Short-day Strawberry Cultivars Research Articles

Impact of Pre-Plant Fertilizer Rates in Combination with Polysulphate® on Soil Nitrogen Distribution and Yield of Short-Day Strawberries (Fragaria × ananassa cv. Camarosa)

Strawberries are by far the most produced soft fruit (blueberries, raspberries, blackberries, and strawberries) worldwide, with China and the US being the two countries with the most production. In the US, strawberries reached a farm gate value of more than USD 3 billion in 2023 and are predominantly grown in the open field on an annual cycle in hilled-up soil beds using plastic mulch (plasticulture). This process relies on adequate pre-plant fertilizer application for plant establishment and fruit development. In North Carolina (US), it is current practice to apply pre-plant fertilizer containing 67 nitrogen (N) kg/ha; however, with increasing fertilizer costs and environmental concerns, questions remain as to whether or not pre-plant full-spectrum fertilizer rates can be reduced and substituted with organic low-N fertilizer sources, such as Polysulphate, without impacting yield or fruit quality. For this reason, field trials were established to evaluate the impact of pre-plant fertilizer rates on strawberry production (‘Camarosa’). Trials were conducted in the 2019–2020 and 2020–2021 seasons at two locations in North Carolina. The following N-rate pre-plant fertilizer treatments were applied: 80.1, 67.3, 54.1, 41.1, 33.6, 28.0, and 0 kg/ha. NO3 and NH4 content were frequently assessed in each replicate in the raised bed profile between planting and spring fertilizer application. Marketable and total strawberry yields were assessed over 6 weeks in the spring of 2020 and 2021. Our trial results showed that, especially in sandy soil, N rapidly declined under plastic within the first 8 weeks after pre-plant fertilizer application. However, no impact between pre-plant fertilizer rates and plant yield was observed. Treatments that contained Polysulphate and lower amounts of full-spectrum fertilizer showed significantly lower N concentrations in the soil while maintaining similar yields and fruit quality compared to grower-standard pre-plant fertilizer treatments. In summary, our results show that it is possible to reduce N content in pre-plant fertilizer by up to 50% compared to current recommendations without causing yield loss in short-day strawberry cultivars.

Effect of Low Temperature on Photosynthetic Physiological Activity of Different Photoperiod Types of Strawberry Seedlings and Stress Diagnosis

During the early growth stage of plants, low temperatures can alter cell permeability, reduce photosynthetic capacity, and have adverse effects on crop growth, development, and yield. Different strawberry cultivars have varying cold tolerance. In this study, we investigated the changes in cell permeability and photosynthetic activity of short-day and long-day types of strawberry cultivars under varying degrees of low-temperature stress, and evaluated the extent of cellular damage using photosynthetic and chlorophyll fluorescence parameters. The experiment utilized short-day strawberry cultivars ‘Toyonoka’ and ‘Red Face’, and long-day strawberry cultivars ‘Selva’ and ‘Sweet Charlie’ seedlings. Low-temperature treatments were set at −20, −15, −10, −5, 0, 5, and 10 °C for 12 h. The research demonstrated that short-day strawberries had greater tolerance to low temperatures, and all four strawberry cultivars began to experience low-temperature stress when the temperature was below 5 °C. A temperature range of 0 to −10 °C played a crucial role in causing severe cold damage to the strawberries. The low-temperature stress levels were constructed based on electrolyte leakage, with photosynthetic physiological characteristics serving as references. The study proves that the photosynthetic and chlorophyll fluorescence parameters can serve as effective probes for diagnosing low-temperature stress in strawberry seedlings, and their combination provides higher accuracy in identifying stress levels than any single type of parameter.

First Report of Sclerotinia Fruit and Crown Rot Caused by Sclerotinia sclerotiorum on Short-Day Strawberry in Maryland.

With over 1,000 producers in the Mid-Atlantic region, short-day strawberry (Fragaria x Ananassa Duch.) represents an economically important industry. In spring of 2016, a white rot was observed on strawberry stem, crown, and fruit tissue at two Maryland farms. Light to dark brown necrotic lesions, white mycelium and medium to large black sclerotia were present on petioles and fruit (Fig. 1). These symptoms were most consistent with Sclerotinia fruit rot and crown rot caused by Sclerotinia sclerotiorum (Lib.) de Bary (Maas 1998), not previously described in the region (Farr and Rossman 2019). Lesion margins were excised, surface disinfested (70% EtOH for 30 s and 0.1% NaClO for 1 min) and placed onto potato dextrose agar (PDA) amended with 0.03% tetracycline. Single hyphal tip cultures were obtained which formed fluffy white to tan mycelium, no asexual conidia, and numerous pigmented sclerotia resembling S. sclerotiorum (Bolton 2006). DNA was extracted from five isolates and the internal transcribed spacer (ITS) region was amplified by PCR using primers ITS1/ITS4; all five ITS sequences (533 bp) had 99-100% similarity with S. sclerotiorum (GQ375746) in Genbank. Sequences of SL1380 and SL1382 were submitted to NCBI under the accession numbers MK429976 and MK429977, respectively. These two isolates were evaluated for abilities to cause fruit and stem petiole rot. Pathogenicity on fruit was examined by placing a 5 mm plug from five-day-old cultures on surface disinfested fruits, with mock-inoculated (PDA plug only) and non-inoculated controls. Fruit were placed in incubators (~98% RH, 22°C, 10:14 hrs L:D) and arranged in a complete block design with three blocks and five fruit/treatment/block; the study was conducted twice. White hyphae and sclerotia formed on 41 to 53% of fruit inoculated with both isolates, necrotizing fruit within 6 days post inoculation (DPI); Sclerotinia fruit rot did not develop in controls. Pathogenicity on petioles was examined in a replicated study on three-month-old cv. Flavorfest using a petiole inoculation method described in (Peltier and Grau 2008); mock-inoculated stems were placed in sterile PDA. Plants were arranged in the greenhouse (~20-28°C; 12:12 hrs L:D) in a randomized complete block design with three blocks and three plants/treatment. Dark brown necrosis averaging 5.8 ± 0.2 mm in length developed on 100% of plants in both isolate treatments within 3 DPI and by 6 DPI had expanded to 42.1 ± 4.8 mm on average, spreading into the crown on some plants. Necrosis did not extend beyond 2 mm from the cut tip in controls. The pathogen was recovered from surface disinfested tissue for both isolates. In a subsequent study, stem rot susceptibility was compared among four short-day strawberry cultivars common to the region, cvs. Flavorfest, Chandler, Allstar and Honeoye (same method as above). Stem lesions were 2 to 3 times longer on cv. Flavorfest (41.78(ave) ± 6.73(se) mm) compared to all other cultivars (13.68(ave) ± 1.56(se) mm) (P < 0.0001, Tukey's test). To our knowledge, this is the first report of both Sclerotinia fruit and crown rot on strawberries anywhere in the mid-Atlantic region. Our results indicate that cv. Flavorfest, a recently developed cultivar with expanding acreage, may be more susceptible to Sclerotinia. These are both unusual diseases circumglobally, especially Sclerotinia fruit rot (Farr and Rosman 2019, Maas 1998); the new occurrence in this region may be associated with increased use of this cultivar.

Exploring Plant Performance, Fruit Physicochemical Characteristics, Volatile Profiles, and Sensory Properties of Day-Neutral and Short-Day Strawberry Cultivars Grown in Texas.

To assist increasing annual acreage of Texas-grown (U.S.A.) strawberries, it is essential to select cultivars with excellent plant and fruit quality characteristics suitable to the diverse environments. This study assessed multiple traits of 10 strawberry cultivars grown under high tunnels. A significant difference (p ≤ 0.05) was observed for all traits, which possessed a wide variability of metabolites. Plant analysis (number of live plants, plant vigor, and harvest yield) indicated that the yield ranged from 226 to 431 g/plant, positively correlated to plant vigor. Fruit physicochemical characteristic analysis, including red color (absorbance at 500 nm) and taste-associated indicators [°Brix, titratable acidity (TA), and total soluble solids (TSS)/TA], showed that °Brix and TSS/TA ranged from 8.0 to 12.9 and from 9.1 to 15.3, respectively. More than 300 volatiles were identified using solid-phase microextraction-gas chromatography-mass spectrometry, and total volatiles varied 1.5 times with high variance of individual compounds between cultivars. Descriptive sensory analysis indicated that strawberry flavor was positively associated with sensory attributes of sweetness, jammy, fruity, buttery, fresh, and creamy while negatively related to bitterness, astringency, and sourness. Partial least squares regression indicated that strawberry flavor was highly correlated with sweet taste and volatile composition. No specific relationship between these traits and day-neutral or June-bearing varieties was identified. Ideal cultivars for Texas growing conditions with superior and balanced flavor qualities were Albion, Sweet Charlie, Camarosa, Camino Real, and Chandler.

Influence of genetic variability on the quality of strawberry cultivars: sensorial, physical-chemical and nutritional characterization

Strawberries are berry-type fruits that are very popular and widely consumed all over the world. The sensorial, physical-chemical and nutritional characteristics of strawberries are parameters of quality that influence the choices of consumers. However, these characteristics may be influenced by intrinsic and extrinsic factors that alter the fruit quality. The concentrations of nutrients and other chemical compounds in strawberries may increase and/or decrease according to the cropping system, maturation stage, climatic conditions, and preservation and storage methods. Factors characteristic of the cultivar, such as the genetic profile, may also influence the composition of strawberries. In this context, the objective of this research was to evaluate the sensorial, physical-chemical and nutritional characteristics of different strawberry cultivars to identify the genotype(s) with the best characteristics for commercialization and human consumption. The day-neutral strawberry cultivar "Aromas" and short-day strawberry cultivars "Camarosa, Camino Real, Dover, Sweet Charlie, and Tudla" were cultivated in the Olericultura Sector of the State University of the Midwest (UNICENTRO), Paraná State, Brazil. The fruits were characterized in relation to their physical-chemical, nutritional and sensorial aspects. According to the sensorial profiles, the Camarosa, Camino Real, Dover, and Tudla genotypes showed greater acceptability among consumers. Camarosa, Sweet Charlie, and Tudla presented better physical-chemical characteristics for human consumption, while the cultivars Camarosa, Dover, and Tudla had the best nutritional contents. In general, it is concluded that the genotypes Camarosa and Tudla are the most favourable for human consumption, according to their sensorial, physical-chemical and nutritional characteristics.

'Florida Brilliance' Strawberry

‘Florida Brilliance’ (PPAF) is a new short-day strawberry cultivar released by the University of Florida and commercialized in 2018. This cultivar was originally evaluated as breeding selection FL 13.26-134. It originated from a 2013 cross between breeding selection FL 11.31-14 (female parent) and selection FL 10-153 (male parent). ‘Florida Brilliance’ has been tested over several years at the University of Florida Gulf Coast Research and Education Center (GCREC) in Wimauma, FL, at the Florida Strawberry Growers Association (FSGA) headquarters in Dover, FL, and on several commercial farms.&#x0D; The target audience of this publication is strawberry growers in West-Central Florida, with nursery growers as a secondary audience. Its main purpose is to describe important attributes of ‘Florida Brilliance’ and make management recommendations that will help growers obtain optimum performance from this cultivar. Comparisons are made to ‘Florida Radiance’ (Chandler et al. 2009) (marketed as ‘Florida Fortuna’ outside the U.S. and Canada), Sweet Sensation® ‘Florida127’ (Whitaker et al. 2015) (hereafter referred to as ‘Florida127’) and ‘Florida Beauty’ (Whitaker et al. 2017).

‘Malling Centenary’, a short-day strawberry cultivar from NIAB-EMR

‘Malling Centenary’, a short-day strawberry cultivar from NIAB-EMR

&lt;b&gt;Mycorrhizal inoculation affects the phytochemical content in strawberry fruits

The aim of this research was to evaluate the effect of the inoculation date of arbuscular mycorrhizal fungi on the fruit quality and the content of phytochemicals in a strawberry soilless growing system. The experiment was performed in Huelva (Spain) and was conducted in a greenhouse on the La Rabida Campus of Huelva University under natural light and temperature from October 2013 to June 2014. Three short-day strawberry cultivars ('Splendor', 'Sabrina' and 'Fortuna') were grown in polyethylene bags filled with coconut fibres. Randomized block design, with 3 repetitions and factorial arrangement (3 cultivars x 3 treatments), was established. Each replicate consisted of one bag with 12 plants supporting structures at 40 cm height. The treatments were: T1 = mycorrhizal inoculation in the transplantation; T2 = mycorrhizal inoculation 30 days after transplantation (DAT); and T0 = control treatment, without inoculation. Arbuscular mycorrhizal fungi inoculation significantly affected the contents of anthocyanin and phenolics. When the inoculation is performed in the transplantation, the fruits showed a high content of anthocyanin and total phenolics. The mycorrhizal inoculation influences decreasing the acidity in fruit throughout the growing season and increase firmness only during the early stage of production.

Initial Crown Diameter of Strawberry Bare-root Transplants Affects Early and Total Fruit Yield

The standard strawberry (Fragaria ×ananassa) production system in Florida uses bare-root transplants with three to five leaves; however, commercial transplants are typically variable in size. The objective of this experiment was to study the effects of transplant crown diameter on the subsequent performance of three short-day strawberry cultivars under central Florida conditions. Trials were carried out during the 2012–13 and 2013–14 growing seasons with six treatments resulting from the combination of three cultivars and two crown diameter categories. Transplants of ‘Florida Radiance’, ‘Strawberry Festival’, and WinterStar™ were sorted into two initial crown diameter size ranges: &lt;10 mm and &gt;10 mm. Treatments were established in a split-plot design with cultivars as the main plot and four replications. Dry plant biomass was collected at 6 weeks after transplant (WAT). Canopy diameter and crown diameter were measured at 6 and 18 WAT and fruit harvest started at 8 WAT. There were no interactions between cultivar and initial crown diameter for any of the measured variables. For early yield, larger crowns led to 46% (3.5 Mg·ha−1) and 38% (3.9 Mg·ha−1) higher early yield than smaller crowns in 2012–13 and 2013–14, respectively. Crown diameters &gt;10 mm also resulted in 18% (23.5 Mg·ha−1) and 27% (17.4 Mg·ha−1) higher total yields in 2012–13 and 2013–14, respectively.

STRAWBERRY PLANT ARCHITECTURE AND FLOWER INDUCTION IN PLANT PRODUCTION AND STRAWBERRY CULTIVATION

Short-day strawberry cultivars induce flowers principally as a result of shorter photoperiod and lower temperatures. Dissection of the strawberry plants gives more information about plant quality. In the present study, the plant architecture is analysed weekly during plant production followed by a commercial strawberry production. An overview of plant development is achieved for strawberry cultivars ‘Elsanta’ and ‘Clery’. The main aim is to understand which buds are responsible for the formation of inflorescences which produce strawberries for the first and the second crop. During the plant production, the two cultivars grow quite similar concerning architecture, but there is a difference in the start of generative growth. Also the development of the axillary bud just below the terminal inflorescence occurs at different dates. The second crop is a result of development of axillary buds just below the terminal inflorescence of the lateral crowns. The plant architecture at planting is not only determining the first, but also the second crop. Logically, the artificial conditions (heating and night-interruption treatments) in the greenhouse affect plant growth and flower induction. Flower development can continue under artificial lighting, but induction and initiation is inhibited by this treatment. Heating after a first crop gives the possibility for the further development of initiated flowers and is crucial for a successful second crop.

Advances in Strawberry Substrate Culture during the Last Twenty Years in the Netherlands and Belgium

Commercial soilless systems for strawberry production were developed in the early 1970s in greenhouses in the Netherlands and Belgium. The use of substrate systems in permanent structures enabled year-round strawberry production and was an alternative to strawberry production on soils contaminated by root diseases, nematodes, and insects under permanent structures where strawberries were grown intensively year-around. In the last 20 years, economically sustainable substrate systems have been developed in the Netherlands and Belgium using production technologies introduced by skilled growers, researchers, and substrate suppliers. The use of high yielding short-day strawberry cultivars Elsanta and Sonata suited for out-of-season production has enabled this system to compete with open-field strawberry production. In 2010, soilless strawberry production in Western Europe exceeded 1,600 ha; with increased restrictions on use of soil fumigants and herbicides, it is expected that substrate culture will continue to expand.

Relationship between plant architecture and fruit production of the short-day strawberry cultivar Gariguette

This research was carried out to assess the relationship between the architecture of strawberry plants before chilling and winter-spring fruit production in a soilless forced culture system. On 11 September 2008, trayplants of the cultivar Gariguette were placed in a heated glasshouse and either exposed to long-day photoperiodic conditions or short-day photoperiodic conditions for 53 days. In addition, plants were held 26 days under short-day photoperiodic conditions followed by 27 days of long-day photoperiodic conditions or 26 days under long-day photoperiodic conditions followed by 27 days of short-day photoperiodic conditions. Architecture prior to chilling gave indications about the first fruit production period in winter-spring (1 March to 30 April 2009). The earliest short-day photoperiodic condition treatments produced the earliest fruits. These treatments exhibited the most developed inflorescences in the pre-chilling architectural analysis and the fewer nodes between the youngest expanded leaf and the terminal inflorescence. The plants that received 53 days of long-day photoperiodic conditions treatment had the least developed terminal inflorescence before chilling and the latest production. The architecture analysis of Gariguette trayplants could predict the earliness rank (first to last) but not the yield rank during the first harvest period.

Produção de cultivares de morango, utilizando túnel baixo em Pelotas

O objetivo deste trabalho foi avaliar o desempenho produtivo de novos cultivares de dia-curto de morangueiro ('Earlibrite', 'Sabrosa' e 'Florida Festival'), nas condições edafo-climáticas de Pelotas (RS), tendo como padrão o cultivar 'Camarosa', usando-se túnel baixo. O experimento foi realizado com sistema de irrigação por gotejamento. O transplantio das mudas foi realizado em maio de 2008, sendo utilizadas mudas procedentes da região da Patagônia, na Argentina. O delineamento experimental foi de blocos casualizados, com parcelas subdivididas no tempo, com quatro repetições. As unidades experimentais foram constituídas por 42 plantas, que foram avaliadas, semanalmente, quanto ao número, massa da matéria fresca e produção de frutos, no período de agosto a dezembro de 2008. Nas avaliações, consideraram-se apenas os frutos comercializáveis, descartando-se aqueles com defeitos e com massa inferior a 5 g. Verificou-se que a produção acumulada de frutos por planta do 'Sabrosa' é maior que a do 'Florida Festival' e do 'Earlibrite', menor, porém, que a do 'Camarosa'. O número de frutos produzidos por planta do 'Sabrosa' e do 'Florida Festival' é maior que o do 'Earlibrite', menor, porém, que o do 'Camarosa'. Quanto à produção de massa da matéria fresca média dos frutos, o 'Sabrosa' e o 'Camarosa' são superiores a do 'Florida Festival' e a do'Earlibrite'. Apesar de apresentarem padrões de desempenho produtivo diferenciados, os três novos cultivares de morangueiro testados mostraram-se com alto potencial produtivo, constituindo-se em interessantes alternativas de produção para os agricultores de Pelotas.

Influence of short day treatment on autumn fruit production of June-bearing strawberry cultivars

Short-day (SD) strawberry cultivars were grown in 2008 and 2009 fall each year to evaluate effects of short-day (SD) treatment on flowering and fall fruit production in the high elevation of South Korea. In 2008, daughter plants of six cultivars ‘Maehyang’, ‘Seolhyang’, ‘Keumhyang’ (Korean short-day cultivars), ‘Akihime’, ‘Red pearl’, and ‘Sachinoka’ (Japanese short-day cultivars) were exposed to short-day (10-h photoperiods) conditions at the high elevation (HE, 800 m elevation) for 35 days beginning in late June. On 31 July, plants were removed from the SD environment and established in a substrate system at the highland. In 2009, the ‘Akihime’ and ‘Seolhyang’ were examined again. In 2008, flower bud initiation rate was above 90.0% for all cultivars except for ‘Akihime’ (83.3%). Fruit harvest commenced 1st of October 2008 and average fruit weight was consistently > 20g except for ‘Sachinoka’ (18 g). By mid-November, plants of ‘Seolhyang’ and ‘Akihime’ produced 222–260 more grams of fruit compared to other cultivars, with ‘Seolhyang’ having the earliest production. In 2009 experiment, flower bud initiation rates of ‘Akihime’ and ‘Seolhyang’ plants were 85.4% and 82.4%. Due to the earlier planting in 2009, fruit harvest commenced on 8 September (one month earlier than in 2008) and extended over 10 weeks. Yield and fruit numbers of ‘Akihime’ and ‘Seolhyang’ were 397.7 g, 22.7 and 331.7 g, 19.8, respectively. Results of this study indicate that exposure to SD photoperiods and relatively cool temperatures at HE can increase autumn fruit production in SD strawberry cultivars ‘Akihime’ and ‘Seolhyang’.

Effects of Runner Tip Size and Plugging Date on Fall Flowering in Short-Day Strawberry (Fragaria × ananassa Duch.) Cultivars

Producing strawberry transplants from runner tips that were plugged ∼1 month earlier (early July) than the standard time (early August) promoted fall flowering in some short-day strawberry cultivars. In 2002,100% of ‘Chandler’ transplants produced in early July flowered in the fall, but none of the August-plugged ‘Chandler’ transplants flowered in the fall. In 2003, 73% of ‘Chandler’ transplants produced in mid-July from average-size runner tips and less than half of transplants from small-size runner tips flowered in the fall. Again, August-plugged plants did not flower in the fall. Flowering was absent in ‘Northeaster’ plants. Under protected cultivation, July-plugged ‘Sweet Charlie’ plants bloomed earlier and produced more fruit in November and December than those plugged in August. This study showed that fall flowering in ‘Chandler’ and ‘Sweet Charlie’ strawberry is possible if the transplants are prepared by plugging runner tips in early July. This novel technique for propagating strawberry transplants for annual plasticulture combined with production under high tunnels creates an opportunity for strawberry production in early winter and again in the spring (double cropping) in the mid-Atlantic coast region.

Allelopathic effects of juglone and walnut leaf extracts on growth, fruit yield and plant tissue composition in strawberry cvs. ‘Camarosa’ and ‘Sweet Charlie’

SummaryWe conducted an experiment in a heated greenhouse to investigate the effects of juglone (5-hydroxy-1,4-naphthoquinone) and walnut (Juglans regia L.) leaf extracts on yield, growth, chemical and plant nutrient element composition of short-day strawberry cultivars ‘Camarosa’ and ‘Sweet Charlie’. Strawberry plants were treated with 1 mM juglone or walnut leaf extracts (undiluted, or diluted 1:2, 1:4, 1:8). Vegetative and generative plant growth was inhibited strongly by treatment with both juglone and undiluted walnut leaf extracts. Fruit yield per plant, numbers of fruit per plant, average fruit weight, crowns per plant, numbers of leaves, leaf area, fresh root weight, total soluble solids, vitamin C, and acidity were all lower for juglone-treated plants compared to controls. All nutrient elements analysed in leaves were generally lower than in controls for all treatments except 1:8 diluted walnut extract. Results from this study should address concerns about growth inhibition of strawberry plants under walnut-based intercropping systems.

Iron Nutrition of Strawberries Grown in Peat Bags

Abstract Plants of short-day strawberry cultivar ‘Elsanta’ (Fraga-ria X ananassa Duch.) were grown in peat bags with six rates of iron (Fe) in the nutrient solution (0,10, 20, 30, 60 and 120 μmol/liter). A Fe leaf value lower than 45 ppm on a dry matter basis was associated with deficiency symptoms. A minimum concentration of 10 μmol/liter Fe in the nutrient solution was considered satisfactory for growth and good fruit production of ‘Elsanta’ grown on peat bags.