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Participation has been proposed to improve agricultural extension programmes in developing countries. This paper reports on experience with COCREATE, an approach to agricultural extension programmes that supports agricultural chain actors in self-directed learning in action research with smallholder farmers and local traders in Indonesia. This approach resulted in the changes in relation and task division between farmers and their local traders in the agricultural production and supply and chains, improved their market position and in new institutions.

Background.Revealing tacit knowledge often is seen as very valuable for organizations, although it is usually challenging to enunciate and share this type of knowledge.Methods.This study uses a participatory design and the application of a board gaming simulation as instruments to extract tacit knowledge. To illustrate this application, the gaming simulation is played with entrepreneurs from horticulture. Horticulture represents a complex social system where tacit knowledge plays a major role in the trade process. A participatory design process is used to explore whether the design and play of gaming simulations enable participants to explicate their tacit knowledge. Participants’ participation in designing the gaming simulation explicated that reconstructing reality was a prerequisite for their commitment.Results.The results from playing simulation sessions show that participants were able to: (1) narrow down the anecdotic behaviour to a few factors; (2) to structure these factors; (3) explore how these factors relate to trade barriers and (4) to explain which tactics are applied to foster trade.Conclusion.The educational value of this study is that it helped entrepreneurs in understanding complex real-life situations.

Supplemental material, sj-pdf-1-sag-10.1177_1046878120927048 for Do Gaming Simulations Substantiate That We Know More Than We Can Tell? by M. A. van Haaften, I. Lefter, H. Lukosch, O. van Kooten and F. Brazier in Simulation & Gaming

Translucency is one of the major problems in fresh-cut fruit. This phenomenon affects the use of tomato fruit by the fresh-cut industries. Techniques for measuring translucency are not readily available. As a consequence, the processes that are important in the development of translucency are little understood, let alone described in detail. The colour of produce depends only on the absorption of light by colouring compounds. Translucency does not change the amount of colouring agents in the product, but it does change its appearance by changing the scattering properties. As a consequence the appearance, which is the result of light absorption and scattering combined, is affected by both translucency and colour development. Consumers do buy or reject products based on total appearance. In the short life time of cut fruits, the development of colouring compounds apart from possible oxidation effects will not be very large. Understanding the development of translucency is therefore of major importance for the fresh-cut industry. The development of translucency was visually assessed in tomato slices, obtained from tomatoes at three stages of maturity (mature green, breaker stage and full red) and stored at 5°C. In a second experiment, tomato slices were stored at three temperatures (5, 9 and 13°C) to assess the effects of temperature. In both experiments, non-cut tomatoes were also assessed. The data of both experiments were analysed using a very simple exponential model based on a massive approximation of the mechanism involved. The more precursor is present, the higher the obtainable translucency will be. A model was developed based on this simplified mechanism, and used to analyse all data. The stage of development (maturity) was found to have a major effect on translucency development regulated by the amount of precursor. The rate constant, however, was the same. The temperature only had a minor effect on the rate constant with the same amount of precursor. Explained parts (R2adj) obtained for mean data were well over 97%, for the individual data the explained part was somewhat less.

Participation of local actors has shown to be of significant importance to the uptake of new approaches to agricultural initiatives in developing countries. This paper proposes a new approach to empower local chain actors to work together to understand their own and others’ challenges, to pursue common understanding of their situations and challenges, and to then co-create solutions. Reflection on each other’s position is crucial to this process, and is core to the participatory approach designed to this purpose. Agricultural chains are the focus of a case study in Indonesia involving both farmers and wholesalers in the chain. Results show that the approach has led to new forms of collaboration between farmers, and between farmers and wholesalers, increasing market potential.

Sustainable agricultural development (SAD) requires empowerment and engagement of all actors in the agricultural production and supply chain to enable change. This paper proposes a novel framework for Participatory Sustainable Agricultural Development (PSAD) that distinguishes four main classes of factors that influence participation in SAD: environmental, economic, social and governance-related. The factors in each of these classes are analysed in relation to their effect over time, on the basis of 49 SAD programmes reported in the literature. Findings show that the social factors of engagement and empowerment, not often addressed in existing SAD programmes, are of significant influence to effect over time, as are the environmental factors of food safety, and the economic factors of production and capacity development. As such this paper shows that in in addition to the well-acknowledged need for knowledge and skills related to food safety, production and capacity development, SAD programmes also need to address the social factors of engagement and empowerment to enable sustainable change over time for SAD through participation.

Introduction In case of clinical suspicion of triangular fibrocartilage complex (TFCC) injury, different imaging techniques are used. The aim of this study was to determine whether MRA is superior to MRI and whether 3.0 T is better than 1.5 T (expresses in sensitivity, specificity and accuracy) in detecting TFCC injury, using arthroscopy as the gold standard. Materials and methods The arthroscopic and MR findings of 150 patients who underwent arthroscopy for ulnar-sided wrist pain between January 2009 and November 2016 were retrospectively reviewed. Results MRA was slightly more accurate compared to conventional MRI, and 1.5 T was slightly more accurate than 3.0 T. 1.5 T wrist MRA had a sensitivity of 80%, a specificity of 100% and accuracy of 90%; 3.0 T wrist MRA 73, 100 and 86%, resp. Conventional 1.5 T wrist MRI had a sensitivity of 71%, a specificity of 75% and accuracy of 73%. For 3.0 T conventional MRI, this was 73, 67 and 70%, resp. Conclusions MRA seems slightly superior to conventional MRI, but one could question whether this difference in diagnostic accuracy outweighs the burden and risks of an invasive procedure for patients with its additional costs. Furthermore, we could not confirm the superiority of 3 T compared to 1.5 T.

It has been shown that the identification of many foods including vegetables based on flavour cues is often difficult. The effect of providing texture cues in addition to flavour cues on the identification of foods and the effect of providing taste cues only on the identification of foods have not been studied. The aim of this study was to assess the role of smell, taste, flavour and texture cues in the identification of ten vegetables commonly consumed in The Netherlands (broccoli, cauliflower, French bean, leek, bell pepper, carrot, cucumber, iceberg lettuce, onion and tomato). Subjects (n = 194) were randomly assigned to one of four test conditions which differed in the sensory cues available for vegetable identification: taste, smell (orthonasal), flavour (taste and smell) and flavour-texture (taste, smell and texture). Blindfolded subjects were asked to identify the vegetable from a list of 24 vegetables. Identification was the highest in the flavour-texture condition (87.5%). Identification was significantly lower in the flavour condition (62.8%). Identification was the lowest when only taste cues (38.3%) or only smell cues (39.4%) were provided. For four raw vegetables (carrot, cucumber, onion and tomato) providing texture cues in addition to flavour cues did not significantly change identification suggesting that flavour cues were sufficient to identify these vegetables. Identification frequency increased for all vegetables when perceived intensity of the smell, taste or flavour cue increased. We conclude that providing flavour cues (taste and smell) increases identification compared to only taste or only smell cues, combined flavour and texture cues are needed for the identification of many vegetables commonly consumed in The Netherlands.

For children it is important to consume enough vegetables to establish healthy dietary patterns. Taste acceptance is an important factor contributing to food choice and consumption. Sweetness and sourness enhancement can increase acceptance of specific foods in children. The aim of this study was to determine the effect of sweetness and sourness enhancement on acceptance of cucumber and green capsicum purees in 5-6-year-old children. Three concentrations of sucrose (2, 5 and 10%) and citric acid (0.05, 0.08 and 0.15%) were added to cucumber and green capsicum purees. Children (n = 70, 5.7 ± 0.5 yrs) assessed acceptance of the vegetable purees using a 5-point hedonic facial scale. Sweetness enhancement significantly increased acceptance of cucumber purees (5 and 10% sucrose) and green capsicum purees (2 and 10% sucrose) compared to unmodified purees. Sourness enhancement (0.05, 0.08 and 0.15% citric acid) did not significantly influence acceptance of cucumber and green capsicum purees compared to unmodified purees. Children differed in acceptance of vegetable purees with added sucrose and citric acid. Sweetness likers (cucumber 77.1%, green capsicum 58.6%) accepted sucrose concentrations better than sweetness non-likers in both vegetables. Sourness likers (cucumber 50.0%, green capsicum 44.3%) accepted medium and high concentrations of citric acid better than sourness non-likers in cucumber and all citric acid concentrations in green capsicum. We conclude that enhancement of sweetness increases acceptance of cucumber and green capsicum purees in most children whereas enhancement of sourness is better accepted by only a few children. This study highlights the challenge to get children to better accept vegetables, since only sweetness enhancement improved acceptance while addition of sucrose is undesirable. For a small subset of children enhancing sourness might be an alternative strategy to increase acceptance of vegetables.

Bitterness has been suggested to be the main reason for the limited palatability of several vegetables. Vegetable acceptance has been associated with preparation method. However, the taste intensity of a variety of vegetables prepared by differentmethods has not been studied yet. The objective of this study is to assess the intensity of the five basic tastes and fattiness of ten vegetables commonly consumed in the Netherlands prepared by different methods using the modified Spectrum method. Intensities of sweetness, sourness, bitterness, umami, saltiness and fattiness were assessed for ten vegetables (cauliflower, broccoli, leek, carrot, onion, red bell pepper, French beans, tomato, cucumber and iceberg lettuce) by a panel (n = 9) trained in a modified Spectrum method. Each vegetable was assessed prepared by different methods (raw, cooked, mashed and as a cold pressed juice). Spectrum based reference solutions were available with fixed reference points at 13.3 mm (R1), 33.3mm(R2) and 66.7mm(R3) for each tastemodality on a 100mmline scale. For saltiness, R1 and R3 differed (16.7 mm and 56.7 mm). Mean intensities of all taste modalities and fattiness for all vegetables were mostly below R1 (13.3 mm). Significant differences (p b 0.05) within vegetables between preparation methods were found. Sweetness was the most intensive taste, followed by sourness, bitterness, fattiness, umami and saltiness.In conclusion, all ten vegetables prepared by different methods showed low mean intensities of all taste modalities and fattiness. Preparation method affected taste and fattiness intensity and the effect differed by vegetable type.

The quantum efficiency of photosynthesis of leaves is wavelength dependent and peaks in red (620–670 nm). However when cucumber plants are raised under pure red light, leaf photosynthesis becomes severely impaired. This “red light syndrome” has been characterized before by a low Fv/Fm, unresponsive stomatal conductance (gs), and a low photosynthetic capacity (Amax). It is not known if the syndrome also occurs in fully developed leaves that are exposed to pure red light after reaching maturity and if initially injured leaves can recover from the syndrome. This study investigates the plasticity leaf photosynthetic apparatus after inducing or releasing the “red light syndrome” in leaves of young cucumber plants. The plants were grown under pure red (R) or mixed red/blue (RB; 70%R) LED light and subsequently exposed to RB (R/RB) and R (RB/R) light (100 μmol PPFD m−2 s−1, 16 h photoperiod) or kept at their initial growth spectrum (R/R) and (RB/RB). Acclimation of fully developed leaves was monitored with gas exchange and chlorophyll fluorescence (CF) over a period of 8–10 days after the shift. After switching to RB, R injured leaves recovered from photodamage within 4 days. Photosynthetic capacity (Amax) and gs partly recovered, but did not restrict the net CO2 assimilation rate at growth irradiance (A100), which increased to the same level as in healthy (RB/RB) leaves. After imposing injurious R to healthy mature leaves, they transiently developed signs of the red light-syndrome: a slightly decreased Fv/Fm and more severely reduced Amax and gs. However, A100 did not significantly decrease. CF quenching analysis revealed an potentially harmful increased quantum yield of non-regulated non-photochemical energy loss in PSII under R, which was higher in leaves that developed under R than in leaves that were exposed to R after reaching maturity. We conclude that exposure to pure red light is harmful to photosynthetic systems in both developing and developed leaves of cucumber, but the effect on CO2 assimilation rate and Fv/Fm is much more severe in developing leaves than in mature leaves at low growth irradiance. Chloroplasts of previously R light injured leaves can recover within a few days after releasing from R light, while stomatal conductance and other (partial) morphologically determined leaf factors do not completely acclimate.

Greenhouse horticulture is an intensive production system with a relatively low resource input per unit of output compared to open field agriculture. It is an essential means of production for large urban conglomerates that are abounding in the present century, while water and chemical resources are dwindling. It is however essential to link these production systems to a consortium of traders, logistic providers and retailers in order to obtain a competitive edge by delivering according to the con-sumers expectations. It will be shown that competition on price, with a concomitant decrease in quality, results in a diminishing market and a viscous circle of declining price and quality. While a strong emphasis on quality will enhance the market and prices will rise as long as a clear and discernable quality of the final product, as it reaches the consumer, is maintained. By doing longitudinal studies of quality development in batches of products it becomes possible to combine deterministic with stochastic models capable of predicting quality evolution throughout the entire production and supply chain. Several examples will be given of this technique and it will be shown that vertical transparency in the supply chain can augment the profit for all participants, while keeping the entire chain competitive in a fast evolving market. By combining predictive quality information with the proper logistic technol-ogy, what we call ‘Quality Controlled Logistics’, it becomes possible to optimize the quality of the separate batches by positioning them in the shelves for the consumers at the moment of optimal maturity. What is necessary are new non-destructive measuring techniques that can determine batch quality characteristics at the period of harvest, or even before that, combined with physiology based models to predict quality evolution from harvest time on. Several models have been developed up till now and examples of their application will be given

Broccoli combines high levels of vitamins, fibres and glucosinolates (GLS) with a low calorie count. GLS are precursors for the characteristic broccoli flavour and have anti-carcinogenic properties. This study describes the effect of controlled atmo¬sphere (CA) and temperature on GLS concentrations in broccoli. Data on GLS behaviour and gas exchange were gathered for broccoli heads that were stored at three temperatures and subjected to four levels of O2 and three levels of CO2. The GLS behaviour of three GLS (raphanin, GB and neo-GB) was examined that showed exponential decrease over time, possibly representing the GLS interaction with myrosinase. The most striking feature is the large variation in GLS concentrations at harvest. The propagation of the variation in GLS over time is clearly affected by CA and temperature. Variation in GLS concentrations over time at the same gas condi¬tions and temperature was interpreted with the moment of harvest as main cause of random variation. Assuming that this random variation is normally distributed, the exponential function over time can be transformed into a batch model that describes the changes of variation over time (Schouten et al., 2004, Hertog et al. 2004). The effect of the CA was modelled using the standard gas exchange model. This calibrated gas exchange model was then linked via the reaction rate constant to the batch model to create an integrated batch model. This integrated batch model was subsequently calibrated to describe the variation of the GLS as function of O2, CO2, time, tempera¬ture and the batch parameters (average biological age and standard deviation). The percentage variance accounted for was on average 85%. Considering that this modelling effort is based on destructive GLS measurements, this is a rather high value. All GLS species were retained by suitable (low O2, high CO2) gas conditions, but remarkably, raphanin was found to be less affected by temperature, indicating that CA storage and low temperature would both retain this GLS species to the same extent, while low temperature storage is a better option for e.g. neo-GB

As of January 1st 2005, a system of reduced checks for phytosanitary inspections of certain plants and plant products imported into the European Union (EU) is in place. Under this system, plants and plant products satisfying special criteria may be inspected with a reduced frequency. These criteria are based on EU-wide data on historical volumes of import and interceptions of harmful organisms in particular products. The objective of this paper is two-fold. Firstly, the paper analyses whether proportions of interceptions of harmful organisms associated with cut flowers imported into the Netherlands ? the largest EU importer of cut flowers ? support the application of reduced checks for certain genera and trades (commodity-exporting country combinations) of cut flowers. Secondly, the paper analyses how effective the reduced checks system is in minimizing the expected costs of introduction of harmful organisms in the EU. For that, a theoretically optimal system for allocating inspection effort to commodities is described. Using an illustrative example and stochastic simulations, the expected costs of introduction of harmful organisms under the theoretically optimal system and the current system of reduced checks are compared. Examination of interceptions of harmful organisms supports application of reduced checks for most genera and trades of cut flowers in the Netherlands. The results of stochastic simulations show that reduced checks may not minimize the expected costs of introduction of harmful organisms into the EU. Accounting for possible economic impacts of harmful organisms in determining the frequencies of reduced checks may help optimize the current system

'Generativity' and 'strength' are elusive concepts. They are in the daily vocabulary of growers, but objective determination and quantification is hard. Therefore they are avoided in science. The incorporation of 'generativity' and 'strength' into the vocabulary of science will increase the understandability of scientific results to growers, and open possibilities for applied research questions. Here we propose a multivariate approach. A tomato crop was monitored with observations that are common in tomato cultivation. The measurements included stem diameter, leaf length, length growth of the stem, harvested fruit weight and brix. A principal component analysis was performed on the plant observations to find out whether the principal components can be linked to the crop attributes 'generativity' and 'strength'. To create a difference in 'generativity' two different irrigation regimes and two different leaf pruning regimes were applied. This article presents a proof of principle. We demonstrate that a multivariate analysis can be used to visualize the crop condition in a way that is recognizable for growers. This opens the possibility for quantification of 'generativity' and 'strength'.

An absolute-sink-strength regulated crop growth model was developed to address the problem of sweet pepper synchronised yield oscillations (flushes). Yield oscillations in sweet pepper production are caused by crop physiology (fruit abortion at times of heavy fruit load per plant) and result in periodic oversupply at the market level, as synchronisation occurs within, but also between glasshouses, due to weather conditions. Smart growers may not only aim to maximise production yields, but also to desynchronise their temporal yield pattern from that of the market, in order to target higher prices during low supply periods. The parameters that growers can change are those concerning pruning, harvesting at a green marketable stage, and climate control, whereas breeders may adjust physiological constants. The model consists of three ordinary differential equations and two partial differential equations, with fruit dry weight as second independent variable. Both the number of fruits per square meter and the average ripeness of fruits with a particular weight are discretised into 40 weight classes. Sinks, from vegetative, fruit growth and maintenance draw on a common assimilate pool, eliminating the need for a relative-sink strength `top-down¿ partitioning approach. The vegetative biomass is considered as two parts, for growing and non-growing biomass respectively. The model arrives at plausible output values for known biological variables and simulates assimilate-dependent abortion and thus fruit set explicitly, although not yet fully validated. A bifurcation analysis is conducted to identify the regions in parameter space where either yield oscillations or a stable growth pattern occurs.

To investigate the changes in total antioxidant activity of fresh-cut tomato during storage, tomato fruits harvested at three different stages of maturity were cut into 7-mm thick slices and stored at 5 °C. Intact fruits were stored in the same conditions as a control. The antioxidant activity was evaluated as the capacity to scavenge the radical ABTS+ in both hydrophilic (HAA) and lipophilic (LAA) extracts. Cutting resulted in a decrease in the HAA compared to the control fruits and did not influence significantly the LAA. Changes in LAA during storage were described by a simple exponential model developing towards an asymptotic end value. The HAA also decreased exponentially in the beginning of the storage time but increased again afterwards. For both hydrophilic and lipophilic antioxidant activity the riper the fruit the higher was the antioxidant activity. Since no relevant interaction was found between time of storage and stage of maturity, the major factor determining the level of antioxidants in tomatoes seems to be the initial level of antioxidant activity at the moment of harvest. The levels of HAA did not differ significantly due to ripening during storage, while the LAA increased with ripening. These results indicate a potential effect of processing to decrease the antioxidant activity in vivo. This would represent a decrease in the value of cut tomatoes as a source of hydrophilic antioxidants in the diet compared with the fruit stored intact. In another experiment, realized at the same conditions, the total antioxidant activity was evaluated using a lipid peroxidation inhibition assay. Antioxidant activity could be measured in methanol extracts, but not in THF extracts. Aqueous extracts showed pro-oxidant activity. No effect of cutting or storage time was observed

Data generated in postharvest research is characterised by its large sources of biological variance. This variance generally obscures the behaviour of interest, complicating both the statistical and conceptual interpretation of the data. To be able to manage the postharvest chain, clear inside is required in the propagation of biological variance during postharvest. Recently, biological variance has gained interest within the postharvest community. To analyse experimental data taking into account biological variance several (statistical) modelling techniques have been applied by different authors. These vary from models that can be solved analytically to analyse the effect of experimental design parameters (e.g., mixed effects models), via hybrid techniques which combine analytical and numerical techniques, to pure numerical models for dynamic simulations based on differential equations (like the variance propagation algorithm). Each of these techniques has its own possibilities and limitations in terms of the type of variance that can be accounted for, their technical complexity, and their applicability to practical situations. The different techniques are suitable to different degrees to answer specific questions in specific settings. Using tomato colour as an example, the different techniques are applied and compared to highlight their strong and weak points in interpreting biological variance. The added value of these techniques are discussed within the framework of managing biological variance in the postharvest chain.

A generic program for mathematical model-supported innovation profiling in fresh food supply chains is presented. Building on top of a crop growth model, strategies to address the problem of sweet pepper yield oscillations (flushes) are analysed quantitatively from both isolated or combined perspectives of the chain players: plant breeders, horticultural growers and traders. Yield oscillations in sweet pepper production, caused by crop physiology, and presumably synchronized by weather conditions, result in periodic oversupply at the market level. Growers try to desynchronise their own temporal yield pattern from that of the market, in order to target higher prices during low supply periods. A complication is that the quality of fruit products, in terms of size and colour/ripeness, may be affected when altering growing practices such as pruning, harvest timing, and climate control. Upstream, breeders can change physiological constants. Downstream, post harvest storage may produce value by better price targeting. The IACCP approach is presented, and is based on systematic decomposition of income, profits, cost and revenues with help of a simulation model. Especially the decomposition of revenues into isolated effects of production yield, price targeting, and various quality characteristics such as fruit size and fruit ripeness/colour shows how synergies between innovation strategies of collaborating (or competing!) players within a supply chain are created (or destroyed). Although the model is not yet fully validated in detail, such simulations may well support discussions on collaborative innovation strategies and on prioritisation of the research agenda.

To investigate the changes in lycopene concentration of fresh-cut tomato during storage, tomato fruits at different stages of maturity were cut into 7 mm slices and stored at temperatures varying from 2°C to 16°C. To assess the effect of cutting, intact fruit were stored in an additional experiment at 5°C. Cutting did not change the accumulation of lycopene in fruit stored at 5°C, compared to intact fruit. The lycopene concentration of the tomato slices stored at different temperatures showed net increases of lycopene concentration for all maturity stages tested at temperatures of 8°C and higher. At lower temperatures no increases or small decreases were observed. The lycopene concentration was considered to be the net result of production and degradation of lycopene. Kinetic models for different pathways were tested. The reaction rate constant for lycopene formation at 8°C was estimated at 2.16 ± 0.24 . 10 -2 μg/mg.day. The estimated activation energy for the lycopene formation (92.4 ± 7.3 kJ/mol) indicates that this process is highly dependent on temperature. The degradation rate constant was estimated at 2.99 ± 0.61 . 10 -2 (l/day) and, over the temperature range studied, the degradation rate was not dependent on temperature.

This paper focuses on the critical success factors in entrepreneurial innovation, and the role of cooperation with chain partners, knowledge institutions and colleague firms in the Dutch glasshouse industry. This industry, typified by a large number of family-owned entrepreneurial firms, is generally acknowledged as one of the world leaders in horticultural production and trade. Not only are the auctions of Aalsmeer and Naaldwijk among the most important horticultural auctions in the world, but the knowledge of cultivation techniques is also highly developed in the Netherlands. In order to maintain its leading position and to compete successfully with low-cost countries, Dutch horticulture is constantly reinventing itself. If we take a closer look, however, we see that only a limited number (3%) of the Dutch glasshouse companies actually take the lead in innovation. Using expert advice, we selected the 74 most successful innovative companies to be included in this study, of which 44 companies were willing to participate. In 2004, all the participating companies were visited. In total 139 innovations were analysed, using a combination of half-structured in-depth interviews with the glasshouse entrepreneurs and a structured questionnaire based on 10-point Likert scales. The entrepreneurs were asked to fill out the questionnaire for their most and least successful innovations. As expected, more successful (87) than failed innovations (52) were reported. Our results show that the characteristics demonstrated by the innovative entrepreneurs are essential for success in innovation. The innovative entrepreneur has a strategic vision of how to serve the market and create value. Also, team communication was extremely important. Successful entrepreneurs maintain an open atmosphere and show real commitment to the innovation process. They are in contact with a diverse network of business relations to develop innovations. Intensifying the network relations, e.g. by clustering glasshouse companies, leads to more successful innovation. The more firms in the horticultural production chain were actively involved in the innovation process, the bigger the chances of success. This was especially true for firms downstream toward the market.

Tomato fruit (cultivar Belissimo) were harvested at three different stages of ripening, sliced and stored at at 2, 5, 8, 12 and 16 °C. Firmness was measured as the force necessary to cause a deformation of 3 mm, in the outer and the radial pericarp, daily or every two days, depending on the combination of stage of ripening and temperature. For constructing a model, firmness was considered to be built up by a variable part (e.g. pectin based firmness) that changes according to a first order reaction mechanism and a fixed part (e.g. cellulose or structure based firmness) that is invariable under the circumstances under study. The firmness of the tomato slices decreased exponentially during storage, with a reference rate constant of 0.0975 ± 0.0183 J/mol/K for the outer pericarp and 0.0712 ± 0.0328 J/mol/K for the radial pericarp and energy of activation of 87.5 and 94.8 kJ/mol, respectively for outer and radial pericarp. The parameters of the model were estimated using multiple variate non-linear regression analysis with time, temperature and stage of ripening of the fruit at harvest simultaneously as explanatory variables. To combine the information on firmness behaviour during the preharvest and the postharvest period at different temperatures, it was assumed that the process of firmness loss during ripening was the same whether the fruit ripened on the plant or off-vine. So, the initial firmness at the postharvest period depends on the time the tomatoes were allowed to ripen on the plant (stage of ripening). The statistical analysis of the mean values of firmness provided a percentage variance which accounted for 92% and 72% for outer and radial pericarp, respectively. Using a fundamental approach to build the reported model and using all available data and information made it possible to describe and simulate the firmness behaviour of tomato slices as a function of the stage of ripening and the applied storage temperature.

Background: In three cases of chronic scrotal lymphedema, histological and immunohistochemical changes were observed that were strikingly similar to an exceedingly rare lesion reported previously under the name of acquired smooth-muscle hamartoma (ASMH) of the scrotum. The clinical context indicated that the cases were reactive rather than hamartomatous in nature. Materials and methods: The histological and immunohistochemical findings of the three cases were compared to macroscopically normal scrotal specimens obtained during sex reassignment surgery in seven male-to-female transsexuals. Results: Compared to the seven controls, the three cases of chronic scrotal edema revealed a marked increase of dartos smooth-muscle tissue and of connective tissue of the scrotal skin and underlying soft tissues. Still, even the normal amount of scrotal smooth-muscle tissue may easily be misinterpreted as smooth-muscle hyperplasia. Conclusions: Chronic scrotal lymphedema may induce hyperplasia of the dartos muscle, resulting in a histological appearance previously described as ASMH. This indicates that ASMH may not always represent a later onset of abnormality similar to congenital smooth-muscle hamartoma but, rather, may constitute a histological simulator.

With the present developments in CA technology it becomes possible to fine tune the storage conditions to the specific needs of the product. This generates the need to know the exact quality conditions of the product before storage starts. By measuring the initial quality we can determine these conditions optimally. At present the most likely candidates to assess the initial quality with fast and non-destructive measurements are colour, chlorophyll fluorescence, and maybe NIR spectroscopy. Two examples are presented where initial colour measurements on all products in a batch can be shown to be indicative for the keeping quality of that batch. The first example focuses on how initial colour measurements using a 3CCD video camera can be utilised to predict the keeping quality of a batch of cucumbers where colour itself is regarded as the most important quality attribute. The second example focuses on how colour measurements can be used to predict the keeping quality of a batch of strawberries where the ability to suppress a Botrytis cinerea infection is the most important quality attribute. Furthermore, attention is given to the use of modulated chlorophyll fluorescence imaging as a possible initial quality indicator for rose leafy stem cuttings. The level of inhomogeneity in the quantum yield of photochmistry od PSII of leaves of rose cuttings may be an indictor of the capability of the cutting to recover from severance, and to form roots and generate regrowth

In many plant species, including chrysanthemum, a strong positive correlation between internode length and DIF [difference between day (DT) and night (NT) temperature] has been observed. However, Langton and Cockshull (1997. Scientia Horticulturae 69: 229-237) reported no such relationship and showed that absolute DT and NT explained internode length rather than DIF. To investigate these conflicting results and to clarify the validity of the DIF concept, cut chrysanthemums (Chrysanthemum 'Reagan Improved') were grown in growth chambers at all 16 combinations of four DT and four NT (16, 20, 24 and 28 degrees C) with a 12 h day length. Length of internode 10, number of internodes and stem length were measured on days 5, 10, 17, 22 and 27 after starting the temperature treatments. Internode length on day 10 showed a positive linear relationship with DIF (R2 = 0.64). However, when internodes had reached their final length in all treatments (day 27), a much stronger positive linear relation was observed (R2 = 0.81). A model to predict final internode length was developed based on the absolute DT and NT responses: both responses were optimum curves and no significant interaction between DT and NT occurred [final internode length (mm) = -32.23 + 3.56DT + 1.08NT - 0.0687DT2 - 0.0371NT2; R2 = 0.91, where TD is day temperature and TN is night temperature]. It is shown that DIF can predict final internode length only within a temperature range where effects of DT and NT are equal in magnitude and opposite in sign (18-24 degrees C). Internode appearance rate, as well as stem length formed during the experiment, showed an optimum response to DT.

Flower size and number of flowers per plant are important external quality aspects in cut chrysanthemum. The present work is conducted in a glasshouse and aims at investigating how these quality aspects can be predicted. To evaluate individual flower size, different levels of supplementary lighting (control and assimilation light), plant density (32, 48 and 64 plants m-2) and lateral flower bud removal (leaving 1 flower, 4 flowers and control) were applied. To analyse the effect of assimilate supply on number of flowers per plant, three light intensities (no shade control, 65␕ight, and 45␕ight) where combined with three plant densities (32, 64, and 80 plants m-2). Individual flower size was negatively influenced by competition for assimilates in the treatments with a fixed number of flowers per plant (1 or 4 flowers). In such treatments, plants grown under no supplementary assimilation light, higher plant density, or with higher number of flowers per plant resulted in significantly lower individual flower dry mass and area. However, when no lateral flower buds were removed (control), higher assimilate supply resulted in more flowers rather than in larger flowers. Number of flowers per plant (including flower buds) showed a positive linear increase with total dry mass per plant. The combination of 32 plants m-2 and no shade resulted in the highest number of flowers per plant (33 flowers) in contrast with 80 plants m-2 and 45␕ight intensity (only 9 flowers).

Post-harvest life of strawberries is largely limited by Botrytis cinerea infection. It is assumed that there are two factors influencing the batch keeping quality: the botrytis pressure and the resistance of the strawberry against infection. The latter factor will be discussed here. A model is presented that describes the development of red colour and anti-fungal function of individual strawberries over time. The model was fitted to colour data from strawberries batches from the same growing conditions stored per batch at 5, 10 or 16 °C after harvest. Batches are considered to be all strawberries from one harvest. Spoilage per batch was recorded during storage. The fitted initial spoilage per batch was found to relate to the fitted amount of precursor of both the colour and the anti-fungal compounds. Batch keeping quality could be predicted from the initial batch colour distributions. An explanation for the predictive ability of the model without having to use a term describing the pH is presented from pigment HPLC measurements.

The prediction of the keeping quality for a cucumber, the time the colour remains acceptable, is until now not possible because of the unknown stage of maturity of the fruit. This is a fundamental problem common to all products that have a decrease of the limiting quality attribute according to the autocatalytic mechanism. For individual cucumbers this problem remains unsolved, but on a batch level an approach to obtain the stage of maturity of a batch is described. The stage of maturity of a batch of cucumbers can be obtained by observing the skewness of the colour distribution. This is demonstrated for four batches differing in growing conditions. The colour distributions obtained from high nutrient density treatments indicate an early stage of maturity because of the typical skewness. The approach to predict the stage of maturity from colour distributions was extended to predict the batch keeping quality, the number of days for which 95% of a batch has an acceptable colour. For four growing conditions the batch keeping quality for cucumbers was calculated by fitting colour data to a model that allows for biological variation between cucumbers. The hypothesis is that characterisation of the colour distribution provides sufficient information to specify the batch keeping quality. This is under further investigation.

The influence of manure and diammonium phosphate (DAP) mineral fertilizer on germination, leaf nitrogen content, nitrate accumulation and yield of vegetable amaranth (Amaranthus hypochondriacus) was investigated. Field trials were set up at the University of Nairobi Field Station at the Upper Kabete Campus during the long rains of March–May in 2007 and 2008. Trials were laid out as complete randomized block design with four fertilization treatments: 20, 40, and 60 kg nitrogen (N) ha-1 supplied by DAP (18:46:0), 40 kg N ha-1 supplied by cattle manure and an unfertilized control variant. The vegetables were harvested at three maturity stages at 6, 7, and 8 weeks after planting. Results indicated that there were significant differences between treatments in germination percentage, leaf nitrogen content, nitrate accumulation and vegetable yield. Plants that received manure had a higher germination percentage than those that received the same amount of N supplied by the chemical fertilizer DAP. The yields generally increased from week 6 to week 8. The highest yield was recorded in plots receiving 40 kg N ha-1 from DAP at eight weeks after planting. Plots that were supplied with manure recorded the lowest yield when compared to the fertilizer treated plots at all rates. Leaf nitrogen content increased with increasing rate of N but only when N was supplied by DAP fertilizer. The leaf nitrogen content decreased with increasing age of the plants. The leaf nitrate content increased with increase in DAP application rate. Results indicate that manure application produced quality vegetables in terms of low nitrate levels, but leaf nitrogen and vegetable yields were low. DAP application effected higher yields, but the vegetables had high though acceptable nitrate levels

Semi-closed greenhouses have been developed in which window ventilation is minimized due to active cooling, enabling enhanced CO2 concentrations at high irradiance. Cooled and dehumidified air is blown into the greenhouse from below or above the canopy. Cooling below the canopy may induce vertical temperature gradients along the length of the plants. Our first aim was to analyze the effect of the positioning of the inlet of cooled and dehumidified air on the magnitudes of vertical temperature and VPD gradients in the semi-closed greenhouses. The second aim was to investigate the effects of vertical temperature gradients on assimilate production, partitioning, and fruit growth. Tomato crops were grown year-round in four semi-closed greenhouses with cooled and dehumidified air blown into the greenhouses from below or above the crop. Cooling below the canopy induced vertical temperature and VPD gradients. The temperature at the top of the canopy was over 5°C higher than at the bottom, when outside solar radiation was high (solar radiation >250 J cm-2 h-1). Total dry matter production was not affected by the location of the cooling (4.64 and 4.80 kg m-2 with cooling from above and from below, respectively). Percentage dry matter partitioning to the fruits was 74% in both treatments. Average over the whole growing season the fresh fruit weight of the harvested fruits was not affected by the location of cooling (118 vs 112 g fruit-1). However, during summer period the average fresh fruit weight of the harvested fruits in the greenhouse with cooling from below was higher than in the greenhouse with cooling from above (124 vs 115 g fruit-1)

Western-European consumers have become demanding on product availability in retail outlets and vegetable attributes such as quality, integrity, safety. When (re)designing vegetable supply chain networks one has to take these demands into consideration, next to traditional efficiency and responsiveness requirements. In post¬harvest research, much attention has been paid to quality decay modelling and the development of Time-Temperature Indicators to individually monitor the temperature conditions of vegetables throughout distribution. This paper discusses opportunities to use time-dependent product quality information in supply chain/logistics decision making to improve the design of vegetable supply chain networks. If product quality in each step of the supply chain can be predicted, product flows based on availability predictions can be controlled and better chain designs can be established. A case is presented to illustrate the value of this innovative concept of Quality Controlled Logistics through a Dutch tomato chain.

Cucumber fruits (Cucumis sativus L. cv. Jessica) and green bell peppers (Capsicum annuum L. cvs. Lokas and Medeo) were stored at different temperatures ranging from 2 to 12°C. After three different storage periods, fruits from each temperature were transferred to 20°C for 7 d to allow for the development of visual symptoms of chilling injury (CI). During storage, the photochemical quantum yield of photosystem II (PSII) in peel tissue adapted to darkness, was calculated from measurements of pulse-amplitude-modulated chlorophyll fluorescence. The decrease in PSII quantum yield during storage at low temperatures in darkness can be described as a temperature-dependent inhibition of an enzyme according to Arrhenius, assuming a negative activation energy. By comparison with the radical-scavenger measurements of Hariyadi and Parkin (1991, Postharvest Biol. Techn. 1, 33–45) it is postulated that the time and temperature dependence of the quantum yield parallels the diminution of radical-scavenging activity at lower temperatures in cucumber and capsicum fruits. This is combined with an equation for the process of radical scavenging itself and an equation for the auto-catalytic radical-producing lipid peroxidation reaction. These three basic processes lead to both a static and a dynamic model for the occurrence of chilling injury in low-temperature-sensitive plant tissue. A statistical fit of the measured data using the static model leads to the estimates of the different activation energies and reaction rates with a high degree of accuracy. The estimated values are in accord with what one would expect on the basis of knowledge of the processes leading to chilling injury, and directly point to meaningful physico-chemical parameters.

A (semi-)closed greenhouse is a novel greenhouse with an active cooling system and temporary heat storage in an aquifer. Air is cooled, heated and dehumidified by air treatment units. Climate in (semi-)closed greenhouses differs from that of conventional open greenhouses. The aims of our research were first, to analyze the effect of active cooling on greenhouse climate, in terms of stability, gradient and average levels; second, to determine crop growth and production in closed and semi-closed greenhouses. An experiment with tomato crop was conducted from December 2007 until November 2008 in a closed greenhouse with 700 W m-2 cooling capacity, two semi-closed greenhouses with 350 and 150 W m-2 cooling capacity, respectively, and an open greenhouse. The higher the cooling capacity, the more independent the greenhouse climate was of the outside climate. As the cooling ducts were placed underneath the plants, cooling led to a remarkable vertical temperature gradient. Under sunny conditions temperature could be 5°C higher at the top than at the bottom of the canopy in the closed greenhouse. Cumulative production in the semi-closed greenhouses with 350 and 150 W m-2 cooling capacity were 10% (61 kg m-2) and 6% (59 kg m-2) higher than that in the open greenhouse (55 kg m-2), respectively. Cumulative production in the closed greenhouse was 14% higher than in the open greenhouse in week 29 after planting but at the end of the experiment the cumulative increase was only 4% due to botrytis. Model calculations showed that the production increase in the closed and semi-closed greenhouses was explained by higher CO2 concentration.

Broccoli combines high contents of vitamins, fibres and glucosinolates with a low calorie count and is sometimes referred to as the 'crown jewel of nutrition'. Colour is one of the most important quality attributes of broccoli, and yellowing due to senescence of broccoli florets is the main external quality problem in the broccoli supply chain. Controlled Atmosphere (CA) is a very effective method to maintain broccoli quality but the effects of CA on colour retention have not been studied extensively. The aim of this paper is to characterise the colour behaviour (measured by RGB colour image analysis) of broccoli as affected by CA and temperature. Data on colour behaviour and gas exchange were gathered for broccoli heads that were stored in containers at three temperatures and subjected to four levels of O 2 and three levels of CO 2 . Gas conditions and temperature have a clear effect on the colour change of broccoli especially at low O 2 in combination with high CO 2 . An integrated colour model is proposed that combines a colour model with a standard gas exchange model. The colour model is based on three differential equations describing the formation of (blue/green) chlorophyllide from the colourless precursor, the bidirectional conversion of chlorophyllide into (blue/green) chlorophyll, and the decay of chlorophyllide. During the first step of building the integrated model, gas exchange data were analysed simultaneously using multi response regression analysis. No fermentation was encountered for this batch of broccoli. During the second step it was found that only one of the reactions of the colour model, the decay of chlorophyllide, is affected by the gas conditions. In the final step, a multi-response approach was applied where gas exchange parameters were estimated using the gas exchange model, the colour parameters were estimated using the colour model with both models linked via the reaction rate constant affected by the gas conditions. Such a calibrated, integrated, model could be used as a tool for predicting colour change in the postharvest chain.

After a general introduction the relations between photosynthesis and chlorophyll fluorescence are explained. Subsequently a brief review is presented of earlier work in the field of remote sensing of chlorophyll fluorescence. The objective of the LIFT project is to investigate the possible use of laser induced fluorescence (LIF) for observing and monitoring vegetation stress due to air pollution. The instrumentation and set-up is briefly described and measuring results are presented. Changes in LIF and air pollution are found to be strongly related. The results can be explained in terms of ozone stress, possibly enhanced by SO⊂2⊂. These effects appear at low concentrations of ozone, i.e., below the concentration limit of 30 ppb, recommended in the Netherlands. It is concluded that this new remote sensing technique has a strong potential in the field of environmental mapping and monitoring.

Background A substantial number of children with an obstetric brachial plexus lesion (OBPL) will develop internal rotation adduction contractures of the shoulder, posterior humeral head subluxations and glenohumeral deformities. Their active shoulder function is generally limited and a recent study showed that their shoulder muscles were atrophic. This study focuses on the role of shoulder muscles in glenohumeral deformation and function. Methods This is a prospective study on 24 children with unilateral OBPL, who had internal rotation contractures of the shoulder (mean age 3.3 years, range 14.7 months to 7.3 years). Using MR imaging from both shoulders the following parameters were assessed: glenoid form, glenoscapular angle, subluxation of the humeral head, thickness and segmental volume of the subscapularis, infraspinatus and deltoid muscles. Shoulder function was assessed measuring passive external rotation of the shoulder and using the Mallet score for active function. Statistical tests used are t-tests, Spearman's rho, Pearsons r and logistic regression. Results The affected shoulders showed significantly reduced muscle sizes, increased glenoid retroversion and posterior subluxation. Mean muscle size compared to the normal side was: subscapularis 51%, infraspinatus 61% and deltoid 76%. Glenoid form was related to infraspinatus muscle atrophy. Subluxation was related to both infraspinatus and subscapularis atrophy. There was no relation between atrophy of muscles and passive external rotation. Muscle atrophy was not related to the Mallet score or its dimensions. Conclusion Muscle atrophy was more severe in the subscapularis muscle than in infraspinatus and deltoid. As the muscle ratios are not related to passive external rotation nor to active function of the shoulder, there must be other muscle properties influencing shoulder function.

When we look at the ornamental supply chain in the Netherlands as a Value Chain (Porter, 1998) it strikes us that most actors in the chain are obsessed by the product and have no idea how the value of these products is developed throughout the entire production and supply chain. Any value chain starts with the value a group of consumers attributes to the product. So it all starts with finding out what consumers want and then finding the most cost effective way of delivering that product with the desired attributes to these consumers. In the USA the South American producers expected to be able to compete with the local production by offering the product (cut flowers) at a lower price (Reid, 2002). In the first instance this worked very well and the local production virtually disappeared. However the quality of the imported product was a dismal failure and while imports surged, total flower consumption plummeted in the 90s. In the UK the retail chains such as Sainsbury’s and Tesco wanted to improve their ornamental categories. They invented the ‘Vase Life Guarantee’ and improved their quality considerably. This resulted in an increase in market share from 18 to 60% over 15 years, while the total flower consumption in the UK doubled in the past 15 years. A research will be shown on the response of stakeholders in the ornamental industry and consumers on the question whether they would see the ‘Vase Life Guarantee’ as a value addition in the supply chain. This research was done in the UK and the Netherlands (where no vase life guarantee was used explicitly in the retail) at the turn of the millennium. It clearly shows the difference between the judgements of the stakeholders versus the opinions of the consumers. If we want to create Value Added Chains in the ornamental industry it is about time to find out what the consumer really wants!

Agri-food supply chains are currently being confronted with many requirements regarding the product quality of their products. In recent years, concerns about food quality have risen among consumers as a result of several outbreaks of diseases and various environmental concerns. This has stimulated governments to introduce stricter regulations concerning food quality and safety issues. Besides governmental regulations, retailers also impose food quality requirements and standards on their supply chains. The goal of this paper is therefore to develop a method for analysing the impact of different quality assurance systems (QAS) requirements on the performance of the different stages of the supply chain and of the chain as a whole. Performance in this study includes components of efficiency, flexibility and responsiveness as well as food quality. This study uses perceptions of the Dutch tomato supply chain members in an effort to understand the perceived impact of different QAS requirements on the performance of the tomato supply chain. These perceptions are obtained using an adapted self-explicated method. Results indicate that some QAS requirements are perceived to have a positive impact on some supply chain members' performance, while they are perceived to have a negative impact on other supply chain members' performance. Overall, results reveal that all selected QAS requirements are perceived to have a positive impact on the performance of the supply chain, as a whole, although the total impact is relatively small. The performance measurement model developed in this study allows supply chain members to develop a clear view of the impact of QAS requirements. Also, the model makes it possible to make trade-offs between issues such as production costs and food safety, within the own firm as well as throughout the chain

The world's fresh accessible water situation is deteriorating at a dismal pace. Though the situation is already quite dramatic in Africa, the near future will bring us great problems in Asia as well, considering the pace at which the population is growing and the rise in water use per capita as the economy induces a raised demand. Agricultural consumption of fresh water is one of the main water uses world wide; however, it appears that protected cultivation of horticultural crops can alleviate the problem. Drip irrigation already reduces water use dramatically. However, novel high technological solutions in greenhouse production can lead the way to highly efficient water use production techniques. Adoption of more efficient water use techniques will contribute to sustainability, especially in highly populated urban areas. The novel Dutch technology of closed greenhouses could help develop water efficient production systems

Phytosanitary inspection of imported plants and flowers is a major means for preventing pest invasions through international trade, but in a majority of countries availability of resources prevents inspection of all imports. Prediction of the likelihood of pest infestation in imported shipments could help maximize the efficiency of inspection by targeting inspection on shipments with the highest likelihood of infestation. This paper applies a multinomial logistic (MNL) regression model to data on import inspections of ornamental plant commodities in the Netherlands from 1998 to 2001 to investigate whether it is possible to predict the probability that a shipment will be (i) accepted for import, (ii) rejected for import because of detected pests, or (iii) rejected due to other reasons. Four models were estimated: (i) an all-species model, including all plant imports (136,251 shipments) in the data set, (ii) a four-species model, including records on the four ornamental commodities that accounted for 28.9% of inspected and 49.5% of rejected shipments, and two models for single commodities with large import volumes and percentages of rejections, (iii) Dianthus (16.9% of inspected and 46.3% of rejected shipments), and (iv) Chrysanthemum (6.9 and 8.6%, respectively). All models were highly significant (P < 0.001). The models for Dianthus and Chrysanthemum and for the set of four ornamental commodities showed a better fit to data than the model for all ornamental commodities. Variables that characterized the imported shipment's region of origin, the shipment's size, the company that imported the shipment, and season and year of import, were significant in most of the estimated models. The combined results of this study suggest that the MNL model can be a useful tool for modeling the probability of rejecting imported commodities even with a small set of explanatory variables. The MNL model can be helpful in better targeting of resources for import inspection. The inspecting agencies could enable development of these models by appropriately recording inspection results.

Tobacco (Nicotiana tabacum L. cv. Samsun) plants inoculated with different strains of tobacco mosaic virus (TMV) inducing mosaic symptoms of widely varying severity were studied with in vivo chlorophyll fluorescence. This method was used to deduce photosynthetic electron transport efficiency in relation to symptom expression. The quantum yields of photosystem II (PS II) electron transport rate were significantly diminished in virus strains inducing loss of chlorophyll. The reduction in young mosaic-diseased leaves appeared to be due in part to a reduction in the fraction of open reaction centers, whereas in older leaves exhibiting less pronounced symptoms the reduction was mainly caused by a reduced efficiency of capture of excitation energy of open PS II reaction centers. Upon infection with any of the five virus strains PS II seemed to be irreversibly damaged in the inoculated leaves and the ones directly above, indicative of a possible increased susceptibility to photoinhibition in these leaves (Somersalo and Krause 1989) even when no symptoms were apparent. Symptom expression did not appear to be related to the influence of the virus on PS II activity, because the severest effects occurred in the inoculated leaves, which either remained symptomless or developed slight yellowing only. This study demonstrates the usefulness or modulated chlorophyll fluorescence measurements for the investigation of plant-virus interactions. It is particularly important when visual symptoms are absent.

LEDs may be a suitable light source for future use as assimilation lighting in protected greenhouse cultivation. LEDs have properties which offer advantages compared to other light sources, but which also raise specific research questions. The narrow band spectrum of LEDs enables manufacturers to produce LED based lightsources specifically suitable for photosynthesis and other horticulturally relevant plant properties. The low radiated heat also makes LEDs suitable for interlighting (i.e. lighting from within the canopy), for which high pressure sodium lamps are not suitable. However, when using LEDs, crops must be able to acclimate their photosynthetic functioning to narrow band lighting (NBL) to efficiently use this light. Also, daylight-adapted leaves must be able to re-acclimate to NBL if LEDs would be used for interlighting in a high-wire grown crop. If low photosynthesis rates in older, lower leaves of the crop are also due to leaf age, besides low light, interlighting would be less effective. For investigating the intrinsic effect of NBL, we used 9 different arrays comprised of a single LED type (peak wavelengths in the range 460-668 nm) at lightlimited irradiance (50 μmol m s). Spirodela polyrrhiza (Lemnaceae) was cultivated as its leaves can not change in distance or orientation towards the light source. This enabled us to compare the effects of the different light sources on parameters such as growth rate and photosynthetic pigment composition. In order to separate the effect of light intensity and leaf age on photosynthesis, tomato plants were grown horizontally, so that older leaves were not shaded by younger leaves. Re-acclimation of leaves to NBL was investigated by illuminating older leaves (low in the canopy) using different LED arrays in a high-wire grown tomato crop. The light-harvesting apparatus of Spirodela polyrrhiza acclimated to the different NBL regimes within 6 days. Leaf age proved to be an irrelevant factor for photosynthetic capacity (Pmax) of greenhouse grown tomato plants. Pmax of leaves at a low position in a high-wire grown tomato crop, with a low Pmax, did re-acclimate to the higher light intensities supplied by the supplemental NBL by progressively increasing their Pmax. However, as it took 14 days for Pmax to increase from 5.6 to 12.4 μmol CO2 m s, maintaining a continuously higher light level within the canopy would be more effective. INTRODUCTION Recently, light emitting diodes (LEDs) are subject of debate and research with respect to their possible future use for assimilation lighting in protected plant cultivation. At this moment LED lighting systems are too expensive and, more important, not efficient enough in terms of light output per Watt energy use, for large scale replacement of high pressure sodium (HPS) assimilation lamps for commercial greenhouse horticulture. However, the light-output efficiency of LEDs increased dramatically in recent years and production costs of LED systems aimed at the horticulture will decrease Proc. XXVII IHC-S6 High-Qual. Crop Prod. under Protect. Cultiv. Ed.-in-Chief: D.J. Cantliffe Acta Hort. 761, ISHS 2007 184 if demand would be sufficient. So as well as yielding new, fundamental knowledge on plant functioning, research on plant responses to LED lighting is highly relevant for the horticultural industry. Compared to other light sources used for plant production, LEDs have several properties which are potentially useful in relation to horticulture. LEDs emit light in a relatively narrow band spectrum, so they can be manufactured with a wavelength output tailored to the plant responses desired by growers. In order to enhance production, LED arrays with wavelengths favourable for photosynthesis would be desired. However, wavelengths influencing other plant properties such as morphology (blue light enhances compactness of plants) could be desirable for ornamental horticulture. Also, nutritional qualities of food crops may be influenced by the illumination spectrum used (e.g. antioxidant content; see e.g. Oelmuller and Mohr, 1985). At this moment, LEDs produce more heat than HPS lamps per Watt energy input, due to their lower energy/light conversion efficiency. However, the radiated heat of LEDs is very low compared to HPS lamps. This affords the opportunity to cool LED lighting systems and to reuse the (low caloric) heat for e.g. greenhouse heating. The low radiated heat output also makes LEDs suitable for interlighting, i.e. lighting inside the canopy, instead of or in combination with lighting above the canopy. Previous research on interlighting with HPS lamps (Hovi et al., 2004) indicated that interlighting may be more efficient than lighting from above. Interlighting could contribute to a more effective use of light by crops, as inside the canopy light levels are low, whereas above the canopy solar radiation already provides a considerable photosynthetic photon flux (PPF) during daytime. Especially in high-wire cultivated crops (e.g. tomato, cucumber and sweet pepper) with low photosynthesis rates lower in the canopy (see e.g. Xu et al., 1997), interlighting could offer a means to enhance production. The considerable percentage of radiated heat HPS lamps produce makes it impossible to situate HPS lamps close to the leaves of a crop. LEDs, on the other hand, with their low radiated heat output and overall lower temperature, can be in contact with the leaves. Though this may not be good for photosynthesis, the leaf will not be burned. LED light output is proportional to electric current through the device, so light intensity can be controlled in a versatile way. Therefore, the light output of LED lighting systems can be easily, rapidly and efficiently adjusted to match environmental conditions or production requirements within the greenhouse, such as natural light or the stage of the crop in the production cycle. Also if lighting systems would be used comprised of different LED types, emitting light with different spectra, light quality could be adjusted to the needs of the crop. For example, the use of near far red light (690 nm) was found to increase the leaf area of developing leaves (Goins, 2002), which would result in a more effective use of the available light in early stages of the production cycle. A socially relevant issue concerning assimilation lighting, called “light pollution” (public agitation and the disturbance of the natural rhythm of birds etc. due to lighted greenhouses at night) may be reduced by the replacement of HPS lamps by LEDS for assimilation lighting. The human eye is much more sensitive to yellow/orange light (the dominant colour of HPS lamps) than it is to red light (a potentially useful colour for LED lighting systems), so an equal amount of μmols PPF can give a very different perception of light intensity for the (human) eye (Fig. 1). Mammals and birds are also more sensitive to yellow/orange light than to red (Goldsmith, 2006). Furthermore, interlighting would reduce radiation loss from the greenhouse considerably due to increased light interception within the canopy. Nonetheless, several questions need to be addressed, concerning the possible use of LEDs for assimilation lighting. In order to grow crops efficiently using narrow band lighting (NBL), plants have to be able to acclimate their photosynthetic apparatus to NBL. Any imbalance in excitation of the photosystems I and II would lead to a loss of quantum yield for CO2 fixation in a leaf. Also, the dynamics of re-acclimation to NBL of daylightadapted leaves in a crop are essential for the efficiency of interlighting in a canopy. As the production time of a leaf in a high-wire grown crop is relatively short (approximately 8

Translucency is one of the major problems in fresh-cut fruit. This phenomenon seriously limits the use of fruit by the fresh-cut industries. Techniques for measuring translucency in this kind of product are not readily available. As a consequence, the processes that are important in the development of translucency are little understood, let alone described in detail. Based on techniques used in the industry of paint, paper and textiles, a measuring technique using video image analysis (VIA) involving light reflected from a sample placed in a double white and black background was used to assess the development of translucency and its interference with colour measurement in fresh-cut tomatoes. The effects of stage of maturity at the time of processing as well as the effect of storage temperature were studied in two separate experiments. The data were expressed as the average intensities per pixel of red (R), green (G) and blue (B) for the white and for the black background separately. A model was developed and presented that describes the change in the RGB values of tomatoes after cutting and during storage. In the model, the observed effects were considered to be the result of two processes namely changes in colour due to the production or degradation of pigments and development of translucency (i.e. physical water-soaking). Both processes resulted in changes in each one of the colour aspects R, G and B. Each colour aspect was considered to be built up by a variable part that changes according to a first order reaction mechanism and a fixed part that is invariable under the circumstances under study. The data obtained on both experiments were used to estimate the model parameters by multiple non-linear regression analysis using R, G and B as response variables and time, temperature, stage of maturity and background simultaneously as explaining variables. The change from opacity to translucency in the pericarp was the main change in appearance of tomato slices during refrigerated storage, for all stages of maturity and storage temperatures. Changes in colour were much less pronounced and related to a small increase in redness for all stages. The susceptibility to develop translucency was very much dependent on the maturity stage of the fruit at harvest and rather independent of temperature.

The world is getting smaller and smaller. All participants to this conference are the best example for that: we come from all over the world to discuss themes related to our daily food. Living in a small world has great advantages but also some drawbacks. We like to think we are ready for a major up scaling of our food supplies, but are we really? What do we need to answer to this challenge? How can we manage these large scale operations? Where do we get useful information? How do we discriminate useful information from misinformation?