Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    The effect of storage time and temperature on the population dynamics and vitality of Meloidogyne chitwoodi in potato tubers
    Teklu, Misghina G. ; Schomaker, Corrie H. ; Been, Thomas H. - \ 2018
    Nematology 20 (2018)4. - ISSN 1388-5545 - p. 373 - 385.
    Hatching curves - infectivity - quarantine pest - root-knot nematode - tuber peel - tuber storage - viability
    The population densities of Meloidogyne chitwoodi in potato tubers stored at 4, 8 and 12°C after 0, 60, 120, 180 and 240 days of storage were assessed. Compared to day 0, storage temperatures of 4 and 8°C reduced population densities to 9 and 35%, respectively, after 240 days of storage, while nematode numbers in tubers stored at 12°C increased 2.5 times. The maximum hatching rate of nematodes from tubers stored at 8 and 12°C increased linearly with storage time. At 4°C it remained constant. The time required for the hatching process to reach the maximum number of second-stage juveniles (J2) decreased with increasing storage temperature. Recovered juveniles of M. chitwoodi from tubers after 180 and 240 days of storage at all three temperatures were still infective and able to multiply on 'Desiree' with estimates of the maximum multiplication rate (a) and the maximum population density (M) of 63.6 and 70.8 J2 (g dry soil)-1, respectively.
    Prolonging the longevity of ex situ conserved seeds by storage under anoxia
    Groot, S.P.C. ; Groot, L. de; Kodde, J. ; Treuren, R. van - \ 2015
    Plant genetic resources: characterization and utilization 13 (2015)1. - ISSN 1479-2621 - p. 18 - 26.
    long-term storage - atmospheric oxidation - lipid-peroxidation - moisture-content - dry conditions - date seed - oxygen - germination - viability - survival
    Plant genetic resources are conserved by genebanks mainly in the form of seeds. In most of the cases, the dried seeds can be stored for a considerable period of time, but eventually seed deterioration results in the inability to generate healthy seedlings. Prolonging seed longevity during storage reduces the frequency of regeneration, which is beneficial from a genetic as well as a management point of view. To reduce the rate of deterioration, cool and dry storage conditions are usually practised for long-term seed storage. In spite of the growing body of evidence that seed deterioration is predominantly caused by oxidative processes, the importance of seed storage under anoxic conditions has received little attention from the genebank community. Herein, we report on the effects of anoxia on seed viability, the oxygen uptake by dry seeds in closed containers and the permeability for oxygen of various seed storage containers. Our results confirm that the ageing of dry seeds is accelerated by the presence of oxygen in the storage environment. Therefore, we recommend that genebanks store dry seeds under anoxic conditions to prolong their longevity during ex situ conservation. To reduce the initial rate of viability loss, we further recommend that the period of temporary storage after seed harvest be minimized and also that the seeds are kept during this period under controlled conditions, including anoxia.
    Alternating electric field fluidized bed disinfection performance with different types of granular activated carbon
    Racyte, J. ; Yntema, D.R. ; Kazlauskaite, L. ; DuBois, A. ; Bruning, H. ; Rijnaarts, H.H.M. - \ 2014
    Separation and Purification Technology 132 (2014). - ISSN 1383-5866 - p. 70 - 76.
    waste-water - 3-dimensional electrodes - bacteria - particles - adhesion - viability - removal - system - point - reuse
    The removal of pathogens from effluents is important to promote the reuse of these water resources and safeguarding human health, especially in water scarce areas worldwide. Previously a proof-of-principle of a method for water disinfection consisting of fluidized bed electrodes (FBE) with RX3 EXTRA granular activated carbon (GAC) and a low strength alternating electric field (AC field) in radio frequency range (80–200 kHz) was published. In the study presented here we investigated the mechanistic role of 10 different types of GAC in radio frequency FBE disinfection with Escherichiacoli YMc10 as the model microorganism. The disinfection performances with only GAC, and GAC combined with an AC field were quantified. Seven GACs showed poor to intermediate and three GACs (Norit RB3 (2.7 Log CFU E. coli decrease), Sorbonorit 3 (2.8 Log CFU E. coli decrease) and RX3 EXTRA (3.4 Log CFU E. coli decrease)) showed substantial disinfection in FBE. The results suggest a relation between the pHpzc of the GAC and the disinfection performance. Disinfection performance increased with bigger particle size and decreasing conductivity of tested GACs. We conclude that these physico-chemical and physical properties of GAC are important factors controlling the disinfection performance of these type FBE systems.
    Regio heeft grote invloed op levensvatbaarheid
    Pellikaan, F. ; Ouweltjes, W. ; Windig, J.J. ; Muskens, J. ; Linden, R. van der; Pelt, M.L. van; Calus, M.P.L. - \ 2014
    Veeteelt 31 (2014)14. - ISSN 0168-7565 - p. 10 - 13.
    melkveehouderij - kalveren - levensvatbaarheid - geboorte - vaarzen - grote landbouwbedrijven - bedrijfsgrootte in de landbouw - landbouwstatistieken - bedrijfsvergelijking in de landbouw - invloeden - dairy farming - calves - viability - birth - heifers - large farms - farm size - agricultural statistics - farm comparisons - influences
    Een afname van zes procent levend geboren kalveren van vaarzen tussen 1995 en 2010 was aanleiding voor nieuw sectoronderzoek. Uit de inventarisatie blijkt dat naast bekende factoren als draagtijd en geboorteverloop de regio waar het bedrijf is gehuisvest en het seizoen van afkalven zorgen voor opmerkelijke verschillen in levensvatbaarheid van kalveren.
    Hatching of Globodera pallida is inhibited by 2-propenyl isothiocyanate in vitro but not by incorporation of Brassica juncea tissue in soil
    Brolsma, K.M. ; Salm, R.J. van der; Hoffland, E. ; Goede, R.G.M. de - \ 2014
    Applied Soil Ecology 84 (2014). - ISSN 0929-1393 - p. 6 - 11.
    potato cyst-nematodes - allyl isothiocyanate - yield losses - mustard - glucosinolate - biofumigation - rostochiensis - root - diversity - viability
    The aim of this study was to assess the feasibility of controlling the potato cyst nematode Globodera pallida through biofumigation with glucosinolate-rich Brassica juncea genotypes. The main glucosinolate of B. juncea is 2-propenyl glucosinolate which is the precursor of 2-propenyl isothiocyanate. Toxicity of 2-propenyl isothiocyanate to encysted G. pallida was tested in vitro. Fifty percent reduction in hatching was found within 2 h of exposure to 0.002% 2-propenyl isothiocyanate. Based on the in vitro results, we hypothesized that biofumigation with B. juncea would reduce hatching of G. pallidain vivo and higher 2-propenyl glucosinolate levels would have a stronger effect. Plant genotype, sulfur fertilization and insect herbivory affected 2-propenyl glucosinolate concentration of B. juncea. However, increasing 2-propenyl glucosinolate concentration of B. juncea did not affect G. pallida hatching after biofumigation. The absence of a biofumigation effect was most likely due to lower concentrations of 2-propenyl isothiocyanate in vivo compared to in vitro conditions. These results show that it is difficult to reach sufficiently high levels of toxicity to reduce hatching of G. pallida under realistic conditions.
    Alternating electric fields combined with activated carbon for disinfection of Gram negative and Gram positive bacteria in fluidized bed electrode system
    Racyte, J. ; Bernard, S. ; Paulitsch-Fuchs, A.H. ; Yntema, D.R. ; Bruning, H. ; Rijnaarts, H.H.M. - \ 2013
    Water Research 47 (2013)16. - ISSN 0043-1354 - p. 6395 - 6405.
    water treatment plants - urban waste-water - antibiotic-resistance - antimicrobial activity - escherichia-coli - inactivation - particles - cells - flow - viability
    Strong electric fields for disinfection of wastewaters have been employed already for several decades. An innovative approach combining low strength (7 V/cm) alternating electric fields with a granular activated carbon fluidized bed electrode (FBE) for disinfection was presented recently. For disinfection performance of FBE several pure microbial cultures were tested: Bacillus subtilis, Bacillus subtilis subsp. subtilis, Enterococcus faecalis as representatives from Gram positive bacteria and Erwinia carotovora, Pseudomonas luteola, Pseudomonas fluorescens and Escherichia coli YMc10 as representatives from Gram negative bacteria. The alternating electric field amplitude and shape were kept constant. Only the effect of alternating electric field frequency on disinfection performance was investigated. From the bacteria tested, the Gram negative strains were more susceptible and the Gram positive microorganisms were more resistant to FBE disinfection. The collected data indicate that the efficiency of disinfection is frequency and strain dependent. During 6 h of disinfection, the decrease above 2 Log units was achieved with P. luteola and E. coli at 10 kHz and at dual frequency shift keying (FSK) modulated signal with frequencies of 10 kHz and 140 kHz. FBE technology appears to offer a new way for selective bacterial disinfection, however further optimizations are needed on treatment duration, and energy input, to improve effectiveness.
    Host plant-mediated effects of climate change on the occurrence of the Alcon blue butter¿y (Phengaris alcon).
    Cormont, A. ; Wieger Wamelink, G.W. ; Jochem, R. ; Wallis de Vries, M.F. ; Wegman, R.M.A. - \ 2013
    Ecological Modelling 250 (2013)2. - ISSN 0304-3800 - p. 329 - 337.
    biotic interactions - species distributions - dispersal - conservation - landscapes - birds - biodiversity - temperature - viability - networks
    Among the expected consequences of climate change are shifts in species’ ranges. Most of current methods to predict such shifts in species distributions consider changes in suitability of climatic conditions for existence. With these models, it is possible to indicate the potential distribution of species that would arise under spatial conditions that cause unlimited landscape accessibility and habitat suitability. At the regional scale, however, detailed predictions of changes in species distributions and performance are pivotal for conservation planning. This study aims to predict species occurrences at the regional scale, incorporating demographic processes and dispersal to assess habitat accessibility and suitability in detail. We investigated a system with trophic dependence: the Alcon blue butter¿y (Phengaris alcon) is fully dependent on the occurrence of its host plant species marsh gentian (Gentiana pneumonanthe). We applied a model chain, consisting of a soil and biomass model, a plant species occurrence and dispersal model and a butter¿y metapopulation model. We investigated the effect of future climate change, both under affected and unaffected habitat conditions as determined by host plant occurrence. Our modelled results show that the butter¿ies perform best when habitat conditions remain unaffected by climate change. However, when climate change does affect the occurrence of its host plant species, butter¿y distribution and performance will be deteriorated. This implies that detailed predictions of changes in species distributions and performance should incorporate dispersal, demographic processes and biotic interactions explicitly. Our approach allows for the identi¿cation of locations that are potentially suitable for the measures increasing network robustness for P. alcon.
    Yeasts preservation: alternatives for lyophilisation
    Nyanga, L.K. ; Nout, M.J.R. ; Smid, E.J. ; Boekhout, T. ; Zwietering, M.H. - \ 2012
    World Journal of Microbiology and Biotechnology 28 (2012)11. - ISSN 0959-3993 - p. 3239 - 3244.
    ziziphus-mauritiana - starter cultures - trehalose - viability - fermentation - survival - efficacy - zimbabwe - storage - fruits
    The aim of the study was to compare the effect of two low-cost, low technology traditional methods for drying starter cultures with standard lyophilisation. Lyophilised yeast cultures and yeast cultures preserved in dry rice cakes and dry plant fibre strands were examined for viable cell counts during 6 months storage at 4 and 25 °C. None of the yeast cultures showed a significant loss in viable cell count during 6 months of storage at 4 °C upon lyophilisation and preservation in dry rice cakes. During storage at 25 °C in the dark, yeast cultures preserved in dry rice cakes, and lyophilised cultures of Saccharomyces cerevisiae and Issatchenkia orientalis showed no significant loss of viable cells up to 4 months of storage. Yeast cultures preserved in dry plant fibre strands had the greatest loss of viable count during the 6 months of storage at 25 °C. Preservation of yeasts cultures in dry rice cakes provided better survival during storage at 4 °C than lyophilisation. The current study demonstrated that traditional methods can be useful and effective for starter culture preservation in small-scale, low-tech applications.
    FutMon activiteiten in Nederland in 2009 en 2010
    Oldenburger, J. ; Briel, J. van den; Bleeker, A. ; Rietra, R.P.J.J. - \ 2011
    Wageningen : Stichting Probos - 47
    bossen - luchtverontreiniging - levensvatbaarheid - monitoring - nederland - forests - air pollution - viability - monitoring - netherlands
    Dit rapport geeft een overzicht en beschrijving van de activiteiten die in 2009 en 2010 in Nederland zijn uitgevoerd in het kader van het Life+ project Future of Forest Monitoring (FutMon). FutMon is het vervolg op Forest Focus en wordt gecoördineerd door het Johann Heinrich von Thünen Institute in Hamburg en de resultaten worden gebruik door ICP Forest om mogelijke effecten van luchtvervuiling op de vitaliteit van de bossen in Europa te bepalen. ICP Forest is in 1985 opgericht onder het Verdrag voor Grensoverschrijdende Luchtverontreiniging Over Lange Afstand van de UNECE.
    Detection of Xanthomonas axonopodis pv. phaseoli in bean seeds by flow cytometry, immunostaining and direct viable counting
    Tebaldi, N.D. ; Peters, J. ; Chitarra, L.G. ; Souza, R.M. ; Zouwen, P.S. van der; Bergervoet, J.H.W. ; Wolf, J.M. van der - \ 2010
    Tropical Plant Pathology 35 (2010)4. - ISSN 1982-5676 - p. 213 - 222.
    carboxyfluorescein diacetate - monoclonal-antibodies - dairy-products - total bacteria - campestris - viability - identification - enumeration - pseudomonas - microscopy
    Flow cytometric analysis of immuno-stained cells (immuno-FCM) was compared to immunofluorescence microscopy (IF) and dilution plating on a semi-selective medium, for quantitative detection of Xanthomonas axonopodis pv. phaseoli (Xap) in bean seed extracts. Cell concentrations of Xap between 103-107 CFU/mL were added to healthy bean seed extracts. A flow cytometry sorting procedure was developed to separate immuno-stained Xap cells from crude seed extracts and confirming by PCR. FCM was evaluated for direct viable counting (DVC) of Xap using combinations of propidium iodide (PI) and carboxy fluorescein diacetate (cFDA) or PI and SYTO 9 and also the combination of immuno-FCM and PI. Dilution plating and IF allowed detection of Xap in bean seed extracts in a range of 103-106 CFU/mL and immuno-FCM from 104-106 CFU/mL. Sorted cells could be detected in crude seed extracts by PCR without further extraction. FCM also allowed quantification of viable cells of Xap after DVC procedures; the red fluorescent dye propidium iodide was used to identify dead cells in combination with the green fluorescent dyes cFDA or SYTO 9, these identifying live cells. The combination of immuno-FCM and PI could be more promising and reliable to detect this pathogen in seeds. Key words: seed pathology, flow sorting, PCR-amplification, viability probes, immunofluorescence, bacteria.
    Culture collections, the new herbaria for fungal pathogens
    Abd-Elsalam, K.A. ; Yassin, M.A. ; Moslem, M.A. ; Bahkali, A.H. ; Wit, P.J.G.M. de; McKenzie, E.H.C. ; Stephenson, S.L. ; Cai, L. ; Hyde, K.D. - \ 2010
    Fungal Diversity 45 (2010)1. - ISSN 1560-2745 - p. 21 - 32.
    long-term preservation - sterile distilled water - anhydrous silica-gel - liquid-nitrogen - aspergillus-fumigatus - filamentous fungi - stock cultures - storage - viability - mycosphaerella
    This paper discusses the importance of culture collections in plant pathology and reviews the methods currently available to store cultures. The preservation and maintenance of plant pathogenic fungi in a viable yet stable state for long periods has always been important, because isolates of these fungi can serve as standards for identification of quarantine taxa. Such isolates are also important for testing disease resistance and for plant breeding programs. The increasing use of molecular sequences analysis in the systematics of plant pathogenic fungi has meant that maintaining fungi in culture collections has become essential. Herein we discuss trends in the identification of plant and post-harvest pathogens, using Aspergillus, Colletotrichum, Phyllosticta and Mycosphaerella and its anamorphs as examples. Herbarium specimens, although still a requirement of the Botanical Code when describing new species are, perhaps, less important in providing useful information when defining a pathogenic species. Many pathogen groups consist of complexes of species and morphology alone can no longer distinguish among species. However, ex-type living cultures are essential for identification and future species comparisons that incorporate the use of molecular techniques. As such, ex-type cultures of any new species of pathogen, or when new diseases are reported or studies involving pathogenic strains are published, cultures of the taxa studied should be deposited in widely available culture collections, preferably in at least three members of World Federation for Culture Collections. Methods for the storage of fungal cultures such as water preservation, freezing, mineral oil overlay, freeze drying and lyophilization are reviewed in this paper. The main objective of culture preservation is to maintain the vigor and genetic characteristics of a pure culture. Therefore, safe long-term preservation methods are required to ensure fungal survival and retention of any valuable characteristics. To minimize the risk of any morphological, physiological, or genetic changes, several different preservation conditions should be used whenever possible. The present review also describes a complete preservation methodology that can be used for plant pathogenic fungi.
    Farm viability in the European Union : assessment of the impact of changes in farm paymen
    Vrolijk, H.C.J. ; Bont, C.J.A.M. de; Blokland, P.W. ; Soboh, R.A.M.E. - \ 2010
    Den Haag : LEI Wageningen UR (Report / LEI : Research area Agriculture & entrepreneurship ) - ISBN 9789086153992 - 67
    landbouwbedrijven - levensvatbaarheid - inkomen van landbouwers - bedrijfsresultaten in de landbouw - subsidies - europese unie - internationale vergelijkingen - farms - viability - farmers' income - farm results - subsidies - european union - international comparisons
    Farm viability is an important issue in the European Union. Farm payments contribute to the viability of farms. This study analyses the differences in farm payments within Europe and analyses the possible impacts of reductions in farm payments in the viability of farms in Europe.
    Keizersnee eikenprocessierups oktober 2009
    Vliet, A.J.H. van - \ 2009
    Wapserveen : Biocontrole
    thaumetopoea processionea - ontwikkelingsstadia - levensvatbaarheid - insectenplagen - rupsen - thaumetopoea processionea - developmental stages - viability - insect pests - caterpillars
    Om te bepalen hoe ver de eikenprocessierupsjes in recent gevonden eipakketjes ontwikkeld zijn is op 3 oktober 2009 een 'keizersnede' uitgevoerd. Het blijkt dat de rupsen al volledig levensvatbaar zijn. Dit kan betekenen dat in warme jaren een tweede generatie van de eikenprocessierupsen mogelijk is. Meer informatie over de ontwikkeling van de eikenprocessierups in Nederland is te vinden op of op
    Acid-base balance of umbilical artery blood of liveborn piglets at birth and its relation with factors affecting delivery of individual piglets
    Dijk, A.D.J. van; Lende, T. van der; Taverna, M.A. - \ 2006
    Theriogenology 66 (2006)8. - ISSN 0093-691X - p. 1824 - 1833.
    newborn piglets - perinatal mortality - parturition - viability - gas - pig - asphyxia - analyzer - ph - stillbirth
    In the limited number of studies that reported on the relation between factors affecting birth of individual piglets and acid-base balance values at birth, predominantly simple correlation coefficients have been used. The aim of the present study was to analyse the relation between factors affecting delivery of individual liveborn piglets and acid-base balance values (pH, P-CO2, HCO3- and BEecf) at birth. In total 201 piglets originating from 44 litters were used for the collection of blood samples from the umbilical artery immediately after birth, preferably in the period of apnea. Blood samples were analysed with the iStat (R) Portable Clinical Analyser. Significantly lower pH, HCO3-, BEecf and significantly higher P-CO2 levels were found in posteriorly presented piglets, independently of the condition of the umbilical cord, birth weight and cumulative birth interval/rank. Independently of presentation, birth weight and rank, piglets born with ruptured umbilical cords showed significantly lower pH values. Next to that, increasing birth weights resulted in increasing HCO3- and BEecf values at birth, independently of presentation, condition of the umbilical cord and cumulative birth interval/rank. Both an increase in cumulative birth interval and in rank was associated with a significant decrease of pH, HCO3-, BEecf and increase of P-CO2 levels in umbilical cord blood at birth. Together these results demonstrate for the first time that a clear relation exists between (factors affecting) the progress of delivery and acid-base balance values in a polytocous species like the pig. (c) 2006 Elsevier Inc. All rights reserved.
    Conserving declining species using incomplete demographic information: what help can we expect from the use of matrix population models?
    Hemerik, L. ; Klok, C. - \ 2006
    Animal Biology 56 (2006)4. - ISSN 1570-7555 - p. 519 - 533.
    growth rate - great tit - survival - conservation - elasticity - management - viability - britain
    Due to human activity, many species have strongly declined in number and are currently threatened with extinction. Management directed at conservation of these species can benefit from the use of simple population models such as matrix models. However, for many species, data on survival and reproduction are scarce. Therefore, we set up a general framework based on a matrix model with three parameters: reproduction, juvenile (=first year survival) and adult survival in which incomplete data can be analysed. This framework is applicable to species that can mature after their first year of life. The point in a calendar year at which the population size is determined, i.e. the census time, is varied. We discuss the differences and the similarities between matrices modelling the same population at different census times. The population growth rate and the elasticity of the survival and reproduction parameters have been determined analytically. From these we made, as a visual diagnostic tool (general framework), plots of the growth rate and the elasticity pattern and their dependence on actual values of the reproduction parameter and the juvenile and adult survival. To illustrate the use of this framework we plot and discuss literature data on survival and/or reproduction of a few bird species with a juvenile stage of one year in the light of our modelling results.
    Analysing population numbers of the house sparrow in the Netherlands with a matrix model and suggestions for conservation measures
    Klok, C. ; Holtkamp, R. ; Apeldoorn, R.C. van; Visser, M.E. ; Hemerik, L. - \ 2006
    Acta Biotheoretica 54 (2006)3. - ISSN 0001-5342 - p. 161 - 178.
    life-histories - temporal variation - marked animals - survival rates - growth rate - elasticity - britain - trends - birds - viability
    The House Sparrow (Passer domesticus), formerly a common bird species, has shown a rapid decline in Western Europe over recent decades. In The Netherlands, its decline is apparent from 1990 onwards. Many causes for this decline have been suggested that all decrease the vital rates, i.e. survival and reproduction, but their actual impact remains unknown. Although the House Sparrow has been dominant in The Netherlands, data on life history characteristics for this bird species are scarce: data on reproduction are non-existent, and here we first present survival estimates based on live encounters and dead recoveries of marked individuals over the period 1976-2003, 14 years before and 14 years during the decline, reported to the Dutch Ringing Centre. We show that there is an indication that both juvenile and adult survival are lower during the period of decline. Secondly, to be able to analyse the relative impact of changes in the vital rates, we formulated a general matrix model based on a range of survival values between zero and one with a step size of 0.01 (both juvenile and adult yearly survival) and a range of realistic reproduction values (one, three or five fledglings per pair per year). With the matrix model, we calculated the finite rate of population change (lambda) and applied elasticity analysis. To diagnose the cause of the decline in the Dutch House Sparrow, we parameterised the model with estimates of survival values before and during the decline and present the resulting lambda. With the survival estimates from the declining period, lambda <1 only if reproduction is relatively low. We discuss this result within the light of available literature data on survival in the House Sparrow. Finally, we evaluate which of the suggested causes of population decline should be reversed to mitigate the decline and how this can be achieved.
    Relationship between variation in quality of individual seeds and bulk seed quality in common bean (Phaseolus vulgaris L.) seed lots
    Muasya, R.M. ; Lommen, W.J.M. ; Auma, E.O. ; Struik, P.C. - \ 2006
    NJAS Wageningen Journal of Life Sciences 54 (2006)1. - ISSN 1573-5214 - p. 5 - 16.
    phaseolus vulgaris - peulvruchten - zaadkwaliteit - gewaskwaliteit - kieming - levensvatbaarheid - elektrische geleidbaarheid - statistiek - gemiddelden - statistische analyse - variantie-analyse - correlatieanalyse - phaseolus vulgaris - grain legumes - seed quality - crop quality - germination - viability - electrical conductivity - statistics - averages - statistical analysis - analysis of variance - correlation analysis - pod fractions - maturity - growth - vigor - crops
    The variation in individual seed electrical conductivity (EC) (µS cm¿¹ g¿¹) of 24 seed lots of two common bean cultivars produced at two locations was quantified using the parameters mean ¿ median, standard deviation (SD), and the range 0¿75%. Also coefficient of variation (CV) was tested, which was regarded not to be a good indicator of this type of variation. Bulk seed lot quality of this material with a very high germination percentage was determined using EC and percentage viable seeds. At physiological maturity (PM), a low variation in individual seed EC as quantified by mean ¿ median, SD and the range 0¿75% was associated with good quality as measured by a low bulk EC and a high percentage of viable seeds. At harvest maturity, associations were less clear than at PM, partly because individual seed variation was smaller and also because bulk EC values differed only slightly among most seed lots. The relationships between individual seed variation and bulk quality were different for the two sites, as shown by a statistically significant improvement of the adjusted R² of the regression when site was included in the regression model, but the relationships were not affected by cultivar. No relationship was found between CV for individual seed EC and bulk quality.
    Effect of individual amino acids and glucose on activation and germination of Rhizopus oligosporus sporangiospores in tempe starter
    Thanh, N.V. ; Rombouts, F.M. ; Nout, M.J.R. - \ 2005
    Journal of Applied Microbiology 99 (2005)5. - ISSN 1364-5072 - p. 1204 - 1214.
    mucor-racemosus sporangiospores - germ-tube emergence - conidial germination - stolonifer sporangiospores - nitrogen requirements - neurospora-crassa - spores - viability - proline - carbon
    Aim: To understand the conditions promoting activation and germination of spores, and to contribute to the control of tempe starters. Methods and Results: Using microscopic counts of fluorescent labelled spores, the following results were obtained: (1) L- alanine plays an important role ( of the same order as that of peptone) in stimulation of germination of dormant spores. Alanine can satisfy the requirements of carbon as well as nitrogen for spore germination; (2) L- proline, on the other hand, inhibits alanine uptake presumably by blocking/ congesting transporters of spore cells, resulting in apparent low viability on agar media; (3) L- leucine and L- isoleucine slightly favour spore germination while L- arginine and L- lysine do not have any stimulating effect; (4) The stimulatory role of glucose was only evident in the presence of phosphate ( in minimal medium); when glucose is used in the absence of phosphate, either alone or in combination with single amino acids its role is hardly distinguishable; (5) Phosphate plays a facilitating role in spore germination. Conclusions: Glucose and amino acids play important roles in activation and germination of sporangiospores of Rhizopus oligosporus in tempe starter ( stored for 12 months). The ability and rate of germination of dormant/ old sporangiospores of R. oligosporus, depend on their ability for uptake of individual amino acids and/ or glucose. Significance and Impact of Study: New light was shed on the counteractive role of proline and the stimulating effect of phosphate. Soybeans subjected to traditional preparation for tempe making are heavily leached; germination of starter spores on such beans is sub- optimal, and bean processing could be optimized.
    Exogenous gibberellins inhibit coffee (Coffea arabica cv. Rubi) seed germination and cause cell death in the embryo
    Silva, E.A.A. Da; Toorop, P.E. ; Nijsse, J. ; Bewley, J.D. ; Hilhorst, H.W.M. - \ 2005
    Journal of Experimental Botany 56 (2005)413. - ISSN 0022-0957 - p. 1029 - 1038.
    abscisic-acid - endosperm - arabidopsis - mutants - tomato - elongation - metabolism - induction - viability - aleurone
    The mechanism of inhibition of coffee (Coffea arabica cv. Rubi) seed germination by exogenous gibberellins (GAs) and the requirement of germination for endogenous GA were studied. Exogenous GA4+7 inhibited coffee seed germination. The response to GA4+7 showed two sensitivity thresholds: a lower one between 0 and 1 µM and a higher one between 10 and 100 µM. However, radicle protrusion in coffee seed depended on the de novo synthesis of GAs. Endogenous GAs were required for embryo cell elongation and endosperm cap weakening. Incubation of coffee seed in exogenous GA4+7 led to loss of embryo viability and dead cells were observed by low temperature scanning microscopy only when the endosperm was surrounding the embryo. The results described here indicate that the inhibition of germination by exogenous GAs is caused by factors that are released from the endosperm during or after its weakening, causing cell death in the embryo and leading to inhibition of radicle protrusion.
    Factors affecting duration of the expulsive stage of parturition and piglet birth intervals in sows with uncomplicated, spontaneous farrowings
    Dijk, A.D.J. van; Rens, B.T.T.M. van; Lende, T. van der; Taverne, M.A.M. - \ 2005
    Theriogenology 64 (2005)7. - ISSN 0093-691X - p. 1573 - 1590.
    perinatal mortality - placental traits - plasma oxytocin - yorkshire sows - genetic merit - stillbirth - behavior - viability - survival - fetuses
    Modern pig farming is still confronted with high perinatal piglet losses which are mainly contributed to factors associated with the progress of piglet expulsion. Therefore the aim of this study was to identify sow- and piglet factors affecting the duration of the expulsive stage of farrowing and piglet birth intervals in spontaneous farrowing sows originating from five different breeds. In total 211 litters were investigated. Breed affected duration of the expulsive stage significantly: the shortest duration was found in Large White x Meishan F2 crossbred litters and the longest duration in Dutch Landrace litters. No effect of parity on the duration of the expulsive stage was found. An increase in littersize (P <0.01), an increase in number of stillborn piglets per litter (P <0.05) and a decrease of gestation length (P <0.05, independently of littersize) all resulted in an increased duration of the expulsive stage of farrowing. A curvilinear relationship between birth interval and rank (relative position in the birth order) of the piglets was found. Besides that, piglet birth intervals increased with an increasing birth weight (P <0.001). Stillborn (P <0.01) and posteriorly presented (P <0.05) piglets were delivered after significantly longer birth intervals than liveborn and anteriorly presented piglets. The results on sow- and piglet factors affecting duration of the expulsive stage and piglet birth intervals obtained in this study contribute to an increased insight into (patho) physiological aspects of perinatal mortality in pigs
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