Bleiswijk, Netherlands
Bleiswijk, Netherlands

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Ludeking D.J.W.,Wageningen UR Glastuinbouw | Paternotte S.J.,Wageningen UR Glastuinbouw | Runia W.T.,Praktijkonderzoek Plant and Omgeving AGV | Molendijk L.P.G.,Praktijkonderzoek Plant and Omgeving AGV
Acta Horticulturae | Year: 2011

Much research has been done on biological disinfestation of soil with grass and other fresh organic materials to suppress persistent diseases like Verticillium dahliae and nematode populations in the soil. After covering the soil with airtight plastic and creating an anaerobic environment, natural processes that will have a disinfesting effect on the soil are stimulated by the organic material. Practical conditions may vary enormously and so it seems that soil disinfestation with grass or other fresh materials is unpredictable. Growers find this method complicated and labor intensive. In particular, growers of horticultural crops are not enthusiastic about biological soil disinfestation with grass. As an alternative for fresh materials, organic fermentation products have been tested. Application is easier and effects occur faster than with fresh organic materials. Therefore, this method offers a chance to explore the possibilities for broad application in horticulture as an alternative for soil disinfestation with steam. Product H7022 (ThatchTec B.V., Wageningen, The Netherlands), consists of organic by-products from the food processing industry, and resulted in a 100% reduction of nematodes and Verticillium dahliae. The major drawback to this method is the treatment time of at least two weeks, which is too long for most greenhouse growers, as the costs of a two week time gap in production are too high, making it difficult to adapt to a greenhouse system. New research on organic fermentation of the soil is necessary to determine which processes cause soil disinfestation, during what time period this method causes an effect, and whether or not this method is suitable for use in soil-bound horticulture.

Holterman M.H.M.,Agroscope Changins Waedenswil | Korthals G.W.,Praktijkonderzoek Plant and Omgeving B.V. Sector AGV | Doroszuk A.,Institute of Biology Leiden | Van Megen H.B.H.,Wageningen University | And 4 more authors.
Nematology | Year: 2011

Biological indicators are highly relevant for assessing the condition of a soil as they are integrative; they reflect the overall impact of physical, chemical and biological changes. Indigenous soil organisms are preferable to other test organisms because the diversity and condition of indigenous soil organisms reflect both acute and chronic effects of soil disturbances. Nematodes are ubiquitous, speciose, easily extractable and present in extremely high numbers. Given the ever increasing amount of sequence data, DNA barcode-based community analysis will soon be possible and a next step would be to define objective criteria for the ecological grouping of soil nematodes. Here, we present a framework to ascertain which traits are correlated with a tolerance to stress. For this, a field study on the effects of pH and copper on nematode communities was re-analysed. Changes in abundances of individual genera were correlated with a number of potentially stress tolerance-related characteristics. The generalised least squares (GLS) method was used to account for the phylogenetic dependence of the data. Only the relationship between the ability to enter a survival stage and tolerance to copper at pH 6.1 was found to be significant, but the quantity of missing data probably had a negative impact on the analyses. This study did, however, clearly demonstrate the importance of accounting for the effects of phylogenetic dependence in the data. When the phylogeny was taken into account, we observed an average change in P value of 0.196 (and in some cases as much as 0.6) for the correlations of possible stress-related characteristics and Cu or pH tolerance. This research constitutes a proof-of-principle for a transparent method to relate stress tolerance to (ecological) characteristics. The usefulness of this powerful method should become even clearer when substantially higher numbers of individuals are analysed (as facilitated by using DNA barcodes) and when missing data are filled in. © 2011 Brill.

De Jong M.M.,University Utrecht | Baggerman J.,Aquamarijn | Van Rijn C.J.M.,Aquamarijn | Sonneveld P.J.,HAN University of Applied Sciences | And 4 more authors.
Materials Research Society Symposium Proceedings | Year: 2012

In this study we compare light trapping in hydrogenated amorphous silicon (a-Si:H) solar cells deposited directly onto polycarbonate (PC) at low temperature (< 130°C). To that end, we embossed PC substrates with 400 nm and 10 μm square based pyramids to induce light trapping based on diffraction and on geometric effects. As a comparison, we deposited a-Si:H cells on flat glass substrates and on Asahi U-type TCO glass. The cells on PC generate current densities comparable (slightly higher) than cells on Asahi TCO glass, but suffer from a slightly lower VOC, resulting in cells with an initial efficiency of 6.8% and 7.4% on sub-micron pyramid and micro- pyramid structured PC substrates respectively, compared to 7.6% for cells on Asahi. This shows great potential for a-Si:H cells deposited directly onto cheap plastics. © 2012 Materials Research Society.

Cuijpers W.J.M.,Louis Bolk Institute | Janmaat L.,Louis Bolk Institute | Van Der Wurff A.W.G.,Wageningen UR Glastuinbouw
Acta Horticulturae | Year: 2011

In a field experiment in an organic greenhouse, an innovative cropping system (the so-called 'Köver' system) was tested. In this system, planting beds are divided below ground in two physically separated strips. In one section, vegetables are cultivated at half the normal planting distance. In the other section, the soil is either left fallow or planted with crops antagonistic towards plant-parasitic nematodes. After one growing season, vegetable and fallow strips are reversed. In this way, crop rotation is broadened, with the aim of improving soil health. Compared to the normal cultivation system, the availability of space and light in the Köver system might be unfavourable for some crops (e.g., sweet pepper), which may lead to an initial production loss. However, improved soil health should ultimately lead to a healthier crop and higher yields. The Köver system was introduced in sweet pepper 'Derby' on rootstock 'Capital'. The aim was to achieve production levels of 88-92% or higher of the maximum production targets on a healthy, previously uncultivated soil, while reducing numbers of plant-parasitic nematodes, particularly Meloidogyne incognita. In the Köver system, the following treatments were compared: (1) Sweet pepper 'Derby' on rootstock 'Capital', (2) fallow, (3) Marigold (Tagetes patula) 'Single Gold' (brand name: Ground Control) and (4) the densely planted rootstock Capsicum annuum 'Snooker'. At the end of the season, the number of Meloidogyne juveniles was significantly reduced by fallow, Tagetes and 'Snooker' treatments, compared with the sweet pepper crop. The 'Snooker' rootstock was less effective in reducing Meloidogyne juveniles than fallow or Tagetes. Numbers of juveniles hatching from eggs increased significantly in the sweet pepper crop compared with other treatments. Due to considerable production loss in the sweet pepper crop, antagonistic plants are not recommended in neighboring strips. The fallow treatment was the most promising in combination with sweet pepper in the Köver system. However, further research is needed to confirm these results.

Tikunov Y.M.,Plant Research International | Tikunov Y.M.,Center for Biosystems Genomics | Molthoff J.,Plant Research International | Molthoff J.,Center for Biosystems Genomics | And 21 more authors.
Plant Cell | Year: 2013

Phenylpropanoid volatiles are responsible for the key tomato fruit (Solanum lycopersicum) aroma attribute termed "smoky." Release of these volatiles from their glycosylated precursors, rather than their biosynthesis, is the major determinant of smoky aroma in cultivated tomato. Using a combinatorial omics approach, weidentified the NON-SMOKY GLYCOSYLTRANSFERASE1 (NSGT1) gene. Expression of NSGT1 is induced during fruit ripening, and the encoded enzyme converts the cleavable diglycosides of the smoky-related phenylpropanoid volatiles into noncleavable triglycosides, thereby preventing their deglycosylation and release from tomato fruit upon tissue disruption. In an nsgt1/nsgt1 background, further glycosylation of phenylpropanoid volatile diglycosides does not occur, thereby enabling their cleavage and the release of corresponding volatiles. Using reverse genetics approaches, the NSGT1-mediated glycosylation was shown to be the molecular mechanism underlying the major quantitative trait locus for smoky aroma. Sensory trials with transgenic fruits, in which the inactive nsgt1 was complemented with the functional NSGT1, showed a significant and perceivable reduction in smoky aroma. NSGT1 may be used in a precision breeding strategy toward development of tomato fruits with distinct flavor phenotypes. © American Society of Plant Biologists. All rights reserved.

De Jong M.M.,University Utrecht | Rath J.K.,University Utrecht | Schropp R.E.I.,University Utrecht | Sonneveld P.J.,Wageningen UR Glastuinbouw | And 5 more authors.
Journal of Non-Crystalline Solids | Year: 2012

We present a novel method to achieve light trapping in thin film silicon solar cells. Unlike the commonly used surface textures, such as Asahi U-type TCO, that rely on light scattering phenomena, we employ embossed periodically arranged micro-pyramidal structures with feature sizes much larger than the wavelength of visible light. Angular resolved transmission of light through these substrates indeed showed diffraction patterns, unlike in the case of Asahi U-type substrates, which show angular resolved scattering. Single junction amorphous silicon (a-Si) solar cells made at 125 °C on the embossed structured polycarbonate (PC) substrates showed an increase in current density by 24% compared to a similar solar cell on a flat substrate. The band gap and thickness of the i-layer made by VHF PECVD are 1.9 eV and 270 nm respectively. A double p-layer (nc-Si:H/a-Si:H) was used to make proper contact with ZnO:Al TCO. Numerical modeling, called DokterDEP was performed to fit the dark and light current-voltage parameters and understand the characteristics of the cell. The output parameters from the modeling suggest that the cells have excellent built-in potential (V bi). However, a rather high recombination voltage, V μ, affects the FF and short circuit current density (J sc) for the cells on Asahi as well as for the cells on PC. A rather high parallel resistance ≫ 1 Mσcm 2 (obtained from the modeling) infers that there is no significant shunt leakage, which is often observed for solar cells made at low temperatures on rough substrates. An efficiency of more than 6% for a cell on PC shows enormous potential of this type of light trapping structures. © 2011 Elsevier B.V.

Van Der Lans C.J.M.,Wageningen UR Glastuinbouw | Meijer R.J.M.,Wageningen UR Glastuinbouw | Blom M.,Biologica
Acta Horticulturae | Year: 2011

As a starting point for future international cooperation in research on Organic Greenhouse Horticulture, an inventory was done to map the state of art of organic greenhouse horticulture worldwide. This inventory resulted in overview of national area sizes, characterisation of practised organic growing systems, regulations, and topics on the national research agenda for each country. The overview is presented and discussed in this paper. The emphasis in this overview is on the EU countries because that information was best available.

Bakker J.C.,Wageningen UR Glastuinbouw
Acta Horticulturae | Year: 2011

In conventional greenhouse systems, recent innovations have contributed to increased production levels, and at the same time, to the decreased ecological footprint in terms of the reduction of water use, nutrients and CO2 emissions. Several examples of application of standard and innovative technologies to improve production, optimize utilization of solar energy and increase efficiency of energy and water use are presented. These technologies can also be applied in organic (soilbased) protected growing systems and the practical application is, as with conventional growing systems, primarily limited by the economic feasibility. The examples include the implementation of modern sensor technology, the use of models in environmental control and innovative covering materials for greenhouses, as well as the latest developments in the field of (semi-) closed greenhouses.

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