The Latest Developments in the Lighting Technologies in Dutch Horticulture

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The influence of leaf area on tomato yield was evaluated, both by simulations and experimental work. Simulated crop growth results from daily crop gross assimilation rate minus maintenance respiration rate, multiplied by a conversion efficiency factor. Dry matter partitioning is simulated based on the relative sink strengths of the plant organs. Within the plant, individual fruit trusses and vegetative units are distinguished. Leaf area increase is calculated based on temperature, unless a maximum specific leaf area is reached. In the standard situation leaves from a vegetative unit are removed one week before the truss above this unit is harvest ripe. Leaf removal could also be based on maintaining a desired leaf area index (LAI).Measurements . The model predicted a yield increase of 1.5% for the maximum LAI treatment compared to the reference, with LAI being input to the model. Simulated yield when leaf picking was based upon a desired LAI of 4, was 4% higher than for a desired LAI of 3, with hardly any effect at higher LAI. Simulations showed that removal of young leaves favored partitioning to the fruits but decreased LAI and total yield. However, if removal of old leaves was delayed such that an LAI of 3 m 2 m -2 was maintained, removal of every second young leaf improved yield by 10%. Methods of optimizing yield by controlling LAI are discussed.

Section: Removal Of Old Leavesmentioning

confidence: 99%

Effect of Leaf Area on Tomato Yield

Heuvelink¹,

Bakker²,

Elings³

et al. 2005

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“…Supplementary lighting is increasingly used in greenhouse horticulture in areas where in part of the year natural light level is not sufficient for acceptable yield and product quality (Marcelis et al, 2002). Particularly in greenhouse ornamental production, supplementary light is a prerequisite to allow a year-round production (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Explanatory simulation models are known to be powerful tools to analyse quantitatively the effects of supplementary lighting on crop growth (Marcelis et al, 2002) and this analysis can be further extended to several external quality attributes (e.g. .…”

Section: Introductionmentioning

confidence: 99%

Combined Effects of Light and Temperature on Product Quality of Kalanchoe Blossfeldiana

Carvalho¹,

Wuillai²,

Heuvelink³

2006

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) combined with four constant temperatures (18, 21, 23 and 26°C; equal day and night temperature) was conducted in growth chambers using the pot plant Kalanchoe blossfeldiana. The current work allows for establishing relationships between these two climatic factors and product quality (plant height, number of flowering shoots, inflorescence size and inflorescence position) and cropping duration. From the studied product quality attributes, temperature and PPFD only showed a marked interaction on number of flowering shoots and on inflorescence size. The huge increase observed on the number of flowering shoots (from 4.6 to 20.5) was a response to higher PPFD, whereas temperature had only a minor effect. Inflorescence size was also enhanced at higher PPFD (especially at lower temperatures) but in contrast with the number of flowering shoots, inflorescence size was drastically reduced at higher temperatures. Plant height varied between 13.5 and 21.6 cm and was strongly influenced by temperature, whereas influence of PPFD was only marginal. Time to flowering decreased quadratically with temperature and with PPFD, and no interaction between these climatic factors was found INTRODUCTIONSupplementary lighting is increasingly used in greenhouse horticulture in areas where in part of the year natural light level is not sufficient for acceptable yield and product quality (Marcelis et al., 2002). Particularly in greenhouse ornamental production, supplementary light is a prerequisite to allow a year-round production (e.g. photoperiodic treatments for flowering control) and to reduce the variation in product quality throughout the year (e.g. increasing the autumn and winter quality). For optimal use of supplementary lighting a good understanding of the effects of light and possible interactions with other climatic factors on crop growth, development, yield and product quality is necessary.Explanatory simulation models are known to be powerful tools to analyse quantitatively the effects of supplementary lighting on crop growth (Marcelis et al., 2002) and this analysis can be further extended to several external quality attributes (e.g. Carvalho and Heuvelink, 2004). Kalanchoe growers aim at producing a compact plant, with richly flowering umbels and one to three open flowers at commercial harvest, in the shortest time as possible. In a previous study a conceptual dynamic model for predicting plant height and number of flower heads in Kalanchoe blossfeldiana was developed (Eveleens-Clark et al., 2004). In order to use this conceptual model as a decision support system for year-round kalanchoe production, it needs to be further extended, parameterised and calibrated for different seasons. Therefore, information is needed on the effects of photosynthetic photon flux density (PPFD) and temperature on product quality and cropping duration.

“…Growers in Holland, operate a farm internationally, for example in Spain, and maintain their greenhouse in the Netherlands, for the primary purpose to have a continuous production throughout the year (Marcelis et al, 2002). In the south of Spain, greenhouse production that ends with each hot summer season in lower coastal areas is being substituted by vegetable produce from the cooler highlands, typically within net-covered greenhouses, thereby enabling the year around supply.…”

Section: Location Specific Technology Levelsmentioning

confidence: 99%

Innovation in Greenhouse Engineering

Giacomelli¹,

Castilla²,

Henten³

et al. 2008

Innovations in greenhouse engineering are technical developments which help evolve the state-of-the-art in CEA (Controlled Environment Agriculture). They occur in response to the operational demands on the system, and to strategic changes in expectations of the production system. Influential operational factors include availability of labor, cost for energy, logistics of transport, etc. Influential strategic factors result from broader, regional issues such as environmental impact, product safety and consistency, and consumer demand. These are industry-wide concerns that have the effect of changing the production system in the long term. Global issues are becoming more influential on greenhouse production sustainability, and include less tangible issues such as social acceptance, political stability, quality of life benefits, and environmental stewardship. These offer much more complex challenges and are generally beyond the realm of engineering. However global issues do affect greenhouse engineering innovation. The most effective innovations in greenhouse engineering design, operations and management, will incorporate input from partnerships with the academic, private and public sectors of society. Furthermore, successful applications include, at least to some degree a multidisciplinary approach of the sciences, engineering and economics, while for ultimate success and sustainability, societal and political support must also be attained. For this overview of innovation in greenhouse engineering a list of influential factors, or "driving forces" affecting the development, application, evolution and acceptance of greenhouse systems have been described. The factors are similar for all greenhouse systems around the world, as they include the plant biology of the crop, the physical components of the structure and production system hardware, the management and logistics of labor and materials, and the mechanism of marketing the crop. Each greenhouse system, wherever located, must resolve similar problems for its specific application. The magnitude of the factors and their relative local importance are different for the specific sites. The design response will be introduced and related to the factors, as examples of innovation.