| 1. |
- Bergstrand, Kjell, et al.
(författare)
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Dynamics of nitrogen availability in pot grown crops with organic fertilization
- 2019
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Ingår i: Biological Agriculture & Horticulture. - : Informa UK Limited. - 0144-8765 .- 2165-0616. ; 35:3, s. 143-150
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Tidskriftsartikel (refereegranskat)abstract
- Pot grown herbs are often cultivated as certified organic products, and there is an increasing demand for organically certified ornamental plants. Supplying the required nutrients using organic fertilizers is a challenge with respect to matching the mineralization and thus the availability of dissolved nutrients in the growing medium with plant demand. In experiments, sweet basil and Pelargonium × hortorum were cultivated using two different organic fertilizer strategies and controlled-release mineral nutrients as control treatment. The two organic strategies were, i) blood meal + Baralith® Enslow (a plant-based organic fertilizer), and ii) poultry manure. The availability of dissolved nitrogen was monitored during the crop cycle by under-pressure lysimeter sampling. Plant development parameters were measured along with chlorophyll fluorescence and chlorophyll concentration of leaves. For both organic treatments, nitrate-N availability was low at the beginning of the experiment, whereas ammonium-N was high. During the experiment, ammonium availability decreased at the same time as nitrate availability increased after a few weeks and then declined again by the end of the experiment. The blood meal + Enslow treatment caused poor germination and slow growth in basil. Plant height and fresh weight was also affected by this treatment for basil but not for Pelargonium. Chlorophyll concentration was affected by treatment, with also visually detectable paler leaves in the treatment with poultry manure. There were no differences in chlorophyll fluorescence (Fv/Fm) between treatments, indicating that plants were not stressed in any of the treatments.
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| 2. |
- Bergstrand, Karl-Johan, et al.
(författare)
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Nulägesanalys trädgård
- 2018
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Rapport (populärvet., debatt m.m.)abstract
- Rapporten Nulägesanalys - trädgård har genomförts inom ramen för projektgruppen Insatsstyrka trädgård. Syftet med inventeringen har varit att ge svar på vem som jobbar med trädgårdsvetenskap, vilka forskargrupper och med vilka forskningsämnen, samt identifiera framtida arbetsfält inom ämnet trädgårdsvetenskap och därmed ge uppslag för framtida utveckling av forskningsfält, utbildning och samverkan. I detta ingår att kartlägga trädgårdsvetenskaplig forskning, utbildning och samverkan vid SLU. Nulägesanalysen förväntas därmed ge en grund för fortsatt strategiskt arbete med att utveckla ämnet trädgårdsvetenskap (Horticultural Science) utifrån inventerade resurser och förutsättningar.
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| 3. |
- Ahlman, Linnéa, 1987, et al.
(författare)
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Stress Detection Using Proximal Sensing of Chlorophyll Fluorescence on the Canopy Level
- 2021
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Ingår i: AgriEngineering. - : MDPI AG. - 2624-7402. ; 3:3, s. 648-668
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Tidskriftsartikel (refereegranskat)abstract
- Chlorophyll fluorescence is interesting for phenotyping applications as it is rich in biological information and can be measured remotely and non-destructively. There are several techniques for measuring and analysing this signal. However, the standard methods use rather extreme conditions, e.g., saturating light and dark adaption, which are difficult to accommodate in the field or in a greenhouse and, hence, limit their use for high-throughput phenotyping. In this article, we use a different approach, extracting plant health information from the dynamics of the chlorophyll fluorescence induced by a weak light excitation and no dark adaption, to classify plants as healthy or unhealthy. To evaluate the method, we scanned over a number of species (lettuce, lemon balm, tomato, basil, and strawberries) exposed to either abiotic stress (drought and salt) or biotic stress factors (root infection using Pythium ultimum and leaf infection using Powdery mildew Podosphaera aphanis ). Our conclusions are that, for abiotic stress, the proposed method was very successful, while, for powdery mildew, a method with spatial resolution would be desirable due to the nature of the infection, i.e., point-wise spread. Pythium infection on the roots is not visually detectable in the same way as powdery mildew; however, it affects the whole plant, making the method an interesting option for Pythium detection. However, further research is necessary to determine the limit of infection needed to detect the stress with the proposed method.
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| 4. |
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| 5. |
- Alsanius, Beatrix, et al.
(författare)
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Degradation of Pesticides in Nutrient Solution from Closed Hydroponic Systems
- 2014
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1034, s. 33-39
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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.
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| 6. |
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| 7. |
- Alsanius, Beatrix, et al.
(författare)
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Integrated greenhouse production in new light: prospects on improved LED-assisted biocontrol of foliar diseases
- 2020
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 293-296
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Horticultural greenhouse production in circumpolar regions (>60°N latitude) is dependent of artificial assimilation lighting, which is a common tool to improve plant performance and consequently profitability of ornamental crops and to secure production of greenhouse vegetables and berries all year round. The anticipated light technology shift in the greenhouse industry not only affects crop growth and development but also quality of the produce. It also influences the interactions with the associated microbiota, i.e., community structure and function as well as establishment, dispersal, survival and propagation of microbial pathogens and biocontrol agents. We present a novel ecological theory and principle based approach for integrated production of greenhouse crops, using improved LED-assisted biocontrol of foliar diseases.
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| 8. |
- Alsanius, Beatrix, et al.
(författare)
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Light and Microbial Lifestyle: The Impact of Light Quality on Plant-Microbe Interactions in Horticultural Production Systems-A Review
- 2019
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Ingår i: Horticulturae. - : MDPI AG. - 2311-7524. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Horticultural greenhouse production in circumpolar regions (>60 degrees N latitude), but also at lower latitudes, is dependent on artificial assimilation lighting to improve plant performance and the profitability of ornamental crops, and to secure production of greenhouse vegetables and berries all year round. In order to reduce energy consumption and energy costs, alternative technologies for lighting have been introduced, including light-emitting diodes (LED). This technology is also well-established within urban farming, especially plant factories. Different light technologies influence biotic and abiotic conditions in the plant environment. This review focuses on the impact of light quality on plant-microbe interactions, especially non-phototrophic organisms. Bacterial and fungal pathogens, biocontrol agents, and the phyllobiome are considered. Relevant molecular mechanisms regulating light-quality-related processes in bacteria are described and knowledge gaps are discussed with reference to ecological theories.
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| 9. |
- Alsanius, Beatrix, et al.
(författare)
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Nedbrytningsstudie av bekämpningsmedel i näringslösning
- 2012
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Ingår i: LTJ-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- I vattendrag i växthustäta områden har bekämpningsmedelsrester kunnat spåras. En trolig väg är att bekämpningsmedelsrester tar sig ur växthuset via dräneringslösningen. För slutna odlingssystem skulle det kunna innebära att bekämpningsmedel som rinner ner i odlingssubstratet, öppna uppsamlingskanaler av dräneringsvatten eller direkt in i näringslösningen inte – som förutsatt – bryts ner, utan förekommer i näringslösningen efter karenstidens slut. Bekämpningsmedel i en recirkulerande näringslösning kan endast försvinna genom kemisk eller biologisk nedbrytning. Vi testade i en inledande studie • om bekämpningsmedelsrester finns efter karenstidens slut och • hur snabbt de eventuellt kan brytas ner. Teldor WG 50 används mot gråmögel i tomatodling. Vi använde Teldor WG50 som modellsubstans (aktiv substans: fenhexamid) i en hundradelskoncentration av en vanlig sprutlösning. Undersökningen pågick under 21 dagar, dvs sju gånger längre än preparatets karenstid. Prover togs vid 6 tillfällen, nämligen 0, 1, 2, 4, 8 eller 21 dagar efter tillsats av substansen. Utöver detta följde vi halten av organiska ämnen, ledningstal och pH samt förekomsten av bakterier och svampar (levande celltal) i medier utan och med Teldor samt dynamiken av mikrobiella samhällen under inkubationen. Vi undersökte också om det fanns bakterier och svampar som kan växa till med Teldor som enda energikälla. Vi konstaterade att • halten fenhexamid inte förändrades under observationsperioden; • halten löst organiskt kol inte förändrades under observationsperioden; • ledningstalet och pH ökade något under observationsperioden; • levande celltal (CFU/ml) av bakterier och svampar varierade inte nämnvärt under observationsperioden; • levande celltal av fluorescerande pseudomonader ökade något under observationsperioden; • levande celltal av svampar påverkades signifikant då de odlades i medium med fenhexamid; • organismer från dräneringslösningen överlevde väl under de näringsfattiga betingelserna på vattenagar med tillsats av Teldor; • sammansättningen av mikrobiella samhällen i dräneringslösningen förändrades över tid i närvaro av Teldor. Vi drar slutsatsen att fenhexamid inte bryts ner i näringslösning under den tre dagar långa karenstiden, att rester av Teldor kan kvarstå under en lång tid i näringslösning och att mikroorganismer i dräneringslösningen inte bidrog till nedbrytningen av det tillsatta bekämpningsmedlet.
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| 10. |
- Alsanius, Beatrix, et al.
(författare)
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New challenges for organic greenhouse horticulture in Sweden
- 2020
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 1079-1084
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Swedish consumers buy increasing amounts of organic food. Also, the Swedish Government aspires to increase food sovereignty and volume of organic food stuff in public meals from 36 (2017) to 60% in 2030. There is a substantial mismatch between demand and the production of organic vegetables. Today, 4.9% of the total greenhouse area in Sweden is used for organic production. The majority of organic production of greenhouse vegetables in Sweden is performed in containers and confined beds. The approval of the revised European regulation for organic farming in 2018 reinforces production in natural soil, leads to dramatic changes for organic greenhouse horticulture in Sweden. Confined beds need to be phased out. Cultivation methods that conserve or increase organic matter in the soil should be used. Thus, soil bound systems using crop rotations and soil fertility maintaining activities need to be implemented. This corroborates with increased burden of soil borne diseases and lower yields. Such systems, well established in southern Europe, cannot be translated to northern European conditions, due to constraints in climate and day length, as well as constraints due to greenhouse construction (permanent construction). This presentation displays the challenges and consequences to meet the changed legislation.
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| 11. |
- Alsanius, Beatrix, et al.
(författare)
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Ornamental flowers in new light: Artificial lighting shapes the microbial phyllosphere community structure of greenhouse grown sunflowers (Helianthus annuus L.)
- 2017
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Ingår i: Scientia Horticulturae. - : Elsevier BV. - 0304-4238 .- 1879-1018. ; 216, s. 234-247
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Tidskriftsartikel (refereegranskat)abstract
- Artificial assimilation lighting is a common practice in greenhouse horticulture in the circumpolar region to compensate for natural low light conditions. To modulate plant architecture, regulate flowering of photoperiodic crops, increase plant performance per energy input and consequently profitability, light emitting diodes (LEDs) have been suggested as a powerful tool for ornamental growers in complementary or replacement of conventional lighting such as incandescent, fluorescent and high pressure sodium (HPS) lamps. As LED light differs from HPS lamps with regard to spectral output, light distribution as well as heat emission, the microclimate within the crop stand is affected. In two independent experiments conducted in fall and winter, we therefore compared the effect of two types of LED light (red 660 nm + blue 460 nm LED, 80:20 RB-LED; white LED, W-LED) with HPS lighting on ornamental sunflowers (Helianthus annuus cv. 'Teddy Bear'). Depending of the solar radiation (fall vs winter experiments), a same PPFD of 70-120 mu mol m(-2) s(-1) of artificial lighting (photoperiod of 16 h) was given at the top of the plants. Plant growth performance and biomass, leaf temperature, photobiological parameters (photosynthetic activity, stomatal conductance, chlorophyll fluorescence) as well as the leaf associated microbiome, assessed using culture dependent and independent methods on apical, directly exposed to the light treatments, and basal leaves, were studied. As expected, significant differences were obtained for plant related parameters between the two repetitions of the experiment due to difference in solar radiation. Light treatments influenced plant growth performance which was lower for all parameters in sunflowers exposed to LEDs than HPS. However, no differences were found with respect to photobiological parameters. Top leaf temperature was higher in the presence of HPS than LEDs, which explained the lower plant growth performance observed under LED regimes. Colony-forming units representing culturable fungi and fluorescent pseudomonads were higher on basal leaves than on apical ones, but did not vary with respect to light treatments. On the other hand, biodiversity estimated with respect to species abundance and evenness (Shannon-H index) and species richness (Chao1) revealed different patterns for the fungal and bacterial microbiome. Regardless of the leaf position, light treatments affected fungal species abundance and evenness, which was highest on leaves exposed to HPS, but not species richness. The fungal microbiome was more diverse on apical than on basal leaves. For the bacterial microbiome, biodiversity estimates differed between the repetitions. Interactions between leaf temperature and bacterial genera were found for several of the dominant genera in the sunflower phyllosphere (Pseudomonas, Staphylococcus, Enhydro bacter) while other decisive bacterial and fungal genera were correlated to photobiological parameters, e.g. Bradyrhizobium, Sphingomonas, Brevibatericum, Bacillus, Hypotrachyna, Aureobasidium. The use of "new light" in greenhouse ornamentals is not only a technological change modifying plant morphology and development, but also affects the microbial ecology on plant surfaces, implying consequences on plant protection issues and biological control strategies. (C) 2017 Elsevier B.V. All rights reserved.
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| 12. |
- Alsanius, Beatrix, et al.
(författare)
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Persistence of fenhexamid in the nutrient solution of a closed cropping system
- 2013
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Ingår i: Agricultural Water Management. - : Elsevier BV. - 0378-3774. ; 127, s. 25-30
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Tidskriftsartikel (refereegranskat)abstract
- There are concerns about emissions of plant protection products (PPP) from protected cultivations, including high-tech production systems. Modern high-tech greenhouse horticulture is performed in cropping systems with closed water and nutrient loops, so PPP residues are not leaked to the external environment, but are captured and may accumulate within the recycled greenhouse solution. In this pilot study, the botryticide fenhexamid (FEX; Teldor WG50®) was used as a model PPP and incubated (0.01 times the recommended concentration spray solution) in the colonized nutrient solution from a closed tomato production system in darkness at 20 ◦C. Samples were taken after 0 h, 24 h, 48 h, 96 h, 192 h and 504 h (0, 1, 2, 4, 8 and 21 days) of incubation to monitor FEX concentration, dissolved organic carbon content (DOC), electrical conductivity, pH and microbial dynamics. Culture-dependent (viable counts for general bacterial, fungal flora and fluorescent pseudomonads on stationary agar, with/without supplement of FEX) and independent (denatured gradient gel electrophoresis, PCR-DGGE) methods were used for microbial analyses. DOC and FEX concentration did not change during incubation, whereas pH and electrical conductivity increased significantly. Density of culturable fungi decreased from the start of incubation, while density of culturable bacteria declined in late incubation. Fluorescent pseudomonads declined in early incubation but increased significantly at later stages. Under nutrient-deprived conditions, density of culturable bacteria decreased during the course of incubation. Microbial community analysis by DGGE supported these findings. Differences between the density of culturable bacteria assessed on semi-selective media with and without FEX supplementation were low. However, addition of FEX to diluted malt extract agar negatively affected the density of culturable fungi.
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| 13. |
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| 14. |
- Alsanius, Beatrix, et al.
(författare)
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The Closed System Tool Box
- 2011
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 1133-1137
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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.
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| 15. |
- Alsanius, Beatrix, et al.
(författare)
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The power of light from a non-phototrophic perspective: a phyllosphere dilemma
- 2024
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Ingår i: Frontiers in Photobiology. - 2813-8228. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Plants and crop stands are considered holobionts, colonized by both autotrophic and by non-phototrophic heterotrophic microbiota. The dilemma in the exisiting body of studies is that the focus is primarily directed towards environmental specificties relevant for phototrophic organisms (predominantly plants), but does not take into account non-phototrophs. By definition, non-phototrophic heterotrophic bacteria do not use light as an energy source. Light energy and wavelength are rather used as a signal that can provoke shifts in both their metabolism and microbial lifestyle. Reaction and recovery time can vary between organisms and is dependent on the organism’s physiological stage. The length of the lighting event affects the energy an organism is exposed to. We argue that to obtain a deeper and more distinct understanding of light exposure (irradiance, exposure length), quantity (light intensity), and quality (wavelength/spectral distribution, bandwidth at full-width half-maximum) related mechanisms on non-phototrophic bacteria in the phyllosphere, the light environment needs to be further strictly characterized. This includes information on the actual energy hitting planktonic or sessile non-phototrophic bacteria resident on and inside plants aboveground. Mapping the light environment in ecosystems aids in unraveling light-phyllosphere interactions and strengthens their transdisciplinary character. This issue is fundamental in order to revisit and repeat others’ experimental approaches and findings but also to be able to translate findings into further action.
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| 16. |
- Asp, Håkan, et al.
(författare)
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Anaerobic digestate as peat substitute and fertiliser in pot production of basil
- 2022
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Ingår i: Biological Agriculture & Horticulture. - : Informa UK Limited. - 0144-8765 .- 2165-0616. ; 38, s. 247-257
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Tidskriftsartikel (refereegranskat)abstract
- The common use of peat as a growing medium for plant production is questioned due to the negative effects on the environment and climate. Therefore, it is of great importance to find substitutes for peat with similar positive properties that have made peat one of the most important substrates in the horticultural sector. Production of biogas from organic residues is a valuable process, producing both energy and a residue, anaerobic digestate (AD), with a high content of plant nutrients. In this study, peat was partly substituted with AD of plant material origin up to 80% in a growing substrate for basil (Ocimum basilicum). Germination, yield and plant nutrient content were measured as well as chemical and physical properties of the growing media. The results showed that with 50% substitution of peat the growth in the AD/peat mix gave the same yield as for the fertilised peat on its own. No toxic or deficiency symptoms could be seen in the 50% mix. The important physical properties of the substrate were similar in peat and AD/peat mixes. However, the water-holding capacity was slightly decreased when part of the peat was substituted.
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| 17. |
- Asp, Håkan, et al.
(författare)
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Biogödsel som näringskälla vid hydroponisk odling - nitrifiering och pH
- 2020
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Möjlighet att odla grönsaker i system som kan vara horisontella, vertikala eller i flera lager och bedrivas i källare och på tak har lett till ett ökande intresse för hydroponisk odling. I denna typ av odling tillförs växten näring genom en näringslösning som cirkulerar i systemet. I dagsläget är mycket av den hydroponiska odlingen baserad på mineralgödselmedel. Att ha möjlighet att i stället använda en recirkulerad näringskälla innebär en fördel ur miljöperspektiv. I detta faktablad beskrivs hur en recirkulerad näringskälla, biogödsel, ska hanteras för att fungera som näringslösning i hydroponisk odling.
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| 18. |
- Asp, Håkan, et al.
(författare)
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Circularity in practice: reusing restaurant waste for in-house vegetable production
- 2021
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Ingår i: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; , s. 281-286
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Konferensbidrag (refereegranskat)abstract
- Production of biogas is a common way to handle organic waste products and it provides not only energy but also an anaerobic digestate (AD) rich in plant nutrients. In order to create a close loop between food consumption and vegetable production this project was undertaken to see if food waste from a restaurant, could be used to produce a liquid fertilizer for lettuce production to the same restaurant. Growth experiments in a hydroponic set up were made with nitrified AD. The AD was tested as a hydroponic fertilizer at two dilution levels. In one trial the solution was also amended with mineral nutrients and all the trials were compared to a mineral nutrient control. Results indicate that it is possible to use the digestate as a fertilizer for lettuce, and that amendment with certain mineral nutrients enhances the growth. Plant concentrations of Na and Cl indicates that there might be a problem with toxicity but it was not clarified by these experiments.
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| 19. |
- Asp, Håkan, et al.
(författare)
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Development and Acclimatisation of Horticultural Plants Subjected to Narrow-Band Lighting
- 2014
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Ingår i: European Journal of Horticultural Science. - 1611-4426 .- 1611-4434. ; 79, s. 45-51
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Tidskriftsartikel (refereegranskat)abstract
- Light-emitting diodes (LED) allow narrow-band light to be easily obtained and can be used for narrow-band lighting in plant cultivation, with possible effects on plant growth and development. This study examined use of narrow-band lighting of different wavelengths in the cultivation of ornamental pot plant (Pelargonium and Petunia), tomato (Solanum lycopersicum) transplants and sunflower (Helianthus annuus), either as sole light source in growth chambers, or as end-of-day (EOD) treatment in a greenhouse environment. Biometric measurements on plant growth and measurements of photosynthesis and stomatal conductance showed that when Helianthus was grown exclusively in blue light, stem elongation was greater than when it was grown exclusively in yellow, red, green or white light. Similar results were obtained when blue light was supplied in EOD treatments for Petunia and Pelargonium and for tomato. However, stem elongation was also high when red light was given as EOD treatment to tomato, whereas green light gave the least elongated plants in these conditions. Biomass production was generally not affected by the different EOD treatments. For Helianthus plants grown solely in monochromatic light, plant biomass production was highest in red light. For Pelargonium, photosynthetic rate was highest in blue light. It was conduded that plant response to different wavelengths is species-dependent and that EOD treatment with narrow-band lighting might be useful for plant growth regulation.
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| 20. |
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| 21. |
- Asp, Håkan, et al.
(författare)
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Nutrient utilization and growth of tomato crops fertilized with solid anaerobic digestate
- 2024
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Ingår i: Scientia Horticulturae. - 0304-4238 .- 1879-1018. ; 329
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestate is a valuable resource for horticultural production, as it contains nutrients and fibers that can be used in plant growing medium. However, compared with hydroponic production based on mineral fertilizers, obtaining accurate nutrient supply at each stage of the growth cycle may be challenging. In an experiment using container-grown tomato crops, we evaluated different fertilization regimes with solid anaerobic digestate (SAD). Four different treatments were compared, two involving different proportions (19 % and 37 % by volume) of SADs in the peat-based growing medium, one treatment where growing medium with 37 % SAD was inoculated with active nitrifying bacteria, and one treatment where 15 % (v/v) of the peat in growing medium with 37 % SAD was replaced with sawdust to control nitrogen (N) availability during cultivation. A mineral-fertilized treatment (N-P-K 5–1-5) with approximately similar N amount as in the treatment with 37 % SAD was used as reference. Nutrient availability, nutrient uptake efficiency, crop performance (plant growth, biomass accumulation), and plant stress (chlorophyll fluorescence) were monitored during cultivation. The concentration of ammonium was initially high (190–416 mg/L substrate) in the growing media fertilized with anaerobic digestate, while the concentration of nitrate was low. Readily available ammonium concentration decreased rapidly during cultivation, to around 50 % after 10 days and to almost 100 % by the end of the cultivation. Available nitrate concentration was initially low (0–8 mg/L in the different treatments) and decreased to zero within a week, but increased slightly from day 40 of cultivation. Nutrient use efficiency was generally higher (15–50 % for different nutrients) in the treatment with 19 % digestate. Inclusion of sawdust in the growing medium decreased nutrient use efficiency by 30–50 %. Compared with the mineral-fertilizer reference, biomass production was lower in all treatments fertilized with digestate, with 37 % and 19 % SAD resulting in 62 % and 47 % of total biomass obtained in the reference, and similar reductions in yield of harvestable fruits. Chlorophyll fluorescence measurements indicated elevated plant stress in the treatments fertilized with SAD. Addition of sawdust or nitrifying bacteria did not help to control nitrogen availability during cultivation. Therefore, anaerobic digestate fertilizers need further optimization before they can be a competitive alternative to mineral fertilizers.
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| 22. |
- Asp, Håkan, et al.
(författare)
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Styr tillväxten med ljuset
- 2019
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Ingår i: LTV-fakultetens faktablad.
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Annan publikation (populärvet., debatt m.m.)abstract
- Ljuset påverkar växterna i stor utsträckning. Både mängden ljus, dagens längd (fotoperioden) samt ljusets kvalité (spektrala sammansättning) påverkar växternas utveckling på olika sätt. Traditionellt har en växthusodlare haft möjlighet att påverka ljusintensiteten (genom skuggning eller tillskotts-belysning) samt fotoperioden (genom dagförlängning eller mörkläggning). Numera är det också möjligt att påverka ljusets spektrala sammansättning genom att anända belysningssystem baserade på LED-teknik. Dessutom har det bli vit allt vanligare med fast installerade mörk-läggningsgardiner för dagslängdsreglering. Detta gör att de tekniska förutsättningarna har förbättrats så att tillväxtreglering med hjälp av ljuset idag är realistiskt som komplement eller alternativ till andra former av tillväxtreglering såsom kemisk retardering eller negativ DIF/Drop.
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| 23. |
- Bergstrand, Karl-Johan
(författare)
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Acclimatisation of greenhouse crops to differing light quality
- 2016
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Ingår i: Scientia Horticulturae. - : Elsevier BV. - 0304-4238 .- 1879-1018. ; 204, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- High-intensity discharge (HID) and light-emitting diode (LED) lights have been widely compared for use in greenhouse plant production but the results are contradictory. In order to obtain more data on the effects of different light sources on plant growth, growth chamber experiments with high pressure sodium (HPS) or LED light and one treatment with alternating HPS and LED light (three days each) were carried out using tomato and rose as model plants. The LED lamps used were composed of blue (B, peak emissions 402, 419, and 445 nm) and red/far red (R/FR, peaks in 663 and 737 nm) LEDs. Plant growth parameters were recorded, as were photosynthesis, chlorophyll fluorescence, chlorophyll content, leaf temperature, leaf spectral properties and light penetration into the canopy. In roses, stem elongation and leaf area were generally lower for plants grown under LED light while fresh and dry weight was unaffected by the lamp type. For tomato, plants grown in alternating LED and HPS lamps had lower fresh weight as compared with HPS. Specific photosynthetic capacity (A(max)) and maximum quantum yield of PSII (F-v/F-m) were higher in leaves developed under LED light than HPS. Leaf transmittance and reflectance were higher for leaves grown in HPS light, which also gave better penetration of light into the canopy. Plants subjected to alternating light regimes generally resembled LED treatment plants more than HPS plants. Leaf temperature was higher under HPS (0.9-1.3 degrees C) favouring plants growing in chambers with HPS light. Leaf temperature and the amount of blue light supplied were concluded to be key factors for plant performance.
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- Bergstrand, Karl-Johan
(författare)
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Approaches for mitigating the environmental impact of greenhouse horticulture
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Greenhouse horticulture creates environmental issues of different kinds. Use of energy for heating and lighting and pollution by pesticides and nutrients are major known problems, but impacts on the landscape and light emissions from supplementary lighting have also attracted attention. However, increased productivity and new technologies provide possibilities for reducing the impact of greenhouse horticulture on the surrounding environment. This thesis presents various approaches for moving greenhouse horticulture towards sustainability. Three main directions are examined: use of recirculating hydroponic systems and slow filters; use of biosurfactants to control root disease; and use of light-emitting diode (LED) technology to save energy and reduce the use of chemical growth retardants. Recirculating systems with slow filters functioned satisfactorily with respect to phytosanitary issues. The resident microflora in these systems possessed the ability to produce biosurfactants that were shown to control zoosporic pathogens. LED lighting proved useful for growth control of flowering plants. These three technologies represent good examples of measures to create the greenhouse of the future.
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