Plug Transplants Research Articles

Determination of strawberry Plug Transplants Planting date in Relation to Yield and Fruit Quality

Determination of strawberry Plug Transplants Planting date in Relation to Yield and Fruit Quality

Susceptibility of seven strawberry cultivars to Belonolaimus longicaudatus and interaction with Phytophthora cactorum

Summary Belonolaimus longicaudatus and Phytophthora cactorum are pathogens threatening Florida strawberry production. The interaction among these and cultivar susceptibility were assessed in this study. Cultivars ‘Sensation® Florida127’, ‘Florida Brilliance’, ‘Florida Radiance’, ‘Winterstar™ FL 05-107’, ‘Florida Elyana’, ‘Strawberry Festival’ and ‘Florida Beauty’ were used to conduct one trial using plug transplants and a second trial using bare-root transplants, which was repeated twice. A factorial combination of P. cactorum (+/−) and B. longicaudatus (+/−) inoculation was applied to evaluate strawberry cultivar resistance to P. cactorum and B. longicaudatus as well as their interaction. The effect of P. cactorum on the canopy, root length, and root and shoot weight was dependent on cultivars. For the plug transplant trial, the overall average of plant mortality among all tested strawberry cultivars was 0.1%, suggesting higher tolerance against P. cactorum when vigorous transplants were used. Conversely, the repeated bare-root transplant trial demonstrated different levels of susceptibility in strawberry cultivars when transplants were inoculated with P. cactorum. ‘Sweet Sensation’ ‘Florida127’, ‘Florida Brilliance’, ‘Florida Radiance’ and ‘Winterstar FL 05-107’ were highly susceptible, whereas ‘Florida Elyana’ and ‘Strawberry Festival’ were resistant. Moreover, ‘Florida Beauty’ was moderately resistant to P. cactorum. Our findings demonstrated the importance of using vigorous transplants to reduce P. cactorum damage. Sting nematode reproduction was suppressed when strawberry transplants were inoculated with P. cactorum, suggesting an antagonistic interaction between the pathogens. None of the cultivars was tolerant to B. longicaudatus as this nematode reproduced from 13.4- to 23.8-fold and caused root damage under glasshouse conditions.

Winter cover crops increased nitrogen availability and efficient use during eight years of intensive organic vegetable production.

Efficient use of nitrogen (N) is essential to protect water quality in high-input organic vegetable production systems, but little is known about the long-term effects of organic management on N mass balances. We measured soil N and tabulated N inputs (organic fertilizers, compost, irrigation water, atmospheric deposition, cover crop seed, vegetable transplant plugs and fixation by legume cover crops) and exports in harvested crops (lettuce, broccoli) over eight years to calculate soil surface and soil system N mass balances for the Salinas Organic Cropping Systems study in Salinas, CA. Our objectives were to 1) quantify the long-term effects of compost, cover crop frequency and cover crop type on soil N, cover crop and vegetable crop N uptake, and yield, and 2) tabulate N balances to assess the effects of these factors on N export in harvested crops, soil N storage and potential N loss. Results show that across all systems only 13 to 23% of N inputs were exported in harvest. Annual compost applications increased soil N stocks but had little effect on vegetable N uptake or yield, increasing the cumulative soil system N balance surplus over eight years by 999 kg ha-1, relative to the system receiving organic fertilizers alone. Annually planted winter cover crops increased N availability, crop uptake and export; however, biological N fixation by legumes negated the positive effect of increased harvest exports on the balance surplus in the legume-rye cover cropped system. Over eight years, rye cover crops improved system performance and reduced the cumulative N surplus by 384 kg ha-1 relative to the legume-rye mixture by increasing N retention and availability without increasing N inputs. Reduced reliance on external compost inputs and increased use of annually planted non-legume cover crops can improve efficient N use and cropping system yield, consequently improving environmental performance.

Alleviating heat stress during early-season establishment of containerized strawberry transplants

BACKGROUND: Earlier planting under subtropical climatic conditions has been proposed as a means of increasing strawberry (Fragaria×ananassa Duch.) profitability but exposes transplants to heat stress. OBJECTIVE: Therefore, physical and chemical methods of ameliorating heat stress on the establishment, growth, and yield of containerized strawberry transplants were evaluated. METHODS: We used a split-plot design with white-on-black (white) mulch and black mulch as main plot treatments; and a factorial arrangement of transplant type and stress-prevention application was randomly assigned to the subplots. ‘Florida Radiance’ Jiffy plug and tray plug transplants were treated either with s-abscisic acid or with kaolin. RESULTS: White mulch resulted in greater plant vigor and vegetative growth than black mulch. Kaolin plus white mulch provided protection against heat stress as indicated by increased photosynthesis rates. At 4 weeks after transplanting, plant vigor and shoot growth were higher and flowering occurred earlier with Jiffy plug transplants than with tray plug transplants. Early marketable yields were higher with white mulch than with black mulch in three of the four site years. CONCLUSIONS: A combination of white mulch, Jiffy plug transplants, and kaolin application appears to have the best potential for alleviating heat stress during early-season strawberry establishment under subtropical conditions.

P-I metalloproteinases and L-amino acid oxidases from Bothrops species inhibit angiogenesis.

Background:Snake venoms are composed of pharmacologically active proteins that are evolutionarily diverse, stable and specific to targets. Hence, venoms have been explored as a source of bioactive molecules in treating numerous diseases. Recent evidences suggest that snake venom proteins may affect the formation of new blood vessels. Excessive angiogenesis has been implicated in several pathologies including tumours, diabetic retinopathy, arthritis, inter alia. In the present study, we have examined the effects of P-I metalloproteinases isolated from Bothrops moojeni (BmMP-1) and Bothrops atrox (BaMP-1) and L-amino acid oxidases (LAAO) isolated from B. moojeni (BmLAAO) and B. atrox (BaLAAO) on biochemical and functional aspects of angiogenesis. Methods:P-I metalloproteinases and LAAO were purified from venom by molecular size exclusion and ion-exchange chromatography and subsequently confirmed using mass spectrometry. The P-I metalloproteinases were characterized by azocaseinolytic, fibrinogenolytic and gelatinase activity and LAAO activity was assessed by enzyme activity on L-amino acids. Influence of these proteins on apoptosis and cell cycle in endothelial cells was analysed by flow cytometry. The angiogenic activity was determined by in vitro 3D spheroid assay, Matrigel tube forming assay, and in vivo agarose plug transformation in mice. Results:P-I metalloproteinases exhibited azocaseinolytic activity, cleaved α and partially β chain of fibrinogen, and displayed catalytic activity on gelatin. LAAO showed differential activity on L-amino acids. Flow cytometry analysis indicated that both P-I metalloproteinases and LAAO arrested the cells in G0/G1 phase and further induced both necrosis and apoptosis in endothelial cells. In vitro, P-I metalloproteinases and LAAO exhibited significant anti-angiogenic properties in 3D spheroid and Matrigel models by reducing sprout outgrowth and tube formation. Using agarose plug transplants in mice harbouring P-I metalloproteinases and LAAO we demonstrated a marked disruption of vasculature at the periphery.Conclusion:Our research suggests that P-I metalloproteinases and LAAO exhibit anti-angiogenic properties in vitro and in vivo.

Production Techniques for Strawberry Plugs in West-central Florida

Florida-produced strawberry (Fragaria ×ananassa) plug transplants (SP) are a potential alternative to bare-root transplants (BR). The adoption of this technology could represent a reduction in water usage for plant establishment and potentially higher early yield, as SP may establish more quickly than BR. Thus, the objective of this study was to evaluate the effect of time in nursery and tray sizes, on early and total strawberry yield for Florida-produced SP for ‘Florida Radiance’, ‘Strawberry Festival’, and Sweet Sensation® ‘Florida127’. Runners from Florida-produced mother plants were collected in mid and late August from 2012 to 2015. SP were grown for either 4 or 6 weeks according to the treatment and established in 30-, 40-, 50-, and 72-cell trays, and compared with BR (control). Additionally, strawberry tips from California were evaluated for SP production. BR consistently had higher early yield than SP, ranging from 36% to 91%, between 2012 and 2016. SP produced the same or higher total yield than BR. Florida-produced SP should be grown for 4 weeks before field transplanting in 50-cell trays based on the results of this study. Furthermore, there was no difference between California and Florida tips for total yield. In all seasons, all SP were established with 20% of the total irrigation water used for the BR. Thus, SP could potentially result in water savings of almost 820,800 gal/acre per season, but the early yield of SP would need to be improved to match BR performance.

Heat stress mitigation effects of kaolin and s-abscisic acid during the establishment of strawberry plug transplants

In Florida, early planting to take advantage of higher prices for early fruit has been proposed for the strawberry (Fragaria ×ananassa Duch.) industry, but it can expose strawberry transplants to heat stress which is common in sub-tropical conditions. Additionally, strawberry plug transplants are of interest for addressing the high sprinkler irrigation requirement for bare-root transplant establishment. The objective of this study was to examine the effectiveness of antitranspirants, s-abscisic acid (s-ABA) and kaolin, in heat stress mitigation for strawberry plug transplants. Trials were conducted in Citra, Florida during three seasons (2015–2016, 2016–2017, and 2017–2018). The s-ABA was applied as a root dip just prior to transplanting. In 2015–2016, s-ABA was applied at 250, 500, 750, and 1000 mg L−1. Lower rates of 50–250 mg L−1 were used during the subsequent years. Kaolin was applied at 56 kg·ha−1 as either a single foliar spray immediately after transplanting or as two consecutive sprays seven days apart. Transient stomatal closure with ≤ 100 mg L−1 of s-ABA provided protection from heat stress with little or no negative side effects and resulted in higher early and total season yields than the untreated control. Both the single and double applications of kaolin consistently protected strawberry transplants from heat stress, enhancing photosynthesis as well as early and total marketable fruit weight. Since the double application of kaolin provided higher early marketable fruit weight than the single kaolin application, the double applications of kaolin appear to have better potential than the single application for mitigating heat stress in sub-tropical conditions during strawberry plug transplant establishment.

Strawberry Plug Transplant Production in Trays: The Influence of Genotype, Initial Ramet Size and Substrate

The present study was conducted during the period 2014-2016 at the greenhouse facilities of the Department of Horticulture, Faculty of Agriculture, Suez Canal University.The experiment tested the effects of growing three daughter plants (ramets) sizes based on crown diameter (large > 7 mm, medium 5-7 mm and small < 5 mm) in combination with three medium types (M1, coco peat + vermiculite + perlite; M2, coco peat + rice hull + sawdust; M3, coco peat + rice hull + rice straw in 1:1:1 v/v) on plug transplant growth in container (84-cell foam trays) of three strawberry cultivars. Results of the main effect of the initial ramet size indicated positive effects of large ramet on obtaining better plug plant vegetative and rooting characteristics than medium or small size ramets. Results of the main effect of medium types showed that both M1 and M2 produced plug plants with better leaf petiole length, leaf fresh weight (FW) and Dry weight (DW) and crown diameter than M3, but root dry mass was not affected by medium types. Plug transplant grown on M3 had better contents of chlorophyll and carotenoids in their leaves than those on M1 or M2. Nutrient analysis of plug plant leaves indicated that plug plants grown on M1 had more P, K, Fe and Cu, and those on M2 had more N, Ca and Mn, while plug plants derived from M3 had more Mg and Zn. Results also indicated that plug transplants were not different in some vegetative and rooting characters among the different strawberry cultivars, especially in number of leaves per transplant, leaves FW and DW, crown DW and root DW, while root length was better in transplants of cv. 'Festival' than 'Tudla' and 'Sweet Charlie'. Leaves of plug plants in cv. 'Tudla' recorded higher chlorophyll and carotenoids than 'Festival' and 'Sweet Charlie' and also had more N, P, and K contents. Generally results indicated that optimum plug transplant production and growth was obtained by the culture of large size ramets in trays filled with any of the tested medium types and cultivars. These results indicated the possibility of producing large number of strawberry plug transplants in Egypt using soilless, suspended growing system as alternative to their production in field nursery to avoid the hazardous effects of soil fumigation and pesticide use.

Growth and Flowering Responses of Seed-propagated Strawberry Seedlings to Different Photoperiods in Controlled Environment Chambers

The present study investigated growth properties and flowering response of seed-propagated strawberry (Fragaria ×ananassa) seedlings under artificial lighting with different photoperiods to support the development of a high-performance system for the indoor production of strawberry plug transplants. Seedlings of ‘Elan’ and ‘Yotsuboshi’ were grown for 38 days under sunlight in a greenhouse or under light-emitting diode (LED) illumination with photoperiods of 8/16, 12/12, 16/8, or 24/0 hours (light/dark) in growth chambers. The photosynthetic photon flux (PPF) in these photoperiods was maintained at 350, 230, 175, or 115 μmol·m−2·s−1, respectively, to provide the same daily light integral (DLI) of 10 mol·m−2·d−1. The average of DLI of sunlight was 9.9 mol·m−2·d−1. Seedling growth was greater with the 16- and 24-hour photoperiods than with sunlight even though all three treatments provided about the same DLI. Flower buds of the seedlings grown under longer photoperiods started significantly earlier after transplanting in ‘Elan’ but not in ‘Yotsuboshi’. Thus, strawberry transplant production under artificial lighting with an optimized photoperiod can provide high-quality transplants, although the effectiveness is cultivar-specific.

Field Evaluation of Insecticides for Control of Cabbage Maggot (Diptera: Anthomyiidae) in Rutabaga in Canada.

At the time of this research, there were only two insecticides registered for control of cabbage maggot, Delia radicum L., in rutabaga in Canada, one of which (diazinon) will be deregistered by 2017, and resistance having been reported in some areas for the other (chlorpyrifos). To screen for chemistries to replace these organophosphates, and obtain efficacy data comparable between key vegetable brassica production areas in Canada, four small plot field studies were conducted concurrently in British Columbia, Saskatchewan, Ontario, and Quebec in 2009. These studies followed standardized protocols for seeding, application of insecticide drenches, sampling and damage assessment, and generally tested the same products. Of the insecticides evaluated, none provided maggot control comparable with the industry standard, chlorpyrifos. However, cyantraniliprole (Cyazypyr 200SC; registered in 2015 as Verimark) applied at 3 g AI (15.0 ml product)/100 m row of seeded rutabagas consistently provided the next highest reduction in % culls, suggesting the efficacy of this chemical may be improved if used at higher rates. The results of these studies are discussed in the context of current literature on D. radicum management in rutabaga. Future management strategies are also discussed, including a transplant plug treatment approach for increasing the dosage per plant and efficacy of chemistries such as Cyazypyr 200SC in the field.

Produção de estolhos de cultivares de morangueiro em função da condutividade elétrica da solução nutritiva

RESUMO As características da solução nutritiva empregada em sistemas de cultivo sem solo com uso de substratos é um dos fatores que influenciam a emissão de estolhos. A condutividade elétrica (CE) da solução nutritiva está relacionada com concentração de nutrientes na solução nutritiva, mas ainda pouco relatada na literatura para produção de mudas de morango no Brasil. Assim, o objetivo do trabalho foi determinar o efeito da condutividade elétrica da solução nutritiva no crescimento de plantas matrizes de morangueiro e na produção de estolhos para produção de mudas com torrão. O delineamento experimental foi inteiramente casualizado, esquema fatorial (5x2), sendo as CEs de 0,4; 0,8; 1,2; 1,6 e 2,0 dS/m e as cultivares de morangueiro a Camino Real e Oso Grande, com 20 repetições de uma planta matriz. O plantio foi feito em vasos com areia, sendo as plantas fertirrigadas com solução nutritiva nas cinco condutividades elétricas. Os estolhos foram coletados semanalmente e contabilizados, sendo descartados aqueles necrosados. Quinzenalmente, foram coletadas amostras de 15 estolhos de cada tratamento, nas quais foi determinado o número de folhas, diâmetro de coroa e massa seca. Em fevereiro, uma amostra de 45 estolhos coletados em cada tratamento foi enraizada em bandejas de poliestireno contendo 40 cm3 de substrato orgânico para determinação da taxa de formação de mudas, do diâmetro de coroa, do número de folhas expandidas e da massa seca da parte aérea e das raízes. Ao final do experimento, foram coletadas, também, plantas matrizes para determinação da área foliar e da massa seca de raízes, coroas, pecíolos e folhas. Concluiu-se que o aumento da condutividade elétrica reduziu o crescimento das plantas matrizes e a produção de estolhos e de mudas com torrão foram maiores com valores de CE na faixa entre 0,8 e 1,1dS/m.

Insecticides applied to soil of transplant plugs for Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) management in broccoli

Chemical control with insecticides, typically applied as foliar sprays or chemigation, is the primary tactic used to manage Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae). We evaluated the efficacy of 14 insecticides, including both systemic and non-systemic insecticides, against B. hilaris applied as a seedling tray drench. Experiments were conducted in both greenhouse and field settings. In all experiments, we used the maximum label rate of insecticides and calculated dose per seedling based on this rate and standard plant density per hectare. Each seedling in the tray received 2-mL insecticide solution, and the seedlings were then exposed to B. hilaris adults after transplanting in cages for greenhouse experiments or natural B. hilaris populations in the field experiments. A scale system (0–4) was used to evaluate the severity of B. hilaris feeding injury on leaves where 0 = no injury and 4=>75% of the leaf margins with B. hilaris feeding injury. We evaluated damage using the rating system, percentage of damaged leaves, number of feeding injury sites, as well as plant height, leaf width, and fresh and dry weight. In the greenhouse experiment, percentage of injured leaves, number of injury sites, and damage rating were significantly lower for transplants treated with acetamiprid, clothianidin, dinotefuran, imidacloprid, and thiamethoxam, and cyclaniliprole compared with the untreated. There was a relationship between feeding injury sites and plant height, leaf width, fresh and dry weight (R2 > 0.5) in both 2015 field experiments. Similarly, the transplants treated with acetamiprid, clothianidin, dinotefuran, imidacloprid, thiamethoxam, thiamethoxam + chlorantraniliprole, imidacloprid + β-cyfluthrin and cyclaniliprole had significantly lower damage ratings than those treated with chlorpyrifos, bifenthrin, tolfenpyrad, flonicamid, cyantraniliprole, spinetoram and the untreated control. For transplanted broccoli, treatment of transplant plugs with neonicotinoid insecticides prior to planting can be an effective method for controlling B. hilaris.

Tomato Transplant Production Method Affects Plant Development and Field Performance

ABSTRACTIn addition to direct seeding of tomato (Solanum lycopersicum L.), several plant establishment methods are used, with each presenting its own set of advantages and limitations. Transplant production methods including normal plug tray, bare root transplants with known plant density, and broadcast seeded bare root transplants were evaluated in peat : perlite 60:40 (v/v) or compost : field soil 1/3:2/3 (v/v) substrates against direct seeding of tomato in the field. The highest plant establishment percentage and leaf number before the first truss were for plug transplants; earlier fruit ripening was from bare root transplants. Broadcast seeded bare root transplants and direct-seeded plants had the greatest first yield. Fruit production increased following the second harvest toward maximum potential yield in transplanted seedlings, regardless of production method. Compared to direct seeding, greater total yield was from transplants due to more possible harvests.

Mechanism of antagonism by Streptomyces griseocarneus (strain Di944) against fungal pathogens of greenhouse-grown tomato transplants

Antagonism by Streptomyces griseocarneus Benedict (strain Di944), a filamentous bacterium isolated from the rhizosphere of a field tomato plant, was investigated in culture and in the rhizospheres of tomato to understand the mechanisms of suppression of damping-off and root rot of tomato plug transplants. The bacterium inhibited Rhizoctonia solani Kühn, the oomycete pathogens Pythium and Phytophthora spp., and fungal pathogens including Alternaria alternata, Botrytis cinerea, Fusarium oxysporum f. sp. lycopersici, F. oxysporum f. sp. radicis-lycopersici, F. solani, Thielaviopsis basicola and Verticillium dahlia, but not bacterial pathogens of tomato as determined by agar diffusion bioassay. Standard physicochemical analyses of the metabolites extracted from cell-free culture filtrates of S. griseocarneus Di944 identified the presence of an antifungal compound, a pentaene macrolide complex, designated as rhizostreptin. This antifungal compound was also detected by ultra-violet spectrophotometry and high performance liquid chromatography in the extract from the rhizospheres of tomato transplants grown from seeds treated with S. griseocarneus Di944 and, thus, found to be suppressive to damping-off caused by R. solani. Germination of spores and growth of mycelia of pathogenic fungi of tomato were inhibited by rhizostreptin at concentrations between 0.5 and 2 µg mL−1. Rhizostreptin was found to be more fungitoxic than other known polyene macrolides, amphotericin-B, nystatin, filipin and candicidin-type heptaene, as determined by agar diffusion bioassay. A substantial growth of S. griseocarneus Di944 in mineral medium supplemented with cell-wall components of R. solani indicated the ability of the bacterium to utilize fungal cell-wall components as carbon and nitrogen sources. This was further confirmed by the production of hydrolytic enzymes chitinase, glucanase, phospholipase and proteinase, by S. griseocarneus Di944 grown in mineral medium supplemented with glucose and (NH4)2SO4 or cell-wall components of R. solani as carbon and nitrogen sources. Secretion of extracellular antifungal pentaene macrolide and fungal cell-wall degrading enzymes is believed to be the major mechanism by which the necrotrophic mycoparasite S. griseocarneus Di944 inhibits fungi and oomycetes responsible for damping-off and root rot of tomato transplants. However, studies involving mutant strains of S. griseocarneus Di944 that are incapable of producing antifungal pentaene and fungal cell-wall degrading enzymes are needed to further confirm the mechanisms of antagonism by S. griseocarneus Di944.

Systemic application of chlorantraniliprole to cabbage transplants for control of foliar-feeding lepidopteran pests

The diamide insecticide chlorantraniliprole is registered for control of lepidopteran pests in cabbage (Brassica oleracea L.). Taking advantage of its root-uptake systemic properties, chlorantraniliprole is labeled for use with a variety of soil application methods in different countries, depending on pests and local practices. We investigated the efficacy of different cabbage transplant application methods using a leaf consumption bioassay. In the laboratory, we compared different transplant water volumes, characterized the effect of transplant plug size when the insecticide is applied by drenching or soaking the seedling tray, and determined the effect of different soil types. At three field sites, we compared the efficacy of chlorantraniliprole applied in transplant water or as a tray drench or tray soak treatment. In the laboratory, transplant water volume did not affect the level or duration of Trichoplusia ni (Hübner) mortality caused by chlorantraniliprole. When seedling trays were drenched with insecticide solution, transplant plug size did not affect mortality, but when trays were soaked with an equivalent volume of solution, mortality was higher with small plugs. Transplanting plugs treated by transplant water, drench or soak into different soil types did not affect mortality caused by chlorantraniliprole. In the field, transplant water application was the most effective method at all three locations. Tray soak was the most variable application method. Different application methods can be used to take advantage of the systemic characteristics of chlorantraniliprole. Among the methods tested, transplant water and tray drench resulted in more consistent mortality under variable field conditions.

Short communication. Irrigation temperature effects on seedling growth and transplant quality of tomato, pepper and eggplant

During production of plug transplants, high plant density and small cell size increases seedling height. The resulting tall, weak-stemmed, plants are difficult to transplant and can be easily damaged. One technique that can prevent excessive seedling elongation is irrigation with cold water. Seedlings of tomato, pepper and eggplant were planted in cell plug trays in greenhouses and irrigated daily, in the morning, with water at different temperatures. The temperaturas tested were 3°C, 9°C and tap water (15.5-16.5°C). Irrigation with cold water reduced seedling stem height by 48-58% in tomato, 24-42% in pepper and 17-36% in eggplant. Cold water irrigation significantly affected stem diameter, number of leaves, shoot and root dry weights and leaf chlorophyll content. These results show that irrigation with cold water can effectively control plant height in plug-grown seedlings.

Fruit yield of strawberry stock plants after of runner tips production

The main objective of this research was to determine fruit yield of strawberry ( Fragaria x ananassa D.) stock plants in a cropping system after producing runner tips and plug plants. Micropropagated stock plants were planted on October 1 st , 2008, in a soilless growing system. Runner tips bearing at least one visible root nodule were harvested at 43, 66 and 87 days after planting, rooted and planted as multiplied stock plants to produce plug plants. On May 26 th , 2009, stock plants were defoliated and plug plants were planted as a control treatment for fruit production. Early fruit yield and number of fruits were higher on stock plants. It was concluded that in a soilless growing system, in the second cropping year after producing runner tips, strawberry stock plants can reach a higher early and total fresh fruit yield than plug transplants. Therefore, they should not be discarded after the production of runner tips.

Fruit yield of strawberry stock plants after runner tip production by different cultivars

The main objective of this research was to determine fruit yield of strawberry (Fragaria x ananassa) stock plants in a cropping system after producing runner tips and plug plants. Micropropagated stock plants were planted in a soilless growing system. Runner tips bearing at least one visible root nodule were harvested at 43, 66 and 87 days after planting, rooted and planted as multiplied stock plants for producing plug plants. Treatments consisted of micropropagated stock plants of cultivars INIA Arazá, INIA Guenoa and INIA Yvapitá, planted on October 1st, 2008 (T1); multiplied stock plants planted on November 28th (T2) and on December 21st, 2008 (T3), and on January, 10th, 2009 (T4). On May 22nd, 2009, stock plants were defoliated and plug plants of the same cultivars were planted as control for fruit production. Early fruit yield and number of fruits were higher on stock plants, but fresh fruit yield was higher on control plants. Total fruit yield and number were higher on stock plants of 'INIA Arazá' and 'INIA Guenoa'. We concluded that strawberry stock plants reach higher early and total fresh fruit yield than plug transplants in the second cropping year after producing runner tips in a soilless growing system. Therefore, plants should not be discarded after the production of runner tips.

Sugar and organic acid contents of day-neutral and ever-bearing strawberry cultivars in high-elevation for summer and autumn fruit production in Korea

This study was conducted to evaluate the contents of sugars and organic acids in the fruits of day-neutral (DN) and ever-bearing (EB) cultivars grown in high-elevation in Korea. Six DN and five EB cultivars were established in bench-top substrate culture system in high tunnel. Plug transplants were planted on 5 May, 2011 and complete nutrition was supplied during the whole experimentation. Fruit harvest started in early June, and lasted until middle of November. The fruits of DN cultivars showed higher organic acid contents but lower sugar contents and total soluble solids than those of EB cultivars. ‘Albion’ showed the highest contents of total soluble solids and sugars, and sugars/acids ratio among DN cultivars. Among EB cultivars, ‘Goha’ possessed mediate contents of sugars, organic acids and total soluble solid without any extreme weakness in qualities. ‘Charlotte’ showed the highest contents of sugars and total soluble solid, and sugar/acid ratio, and the lowest contents of organic acids; the unique character of ‘Flamenco’ was its lowest contents of organic acids among EB cultivars. Fruit total soluble solid contents, sugars, organic acids, and sugar/acid ratio all significantly varied with the progressive seasons and an interactive effects between cultivars and harvest time on above fruit quality parameters were found. Integrated cultural strategy based on contents of sugars and organic acids was discussed according to fresh consumption and process purposes.

Effects of Short Day Conditioning, Chilling and GA3 Treatments to Yield and Fruit Quality in Strawberry Plug Transplants Aiming Early Fruit Production

In this study, we tested the effects of short day (SD), chilling (Ch) and gibberalic acid (GA3) treatments on the yield and fruit characteristics of ‘Camarosa’ and ‘Sweet Charlie’ plug plants under a freeze-protected greenhouse in Mediterranean conditions for two growing seasons in 2006-2007 and 2007-2008. The treatments included control (ambient day length and temperature); SD (8 h days) and ambient temperature; SD + Chilling (Ch) (18/12°C day/night temperatures); SD + Ch (10°C); SD + Ch (2°C); and, GA3 (10 ppm applied to the plants in November). In each growing season, the plug plants were planted in mid-August using bag culture. Yield, fruit weight, firmness, total soluble solids (SS), titratable acidity (TA), and SS/TA ratio were investigated. Considerable amounts of early yield (March and April) were recovered from ‘Sweet Charlie’; 116 and 72 g/plant in the first and second growing seasons, respectively. ‘Sweet Charlie’ also had consistently higher total yield than ‘Camarosa’ (457 vs. 400 g/plant in the 2006-2007 season and 446 vs. 406 g/plant in the 2007-2008 season). Treatment did not have a consistent effect on the fruit quality traits measured. The results indicated that although SD conditioning, Ch and GA3 treatments may have an effect on the total and early yield of strawberries, these effects may be cultivar-dependent and further regulated by environmental factors. Therefore, we propose that low-chilling varieties be utilized for early fruit production that can initiate flower buds in warmer, longer days.