| 1. |
- Alsanius, Beatrix, et al.
(författare)
-
Decontamination of Irrigation Water under Field Conditions: Preliminary Results
- 2011
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 922, s. 61-66
-
Konferensbidrag (refereegranskat)abstract
- Outbreaks of foodborne diseases (Norovirus, Salmonella spp., verotoxin producing E. coli, Campylobacter spp., Shigella spp.) related to fruit and vegetable have increased worldwide. Microbial hazards cause considerable and in some cases life-long suffering. Contamination may occur during the entire farm-to-fork continuum with irrigation water as one of the major vehicles for contamination. Therefore, the potential of photocatalytic oxidation water treatment (POWT) to improve inferior irrigation water quality was studied. A prototype of a photocatalytic unit was installed on an irrigation ramp at a commercial field site growing leafy vegetables. Water samples were collected at five distinct sites within the water pipe namely from (i) the irrigation pond, (ii) after coarse filtration, (iii) at the beginning of the field water pipe as well as (iv) before and (v) after treatment using photocatalysis at three occasions with three independent replicates at each event. The water samples were analyzed with respect to indicator organisms for water quality (heterotrophic microorganisms at 22 degrees C, total coliform bacteria, thermotolerant coliform bacteria, E. coli, intestinal enterococci, Salmonella spp.). After the photocatalytic treatment, the number of indicator organisms in the irrigation water decreased with respect to all monitored organisms. This was also observed for Salmonella spp. which was detected at a couple of incidents at the sampling sites prior to the photocatalytic unit. Indicator organisms in the treated water at the irrigation ramp were beyond the thresholds stipulated by guidelines for irrigation water quality in examples such as British Columbia in Canada and Germany.
|
|
| 2. |
- Alsanius, Beatrix, et al.
(författare)
-
Degradation of Pesticides in Nutrient Solution from Closed Hydroponic Systems
- 2014
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1034, s. 33-39
-
Konferensbidrag (refereegranskat)abstract
- To protect aquatic systems in the Baltic Sea area, zero eutrophication has been proclaimed as one of the Swedish environmental goals. Closed hydroponic systems are generally used today to meet standards on reduced release of excess nutrient-rich drainage water from horticulture. In recent years, concerns have been expressed about emissions of plant protection products (PPP) from indoor cultivation systems to aquatic environments in the vicinity of commercial greenhouses. Some of the active ingredient in pesticides applied to the crop can end up in the nutrient solution (i) after canopy application, through plant run-off and infiltration through the growing medium or into collecting gutters, or (ii) after direct administration to the nutrient solution. This study monitored the concentrations of three PPP (fenhexamid, FEX; pyrimethanil, PYR; imidacloprid, IMI) on six occasions over 21 days in colonised nutrient solution obtained from a closed cropping system for greenhouse tomatoes and incubated at 20°C in darkness. The experiment with FEX (added at 0.01 times the recommended spray concentration) was conducted as a full-scale experiment with six replicates and examined the dynamics of microbiota associated with the nutrient solu¬tion. Monitoring of PYR and IMI (added at 0.01 and 1 times the recommended spray concentration, respectively) comprised chemical analysis of the compound in single samples on six sampling occasions. The results indicate that all three PPP persisted for 21 days in the microbe-colonised nutrient solution under the experimental conditions used.
|
|
| 3. |
- Alsanius, Beatrix, et al.
(författare)
-
Microbiological Aspects on Irrigation Water Quality to Field Grown Vegetables
- 2010
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 852, s. 53-60
-
Konferensbidrag (refereegranskat)abstract
- Food safety is an increasing problem in relation to vegetables, regarding both ready-to-eat produces, such as leafy salad, spinach and fruit as well as frozen produces that have not been exposed to pasteurization prior to freezing. Contamination may occur during the entire production chain. However, in connection with invasive enteric pathogens, slurry, farmyard manure, sewage sludge and irrigation water have been highlighted as potential sources for pathogen dispersal. Especially, the dispersal of Escherichia coli O157:H7 and Salmonella spp. is a considerable threat. An increasing number of outbreaks have been reported. To prevent the spread of invasive enteric bacteria by irrigation water, water sources, such as well water as well as community potable water have been proposed. The present paper describes pathogens of significance that may be spread by irrigation water supplied to field vegetables and presents some recent results on survival of human pathogens in water, soil and on vegetables. The current status of standards for microbiological quality of irrigation water to fresh or minimally processed fruit and vegetables is discussed.
|
|
| 4. |
- Alsanius, Beatrix, et al.
(författare)
-
Preharvest Measures for Increased Biosafety of Field Grown Crops
- 2011
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 922, s. 269-276
-
Konferensbidrag (refereegranskat)abstract
- Outbreaks of foodborne diseases (Norovirus, Salmonella spp., verotoxin producing E. coli, Campylobacter spp., Shigella spp.) related to fruit and vegetable consumption have increased worldwide. Contamination may occur at any point during the entire farm-to-fork continuum with irrigation water and organic manure as major routes for contamination. Microbial related sickness causes considerable and in some cases life-long suffering and death as well as substantial economic losses. In this study we focused on irrigation water quality from surface water sources. The study was divided into three parts (i) monitoring of the hygienic status of five surface water sources in Southern Sweden, (ii) selection of indicator organisms for an irrigation water quality criteria and (iii) improvement of surface water with inferior microbial quality. Water samples were collected in both a long-and short-term study and analyzed with respect to process indicators and indicators for short term and long term fecal contamination as well as enteric pathogens. Considerable variation occurred between and within sampling incidents and between categories of surface water sources, with lake and creek water as the most hazardous sources. Salmonella spp. was identified repeatedly in four of five surface water sources. Due to high similarity, E. coli may serve as a sole parameter for short term contamination. This together with the analysis of intestinal enterococci and Salmonella spp., should be integrated in a future risk assessment of surface water. Photocatalytic water treatment reduced the number of all indicator organisms and therefore appears to be a potential tool to improve surface water of inferior quality.
|
|
| 5. |
- Alsanius, Beatrix, et al.
(författare)
-
Sustainable Greenhouse Systems - the Potential of Microorganisms
- 2011
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 155-167
-
Konferensbidrag (refereegranskat)abstract
- Due to the high input of means of production and productivity, environmental issues have been highlighted in horticulture for some years. They concern the impact of horticultural production systems on the environment in a narrow (i.e., occupational, crop) and broader (CO2 emission, nutrient leakage, chemical pollution) sense. In all production systems, multiple plant-microbial interactions occur. The resident microflora may be plant growth-enhancing, -neutral or -deleterious. Also microorganisms hazardous to the consumer may occur. To create sustainable horticultural cropping systems, irrespectively of the type of production management (organic or conventional/integrated production), microorganisms can enhance productivity by improved nutrient availability and crop health if their demands are optimized. Stimulatory growth responses encompass direct (i.e., production of plant hormones) or indirect (i.e., formation of compounds antagonizing plant pathogens, induced resistance) effects. Early reports indicate at the stimulatory effect of microorganisms on crop development (emergence, time of blossom) and yield. Their effect could be optimized when added as multiple strain treatments. In this context, organic carbon availability is an important factor. Organic compounds in sustainable greenhouse systems initially received negative attention as they were suspected as the causal agent for phytotoxic plant response. However, various recent studies could show the potential of microorganisms to degrade organic compounds in the nutrient solution of sustainable greenhouse cropping systems and consortia of efficient degraders of specific phenolic compounds were found to provoke higher biomass production in the presence of the phenolic compound. Other investigations indicate that the quality and quantity of organic compounds available is crucial for microbial metabolite production and thus level of growth promotion or antagonism. By habitat management, the preconditions for metabolite formation and crop response by introduced microorganisms or the indigenous microflora may be optimized. However, key mechanisms have to be identified in order to provoke the consistent formation of the appropriate metabolite at relevant sites within the growing system. Microbial markers may be used in order to predict the health status in closed cropping systems and to time microbial management in the cropping system.
|
|
| 6. |
- Alsanius, Beatrix, et al.
(författare)
-
The Closed System Tool Box
- 2011
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 1133-1137
-
Konferensbidrag (refereegranskat)abstract
- "Zero eutrophication" is one of the Swedish environmental goals in order to preserve the Baltic Sea area. Minimizing the release of nutrient enriched drainage water from greenhouse operations is one important action in this context; among these, closed growing systems are an internationally recognized way for minimized environmental impact. Greenhouse vegetables are the most nutrient intensive crops. Although most of these operations are situated in the environmentally most vulnerable areas in Southern Sweden, only about 25% of the tomato and almost none of the cucumber production have adopted this environmentally sound practice. Implementation of closed rowing systems inhabits obvious savings with respect to water and fertilizer costs. Growers explain their reluctance to use environmentally sound production technology by the risk for dissemination of root borne plant pathogens and the potential enrichment of organic compounds. These aspects have been studied scientifically in Sweden during the last 1.5 decades and key growers have been involved in a demonstration project to show the potential of this production technology. These actions have not reduced the barrier to invest. Therefore a closed system tool box has been extracted in collaboration between university staff and extension service for individual advice on a farm base. It is a three step approach towards use of closed systems, consisting of a general demonstration of choice of cropping technology, which actions have to be taken in order to be able to close the nutrient circuit in the growing system, risk assessment for dissemination of root born diseases and their prevention as well as crop individual management advices with respect to both plant disease and fertilization strategies.
|
|
| 7. |
- Bergstrand, Karl-Johan, et al.
(författare)
-
Development of Strategies for Hydroponic Cultivation in Vertical Systems
- 2014
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1034, s. 149-154
-
Konferensbidrag (refereegranskat)abstract
- Urban horticulture in vertical systems seems to be a feasible solution to supply a growing urban population with healthy, locally grown vegetables and to utilise waste products such as heat, CO2 and nutrients from cities. However, growing vegetables in such systems is somewhat different than in conventional planar greenhouse systems, with respect to climate and light interception. As part of a completely novel concept, a system for growing Asiatic vegetables (pak choi, mizuna) in a continuous, pumice-based hydroponic system was developed. Factors such as suitable nutrient solutions, cultivars and lighting strategies were evaluated with respect to their influence on production time and product quality, with the aim of producing 300 g pak choi plants within a 35 day cultivation period. The system comprised 0.75-L containers with pumice intended to be reused several times, with the seeds sown directly in the pumice. Nutrient solution was supplied via capillary uptake. Supplementary lighting (HPS/LED) was used to obtain a daily light integral of 12 mol m(-2). Biometric measurements were performed on the plants and climate parameters in the stand and nutrient uptake were monitored. It was concluded that the basic system design was feasible from a crop related perspective, with an overall cropping time of around 42 days.
|
|
| 8. |
- Bergstrand, Karl-Johan, et al.
(författare)
-
Growth and Photosynthesis of Ornamental Plants Cultivated under Different Light Sources
- 2012
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 956, s. 141-148
-
Konferensbidrag (refereegranskat)abstract
- New light sources for horticultural applications, intended to replace HPS lamps or fluorescent tubes, are currently being introduced in the market. Special attention is being devoted to LED technology, which permits optimisation of the spectral distribution of a light source. Consequently, LED lamps are generally assumed to be more efficient for driving photosynthesis that HPS lamps, for which much of the wavelength is outside the photosynthetic optimum range. In order to investigate the efficiency of LED technology in greenhouse applications, different types of LED lamps were compared with conventional HPS lamps in a series of experiments with Euphorbia pulcherrima. Cultivation took place in greenhouse conditions with natural daylight and 100 mu mol m(-2) s(-1) supplementary lighting, supplied by white LED, red/blue LED or conventional HPS lamps (control). Plant development and photosynthesis rate were monitored over 4 months. Shoot elongation was highest for plants grown under HPS lamps, as was fresh weight. Measurements of photosynthesis under the different light sources revealed a trend for higher photosynthesis when white LEDs were used. However, when photosynthesis was measured at different light intensities using red/blue LEDs, plants grown under HPS lamps had the highest photosynthesis. The air temperature in the canopy was lower when the light was supplied with LEDs than with HPS lamps, thus delaying development. We concluded that the quality of light supplied was a significant factor for plant development in greenhouse conditions with supplementary light. There was a lack of correlation between measured photosynthesis and biomass production.
|
|
| 9. |
- Bergstrand, Karl-Johan, et al.
(författare)
-
Prospects on LED Lighting for Growth Regulation and Energy Saving in Pot Plant Production
- 2011
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 893, s. 269-274
-
Konferensbidrag (refereegranskat)abstract
- Rapid development towards higher effects and lower costs makes Light Emitting Diodes (LEDs) highly interesting for assimilation- and photoperiod-regulating lighting in greenhouse pot plant production. LED lighting is energy efficient and can deliver monochromatic light. This study examined the possibilities for using monochromatic light from LEDs for growth regulation. Possible benefits for plant morphology and quality and in reducing the need for chemical growth regulation were screened in three pot plant species (Euphorbia, Kalanchoe and Chrysanthemum). Monochromatic LED light at different wavelengths was given before daybreak. Plant development was continuously measured and plant quality was assessed at the end of the experiment. Our results indicate that light of certain wavelengths supplied before dawn can have a beneficial influence on the quality of common commercial pot plants. The practice of LED lighting holds great prospects for greenhouse pot plant production.
|
|
| 10. |
- Bergstrand, Karl-Johan, et al.
(författare)
-
Recent Progresses on the Application of LEDs in the Horticultural Production
- 2012
-
Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 927, s. 529-534
-
Konferensbidrag (refereegranskat)abstract
- The use of Light Emitting Diode (LED) technology for horticultural lighting is becoming increasingly feasible from an economic point of view. Rapid development of the technology is continuously bringing cheaper and more efficient equipment to the market. The possible use of monochromatic LED light for assimilation support and growth regulation in ornamental pot plants was examined in a series of studies. Different wavelengths including polychromatic white light were employed either as sole light source or in combination with natural light in greenhouse conditions. Plant growth and development was strongly affected by the different treatments. White light and blue light were found to be the most efficient for plant growth. However, stem elongation was dramatically enhanced by blue light in certain circumstances.
|
|
