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10 solbærsorter ble plantet i et feltforsøk på NIBIO Apelsvoll i 2017, og vekst, avling, bladsykdommer, blomstring- og høstetidspunkt og innholdsstoff i bæra ble registrert i åra 2019-2022. Sortene ble i 2016 valgt ut som lovende enten til industriformål, eller til friskkonsum av ‘Sortsgruppe Ribes’ som består av representanter fra dyrking, planteproduksjon, rådgiving og forskning. Sortene/seleksjonen var: ‘Ben Tron’ (referansesort), ‘Ben Hope’, ‘Ben Tirran’, JHI 9163-5, ‘Augustus’, ‘Gjest’, ‘Joniniai’, ‘Almiai’, ‘Tihope’ og ‘Mortti’. Dato for blomstring og høstemodne bær, vinterskade, vokseform, bladsykdommer, plantevolum, avling, klase- og bærstørrelse, kartfall og bærkvalitet ble registrert årlig. Sortene ‘Ben Tron’, JHI 9163-5, ‘Augustus’ og ‘Mortti’ er valgt ut i samarbeid med NLR og dyrkere til å testes videre i storskalafelt for industriformål hos dyrkere. ‘Almiai’ blir testet videre i et dyrkingssystem (espalier) for friskkonsum-formål. Disse sortene har også et godt potensial for å dyrkes økologisk.

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High yields are needed for profitability under shielded strawberry production. June bearing strawberry cultivars require a short day (SD) period in order to initiate generative growth. Nitrogen availability going into the SD-period, as well as during the period, can affect the process. To increase the knowledge about optimized nitrogen fertilizing, an experiment was set up under controlled conditions. Strawberry plants of the cultivar ‘Sonata’ were grown under combinations of different levels of nitrogen to evaluate its effect on timing on growth, flowering time and the number of flowers produced. The result showed that the time for opening of the first flower, the interaction between the pre-SD nitrogen level and the nitrogen level applied during the SD had the highest impact, and that low levels pre-SD flowered earlier. The number of flowers produced was affected by both pre-SD and SD nitrogen level as well as its interactions. Low nitrogen levels throughout had low yield potential while when low pre-SD nitrogen level was followed by high levels during SD, the yield increased.

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The effect of steam thermotherapy on Botrytis spp. populations in strawberry transplants was evaluated. Tray plants rooted in 0.2 L peat plugs of seasonal flowering cvs. Falco, Sonsation, and Soprano, and everbearing cvs. Favori and Murano were pre-treated with steam at 37 °C for 1 h, followed by 1 h at ambient temperature and air humidity, and then 2 or 4 h steam treatment at 44 °C. Except for one cultivar with a slight reduction in yield, there were no negative effects on plant performance. Compared to untreated transplants, mean incidence of Botrytis on the five cultivars was reduced by 43 and 86% with the 2 and 4 h treatments, respectively. Within cultivars the reduction was significant in 2 and 3 experiments following the 2 and 4 h treatments, respectively. Sclerotia from four different isolates of Botrytis were subjected to treatment including 4 h of steam thermotherapy and subsequently tested for viability. Following 14 days of incubation, 90 to 100% (mean 97%) of treated sclerotia failed to produce mycelial growth compared with untreated sclerotia, which all germinated and produced mycelia. Botrytis isolates recovered from both treated and untreated strawberry transplants were tested for resistance to seven fungicides, including boscalid, fenhexamid, fludioxonil, fluopyram, pyraclostrobin, pyrimethanil and thiophanate-methyl. Multiple fungicide resistance was common; 35.5% of isolates were resistant to fungicides from at least three FRAC groups. Results indicate that steam thermotherapy treatment strongly reduces populations of Botrytis spp., including fungicide-resistant strains, in strawberry transplants with negligible negative impacts on the transplants.

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Little is known about the environmental control of growth and flower bud initiation (FBI) in commercial blackberries. We studied the processes in the cultivars ‘Lock Ness’, ’Ouachita’ and ‘Sweet Royalla’ at 12, 16 and 20 °C in a daylight phytotron under naturally decreasing autumn daylength at Ås, Norway (59°40′ N). Growth rate increased with increasing temperature but was much lower at all temperatures in the erect ‘Ouachita’ than in the trailing cultivars ‘Lock Ness’ and ‘Sweet Royalla’. In all cultivars, FBI occurred earliest at 16 °C, whereas little or no FBI took place in ‘Ouachita’ and ‘Lock Ness’ at 12 °C. Growth cessation was earliest at 16 °C where it occurred in early September in all cultivars, suggesting a critical daylength of approximately 14 h. At variance from earlier statements, FBI started in lateral buds situated several nodes below the apex and progressed in both acropetal and basipetal directions as previously reported for red raspberry. Winter chill at 0 °C enhanced flowering in spring in marginally induced plants of all cultivars except ‘Ouachita’ grown at 12 °C, which remained vegetative in spring. The results suggest that temperature is as important as daylength for FBI in biennial-fruiting blackberry, and that winter chilling may enhance flowering and yield potential in partially induced plants.

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There is an increased interest in the hydroponic production of strawberries in protected cultivation systems, and it is, therefore, urgent to develop new, more sustainable growing media alternatives. This study investigated the physical properties of wood fiber produced from Norway spruce (Picea abies (L.) H. Karst.) and peat:wood fiber substrate blends as well as the performance of the wood fiber in comparison to the industry standards, i.e., peat and coconut coir in the cultivation of hydroponic strawberry. Tray plants of the June-bearing strawberry (Fragaria × ananassa Duch.) cultivar ‘Malling Centenary’ were transplanted into five different growing media: a peat (80%) and perlite (20%) mixture, stand-alone (100%) coconut coir and three stand-alone (100%) Norway spruce wood fiber substrates (including coarse textured fibers with compact and loose packing density and compacted fine-textured fibers). Ripe strawberries were harvested and registered throughout the production season. The overall marketable yield was comparable across all the tested growing media; however, after 4 weeks of harvest, both coarse wood fiber and fine wood fiber showed better fruiting performance than the peat-perlite mixture. A trend for earlier berry maturation was observed for all wood fiber-based substrates. Plant parameters recorded after the end of production showed that plant height, number of leaves, and biomass production were higher in coarse wood fiber than in the peat-perlite mixture. Moreover, plants grown in wood fiber-based substrates had less unripe berries and flowers not harvested in comparison to both the peat and coir treatments.

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Cultivation of strawberries in greenhouses and polytunnels is increasing, and new sustainable growing media are needed to replace peat and coconut coir. This study investigated the effect of wood fiber and compost as growing media on hydroponically cultivated strawberries. Two experiments were conducted, where the everbearing cultivar ‘Murano’ was grown in mixtures of wood fiber and compost (Experiment 1) and the seasonal flowering cultivar ‘Malling Centenary’ was grown in mixtures of wood fiber and peat (Experiment 2). Additionally, in Experiment 2, the effect of adding start fertilizer was assessed. The yield potential of ‘Murano’ plants was maintained in all substrates compared to the coconut coir control. However, a mixture of 75% wood fiber and 25% compost produced the highest yield, suggesting that mixtures of nutritious materials with wood fiber may improve plant performance. The chemical composition of the berries was not affected by the substrate composition; however, berries from plants grown in the best performing blend had a lower firmness than those grown in coconut coir. ‘Malling Centenary’ plants produced higher yields in substrates enriched with start fertilizer. Generally, the productivity of ‘Malling Centenary’ plants was maintained in blends containing up to 75% of wood fiber mixture even without start fertilizer.

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This work aims to determine the effect of genotype x environment (GxE) interaction that influence blackcurrant (Ribes nigrum) fruit quality. We applied metabolomics-driven analysis on fruits from four cultivars grown in contrasting European-locations over two seasons. By integrating metabolomics and sensory analysis, we also defined specific metabolic signatures associated with consumer acceptance. Our results showed that rainfall is a crucial factor associated with accumulation of delphinidin- and cyanidin-3-O-glucoside, the two mayor blackcurrant pigments meanwhile temperature affects the main organic acid levels which can be decisive for fruit taste. Sensorial analysis showed that increases in terpenoid and acetate ester volatiles were strongly associated with higher appreciation score, while proacacipetalin, a cyanogenic-glycoside, was positively associated to bitter taste. Our results pave the way for the selection of high-quality cultivars and suitable production sites for blackcurrant cultivation.

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The morphogenetic changes of the bud meristem during floral initiation in gooseberry were examined by scanning electron microscopy. Six floral stages, similar to those reported for black currants, were identified. We also studied the environmental control of shoot growth and floral initiation of cvs. Mucurines, Pax and Xenia in two experiments in daylight phytotron compartments at 12, 18 and 24°C. Under natural daylength conditions at Ås, Norway (69°40’N), shoot growth started to decline by mid-August and ceased in early September. Cessation of growth was associated with floral initiation at 18 and 12°C, while at 24°C, only ‘Mucurines’ initiated floral primordia. Floral Stage 2 was reached by 3 September in ‘Mucurines’ and ‘Xenia’ at 18 and 12°C and nearly 2 weeks later in ‘Pax’. In a second experiment with controlled photoperiods, all cultivars ceased growing and initiated flowering in 10-h SD within 2–3 weeks, while in 20-h LD, growth continued for 8 weeks without floral initiation. Under 10-h SD conditions, all cultivars initiated flowers also at 24°C. Flowering performance in the following spring verified these results. We conclude that gooseberry is an obligatory SD plant with a critical photoperiod of 15–16 h.

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Environmental conditions during plant raising determine the yield potential of everbearing strawberries. We studied the effect of three rooting dates in the cultivars ‘Favori’ and ‘Murano’ in a greenhouse with 18 ℃ and 20-h long day and under outdoor conditions in Norway. The highest yield of 1.350 g/plant was obtained in ‘Favori’ plants rooted on 1 August and raised outdoors, being at level with ‘Favori’ plants produced in The Netherlands. High yields were mainly related to fruit size and less to fruit number, and determined by a complex three-factor interaction of rooting date, raising environment, and cultivar. The seasonal pattern of fruit flushes and off periods varied significantly between cultivars and treatments. The large first flush of high yielding ‘Favori’ plants was associated with a long off period, while the small first flush in ‘Murano’ resulted in a more even crop distribution. Earliness of ripening and berry harvest was superior in ‘Favori’, which had a larger share of its crop during the first half-season. We conclude that it is possible by choosing the right rooting date and raising environment to produce plants with the same high quality and yield potential under the cool Nordic conditions as those currently produced in Central Europe.

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Horticultural production systems are under pressure to find environmentally friendly growing media. Peat is currently the most popular substrate for fresh potted herbs production; however, this raw material is not sustainable due to the large amount of greenhouse gases released during its harvesting. Therefore, the goal of the study was to test the performance of various commercial wood fiber products and compare them with peat and coir in an ebb-and-flow production system with basil (Ocimum basilicum L. 'Marian'). Basil plants were grown in three different pot sizes (6, 9 and 12 cm in diameter) and under various fertigation regimes (EC 1, 2 and 3). Height and biomass of the plants were recorded when the best performing plants reached the commercial stage. The tallest plants and greatest biomass were produced in peat and coir, however, the results confirm that wood fiber can be a promising substrate alternative. Further research is needed to study, among others topics, how to modify some properties of wood fibers to fulfil their potential as a replacement for non-sustainable growing media in production of herbs in pots.

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It is not known to what degree growth and fruit yield are source-limited in everbearing strawberry plants. The growth and yield performance effect of bi-weekly removal of all runners and/or one or two leaves during the cropping season of tunnel-grown ‘Favori’ everbearing strawberry plants was determined. Plants were grown on a table-top system in an open plastic tunnel under natural light conditions in Norway from May to October. Removal of runners and leaves was bi-weekly from 5 June until 25 September. Fruits were harvested from 5 July to 7 October. Bi-weekly runner removal increased total and marketable yield and number and size of fruits, while increasing leaf thinning had the opposite effects. However, none of the treatments affected the fruit number and yield of the first fruiting flush. The treatments did not affect realization of the yield potential of the plants at planting, whereas the continued floral initiation and fruit growth were enhanced by runner removal. Increasing leaf thinning had the opposite effects. Both floral initiation and fruit growth in heavily flowering and fruiting everbearing strawberry are source-limited owing to the high fruit/leaf ratio of such plants.

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The growing interest in using everbearing (EB) strawberry cultivars to extend the cultivation period has faced some challenges. These include poor runner production due to its perpetual flowering nature; irregular flowering behavior and extended periods of high temperature have caused floral inhibition and reduced yield. As flowering is an interplay between temperature and photoperiod, it is important to investigate the effects of this interaction on the cultivation. Therefore, this study used meristem dissection as a tool to study the effect of temperature and photoperiod on meristem development. Tray plants of two EB strawberry cultivars ‘Florentina’ and ‘Favori’ were grown at 20 °C, 25 °C, and 30 °C under short day (SD) conditions, and subsequently at 20 °C under long day (LD) conditions. The meristem development was analysed every 6 weeks for a 15-week period in SD and for 14 weeks in LD conditions using meristem dissection. The plants showed similar flowering patterns to previously studied everbearing cultivars, which was qualitative LD plants at high temperatures and quantitative LD plants at lower temperatures. Our results show that meristem dissection can be used to determine the temperature and photoperiodic effect on meristem development, and for the occurrence of cropping peaks, and can therefore be used to decide the environmental input and to evaluate yield potential.

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There is little knowledge about photosynthesis in everbearing strawberry cultivars. We therefore grew three everbearing strawberry cultivars in daylight phytotron compartments at temperatures of 9, 15, 21 and 27°C and photoperiods of 10 h (SD) and 20 h (LD). After three weeks, the rates of dark respiration and photosynthesis and their acclimation were measured in 'Favouri'. Photosynthesis of plants grown in the various conditions was measured as CO2-uptake with an infrared gas analyzer at increasing irradiances (50-1000 µmol quanta m‑2 s‑1) and temperatures ranging from 9 to 27°C. In the dark, CO2-production (dark respiration) increased with increasing measuring temperature and was always largest in plants grown at low temperature (9°C) with no significant effect of photoperiod. Photosynthetic CO2-uptake was lowest at almost all irradiances in plants grown at 9°C, and with no clear effect of growth temperatures in the 15-27°C range. At saturating irradiances (500-1000 µmol), CO2-uptake increased with increasing measuring temperatures, reaching a plateau at about 21°C for plants grown at 15-27°C in SD and at 21-27°C in LD. For plants grown at 15°C in LD, the maximum CO2-uptake rate was obtained at 27°C. Light response curves showed that CO2-uptake increased with increasing irradiance and measuring temperatures and that the irradiance effect was markedly enhanced by increasing growth temperature. Maximum uptake rates were lowest for plants grown at 9°C at both photoperiods and highest for plants grown at 15°C in SD. Comparison of plants of 'Altess', 'Favouri' and 'Murano' at 500 µmol irradiance and 21°C revealed no significant differences in photosynthetic efficiency between the cultivars. Generally, the everbearing strawberry cultivars showed considerable photosynthetic plasticity to temperature within the 9-27°C range, although with an overall optimum at 15-21°C.

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The environmental control of dormancy and its relation to flowering and runner formation is poorly understood in everbearing (EB) strawberry cultivars. We studied the topic by growing plants of the seed-propagated F1-hybrid ‘Delizzimo’ and the runner-propagated ‘Favori’ cultivar in daylight phytotron compartments under short day (SD) and long day (LD) conditions at temperatures of 6, 16 or 26 °C for 5 and 10 weeks. This was followed by forcing at 20 °C and 20-h photoperiod for 10 weeks with and without preceding chilling at 2 °C for 6 weeks. The results showed that dormancy in EB strawberry is regulated by a complex interaction of temperature, photoperiod and chilling in much the same way as known for seasonal flowering (SF) cultivars. Surprisingly, the EB cultivars exhibited the same SD dormancy induction response as SF cultivars, despite their opposite photoperiodic flowering requirements. However, at 26 °C the EB cultivars developed partial dormancy also under LD conditions. As known for SF cultivars, none of the EB cultivars became dormant at 6 °C regardless of daylength conditions, whereas they were increasingly sensitive to SD dormancy induction at intermediate and high temperatures. Similar to SF cultivars, the EB cultivars needed exposure to SD and relatively high temperatures for at least 10 weeks for attainment of the semi-dormant state that is typical for strawberry in general. As reported for SF cultivars, there was a close interrelation between the control of flowering, runner formation and dormancy also in the EB cultivars. ‘Favori’ had an obligatory LD requirement for flowering at 26 °C and was almost day neutral at 16 °C, while ‘Delizzimo’ behaved as a quantitative LD plant at both temperatures, and both cultivars were completely day neutral at 6 °C. Except for the stricter LD control of flowering in ‘Favori’, the overall environmental responses were quite similar in the two genetically distant cultivars. Chilling for six weeks at 2 °C was adequate for complete reversal of the constrained elongation of leaf petioles and flower trusses in dormant plants, but had little or no effect on the degree of flowering and runner formation.

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The use of peat as a growing media in horticulture is supposed to be reduced due to negative effects of its production on the environment. Interest in development of alternative growing media is therefore increasing and is enhanced by both political pressure and industry demands. Therefore, the influence of 33 growing media on the performance and productivity of two strawberry cultivars were examined in a polytunnel under Nordic conditions (60.7 N). Alternative substrates including fibers of spruce, birch and flax and coffee grounds were tested standalone or in mixes. Peat and coir were included as controls. Additionally, impregnation of the wood fibers with organic and inorganic substances was examined. All investigated growing media received identical fertigation strategies (EC 1.5). The highest average biomass production was observed for plants grown in bare peat; however, the best yield performance was noted for peat mixed with perlite and for coarse spruce fiber. Strawberries grown in these two best performing substrates showed comparable overall productivity, with 272 and 268 g of berries per plant, respectively. Both peat/perlite mix and the coarse spruce fiber had also a similar weight of berries larger than 25 mm, with 210 and 198 g plant-1, respectively. Moreover, improvement of the substrate structure by adding perlite or wood chips may have had a pronounced effect on fruiting performance. When compared to peat with added perlite (which gave the highest berry yield in the experiment; 272 g plant-1), strawberries grown in pure peat produced only 187 g plant-1. Furthermore, impregnation of spruce fiber with humic acid enhanced fruiting performance by increasing the total yield and number of large berries (≥25 mm). Future prospects for this study include establishment of an optimal structure of spruce fiber substrate suitable for strawberry production and development of the fertigation strategy optimized for the new growing media.

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Promoting the consumption of fruits is a key objective of nutrition policy campaigns due to their associated health benefits. Raspberries are well appreciated for their remarkable flavor and nutritional value attributable to their antioxidant properties. Consequently, one of the objectives of present-day raspberry breeding programs is to improve the fruit’s sensory and nutritive characteristics. However, developing new genotypes with enhanced quality traits is a complex task due to the intricate impacts genetic and environmental factors have on these attributes, and the difficulty to phenotype them. We used a multi-platform metabolomic approach to compare flavor- and nutritional-related metabolite profiles of four raspberry cultivars (‘Glen Ample’, ‘Schönemann’, ‘Tulameen’ and ‘Veten’) grown in different European climates. Although the cultivars appear to be better adapted to high latitudes, for their content in soluble solids and acidity, multivariate statistical analyses allowed us to underscore important genotypic differences based on the profiles of important metabolites. ‘Schönemann’ and ‘Veten’ were characterized by high levels of anthocyanins and ellagitannins, respectively, ‘Tulameen’ by its acidity, and ‘Glen Ample’ for its content of sucrose and β-ionone, two main flavor contributors. Our results confirmed the value of metabolomic-driven approaches, which may foster the development of cultivars with enhanced health properties and flavor.

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The effect of cultivar and environmental variations and their interaction on anthocyanin components of strawberry were assessed for six cultivars grown in five locations from North to South of Europe in two different years. To evaluate the impact of latitude- and altitude-related factors, daily mean (Tmean), maximum (Tmax) and minimum (Tmin) temperature and global radiation accumulated for 3, 5, 10 and 15 days before fruit sampling, was analyzed. In general, fruits grown in the south were more enriched in total anthocyanin and pelargonidin-3-glucoside (pel-3-glc), the most abundant anthocyanin in strawberry. Principal component analysis (PCA) provided a separation of the growing locations within a cultivar due to latitudinal climatic differences, temporary weather changes before fruit collection and cultivation technique. PCA also depicted different patterns for anthocyanin distribution indicating a cultivar specific reaction on the environmental factors. The linear regression analysis showed that pel-3-glc was relatively less affected by these factors, while the minor anthocyanins cyanidin-3-glucoside, cyanidin-3-(6-O-malonyl)-glucoside, pelargonidin-3-rutinoside and pelargonidin-3-(6-O-malonoyl)-glucoside were sensitive to Tmax. The global radiation strongly increased cya-3-mal-glc in ‘Frida’ and pel-3-rut in ‘Frida’ and ‘Florence’. ‘Candonga’ accumulated less pel-3-glc and total anthocyanin with increased global radiation. The anthocyanin profiles of ‘Gariguette’ and ‘Clery’ were unaffected by environmental conditions.

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En prosjektgruppe med deltagelse fra Gartnerhallen, Graminor, Njøs Frukt- og Bærsenter, NLR, NIBIO, Gartnerforbundet, Norges Bondelag og Norsk Bonde- og Småbrukarlag har utredet behovet for, organiseringen av, og innholdet i et nasjonalt system for sortsprøving i frukt og bær. Prosjektgruppen foreslår at alle sorter i frukt og bær som skal dyrkes profesjonelt i Norge skal prøves for dyrking under norske dyrkingsforhold, gjennom et kvalitetssikret nasjonalt system for sortsprøving. Det skal også vurderes om prøvingen bør inneholde en form for sertifisering, f.eks. ved at sortsprøvingssystemet sertifiserer og at sorter som har gjennomgått prøvingen får en slags godkjenning. Både norske og utenlandske sortseiere, eller representanter for utenlandske sortseiere, skal ha mulighet for å få testet sorter i systemet, og det forutsettes at alle dyrkere har tilgang til informasjon om sorter som er testet ut.

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Hydroponic production of strawberry (Fragaria × ananassa Duch.) in protected cultivation systems using substrates (growing media) is gaining popularity worldwide. Therefore, it is necessary to develop more sustainable growing media alternatives. This study focused on growth performance of strawberry plants grown in wood fibre from Norway spruce (Picea abies (L.) H. Karst.), in comparison to two industry standards (peat and coco fibres). Plug (tray) plants of the June-bearing strawberry cultivar 'Malling Centenary' and bare root (WBH) plants of cultivar 'Sonata' were transplanted into three different growing media: peat (80%) and perlite (20%) mixture, coconut coir (100%) and Norway spruce wood fibre (100%). The plants received four fertigation strategies (various potassium and nitrogen concentrations) from flowering onwards. Throughout the production season ripe berries were harvested and frozen for later analyses of chemical composition. Plant architecture was also recorded after termination of the experiment. The results revealed that the most significant differences among the majority of the fruit and plant parameters were due to cultivar traits. Strawberries grown in wood fibre produced slightly smaller berries with elevated °Brix and dry matter compared to berries from plants grown in peat and coir. This was most likely caused by the common fertigation strategy applied to all substrates. Nevertheless, among the tested fertigation strategies, application of solutions with elevated potassium resulted in the highest sugar accumulation in berries grown in wood fibre substrate. In general, the experiment revealed relatively negligible differences between the growing media, and we therefore conclude that wood fibre from Norway spruce may be a viable alternative as a growing media in hydroponic strawberry production when the fertigation strategy is precisely adjusted.

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Bærproduksjon i plasttunnel har blitt trukket frem som en løsning for økologisk bærdyrking. Et slikt produksjonssystem er relativt nytt i Norge, og det er behov for mer kunnskap for å optimalisere produksjonen. I perioden 2017-2019 har vi gjennom prosjektet “Økologisk tunnelbær og flytende næring”, finansiert av Kunnskapsutviklingsmidler for økologisk produksjon i NIBIO, hatt ulike forsøk ved forskningsstasjonene Holt og Apelsvoll for å øke kunnskapen om dyrkingstekniske utfordringer for økologisk bærproduksjon.

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BACKGROUND: Bud dormancy is a quantitative condition that is gradually acquired and lost. Better and more convenient methods for assessment of the time of dormancy entrance of woody plants are highly needed. OBJECTIVE: To demonstrate a simple and convenient method for determination of dormancy in woody plants. METHODS: We employed a seasonal series of soft tipping of vigorously growing annual shoots and used the loss of ability of subtending lateral buds to break and grow as a measure of entrance into dormancy. RESULTS: There was a gradual decline in the ability of the buds to burst and grow during the month of July and early August, culminating with a complete loss of this ability. This coincided with the known time of growth cessation and dormancy induction in shoots of intact plants and occurred in the berry shrubs raspberry and black currant and the forest tree silver birch. CONCLUSIONS: The decline and loss of ability of the buds to grow during late summer is a direct expression of the entrance of buds into the state of endodormancy, rendering the tipping method a simple and convenient method for precise determination of the time of entrance into dormancy in woody plants.

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BACKGROUND:The predicted and ongoing climate warming can have far-reaching effects on plant growth and life cycle. Therefore, there is need for simple and convenient methods for analysis and monitoring of consequences of the ongoing warming. OBJECTIVE:To demonstrate the usefulness of so-called climate-photothermographs for studying the consequences of the ongoing warming for production of berry crops. METHODS:Local photothermal climates can be expressed by so-called climate-photothermographs, which show the relationship between temperature and daylength for each month of the year in a rectangular coordinate diagram. When superimposing critical response curves for plant development processes on top of such a diagram, the limitations of the given climate for fulfilment of the processes can be readily assessed. RESULTS:Consequences of 2°C warming for critical development processes such as transition to flowering and breaking of winter dormancy in the berry crops raspberry, black currant and strawberry were clearly exposed by the technique. The locations Geisenheim, Germany and Ås, Norway were used as examples. Inadequate winter chill was identified as the most limiting factor for these crops. CONCLUSIONS:We conclude that the technique is an efficient and convenient tool for monitoring the consequences of climate warming for berry crops.

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Four raspberry cultivars were grown at two different latitudes namely in Geisenheim (DE, 49°60’N; 7°57’E) and in Kapp (NO, 60°42’N; 10°52’E) to investigate the impact of these growing sites on primary and secondary fruit chemical ingredients in the 2017 season. Fruits were harvested at two picking dates each with three field replications. Contents of °Brix, glucose, fructose, sucrose, organic acids, ascorbic acid, polyols, total polyphenols, and anthocyanins were analyzed in the fruits. The geographic growing sites, which in this case is more than10 latitudes between HGU in Germany and NIBIO in Norway, has partly no, partly significant effects on the primary and secondary ingredients of the investigated raspberry cultivars. In respect to the created data set, temperatures shortly before or at the picking dates were not considered. It may be expected that temperatures at harvest have an effect on the fruit ingredients and therefore on a further classification of the samples.

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Growth cessation and floral initiation in black currant and red raspberry are jointly controlled by the interaction of temperature and short-day (SD) conditions, and the processes coincide in time in both natural and controlled environments. The critical photoperiods for the two successional responses were found to be approximately 15 and 16 h, respectively, for a range of Western-European black currant cultivars. Both cessation of growth and floral initiation are promoted and enhanced by increasing temperature in the 9 to 24°C range. In contrast, biennial-fruiting red raspberry has a maximum temperature limit for growth cessation and floral initiation. At temperatures above 16°C, most cultivars grow and remain vegetative regardless of day length conditions, at 12 to 16°C they cease growing and initiate flower primordia in photoperiods <15 h, while at temperatures ≤12°C they cease growing and initiate floral primordia regardless of day length. In the annual-fruiting (primocane) types of red raspberry on the other hand, floral initiation is not constrained by high temperature, but readily takes place at temperatures up to 30°C. In addition, floral initiation is also enhanced by long day (LD) conditions in most of these cultivars. Another fundamental physiological difference is that while floral primordia of the biennial types become dormant after initiation, they proceed directly to anthesis in the annual-fruiting types. Chilling at -5°C, and in the -5 to +5°C temperature range were found to be optimal for breaking of bud dormancy and promotion of flowering in black currant and red raspberry, respectively. In black currant, 14 weeks of chilling were optimal, while for raspberry, 20 or more weeks were required for full dormancy release and promotion of flowering along the entire length of the raspberry cane. The consequences of climate warming for the production of these species in different climatic regions are discussed.

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Introduction Blackcurrant (Ribes nigrum L.) is an excellent example of a “super fruit” with potential health benefits. Both genotype and cultivation environment are known to affect the chemical composition of blackcurrant, especially ascorbic acid and various phenolic compounds. Environmental conditions, like temperature, solar radiation and precipitation can also have significant impact on fruit chemical composition. The relevance of the study is further accentuated by the predicted and ongoing changes in global climate. Objectives The aim of the present study was to provide new knowledge and a deeper understanding of the effects of post flowering environmental conditions, namely temperature and day length, on fruit quality and chemical composition of blackcurrant using an untargeted high performance liquid chromatography–photo diode array–mass spectrometry (HPLC– PDA–MS) metabolomics approach. Methods A phytotron experiment with cultivation of single-stemmed potted plants of blackcurrant cv. Narve Viking was conducted using constant temperatures of 12, 18 or 24 °C and three different photoperiods (short day, short day with night interruption, and natural summer daylight conditions). Plants were also grown under ambient outdoor conditions. Ripe berries were analysed using an untargeted HPLC–PDA–MS metabolomics approach to detect the presence and concentration of molecules as affected by controlled climatic factors. Results The untargeted metabolomics dataset contained a total of 7274 deconvolved retention time-m/z pairs across both electrospray ionisation (ESI) positive and negative polarities, from which 549 metabolites were identified or minimally annotated based upon accurate mass MS. Conventional principal component analysis (PCA) in combination with the Friedman significance test were applied to first identify which metabolites responded to temperature in a linear fashion. Multi-block hierarchical PCA in combination with the Friedman significance test was secondly applied to identify metabolites that were responsive to different day length conditions. Temperature had significant effect on a total of 365 metabolites representing a diverse range of chemical classes. It was observed that ripening of the blackcurrant berries under ambient conditions, compared to controlled conditions, resulted in an increased accumulation of 34 annotated metabolites, mainly anthocyanins and flavonoids. 18 metabolites were found to be regulated differentially under the different daylength conditions. Moreover, based upon the most abundant anthocyanins, a comparison between targeted and untargeted analyses, revealed a close convergence of the two analytical methods. Therefore, the study not just illustrates the value of non-targeted metabolomics approaches with respect to the huge diversity and numbers of significantly changed metabolites detected (and which would be missed by conventional targeted analyses), but also shows the validity of the non-targeted approach with respect to its precision compared to targeted analyses. Conclusions Blackcurrant maturation under controlled ambient conditions revealed a number of insightful relationships between environment and chemical composition of the fruit. A prominent reduction of the most abundant anthocyanins under the highest temperature treatments indicated that blackcurrant berries in general may accumulate lower total anthocyanins in years with extreme hot summer conditions. HPLC–PDA–MS metabolomics is an excellent method for broad analysis of chemical composition of berries rich in phenolic compounds. Moreover, the experiment in controlled phytotron conditions provided additional knowledge concerning plant interactions with the environment.

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The predicted and ongoing climate warming is expected to affect many aspects of plant development. We analysed data from a 31-year series of observations (1985–2016) on spring phenology and flowering and fruiting performance of three plum cultivars in an experimental orchard at Ås in southeast Norway (59° 40′N; 10° 50′E). Regression analyses revealed a trend of increasing March and April temperature during the study period that was highly significantly (P <  0.001) negatively correlated with the date of full bloom (FB). On average for all cultivars, blooming was advanced by 10 days over the study period. August and September temperature, which also increased significantly during the study period, was closely positively correlated with the amount of flowering in the subsequent spring and also interacted with early spring temperature in advancing blooming time. Investigation of the time of floral initiation in two of the studied plum cultivars revealed that the transition to reproductive development took place in early to mid-August. This finding strongly suggests that the close positive correlation between August-September temperature and the amount of flowering in plum observed in this and other studies, is causally linked to a specific physiological effect of elevated temperature on the flower bud formation process. Increasing March and April temperatures during the last 30 years has advanced blooming and spring phenology in plum and the resulting extension of the growing season has led to increasing fruit size at harvest. We conclude that so far, the ongoing climate warming appears to have been positive for plum production in the cool Nordic environment. However, an increasing risk of frost associated with earlier blooming will represent a potential negative effect of continued warming.

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Flowering performance and phenology of six new pear cultivars of Nordic origin were examined during a 12 year period. The seasonal timing of shoot growth and flower initiation were monitored in three years. The morphological floral stages of the flower bud formation process were examined for the cultivar ‘Celina’. Seven floral stages were identified and described. The date of full bloom varied between years as a function of the currently accumulated heat sum in early spring. Still, the earliness ranking of the cultivars was consistent across years for both flower initiation and blooming. The cultivars ‘Anna’ and ‘Ingeborg’ consistently initiated floral primordia 2–3 weeks earlier than ‘Celina’, ‘Clara Frijs’, ‘Fritjof’ and ‘Kristina’, and this was accompanied with 4–5 days earlier blooming in the following spring. The early flower initiation cultivars ‘Anna’ and ‘Ingeborg’ also had richer flowering than the late-blooming cultivars. ‘Fritjof’ was identified as a suitable pollinator for ‘Celina’ in the Nordic climate. Comparison of the flowering phenology of pear and apple cultivars showed that while the pears, on average, flowered a week ahead of the apples, they initiated flower primordia almost two weeks later, thus rendering the intervening period approximately three weeks longer in pear than in apple

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BACKGROUND: There is a search for raspberry cultivars with high sensory quality. The best way to determine sensory quality is by descriptive analysis. To perform sensory analysis by a trained panel is, however, not always feasible. Therefore, there is a need for instrumental measurements that correlate with sensory attributes. OBJECTIVE: To characterize eight genotypes of raspberry (Rubus idaeus L.) and to correlate sensory attributes with instrumentally determined quality. METHODS: Raspberry fruits were analysed by descriptive sensory analysis and by instrumental measurements, i.e. colour, total monomeric anthocyanins, soluble solids (SS), pH, titratable acidity (TA) and volatile compounds. The relationships between sensory attributes and instrumentally measured quality were determined by partial least square regression and by univariate correlation analysis. RESULTS: Sour and green odours/flavours versus chemical and cloying odours/flavours described most of the sensory variation of the raspberry genotypes. TA correlated with acidic taste, astringency and flavour intensity. SS/TA was positively correlated with sour flavour and sweet taste and negatively correlated with acidic taste and astringency. C6-aldehydes and (Z)-3-hexen-1-ol correlated positively with green flavour. _-ionone and _-ionone correlated with flower odour and flavour, respectively. CONCLUSIONS: Eight raspberry genotypes were characterized. Important sensory attributes could be predicted by instrumental measurements.

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We grew young sweet cherry (Prunus avium L.) trees under controlled temperature and natural summer daylight conditions in order to study the control of flowering of the species. Two experiments with the cultivars ‘Lapins’ and ‘Van’, were conducted and compared with field results with the same cultivars at Ås in southeast Norway (59° 40′N, 10° 50′E, 90 m a.s.l.). Shoot growth increased with increasing temperature in the 12–21 °C range, but ceased in late summer (August) regardless of temperature conditions. A marked drop in temperature always induced an immediate cessation of growth. Under field conditions at Ås, both growth cessation and floral initiation took place by about 1 August. Low temperature (12–15 °C) significantly enhanced flowering of both cultivars compared with 21 °C, which tended to depress flower bud formation during the summer but stimulated the subsequent flower differentiation process. These results concur with earlier regression analyses, which revealed a close positive correlation between historical records of sweet cherry yields over a 40-year period in farmer’s fields in the fjord districts of western Norway and previous year August-September temperature, and a negative correlation with previous year July temperature. Practical implications of the results are discussed and it is suggested that inadequate temperature control in rain-protected cultivation in plastic tunnels might have negative consequences for next year’s flowering and yield.

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The aim of the investigation was to assess and compare the environmental limits for growth cessation and floralinitiation in a range of new and established biennial-fruiting red raspberry (Rubus idaeus L.) cultivars of diverseorigin under phytotron and field conditions. The results confirmed that growth cessation and floral initiation inbiennial-fruiting red raspberry are jointly controlled by the interaction of low temperature and short days (SD).When transferred from non-inductive high temperature and long day (LD) conditions to naturally decreasingautumn daylengths at varying phytotron temperatures on 18 August, growth immediately levelled off and ceasedcompletely within 2 weeks in all cultivars at 9 °C. Serial dissections of lateral buds revealed that floral initiationsimultaneously took place. At 15 °C on the other hand, the plants continued growing and remained vegetativeuntil around 15 September when the daylength had decreased to approximately 13 h. The change to 9 °C resultedin an immediate but short-lasting floral induction response that did not bring about initiation in buds situatednear the base of the canes, as was the case at 15 °C. At 18 °C, marginal floral induction took place only in thecultivars ‘Glen Ample’, ‘Balder’ and ‘Vene’, even at photoperiods down to 10 h, whereas at 21 °C, all cultivarsgrew vegetatively regardless of daylength conditions. However, exceptions were some plants of ‘Vene’ and‘Anitra’ that initiated terminal flowers at 18 and 21 °C and flowered directly without chilling (so-called tipflowering). Although some cultivars of Northern origin ceased growing and initiated floral primordia somewhatearlier (at longer photoperiods) than those of more southerly origin, the differences were relatively minor andnot consistent (no latitudinal cline). Results obtained in the field under decreasing autumn temperature anddaylength conditions agreed closely with the results in the phytotron. We therefore conclude that results ob-tained with raspberry in properly controlled daylight phytotron experiments are generally applicable to fieldconditions.

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Effects of annual versus biennial cropping with varying shoot densities on plant structure, berry yield and quality were studied in ‘Glen Ample’ raspberry over a period of four seasons (two cropping years). In the vegetative phase, primocane height and internode length were larger in the annual than in the biennial cropping system. These parameters as well as Botrytis infestation increased with increasing shoot density. In both cropping years, berry yields per unit area were about 20% higher in the biennial cropping system, whereas yields per shoot were not significantly different in the two systems. In both cropping systems, yields per shoot strongly declined with increasing shoot density, while yields per metre row increased slightly. Regardless of cropping system, yields per metre row did not increase with increasing shoot density beyond eight shoots per metre. The concentrations of dry matter, soluble solids, titratable acidity and ascorbic acid as well as the intensity of juice colour all declined with increasing shoot density. We conclude that under controlled shoot density conditions, there is little scope for biennial yield increases that fully compensates for the lost crops every second year. However, the system greatly facilitates berry harvest and eases plant disease pressure.

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The effect of controlled nutrient feeding during the period of short day (SD) induction of flowering has been studied in three SD berry crops. An experimental system with standardized plant material grown with trickle fertigation in controlled environments was used. In strawberry, flowering was advanced and increased when an additional N pulse was given 1-2 weeks after commencement of a 4-week SD induction period, while the opposite resulted when the treatment was applied 2 weeks before start of SD. In blackcurrant, the highest flowering and yield were obtained when fertilization was applied shortly after the natural photoperiod had declined to the inductive length in September. While generous nutrient supply during spring and summer reduced berry soluble solids in blackcurrant, this was not observed with autumn fertilization. Autumn fertilization did not adversely affect plant winter survival or growth vigour in spring. Withdrawal of fertilization prior to, or at various stages during floral induction, did not significantly affect flowering and yield in raspberry, but marginally advanced flowering and fruit ripening.

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We examined the influence of fertigation on vegetative and generative parameters of strawberry plants (Fragaria × ananassa Duch.) and evaluated rapid analysing tools for N and K in leaf tissue. The experiments were undertaken in an open polytunnel on “table top” with ‘Sonata’ and ‘Korona’ grown in 2-L pots filled with a peat-based soil mixture. The experimental design was a randomized plot with three replications. Plants were fertigated with EC levels of 0.5, 1.0, 1.5 and 2.0 mS cm-1, based on two stock solutions of 7.5 kg YaraLiva™ Calcinit and 7.5 kg Kristalon™ Indigo, both dissolved in 100 L of water. Percentage N and K in leaves differed between analysing methods, cultivars, EC and date. We found interactions between the cultivar and EC level and between date and cultivar for N and K in leaf. Analysing NO3- by a photometric method (PM) in a lab, and by Laqua twin (LT), showed significant interaction with N% of leaf dry matter (DM) only for LT (r2=0.36). N% increased with higher EC level, more for ‘Korona’ than for ‘Sonata’. LT K+ did not correlate with K% (r2=0.014). The number of crowns and runners increased for both cultivars up to EC 1.5, while the number of leaves was unaffected. Petioles were the shortest at the lowest EC. Flower initiation was earlier at low EC in both cultivars. In the following spring, the time to flowering and first harvest was reduced with the decreasing EC. The number of flowers per plant increased up to EC 1.5, but dropped strongly at EC 2.0 for ‘Korona’, while ‘Sonata’ had a gradual increase of flowers with the increasing EC, but the number was only a third of ‘Korona’, except at EC 2.0, where the amount was equal for both cultivars. The conclusion can be drawn that LT correlated better than ChlDualex with N in strawberry leaves. However, r2 was only 0.36 indicating that LT NO3- is a coarse management tool. LT K+ was not a promising tool for rapid K+ test in these experiments. ‘Korona’ seemed to benefit of higher N levels for both vegetative growth and generative development than ‘Sonata’ up to EC 1.5, but ‘Sonata’ reached a higher floral primordia development stage in early October.

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• Vernalisation requirement is an agriculturally important trait that postpones the development of cold-sensitive floral organs until the spring. The family Rosaceae includes many agriculturally important fruit and berry crops that suffer from crop losses caused by frost injury to overwintering flower buds. Recently, a vernalisation-requiring accession of the Rosaceae model woodland strawberry (Fragaria vesca) has been identified in northern Norway. Understanding the molecular basis of the vernalisation requirement in this accession would advance the development of strawberry cultivars better adapted to temperate climate. • We use gene silencing, gene expression analysis, genetic mapping and population genomics to study the genetic basis of the vernalisation requirement in woodland strawberry. • Our results indicate that the woodland strawberry vernalisation requirement is endemic to northern Norwegian population, and mapping data suggest the orthologue of TERMINAL FLOWER1 (FvTFL1) as the causal floral repressor. We demonstrate that exceptionally low temperatures are needed to downregulate FvTFL1 and to make these plants competent to induce flowering at low postvernalisation temperatures in the spring. • We show that altered regulation of FvTFL1 in the northern Norwegian woodland strawberry accession postpones flower induction until the spring, allowing plants to avoid winter injuries of flower buds that commonly occur in temperate regions.

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BACKGROUND: It is questioned if Norwegian nurseries can compete with the continental nursery industry in an open market. OBJECTIVE: Investigated how quality of certified Norwegian strawberry transplants, developed and yielded from planting to first cropping year. METHODS: Plant qualities of Norwegian fresh and cold stored bare root- and plug-plants of ‘Korona’ and ‘Sonata’ were examined for establishing and yield parameters in the open, after three intervals of planting. Fresh plug-plants were delivered when available. Trials were established at NIBIO Research Station Kvithamar, Norway. Growth and yield parameters were registered in the establishing and cropping years. RESULTS: Plant establishment was poor in 2013 compared with 2014. Bare-root plants stored at 2–4°C generally developed poorly. Plug-plants established well at all delivery dates, except fresh plug in one year. Development of runner plants depended on plant type, cultivar and year. Plug- and bare root-plants planted immediately after first delivery generally developed best crowns. Primary flower primordia reached a more developed stage for ‘Sonata’ than for ‘Korona’. Fruit yield of bare root was low in the establishing years. Plant-types differed in yield and fruit weight between cropping years. CONCLUSIONS: Bare-root and plug- plants planted one day after delivery generally yielded best. Storage of bare-root plants generally reduced yield. Fresh plug plants had low yield when planted late. Fruit yield of A15 and A13 in the establishing year was not satisfactory.

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Plants of six strawberry cultivars were raised under controlled conditions and tested for flowering and yield potential. Short days (SD) at intermediate temperatures for 4 weeks in August induced profuse flowering in subsequent long days (LD) in all cultivars except the late-flowering ‘Malwina’. LD conditions induced flowering only in ‘Nobel’, which has an everbearing parent. ‘Nobel’ and ‘Saga’ exhibited broad temperature adaptation for SD floral induction, which was generally reduced or suppressed at 9 and 27°C. After autumn planting, all cultivars flowered most abundantly in plants raised in SD and intermediate temperatures. Flowering was earliest in ‘Nobel’ and ‘Rumba’. Plants that did not reach floral commitment after 4 weeks in SD continued and completed induction under subsequent natural SD conditions after planting in the field, demonstrating the capability of fractional induction. Berry yield varied in parallel with flowering in the field and was always higher in plants raised under SD conditions. The traditional cultivars ‘Florence’ and ‘Sonata’ out-yielded the more recent cultivars. Some cultivars lost more than two thirds of their initiated flowers during the winter with obvious consequences for their yields. With proper raising management, acceptable yields were obtained after autumn planting even in a cool Nordic climate.

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BACKGROUND Marked effects of the climatic environment on fruit chemical composition have often been demonstrated in field experiments. However, complex covariations of several climatic factors in the natural environment complicate the interpretation of such experiments and the identification of the causal factors. This can be better achieved in a phytotron where the various climatic factors can be varied systematically. Therefore, we grew four black currant cultivars of contrasting origin in a phytotron under controlled post-flowering temperature and photoperiod conditions and analysed the berries for their ascorbic acid, sugar and organic acid contents. RESULTS The analyses revealed significant effects of genotype on all investigated compounds. Particularly large cultivar differences were observed in the concentrations of l-ascorbic acid (AA) and sucrose. The concentrations of both AA and dehydroascorbic acid (DHAA), as well as the concentrations of all major sugars, decreased consistently with an increasing temperature over the temperature range 12–24 °C. Fructose and glucose were the predominant sugars with concentrations several fold higher than that for sucrose. AA was the main contributor to the total ascorbate pool in black currant berries. The AA/DHAA ratio varied from 5.6 to 10.3 among the studied cultivars. The concentration of citric acid, which was the predominant organic acid in black currant berries, increased with an increasing temperature, whereas the opposite trend was observed for malic and shikimic acid. Quninic acid was always present at relatively low concentrations. By contrast, photoperiod had no significant effect on berry content of any of the investigated compounds. CONCLUSION It is concluded that the post-flowering temperature has marked effects on the concentration of important chemical compounds responsible for taste and nutritional value of black currant berries, whereas photoperiod has no such effect in the studied cultivars. © 2016 Society of Chemical Industry

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Black currant is a woody plant in which growth and development are intimately controlled by, and synchronised with seasonal changes in photoperiod and temperature. Concern over the potential impact of global warming on plant phenology and yield, led us to initiate relations. An experimental system with single-stemmed potted plants was developed which allowed a research program to address both qualitative and quantitative assessment of climatic responses. Growth cessation and flowering were both induced by short days, with critical photoperiods of approximately 17 and 16 h, respectively, for most cultivars. Both processes were advanced and promoted by increasing autumn temperature with an optimum in the 18-21°C region. An exception was cultivars of high-boreal origin, which had an early growth cessation at low temperature. Unexpectedly, however, not all plants flowered after exposure to 10 h photoperiod, and the number of flowers decreased as the photoperiod was reduced from the near-critical length of 15 h. This was due to premature dormancy induced by an abrupt change to photoperiods well below the critical level. Field experiments revealed that cultivars of varying geographic origin, exhibited a typical latitudinal cline in their photoperiodically controlled timing of growth and flowering responses. Breaking of bud dormancy and promotion of flower bud development required chilling at -5°C for 14 weeks or more for optimal responses. However, while chilling at -10°C for 8 weeks resulted in dormancy release, continued chilling to 16 weeks inhibited bud break completely. We therefore propose that excessive chilling induces secondary bud dormancy in black currant. The observed high chilling requirements of black currants concur with the reported vulnerability of this crop to declining winter chill in the wake of the ongoing global warming. Furthermore, such conditions also induce a particularly deep bud dormancy state that further increases the chilling need.

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The paper is a mini review on the climatic effects on berry production and berry quality in the Arctic north. Plants in the north are facing short growing seasons with low temperatures and long days with a unique light quality. The winter time is cold but with fluctuating temperatures, especially along the coast. Fluctuating winter temperatures and unstable snow cover is a challenge for the perennials that need to be dormant during winter time. Dormancy is induced in the autumn by a combination of day length and temperature. The wild berries domestic to the Nordic countries are adapted to these growth conditions while many of the commercially important berry species originate from more southern areas. Pre-breeding studies on interactions between genotype and environment are essential in order to develop climatically adapted berry cultivars for northern growth conditions.

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The effect of fertility status and temperature conditions during floral induction on flowering, berry yield,and weight and drupelet numbers of individual berries were studied in ‘Glen Ample’ raspberries grownunder controlled conditions. Withdrawal of normal fertilization prior to and at various stages duringfloral induction did not affect yield and berry size, but marginally advanced flowering and fruit ripening.The successive stages of floral initiation and differentiation were studied and identified by scanning elec-tron microscopy of the uppermost lateral buds of plants grown for six weeks under naturally decreasingautumn photoperiods at temperatures of 9, 15 and 21◦C. Low temperature advanced floral initiation, andadvanced and enhanced flowering and berry yield in the following season. However, at variance fromearlier studies, the plants eventually initiated flower primordia even at 21◦C. Marginal low temperatureand short day conditions during the last days before the temperature treatments were started on 17September might possibly have reduced the subsequent induction requirements enough to explain thisunexpected result. Correlation analyses revealed an over-all positive correlation between fruit weightand drupelet numbers (r = 0.568, P = 0.01). In berries from the early harvests, the number of drupelets perberry increased with decreasing temperature, while the numbers converged to the same level regardlessof temperature in the later harvests. Based on the progress of the floral initiation process at the vari-ous temperatures, we interpret this to mean that only the early initiated flowers, that gave rise to theearly maturing berries, were differentiated during the actual period of controlled temperature exposure,whereas the remaining flowers were differentiated afterwards when all plants were exposed to identicallow temperature conditions. Increased femaleness under optimal floral induction conditions is in agree-ment with results in both monoecious and dioecious plants and circumstantial evidence suggest that,in the raspberry, this might be mediated by changes in gibberellin activity which acts as a male sexualhormone in plants and is known to inhibit growth cessation and floral initiation in raspberry.

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Berry yield and chemical composition of four commercial black currant cultivars were recorded in a field experiment in Norway over an 8-year period and related by linear regression analysis to temperature and precipitation conditions prevailing during the May-July preharvest period. Highly significant differences between cultivars and among years were found for all measured parameters. Fruit dry matter, soluble solids and pH were positively correlated with temperature and negatively correlated with precipitation during May-July, while yield, berry weight, and the concentration of total phenols and ascorbic acid showed the opposite relationship, being highly negatively correlated with temperature and positively correlated with precipitation. Similar black currant experiments elsewhere in Europe have often given deviating results, varying from opposite to no effects of the same weather variables, suggesting that fruit composition is influenced by several interacting genetic and environmental parameters. We conclude that differences in local weather and soil conditions and the use of different cultivars complicate direct comparison of such field experiments. Nevertheless, the observed strong and opposite correlations with precipitation and temperature suggest an inherently low drought tolerance of black currant plants.

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In order to investigate the relationship between environmental conditions and vegetative growth and reproductive development in the strawberry, freshly rooted runner plants of the cultivar ‘Sonata’ were grown in a phytotron at temperatures of 12, 18 and 24 °C and photoperiods of 10 h short day (SD) and 20 h long day (LD) for 31 d and harvested at 10 d intervals. Plant dry weight and leaf area increases were exponential versus time, giving a linear regression with the natural log (ln). This rendered the relative growth rate (RGR) constant over time at each environmental condition. Over the entire 31 d growth period, the RGR increased linearly with increasing temperature across the range of temperatures with a further 10–13% enhancement by LD. A maximum RGR value of 0.077 g/g/d was determined in LD at 24 °C. Increases in the RGR was driven by a combined increase in net assimilation rate (NAR) and leaf area ratio (LAR) and was associated with an increased allocation of dry matter production into leaves and less into crowns and roots. Because of this, the shoot/root ratio increased consistently with increasing temperature and photoperiod, which was also associated with a significant increase in the tissue C/N concentration ratio. Low temperature promoted starch accumulation markedly in all parts of the plants, with a further enhancement by LD conditions, while the concentrations of soluble sugars were less affected by the climatic environment. Forcing of plants exposed to the various growth conditions for 31 d showed that all plants at 12 and 18 °C and 80% of those at 24 °C had initiated flowers in SD, whereas none had initiated flowers in LD regardless of temperature conditions. All these results demonstrate an opposite environmental relationship between vegetative growth and reproductive development in the strawberry.

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The effects of postflowering temperature and daylength on the concentration of individual phenolic compounds were studied in black currant (Ribes nigrum L.) berries under controlled phytotron conditions. The four cultivars studied varied greatly in their concentrations of individual phenolic compounds and temperature stability for accumulation. The concentrations of a wide range of identified phenolic compounds were strongly influenced by temperature over the 12–24 °C range, often with opposite temperature gradient patterns for compounds within the same subclass. Accumulation of anthocyanins and flavonols increased under natural long day conditions, which provided an increased daily light integral, while under identical light energy conditions, photoperiod had little or no effect on the concentration of phenolic compounds. Furthermore, with the exception of members of the hydroxycinnamic acid subclass, the concentration of most phenolic compounds was higher in berries ripened outdoors than in the phytotron, apparently due to screening of UV-B radiation by the glass cover.

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As part of an overall assessment of the commercial suitability of strawberry cultivars for the Nordic environment, we studied 13 diverse cultivars in an experimental field in South East Norway. Early-maturing cultivars were characterized by early initiation of floral primordia and early flowering and fruit maturation. High temperatures in July and early August delayed floral initiation in the early cultivars, resulting in more synchronous initiation of early and late cultivars. The recent Norwegian cultivar ‘Nobel’, which has an everbearing parent, differed from the other cultivars by early initiation also at elevated summer temperature. Inadequate yield and berry size were identified as important causes for outdating of older cultivars, such as ‘Senga Sengana’ and ‘Glima’. Overall, the high-yielding and large-fruited ‘Sonata’ was judged as the best fresh consumption cultivar in Norway, and market trends indicate that it will continue to expand its market share at the expense of ‘Korona’, mainly because of inadequate fruit firmness and shelf life of the latter. Adequate yields and berry quality justify the use of the late maturing ‘Florence’ for prolongation of the fresh market season. The results are discussed together with practical experiences and market preferences in an attempt to provide overall cultivar recommendations for Norway.

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The effects of daylength and temperature on flowering of the cultivated octoploid strawberry (Fragaria × ananassa Duch.) have been studied extensively at the physiological level, but information on the molecular pathways controlling flowering in the species is scarce. The flowering pathway has been studied at the molecular level in the diploid short-day woodland strawberry (F. vesca L.), in which the FLOWERING LOCUS T1 (FvFT1)–SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (FvSOC1)–TERMINAL FLOWER1 (FvTFL1) pathway is essential for the correct timing of flowering. In this work, we show by transgenic approach that the silencing of the floral repressor FaTFL1 in the octoploid short-day cultivar ‘Elsanta’ is sufficient to induce perpetual flowering under long days without direct changes in vegetative reproduction. We also demonstrate that although the genes FaFT1 and FaSOC1 show similar expression patterns in different cultivars, the regulation of FaTFL1 varies widely from cultivar to cultivar and is correlated with floral induction, indicating that the transcription of FaTFL1 occurs at least partially independently of the FaFT1–FaSOC1 module. Our results indicate that changing the expression patterns of FaTFL1 through biotechnological or conventional breeding approaches could result in strawberries with specific flowering and runnering characteristics including new types of everbearing cultivars.

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In order to identify the optimal harvest time and monitor changes in raspberry (Rubus idaeus L. cv. Glen Ample) fruit quality during ripening and storage, quality was assessed and compared by physical, chemical and sensory fruit quality criteria. Visual classification of fruit colour according to the Natural Colour System (NCS) chart and by physical measurement of fruit adherence to the receptacle or fruit compression resistance yielded parallel and highly significant results. The light red colour stage corresponding to NCS S code 3060-Y90R was identified as the optimal harvest stage for commercial fresh marketing of the ‘Glen Ample’ cultivar. Fruit harvested at this stage developed the same chemical and sensory qualities as in situ matured fruits and maintained high sensory quality after 8 days of storage in the dark at 2–3 °C. As the fruits mature, the concentration of titratable acids decreases, whereas the concentrations of anthocyanins and the sugar:acid ratio increase in parallel with colour development. While correlation analysis revealed a correlation between sensory traits like sweetness and acidity with sucrose and the sugar:acid ratio, respectively, the overall fruit tastefulness was not strongly correlated with any specific phytochemical component, thus illustrating the complex nature of this sensory trait. Due to its ease of performance, picking raspberry fruits related to a standardised colour chart is recommended for picking raspberry fruits with optimal quality.