Proefstation voor de Groenteteelt

Sint-Katelijne-Waver, Belgium

Proefstation voor de Groenteteelt

Sint-Katelijne-Waver, Belgium
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Decombel A.,Inagro | Bleyaert P.,Inagro | Van Lommel J.,Proefstation voor de Groenteteelt | Vandevelde I.,Proefstation voor de Groenteteelt | And 2 more authors.
Acta Horticulturae | Year: 2017

Lamb's lettuce (Valerianella locusta L.) that is presented to the market is not always freshly harvested. The product can be stored for up to 28 days and is indistinguishable from fresh material by the human eye. However, due to the prior storage period, the shelf-life potential is limited, and this leads to losses in distribution and a lower quality for the consumer. This work aims to develop a rapid and non-destructive methodology using visible/near-infrared (Vis/NIR) reflectance spectroscopy to quantify the postharvest age. Vis/NIR reflectance spectra were linked to the time in storage by partial least-squares regression (PLS). Two variable selection techniques, genetic algorithms PLS and Monte Carlo uninformative variable elimination PLS, were combined to improve the accuracy and robustness of the prediction model while decreasing the number of wavelengths used. The final model used only 10% of the original wavelength variables, while the root mean squared error of cross validation decreased from 6.0 to 3.6 days. The final model was tested using two external test sets and had a maximum root mean squared error of prediction of 3.7 days. Therefore, it was concluded that Vis/NIR reflectance spectroscopy can be a valid, rapid and non-destructive method for identifying and quantifying the postharvest age of lamb's lettuce.

Moerkens R.,Tomato Research | Moerkens R.,University of Antwerp | Berckmoes E.,Proefstation voor de Groenteteelt | Van Damme V.,Belgium Institute for Agricultural and Fisheries Research | And 6 more authors.
Journal of Plant Diseases and Protection | Year: 2017

Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a key biological control agent in greenhouse tomato crops. In the present study, we describe the population dynamics of M. pygmaeus after release during two generations in semi-commercial greenhouses in order to optimize biocontrol programs. We tested the effect of the number of weekly supplementary food applications consisting of a mixture of Ephestia kuehniella Zeller and Artemia franciscana Kellogg in a tomato crop on population numbers of M. pygmaeus at low and high initial release densities of the predator. Also, the effect of supplementary feeding on the predator’s dispersal was studied. Larger population densities of M. pygmaeus were obtained when food was supplied for a longer period. However, we observed fruit damage by M. pygmaeus at high densities resulting from too frequent food applications. Also, dispersal was slowed down as the number of supplementary food applications increased. Distributing M. pygmaeus over more plants at release results in higher total population densities. The optimal inoculative release strategy of M. pygmaeus is a trade-off between high population densities and fruit damage, fast or slow dispersal throughout the greenhouse and the number of release plants and work/costs related to the supplementation of food. The optimal strategy to overcome negative effects like fruit damage, slow dispersal and potential cannibalism proved to be a weekly provision of supplementary food during 6–8 weeks, with an initial release density strategy of 20 M. pygmaeus adults per plant. These results contribute to a more sustainable tomato production. A reliable and efficient inoculative release strategy for the key predator M. pygmaeus enhances the biocontrol potential and is of great value for tomato growers. © 2017, Deutsche Phythomedizinische Gesellschaft.

Franca S.C.,Ghent University | Spiessens K.,Proefstation voor de Groenteteelt | Pollet S.,Inagro | Debode J.,Belgium Institute for Agricultural and Fisheries Research | And 3 more authors.
Crop Protection | Year: 2013

Verticillium wilt, caused by the soil-borne fungus Verticillium longisporum, leads to economic losses in cauliflower production in Belgium. Development of sustainable control measures of the disease is necessary. Previous studies in our laboratory have shown that incorporation of ryegrass can reduce the viability of V.longisporum microsclerotia in soil. However, field experiments are lacking in Belgian conditions. To gain knowledge about the population dynamics of V.longisporum and its relationship with Verticillium wilt, experiments were conducted from 2006 to 2010 in two cauliflower fields (Oppuurs and Ardooie) with history of Verticillium wilt. Three main crop systems (fallow, cauliflower and cauliflower followed by removal of debris) and two cover crop systems (no cover crop and ryegrass) were tested. The results of this study showed that (i) crop rotation intensity of cauliflower cultivation does not affect the inoculum density of microsclerotia forming Verticillium species in soil, (ii) amendment of lignin-rich ryegrass may reduce the soil inoculum, and (iii) seasonal fluctuations of inoculum densities occur but any soil inoculum variation above a level of one microsclerotium per gram of soil does not affect disease levels. Furthermore, we found that Verticillium wilt of cauliflower in Ardooie was reduced in soil containing Verticillium tricorpus-like organisms. The Verticillium isolate Vt305 obtained from the cauliflower field in Ardooie was morphologically similar to V.tricorpus, but its rDNA ITS region showed 100% identity with the non-pathogenic species Verticillium isaacii, recently described in literature. © 2013 Elsevier Ltd.

Agency: European Commission | Branch: H2020 | Program: CSA | Phase: WATER-4b-2015 | Award Amount: 3.00M | Year: 2016

In European countries, the cultivation of fertigated crops experience scarcity of water, and the intensity of cultivation poses significant risks to water quality. The main objective of the FERTINNOWA thematic network is to create a meta-knowledge database on innovative technologies and practices for fertigation of horticultural crops. FERTINNOWA will also build a knowledge exchange platform to evaluate existing and novel technologies (innovation potential, synergies, gaps, barriers) for fertigated crops and ensure wide dissemination to all stakeholders involved of the most promising technologies and best practices. A multi-actor integrated approach will be used through the FERTINNOWA platform which will involve various stakeholders (researchers, growers, policy-makers, industry, environmental groups etc.) at several levels including the socio-economic and regulatory level (national and European) with a special focus on the EU Water Framework Directive and Nitrate Directive. Information will be gathered at national level to feed a European benchmark study that will evaluate and compare existing technologies used at various horticulture sectors, including vegetables, fruit and ornamentals in different climate zones. All tools, databases and other resources generated will be shared within the consortium and the stakeholders group and will be made available to the broader scientific community, policy-makers, the industry and the public at large. FERTINNOWA will help the growers to implement innovative technologies in order to optimize water and nutrient use efficiency thus reducing the environmental impact.

Hanssens J.,Ghent University | De Swaef T.,Ghent University | Steppe K.,Ghent University | Goen K.,Proefcentrum Hoogstraten | And 4 more authors.
Acta Horticulturae | Year: 2012

Plant water status plays a major role in glasshouse cultivation of tomato (Solanum lycopersicum L.). New climate control technologies alter the glasshouse climate and make it less dependent on solar radiation. However, irrigation strategies are still often based on solar radiation sums. In order to maintain a good plant water status, it is interesting to use plant-based methods such as monitoring sap flow (F) or stem diameter variations (SDV). Though SDV give important information about plant water status, an unambiguous interpretation might be difficult because other factors such as stem age, fruit load and sugar content of the stem also affect SDV. In this study, an analysis of the effect of stem age on the response of SDV to water status was performed by calibration of a mechanistic flow and storage model. This allowed us to determine how parameter values changed across the growing season. Tissue extensibility decreased over the growing season resulting in a lower growth rate potential, whereas daily cycles of shrinking and swelling of the stem became more pronounced towards the end of the growing season. Parameters were then adapted to time-dependent variables and implemented in the model, allowing long term simulation and interpretation of SDV. Sensitivity analysis showed that model predictions were very sensitive to initial sucrose content of the phloem tissue and the parameters related to plastic growth.

Hanssens J.,Ghent University | De Swaef T.,Ghent University | Steppe K.,Ghent University | Pinxteren D.,Proefcentrum Hoogstraten | And 3 more authors.
Acta Horticulturae | Year: 2014

The importance of plant water status for a good production and quality of tomato fruits (Solanum lycopersicum L.) has been emphasized by many authors. Currently, different new energy-saving technologies and growing strategies are under investigation to cope with the increasing fossil fuel prices. However, these technologies and growing strategies typically alter the greenhouse climate, thereby affecting the plants' response. Hence, the question arises how to adapt the microclimate to reduce the energy consumption of greenhouse tomato cultivation without compromising fruit yield or quality. Nowadays, the use of plant-based methods to steer the climate is of high interest and it was demonstrated that monitoring of stem diameter variations and fruit growth provides crucial information on both the plant water and carbon status. However, interpretation of these data is not straightforward and, hence, mechanistic modelling is necessary for an unambiguous interpretation of the dynamic plant response. During a 4-year research period, we investigated the response of different plant processes of tomato to dynamic microclimatic greenhouse conditions. The final aim was to develop a decision support system that helps growers to find an optimal balance between energy consumption, plant response and fruit yield. To this end, an integrated plant model, including stem, leaves, roots and fruits, was developed in which the various plant processes are mechanistically described. The plant model was calibrated and extensively validated on datasets collected throughout the different growing seasons in different research facilities in Flanders. This plant model was finally integrated into an existing greenhouse climate model and validated with data from the greenhouse climate and energy consumption. After validation, this integrated model was used to run scenarios on growing strategies and their impact on energy consumption, plant photosynthesis and fruit growth.

Agency: European Commission | Branch: H2020 | Program: IA | Phase: ICT-23-2014 | Award Amount: 4.46M | Year: 2015

In modern greenhouses there is a high demand to automate labour. The availability of a skilled workforce that accepts repetitive tasks in harsh greenhouse climate conditions is decreasing rapidly. The resulting increase in labour costs and reduced capacity puts major pressure on the competitiveness of the European greenhouse sector. Present robotization of this labour has entered an high level of technological readiness. However, a gap remains which halts the transition from science to economic and societal impact; the so called Technological Innovation Gap. In the EU-FP7-project CROPS extensive research has been performed on agricultural robotics. One of the applications was a sweet pepper harvesting robot. It was shown that such a robot is economically and technically viable. The proven hardware and software modules (TRL:6) developed in CROPS will be used as the groundwork. The successful CROPS software modules based on the Robotic-Operating-System (ROS) will be maintained and expanded in SWEEPER. Also the gripper end-effector will be retained. This patent pending module is able to grasp the sweet pepper without the need of an accurate measurement of the position and orientation of the fruit. From the CROPS project, also gained knowledge will directly be put to benefit. In several experiments, it turned out that different growers use different cropping systems ranging in crop density. In SWEEPER, the cropping system itself will be optimized to facilitate robotic harvesting. In CROPS it was concluded that instead of a 9DOF, a 4DOF robot arm is sufficient , greatly reducing costs. To improve the level of robotic cognitive abilities, plant models will be applied to approximate location of sweet peppers. This model-based vision will increase and speed up fruit detection. Based on the insights of CROPS, sensors will be placed onto the gripper only. Also a LightField sensor will be introduced which is able to record both colour and 3D information simultaneously.

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