continuous variation of vegetation, which was mainly governed by pH variation. The twofold differentiation of the interrelated height and pH is termed ecological amplification and discussed. The relation between floristic fall and gradient range and between floristic difference of vegetations and their distance along a gradient are discussed. The diversity pattern found is interpreted in terms of niche differentiation governed by spatial and temporal variation of the environment. The possible relation between niche differentiation and gradient structure of the environment is discu

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00052.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYBy means of a double chromatographic separation technique applied to the acid fraction of methanol extracts of root nodules, parental roots, and 14 day old roots ofLupinus luteusL., indoleacetic acid and indolecarboxylic acid were demonstrated spectrofluorometrically and the amounts determined. The difference between the IAA content of nodules and parental roots on a fresh‐weight basis was not as great as is generally believed: we found about 3 times more IAA in nodules than in roots. The 14 day old roots contained the lowest amount of IAA: about half the amount found in roots on which nodules had been present. The ICA content of roots that had been in contact with nodules was about 3 times higher than the ICA content of the nodules. The ICA content of 14 day old roots was the lowest. These results are discussed in the light of a possible alteration of the indole metabolism of the root caused by infection with the bacterial symbiontRhizobium lupini, as an indication for a fundamental alteration of growth‐regulation leading to the genesis of nodu

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00053.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYDescription ofAdenia letouzeyide Wilde,spec. nov. (Passifloraceae)from West tropical Africa, with a key to the three species ofAdeniaSect.Blepharanthesoccurring in that region.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00054.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYDiscs of cucumber leaves were kept at 2 °C in the dark. When, subsequently, transferred to a temperature of 24 °C they develop symptoms of damage. The degree of injury depends on the length of the period at 2 °C. An interruption of the treatment at 2 °C by a short period at 24 °C reverses the damage induced by the cold treatment. The degree of reversal depends on the length of the cold period before the interruption and on the length of the interruption at 2

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00055.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYDescription is given of a number of abnormalities.Oenothera biennisL. Short axillary racemes with small flowers instead of the normal axillary flowers.Chrysanthemum coccineumWilld. Heads without a single flower, resembling a small toadstool.Aquilegia vulgarisL. Several cases of petaloid stamens with their spurs enclosed in the spurs of normal petals.Potentilla vernaL. A specimen with incised petals.Euphrasia officinalisL. Fasciation of flowers.Rubus fruticosusL.s.l. Prolification of flowers.Myosotisspec. Pleiotaxy of the corolla.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00056.x

年代:1967

数据来源: WILEY

摘要:

SUMMARYExcised parts of the stalk of young inflorescences ofYucca flaccidaHaw. were placed with one end in a solution of either fructose‐14C(U) or glucose‐14C(U).The phloem exudate collected from the opposite ends of the stalk parts always contained sucrose as the major14C‐labelled component, while14C‐hexoses could not be detecte

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1967.tb00057.x

年代:1967

数据来源: WILEY