ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00739.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SUMMARYAddition of natural polyamines (putrescine, spermidine or spermine) to the culture medium stimulates growth ofDunaliella primolectaand results in an increased photosynthesis (+200%), chlacontent (+300%) and ATP content (+182%). The results are compared with those induced by synthetic polyamines, such as N,N'‐bis (3‐aminopropyl) diaminoethane (BAPDE) or 1,4,8,11,tetra‐azacyclotetradecane (CYCLAM). BAPDE and CYCLAM increase photosynthesis, ATP level and chlacontent to the same extent, but have a negative effect on the growth of the alga. The synthetic polyamines increase oxygen uptake, whereas the natural polyamines have no effect. These results are discussed in relation to the hypothesis of polyamines acting as growth regulators or as nitrogen source for the

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00740.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SUMMARYUncoupled Photosystem I (PS I) activity driven by either reduced 2,6‐dichlorophenolindophenol (DCPIPH2) or N,N,N',N'‐tetramethyl‐p‐phenylene diamine (TMPDH2) showed a stimulation following pre‐treatment at 40–50°C, followed by inhibition at higher temperatures. The stimulation was more marked in thylakoids isolated from warm‐grown plants than in those isolated from cool‐grown plants. Approximately maximal rates of PS I activity were achieved at physiological temperatures (25–35°C) using highly lipophilic‐reduced diaminodurene (DADH2) as an electron donor with little stimulation occurring as a result of high temperature pre‐treatment. Electron transport driven by all three electron donors was markedly inhibited by KCN/HgCl2following all pre‐treatment temperatures, but relatively insensitive to ethyldimethylaminopropyl‐carbodiimide (EDAC). It is suggested that the stimulation of PS I activity involves a phase change in the thylakoid membrane leading to an increase in permeability which allows enhanced access of DCPIPH2and TMPDH2to a common electron acceptor site located in the region of cytochrome f. The greater stimulation of electron transport in thylakoids isolated from warm‐grown plants may be due to a more pronounced phase change occurring as a consequence of altered membrane composition as m

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00741.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SUMMARYAn analysis of ecological groups has been performed on the Dutch Holocene palaeobotanical record excluding wood and pollen data and compared with the recent flora.Although all ecological groups are represented by plants that are preserved by both waterlogging and charring, this especially concerns plants indicative of ruderal places, arable fields, dry underwood, fresh water and banks. On the level of environmental conditions, it is shown that the representation of the subfossil record is biased by the type of preservation, the archaeological context and the frequency by which plants are found.For the reconstruction of environmental conditions on the basis of a select number of plants, groups of indicator plants have been compiled for the following (a)biotic characteristics: salinity, moisture regime, nutrient availability, and the structure of vegetation and the stage of succession. These groups are suitable for the comparison of samples and sites with respect to different feature types, locations and periods.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00742.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SUMMARYThis paper reports the result of a 4‐year fertilization experiment using nitrogen, on a level with current deposition, on the demography of aDrosera rotundifoliaL. population on a raised bog. Five different fertilization treatments were employed: (i) control with no extra nitrogen, (ii) 0.5, (iii) 1.0, (iv) 2.0, and (v) 4.0 gNm−2year−1.Spearman rank correlation test unveiled a significant increase in the daily killing power in relation to the amount of nitrogen fertilization. This was valid for all cohorts studied during the 4 years. The addition of nitrogen fertilizer influenced the reproductive behaviour of theD. rotundifoliaplants. The proportion of flowering individuals increased in the second year, after which the frequency of flowering gradually decreased compared with the control plots. The number of flowers per individual was not influenced by the nitrogen treatment.The population size in the control plots remained rather constant over the 4 years. Population size also remained constant when low‐concentration fertilizer was added. In these nitrogen‐treated plots, however, the three youngest age classes represented more than 55% of the total population compared with less than 40% in the control plots. In the plots treated with 2.0 and 4.0 N m−2year−1, the population size decreased dramatically between the first 2 years. From then and up to the end of the study these populations remained at a nearly constant low level.The nitrogen treatment resulted in a significantly increased density of bothAndromeda polifoliaandEriopho

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00743.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SUMMARYThe development of the soil nitrogen cycle in a coastal dune succession (xerosere) on the East Frisian Island Spiekeroog was investigated. In 13 sites of different successional age the nitrogen pools in the topsoil (0–30 cm) and the organic soil layers were determined. The nitrogen mineralization was studied at the sites during the vegetation period in 1987 (38 weeks) and winter 1990‐91 (14 weeks). Turnover rates and nitrification rates were calculated.The nitrogen pool of the soil was very low in the first stage of the succession (<100 kg N ha−130cm−1)and increased rapidly to more than 1500 kg N ha−1within approx. 200 years. This accumulation rate was strongly exposition‐dependent. Mineralization of nitrogen was low in the young sites (15 kg Nminha−1year−130 cm−1) and increased to more than 100 kg Nminha−1year−1in sites covered by buckthorn(Hippophaé rhamnoides)and in dune forest. Mineralization was also exposition‐dependent. The annual nitrogen turnover rate was very high in the young dune sands (up to 18%) and was only 2% in the brown dune sand podsols underEmpetrumheathland. Nitrification dropped as well in the course of the dune development from 80–90% to 20% nitrate of total mineral nitrogen production over a year. Some hypotheses on nitrogen accumulation and retention during ecosystem and plant cover

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00744.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SUMMARYA rapid and quantitative method has been developed to determine the amount of soluble and insoluble pectins. The method does not require extraction or purification, even plant homogenates may be used, and it can be applied to pectins of various origin. The determination of pectic substances by previous methods can be performed only on pectins in solution. The present rapid method is based on the titration of deesterified pectins after acid precipitation. The speed and simplicity also makes this quantitative method highly useful for the determination of pectins during food processing.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00745.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00746.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Book reviewed in this article:Carbon Partitioning: Within and Between OrganismsC.J. Pollock, J.F. Farrar&A.J. Gordon (eds).Principles of Plant PathologyJ.G. MannersThe Africa‐South America Connection: Oxford Monographs on Biogeography No. 7Wilma George and René Lavocat (eds).East Africa's Grasses and Fodders: Then‐Ecology and HusbandryJoseph G. BoonmanPlant Structure: Function and DevelopmentJ.A. Romberger, Z. Hejnowicz&J.F. HillPhotosynthesis: Photoreactions to Plant ProductivityYash Pal Abrol, Prasanna Mohanty&Govindjee (eds)Arboles y Arbustos de los Andes del Ecuador; AAU Report No. 30Carmen Ulloa Ulloa&Peter M0ller JørgensenNeotropical Montane Forests, Biodiversity and Conservation; AAU Report No. 31Henrik Balslev (ed.)Die Züchtung der Sonnenblume(Helianthus annuusL.): Fortschritte der Pflanzenzuchtung, No. 14Walter H. SchusterDisease Management in Cocoa: Comparative Epidemiology of Witches' BroomS.A. Rudgard, A.C. Maddison&T. Andebrha

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00747.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1994.tb00748.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY