Complete genome sequences of two highly divergent Japanese isolates of Plantago asiatica mosaic virus
Komatsu, Ken ; Yamashita, Kazuo ; Sugawara, Kota ; Verbeek, Martin ; Fujita, Naoko ; Hanada, Kaoru ; Uehara-Ichiki, Tamaki ; Fuji, Shin Ichi - \ 2017
Archives of Virology 162 (2017)2. - ISSN 0304-8608 - p. 581 - 584.
Plantago asiatica mosaic virus (PlAMV) is a member of the genus Potexvirus and has an exceptionally wide host range. It causes severe damage to lilies. Here we report on the complete nucleotide sequences of two new Japanese PlAMV isolates, one from the eudicot weed Viola grypoceras (PlAMV-Vi), and the other from the eudicot shrub Nandina domestica Thunb. (PlAMV-NJ). Their genomes contain five open reading frames (ORFs), which is characteristic of potexviruses. Surprisingly, the isolates showed only 76.0–78.0 % sequence identity with each other and with other PlAMV isolates, including isolates from Japanese lily and American nandina. Amino acid alignments of the replicase coding region encoded by ORF1 showed that the regions between the methyltransferase and helicase domains were less conserved than other regions, with several insertions and/or deletions. Phylogenetic analyses of the full-length nucleotide sequences revealed a moderate correlation between phylogenetic clustering and the original host plants of the PlAMV isolates. This study revealed the presence of two highly divergent PlAMV isolates in Japan.
Role of MLO genes in susceptibility to powdery mildew in apple and grapevine
Pessina, Stefano - \ 2016
Wageningen University. Promotor(en): Richard Visser, co-promotor(en): Henk Schouten; M. Malnoy; Yuling Bai. - Wageningen : Wageningen University - ISBN 9789462576209 - 222
malus domestica - apples - vitis vinifera - grapes - plant pathogenic fungi - podosphaera leucotricha - erysiphe necator - disease resistance - susceptibility - genes - gene expression - gene knock-out - resistance breeding - malus domestica - appels - vitis vinifera - druiven - plantenziekteverwekkende schimmels - podosphaera leucotricha - erysiphe necator - ziekteresistentie - vatbaarheid - genen - genexpressie - inactivering van genen - resistentieveredeling
Powdery mildew (PM) is a major fungal disease that threatens thousands of plant species. PM is caused by Podosphaera leucotricha in apple and Erysiphe necator in grapevine. Powdery mildew is controlled by frequent applications of fungicides, having negative effects on the environment, and leading to additional costs for growers. To reduce the amount of chemicals required to control this pathogen, the development of resistant apple and grapevine varieties should become a priority.
PM pathogenesis is associated with up-regulation of specific MLO genes during early stages of infection, causing down-regulation of plant defense pathways. These up-regulated genes are responsible for PM susceptibility (S-genes) and their knock-out causes durable and broad-spectrum resistance. All MLO S-genes of dicots belong to the phylogenetic clade V. In grapevine, four genes belong to clade V. VvMLO7, 11 and 13 are up-regulated during PM infection, while VvMLO6 is not.
Chapter 2 reports the genome-wide characterization and sequence analysis of the MLO gene family in apple, peach and woodland strawberry, and the isolation of apricot MLO homologs. Twenty-one homologues were found in apple, 19 in peach and 17 in woodland strawberry. Evolutionary relationships between MLO homologs were studied and syntenic blocks constructed. Candidate genes for causing PM susceptibility were inferred by phylogenetic relationships with functionally characterized MLO genes and, in apple, by monitoring their expression following inoculation with the PM causal pathogen P. leucotricha. In apple, clade V genes MdMLO11 and 19 were up-regulated, whereas the two other members of clade V, MdMLO5 and 7, were not up-regulated. The clade VII gene MdMLO18 was also up-regulated upon P. leucotricha infection.
Chapter 3 reports the knock-down, through RNA interference, of MdMLO11 and 19, as well as complementation of the mutant phenotype by expression of the MdMLO18 gene in the Arabidopsis thaliana triple mlo mutant Atmlo2/6/12. The knock-down of MdMLO19 resulted in a reduction of PM disease severity up to 75%, whereas the knock-down of MdMLO11, alone or combined with MdMLO19, did not cause any reduction or additional reduction of susceptibility compared to MdMLO19 alone. Complementation by MdMLO18 did not restore susceptibility. Cell wall appositions (papillae), a response to PM infection, were found in both susceptible plants and PM resistant plants where MdMLO19 was knocked-down, but were larger in resistant lines. The expression analysis of 17 genes related to plant defense, and quantification of phenolic metabolites in resistant lines revealed line-specific changes compared to the control.
Chapter 4 evaluates the presence of non-functional alleles of the MdMLO19 S-gene in apple germplasm. The screening of the re-sequencing data of 63 apple genotypes led to the identification of 627 SNP in five MLO genes (MdMLO5, MdMLO7, MdMLO11, MdMLO18 and MdMLO19). Insertion T-1201 in MdMLO19 caused the formation of an early stop codon, resulting in a truncated protein lacking 185 amino-acids and the calmodulin-binding domain. The presence of the insertion was evaluated in a collection of 159 apple genotypes: it was homozygous in 53 genotypes, 45 of which were resistant or very resistant to PM, four partially susceptible and four not assessed. These results strongly suggest that this insertion is causative for the observed PM resistance. The absence of a clear fitness cost associated to the loss-of-function of MdMLO19, might have contributed to the high frequency of the mutation in breeding germplasm and cultivars. Among the genotypes containing the homozygous insertion, ‘McIntosh’ and ‘Fuji’ are commonly used in apple breeding. After barley and tomato, apple is the third species with a reported natural non-functional mlo allele in its germplasm, with the important difference that the allele is present in a relatively large number of apple genotypes, most of which not related to each other.
Chapter 5 reports the knock-down through RNA interference of four grapevine MLO genes, all members of clade V. VvMLO7, 11 and 13 are up-regulated in early stages of infection, whereas VvMLO6 is not responsive to the pathogen. Knock-down of VvMLO6, 11 and 13, alone or combined, did not decrease PM severity, whereas the knock-down of VvMLO7, alone or in combination with VvMLO6 and VvMLO11, caused a reduction of severity of 77%. Cell wall appositions (papillae), a response to PM attack, were present in both resistant and susceptible lines, but were larger in resistant lines. Thirteen genes involved in defense were less up-regulated in resistant plants, highlighting the reduction of PM disease severity.
In Chapter 6 we discuss the results presented in this thesis. The pivotal role of MLO genes in the interaction of PM pathogens with apple and grapevine is described and further experiments aimed at addressing open questions are proposed. The results described in this thesis open interesting avenues in MLO genes research, particularly the finding that a natural mlo mutation in apple appeared to be more common than expected. This mutation is directly applicable in marker assisted breeding for durable PM resistance in apple.
Consumer eating quality acceptance of new apple varieties in different European countries
Bonany, J. ; Buehler, A. ; Carbo, J. ; Codarin, C. ; Donati, F. ; Echeverria, G. ; Egger, S. ; Guerra, W. ; Hilaire, C. ; Hoeller, I. ; Iglesias, I. ; Jesionkowska, K. ; Konopacka, D. ; Kruczynska, D. ; Martinelli, A. ; PItiot, C. ; Sansavini, S. ; Stehr, R. ; Schoorl, F.W. - \ 2013
Food Quality and Preference 30 (2013)2. - ISSN 0950-3293 - p. 250 - 259.
fruit color development - anthocyanin content - scab-resistant - strains - acceptability - preferences - gala - cultivars - firmness
During January and February 2007 a European consumer test of eight new apple varieties and three standard ones was carried out in different European countries. The most common apple varieties were compared to new ones, focusing on consumer acceptance and the potential for increasing apple consumption. We sought to test the hypothesis that the introduction of new improved varieties would help to increase fruit consumption. Data from a sensory test involving 4290 consumers in seven different countries were analysed for the effects of variety and test country, age, gender and apple consumption habit of the consumer on eating quality acceptance. The results obtained showed a strong interaction between country and variety, although a group of four varieties (‘Gold Pink’, ‘CIVni’, ‘Cripps Pink’ and ‘Fuji’) formed part of a group of the varieties that were most accepted in all of the countries except Germany. Significant interactions between variety and age and variety and gender were observed, but their magnitudes were not considered to be of any practical significance. No statistically significant interaction was found between variety and apple consumption habit on eating quality acceptance.
Quantitative analyses of empirical fitness landscapes
Szendro, I.G. ; Schenk, M.F. ; Franke, J. ; Krug, J. ; Visser, J.A.G.M. de - \ 2013
Journal of Statistical Mechanics: Theory and Experiment 2013 (2013)1. - ISSN 1742-5468 - 24 p.
adaptive protein evolution - beneficial mutations - escherichia-coli - sign epistasis - mean number - rna virus - nk model - adaptation - populations - walks
The concept of a fitness landscape is a powerful metaphor that offers insight into various aspects of evolutionary processes and guidance for the study of evolution. Until recently, empirical evidence on the ruggedness of these landscapes was lacking, but since it became feasible to construct all possible genotypes containing combinations of a limited set of mutations, the number of studies has grown to a point where a classification of landscapes becomes possible. The aim of this review is to identify measures of epistasis that allow a meaningful comparison of fitness landscapes and then apply them to the empirical landscapes to discern factors that affect ruggedness. The various measures of epistasis that have been proposed in the literature appear to be equivalent. Our comparison shows that the ruggedness of the empirical landscape is affected by whether the included mutations are beneficial or deleterious and by whether intra- or intergenic epistasis is involved. Finally, the empirical landscapes are compared to landscapes generated with the Rough Mt.\ Fuji model. Despite the simplicity of this model, it captures the features of the experimental landscapes remarkably well
Effect of location in the canopy on the colour development of three apple cultivars during growth
Unuk, T. ; Tijskens, L.M.M. ; Germsek, B. ; Zadravec, P. ; Vogrin, A. ; Hribar, J. ; Simcic, M. ; Stanislav Tojnko, S. - \ 2012
Journal of the Science of Food and Agriculture 92 (2012)12. - ISSN 0022-5142 - p. 2450 - 2458.
granny-smith apples - golden delicious apples - biological variance - fruit color - light - quality - orchard - peel
BACKGROUND: Homogeneity in appearance is one of the quality aspects asked for in the supply chain. Decreasing the biological variation in batches of harvested apples (cultivars Braeburn, Fuji and Gala) becomes increasingly important. Skin colour is one of the aspects that determine both optimal harvest and stage of development. Skin colour is affected by location in the canopy. The rules of development of biological variation are now established and will be used on skin colour data. RESULTS: The Minolta colour aspects a*, b* and L* measured before commercial harvest change in a sigmoidal fashion and can be analysed including the biological variation, with a logistic model in indexed nonlinear regression, obtaining explained parts of above 90%. The mechanism of colour change is not affected by state of development or location in the canopy. The location in the canopy affects the intensity of both red and green colouring compounds. The variation in colouration is not affected by the location in the canopy. CONCLUSION: The red-coloured apple cultivar (Gala) depends more on the location in the canopy than the less-coloured cultivars (Fuji and Braeburn). The colour development in Fuji apples is considerably slower, with a much larger variation in stage of development. The location in the canopy affects all aspects of biological variation (biological shift factor and asymptotic starting level of colouration) for all three colour aspects L*, a* and b*, but only the mean value, not the standard deviation. The biological shift factors per colour aspects are linearly related. Once induced, variation remains constant during development.
Scleroramularia gen. nov. associated with sooty blotch and flyspeck of apple and pawpaw from the Northern Hemisphere
Li, H. ; Sun, G. ; Batzer, J.C. ; Crous, P.W. ; Groenewald, J.Z. ; Karakaya, A. ; Gleason, M.L. - \ 2011
Fungal Diversity 46 (2011)1. - ISSN 1560-2745 - p. 53 - 66.
complex davidiellaceae - phylogeny - capnodiales - fungi - china - mycosphaerella - morphology - diversity - taxonomy - eyespot
Scleroramularia is proposed as a new hyphomycetous fungal genus associated with sooty blotch and flyspeck (SBFS) blemishes of apple and pawpaw fruit in the Northern Hemisphere. Morphologically the genus closely resembles Ramularia (Mycosphaerellaceae), based on its chains of hyaline conidia, with thickened, darkened, somewhat refractive conidiogenous loci. Scleroramularia is distinguished by forming black sclerotial bodies in culture, and having conidial chains that do not quickly disarticulate as observed in Ramularia. Based on the nuclear ribosomal DNA phylogeny (LSU), Scleroramularia represents an undescribed order in the Dothideomycetes, clustering between the Pleosporales and the Botryosphaeriales. Further analysis of morphology in combination with DNA phylogeny of the nuclear ribosomal ITS region and partial translation elongation factor 1-alpha (TEF) gene sequences delimited five species. These include S. asiminae on Asimina triloba (pawpaw fruit) in the U.S.A., and four other species occurring on apple fruit, namely S. abundans (on a local cultivar in Ardesen, Rize, Turkey), S. shaanxiensis (on ‘Fuji’ in China), S. pomigena (on ‘Golden Delicious’ in the U.S.A.), and S. henaniensis (on ‘Fuji’ in China, and ‘Golden Delicious’ and ‘Gold Rush’ in the U.S.A.). Morphologically these taxa can be distinguished based on a combination of culture characteristics and conidial morphology in vitro, which is reflected in a key to the species treated
Colour development in the apple orchard
Tijskens, L.M.M. ; Unuk, T. ; Stanislav Tojnko, S. ; Hribar, J. ; Simcic, M. - \ 2011
Journal of Fruit and Ornamental Plant Research 19 (2011)1. - ISSN 1231-0948 - p. 113 - 121.
Colour is traditionally one of the important appearance features of all fruit for consumers in deciding to buy them. Colour is therefore important in the postharvest supply chain. But where does that colour of fruit come from? Clearly the period of growing and the circumstances during growth are important for developing this important feature. During several seasons (2007-2009), the skin colour of individual apples of different cultivars (‘Braeburn’, ‘Fuji’, ‘Gala’, ‘Golden Delicious’) were measured using a Minolta CR-400 chromameter during the last 40-60 days before (commercial) harvest. By including the biological variation between individual apples in the analyses and applying non linear indexed regression analysis based on process oriented models, explained parts were obtained for the a*-value, all exceeding 90%. The estimated rate constants for the colouration process were remarkably similar for all cultivars (except ‘Fuji’) and growing conditions. That would indicate that the process of colouration is really reflecting the degradation of chlorophyll and not the production of red or yellow coloured blush (anthocyanins). The expected effect of growing conditions (fertilization and crop level, hail net or not, sunny side or shady side of the tree) did change the mechanism nor the kinetic parameter values but could all be attributed to the minimal obtainable skin colour (asymptotic values of the logistic model). This type of information from the production period may constitute an important link to postharvest supply chain management.
Identifying habitat patches and potential ecological corridors for remnant Asiatic black bear (Ursus thibetanus japonicus) populations in Japan
Doko, T. ; Fukui, H. ; Kooiman, A. ; Toxopeus, A.G. ; Ichinose, T. ; Chen, W. ; Skidmore, A.K. - \ 2011
Ecological Modelling 222 (2011)3. - ISSN 0304-3800 - p. 748 - 761.
geographic distributions - models
The Japanese National Biodiversity Strategy 2010 calls for the creation of ecological networks as a biodiversity conservation policy. However, there is an obvious lack of information on the spatial distribution of many species and a lack of scientific methods for examining habitat requirements to establish the need for constructing these networks for target species. This study presents a quantitative method for assessing the need for ecological networks through modeling the potential geographic distributions of species based on a case study of local populations of Asiatic black bear (Ursus thibetanus japonicus) in Fuji and Tanzawa, Japan. A total of 1541 point records of occurrences of Asiatic black bears and 11 potential predictors were analyzed in a GIS environment. After a predictive distributional map was obtained using the Maximum Entropy (MaxEnt) algorithm, a gap analysis was carried out and population size was estimated. Approximately 24% of the bear's predicted habitat area fell within a wildlife protection area, 2% within a nature reserve, and 37% within natural parks. Conservation forest comprised 54% of the total area of predicted habitat; of this, national forest comprised 2%, and private and communal forest comprised 37%. The total estimated Asiatic black bear population in this region was 242, with 179 individuals in the Fuji local population, 26 in the Tanzawa local population, and 37 in the corridor patch between the two local populations. Our study also found a potential corridor connecting the Fuji and Tanzawa local populations, as well as potential habitat corridors in the Fuji region containing subpopulations on Mt. Fuji (119 individuals) and Mt. Kenashi (53 individuals). An additional subpopulation on Mt. Ashitaka (7 individuals) is isolated and not fully protected by a zoning plan. Mt. Furo's subpopulation is considered to be almost extinct, although black bears were observed here until 2002 based on the report by Mochizuki et al. (2005). The total black bear population of the Fuji-Tanzawa region is considered to be "endangered" ; thus, an adequate population size might be difficult to maintain even if this region were to be internally connected by means of an ecological network.
QTL dynamics for fruit firmness and softening around an ethyle-dependent polygalacturonase gene in apple (Malus domestica Borkh.).
Costa, F. ; Peace, C.P. ; Stella, S. ; Serra, S. ; Musacchi, S. ; Bazzani, M. ; Sansavini, S. ; Weg, W.E. van de - \ 2010
Journal of Experimental Botany 61 (2010)11. - ISSN 0022-0957 - p. 3029 - 3039.
x-domestica borkh. - 1-aminocyclopropane-1-carboxylate synthase - endopolygalacturonase gene - melting-flesh - candidate gene - melon fruit - shelf-life - expression - md-acs1 - plants
Apple fruit are well known for their storage life, although a wide range of flesh softening occurs among cultivars. Loss of firmness is genetically coordinated by the action of several cell wall enzymes, including polygalacturonase (PG) which depolymerizes cell wall pectin. By the analysis of ‘Fuji’ (Fj) and ‘Mondial Gala’ (MG), two apple cultivars characterized by a distinctive ripening behaviour, the involvement of Md-PG1 in the fruit softening process was confirmed to be ethylene dependent by its transcript being down-regulated by 1-methylcyclopropene treatment in MG and in the low ethylene-producing cultivar Fj. Comparing the PG sequence of MG and Fj, a single nucleotide polymorphism (SNP) was discovered. Segregation of the Md-PG1SNP marker within a full-sib population, obtained by crossing Fj and MG, positioned Md-PG1 in the linkage group 10 of MG, co-located with a quantitative trait locus (QTL) identified for fruit firmness in post-harvest ripening. Fruit firmness and softening analysed in different stages, from harvest to post-storage, determined a shift of the QTL from the top of this linkage group to the bottom, where Md-ACO1, a gene involved in ethylene biosynthesis in apple, is mapped. This PG–ethylene-related gene has beeen positioned in the apple genome on chromosome 10, which contains several QTLs controlling fruit firmness and softening, and the interplay among the allelotypes of the linked loci should be considered in the design of a marker-assisted selection breeding scheme for apple texture.
In vivo assessment with prick-to-prick testing and double-blind, placebo-controlled food challenge of allergenicity of apple cultivars
Bolhaar, S.T.H.P. ; Weg, W.E. van de; Ree, R. van; Gonzalez-Mancebo, E. ; Bruijnzeel-Komen, C.A.F.M. ; Fernandez-Rivas, M. ; Jansen, J. ; Hoffman-Sommergruber, K. ; Knulst, A.C. ; Gilissen, L.J.W.J. - \ 2005
Journal of Allergy and Clinical Immunology 116 (2005)5. - ISSN 0091-6749 - p. 1080 - 1086.
lipid transfer protein - birch pollen allergen - rosaceae fruits - skin-tests - ige - identification - extracts - hazelnut - cloning - potato
Background: Apple cultivars have been reported to differ in allergenicity on the basis of in vitro and skin prick tests with apple extracts. Objectives: We sought to evaluate the efficacy of the prick-to-prick method in assessing differences in allergenicity of apple cultivars and to confirm differences by means of double-blind, placebo-controlled food challenge (DBPCFC). Methods: Intra-assay and intracultivar variation of prick-to-prick test results were determined in 6 Dutch and 8 Spanish patients with apple allergy by using 5 apples of the cultivars Golden Delicious, Fuji, and Ecolette in duplicate. In addition, 21 cultivars were screened for allergenicity in 15 Dutch patients with birch pollen and apple allergy. Two selected cultivars (Golden Delicious and Santana) were tested with DBPCFCs. The influence of storage conditions on allergenicity was assessed in 5 cultivars. Results: Intra-assay variation of skin prick testing was 3.9%, and intracultivar variation was 4.1%. A ranking of 21 cultivars was made on the basis of prick-to-prick tests in 9 patients. Apple cultivars were classified as of low, intermediate, and high allergenicity, with a significant difference between low and high allergenicity (P <.001). A significant difference in allergenicity determined between Golden Delicious and Santana cultivars (P <.05) was confirmed by means of DBPCFC. With 5 cultivars, controlled atmosphere (2.5% oxygen/1% carbon dioxide) was shown to reduce allergenicity (P <.001) by 15% compared with storage at 2°C. Conclusion": Prick-to-prick testing with fresh apples is a reproducible method of assessing allergenicity. Apples can be classified as of low or high allergenicity for the majority of patients. This was confirmed by using DBPCFCs. Selection of cultivars and control of storage conditions are both viable strategies for reduction of symptoms in patients with apple allergy
Role of the genes Md-ACO1 and Md-ACS1 in ethylene production and shelf life of apple (Malus domestica Borkh)
Costa, F. ; Stella, S. ; Weg, W.E. van de; Guerra, W. ; Cecchinel, M. ; Dallavia, J. ; Koller, B. ; Sansavini, S. - \ 2005
Euphytica 141 (2005)1-2. - ISSN 0014-2336 - p. 181 - 190.
1-aminocyclopropane-1-carboxylate synthase - pumila mill. - fruit - expression - biosynthesis - tomato - oxidase - allele - plants
Shelf life determines the economic life time of mature apples, which can be either freshly harvested or stored. Good shelf life is highly associated with a slow decrease of fruit firmness at room temperature. Apple is a climacteric fruit, in which loss of firmness seems to be physiologically related to ethylene. Ethylenes biosynthetic pathway is controlled by two large gene families coding for 1-aminocyclopropane-1-carboxylate synthase (ACS) and 1-aminocyclopropane-1-carboxylate oxydase (ACO). In this study, one ACS and one ACO gene were examined for their effect on ethylene production and shelf life in apple using gene specific molecular marker, and have also been positioned on a molecular marker linkage map. The ACO marker was developed in this research and mapped on linkage group (LG) 10 of the crosses Prima × Fiesta and Fuji × Mondial Gala, within the 5% border of a previously identified fruit firmness QTL [Theor Appl Genet 100 (2000) 1074]. We denoted this locus as Md-ACO1. In addition, we mapped the previously developed Md-ACS1 marker [Theor Appl Genet 101 (2000) 742] on LG15. Studies on the cross Fuji × Braeburn revealed that Md-ACS1 and Md-ACO1 independently affect the internal ethylene concentration (IEC) as well as shelf life of apple, Md-ACS1 having the strongest effect. Descendants homozygous for Md-ACS1-2 and Md-ACO1-1 showed to have the lowest ethylene production as well as superior shelf-life. These two genes are candidates to be included in marker assisted breeding
Voorkomen uitval bij Lisianthus : onderzoek op 3 praktijkbedrijven
Burg, A.M.M. van der; Kreij, C. de; Paternotte, S.J. ; Werd, H.A.E. de - \ 2003
Wageningen : Praktijkonderzoek Plant & Omgeving, Sector Glastuinbouw - 29
eustoma - afwijkingen, planten - plantenziektebestrijding - glastuinbouw - snijbloemen - eustoma - plant disorders - plant disease control - greenhouse horticulture - cut flowers
Eén van de problemen in de teelt van Lisianthus (Eustoma) is de uitval in de tweede helft van de teelt. Er zijn verschillen tussen de rassen: ‘Picolo’, ‘Fuji Aprico’, ‘Fuji White’, ‘Kyoto Purple’ en ‘Blue Purple’ zijn gevoelig. De uitval heeft een negatief effect op het bedrijfsrendement. Voor de oorzaak van het probleem werd aan de volgende oorzaken gedacht; 1. Het vermoeden was dat de uitval samenhangt met een toxische stof in de grond, die ontstaat bij de vertering van het restmateriaal van voorgaande Lisianthusteelten. Uit een literatuurstudie (Kreij, 2001) blijkt, dat bij andere gewassen aanwijzingen zijn voor autotoxiciteit; het gaat om luzerne, asperge, appel, perzik, druif en ander fruit. Uit de praktijk komen signalen, dat een goede organische stofvoorziening van de grond een vermindering geeft van de uitval bij Lisianthus. Waarschijnlijk moet dit dan organische stof zijn, die snel afbreekbaar is. Dat dit het geval is, zou kunnen komen door het microleven in de grond, wat beter wordt bij toevoer van organische stof. Dit microleven is in staat om de toxische stof af te breken. Ook is het denkbaar, dat de toxische stof geadsorbeerd wordt aan de organische stof. 2. Een andere veronderstelling was dat door een slechte beworteling in de bovengrond en een droge grond er vochtgebrek ontstaat. Door in de tweede helft van de teelt nagenoeg geen water te geven wordt bij de Lisianthusteelt bloemknopvorming geïnduceerd. Een te extreme droogte zou mogelijk uitval geven. 3. In uitgevallen plantmateriaal worden meermalen vaatziekten zoals Myrothecium en Fusarium geïsoleerd. Bij determinatie blijkt, bij monde van Dhr. J. Meffert van de PD het voornamelijk te gaan om F. avenaceum en F. solani . Mogelijk wordt de grond onvoldoende goed gestoomd. Stomen met onderdruk in de grond zou aanzienlijk beter resultaat opleveren. 4. Voor de vertering van het restmateriaal is extra zuurstof nodig. Mogelijk ontstaat er zuurstof tekort in de grond, waardoor de wortels afsterven, wat ook tot uitval van de planten kan leiden.
Effect van belichtingsregime en verrood licht op stekken van roos 'Frisco' en 'Madelon' en op Eustoma 'Fuji donker blauw'
Bakker, J.A. ; Blacquiere, T. ; Hoog, J. de - \ 1995
Aalsmeer : Proefstation voor de Bloemisterij (Rapport / Proefstation voor de Bloemisterij 197) - 30
kunstlicht - snijbloemen - verlichting - nederland - rosa - artificial light - cut flowers - lighting - netherlands - rosa
|Effect van belichtingsregime en verrood licht op roos Frico en Madelon en op Eustoma Fuji donkerblauw
Hoog Bakker, J.A.J. de; BlacquiOre, T. - \ 1995
Unknown Publisher - 30 p.