Strawberry Production in Central Europe

Abstract

This paper focuses on the cropping systems in central European countries such as Belgium, The Netherlands, UK, Ireland, Germany, Switzerland and the northern part of France and Italy. During the last decade there has been a consistent increase in programmed “out-of-season” strawberry production in several central European countries. This is being achieved in part, by using cultivars with different cropping seasons, but mainly by sequential planting of cold-stored plants and by growing strawberries in greenhouses and plastic tunnels. These methods have made it possible to extend the strawberry production for 11 months, from the end of February until mid January in central European countries with moderate climates.     

The effect of thermal environment,planting date and crown size on growth,development and yield of Fragaria × ananassa Duch. cv. Elsanta

Summary

The effects of environmental conditions, planting date and crown size on the timing, intensity and duration of cropping in the strawberry Fragaria × ananassa cv. Elsanta were investigated. Temperature was positively correlated with the rate of progress to fruiting whereas crown size had no effect. The first fruit reached harvest maturity after an estimated 891 day-degrees had elapsed above a base temperature of 2.9°C for waiting bed plants and 831 day-degrees above a base temperature of 2.4°C for cold stored plants. Temperature was negatively correlated with total yield, berry number and average berry weight for both waiting bed and cold stored plants of different crown sizes. Yield, berry number and average berry weight were positively correlated with crown size. The effect of temperature on the yield components appeared to be due to its effect on vegetative growth of the plants: canopy development was more limited at warmer temperatures. These results can be used to generate models to predict the effect of growth environment on cropping in strawberry.     

Strawberry Production,Growth and Development in Northern Climates

Abstract

This paper focuses on the cropping systems in northern European countries such as Norway and Finland. Winter injury commonly occurs in strawberry fields in northern climates and inadequate snow cover further aggravates the problem. During the last decade there has been an increase in programmed “out-of-season” strawberry production. Greenhouse producers aim for year-round production, whereas those using polyethylene tunnels extend the main production season to include May/June and September/October. The dominant strawberry cultivars in Nordic countries are ‘Senga Sengana’ for the processing industry and the Dutch cultivar ‘Korona’ is preferred for direct fresh market consumption due to its good flavor and high yields. Recently, ‘Honeoye’ has gained considerable interest among Danish and Swedish growers due to its high productivity and its relatively low susceptibility to grey mold. In Finland, the Norwegian cultivar ‘Jonsok’ is one of the most popular cultivars due to its high tolerance to winter injury and grey mold.     

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

Abstract

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.     

Crown branching and cropping potential in strawberry (Fragaria ananassa Duch.) can be enhanced by daylength treatments

Summary

When strawberries (Fragaria ananassa Duch.) are produced in a greenhouse, usually two crops a year are obtained; in the fall and in the spring. To increase productivity, new cultivation techniques are needed. The aim of this study was to examine the effect of daylength treatments on the performance of strawberry plants to improve plant production protocols. The possibility of obtaining two successive crops during forcing was explored by exposing plants of cultivar Korona to two successive short day (SD) treatments followed by cold storage. The following daylength treatments were studied: 3 wk SD + 2 wk long day (LD) + 3 wk SD (3SD2LD3SD), 3 wk SD + 4 wk LD + 3 wk SD (3SD4LD3SD), and 10 wk SD (10SD). In addition, crown branching was studied in plants subjected to SD treatments. Two successive SD treatments enabled two successive flowering and cropping periods during greenhouse forcing after eight weeks of cold storage.The first SD treatment caused crown branching and induced flowering in the apical meristem of the main-crown and in the oldest axillary meristem(s), whereas younger axillary meristems were induced during the second SD treatment. Marketable yield and the number of inflorescences were comparable in 3SD4LD3SD and 10SD, but considerably lower in 3SD2LD3SD. However, this study demonstrated the high cropping potential of artificially SD treated plants, which makes them a potential alternative for greenhouse strawberry cultivation. Multi-crowned plants of ‘Korona’ can be produced by subjecting young plants to a three week SD treatment, and crown branches can be induced to flowering by a new SD treatment resulting in a very high cropping potential. Induced plants can be stored at –1°C for later forcing.     

Manipulating Flower Induction Through Temperature and Photoperiod Fluctuations

Abstract

In Norway and Finland strawberry cultivation in greenhouses is limited. However, interest in strawberry cultivation in greenhouses or under high tunnels is increasing rapidly. Controlled environments offer growers an opportunity to produce strawberries year-round, and specifically during the off-season (September to June) when Norwegian and Finnish strawberries are not readily available and carry a high price. In Norway, Grimsby Gartneri has developed one method for winter production of strawberries, using artificial light. In this system ‘Korona’ strawberry plants are induced to flower three times during the season using artificial short days resulting in a continual harvest from November until June. In Finland, there are few greenhouse strawberry producers. They grow Junebearing cultivars and obtain a maximum of two crops a year, in the spring and in the fall. Artificial light is not used in this production system. In order to develop out-of-season strawberry production in Finland, artificial short day treatments have been studied at the University of Helsinki since 1998     

四季草莓寒地高效栽培技术研究

利用四季草莓新品种‘四季公主2号’为试材,在吉林省开展四季草莓寒地高效栽培技术研究。结果表明,秋季定植四季草莓的产量和经济效益比春季定植的高,最佳定植时期8月10—25日;最佳栽培方式是平畦;春季采收后修剪使植株更新复壮,可提高草莓秋季产量和品质。     

Effect of prolonged cold storage on the production capacity of strawberry plants

After cold storage for various periods (42, 99, 155, 189, 227 and 259 days) strawberry waiting-bed plants cultivar ‘Elsanta’ were planted on six dates between January and August. Plant performance was evaluated simultaneously in a growth chamber under controlled environmental conditions and in a greenhouse. Starch content in the crown tissue was clearly reduced during the cold storage period.

In the greenhouse trials a variable decline in fruit number and yield per plant was found in relation to the length of cold storage and the temperature conditions during the growth and harvest period. Also in the growth chamber, under a constant temperature regime, a significant decline in the number of flowers per plant developing up to anthesis was observed after increasing periods of storage. This indicates that it is not only stressing climatical conditions after planting which are influencing the performance of cold stored plants. Also, the length of cold storage strongly affects plant vigour and productivity. This is related to the carbohydrate status of the plants after cold storage.     

Characterisation of the thermodormancy response in the everbearing strawberry ‘Everest’.

Summary

Temperature regimes that induce and ameliorate cropping troughs (“thermodormancy”) were evaluated over two seasons for the everbearing strawberry ‘Everest’. When plants were exposed to 26°C for 5, 10, 20 or 30 d in July, heat-induced troughs in cropping were observed in August. An important discovery was that cool (13°C) night temperatures ameliorated the severity of thermodormancy. In this study, thermodormancy appeared to be due principally to flower abortion post-anthesis, as large numbers of flowers emerged in mid-July, during the high temperature treatments, but went on to produce low fruit numbers in mid-August. Flower initiation itself (monitored by crown dissection) was not reduced by high temperatures. The observation that night-time temperature is critical for thermodormancy has significance for commercial production, in which protected cropping tends to increase average temperatures throughout the season, and venting tends to focus on day-time temperatures.     

Effect of propagation material on some quality attributes of strawberry fruit (Fragaria x ananassa, var. Selva)

In the Mediterranean region, cold-stored plants (summer planting system) are used as the main strawberry planting material (plant establishing period July–August). However, recently fresh plants (winter planting system) have also started being used for strawberry production (plant establishing period October–November). As the plantations originated from cold-stored or fresh plants differ in plant growth and yield, some differences in fruit quality have also been expected; therefore, the objective of the current study was to compare fruit quality of plants originated from different propagation material. Cold-stored plants were well developed before the beginning of the spring harvest, while fresh plants continued growth concomitantly with fruiting. The harvesting period of cold-stored plants lasted 4–6 weeks (second week of April–second half of May). Fresh plants produced fewer and larger fruits than cold-stored plants, but for a longer harvest period, which lasted throughout all summer. Differences in soluble solids and dry matter content between the fruits from cold-stored and fresh plants were observed in the first three sampling dates in both years of the experiment. In some sampling dates, significant differences in anthocyanin, titratable acidity and ascorbic acid content, were observed between fruits of plants originated from different propagation material.     

Veränderte Temperaturbedingungen als Folge des Klimawandels und ihre Bedeutung für den Erdbeer- und Himbeeranbau

The importance of the predicted temperature increase as a consequence of change in climate on strawberry and raspberry production is discussed with regard to flower initiation, dormancy and temperature optimum for photosynthesis on the basis of a literature review and temperature data from the location of Geisenheim, Germany. June-bearing strawberry and biennial fruiting raspberry cultivars and remontant cultivars for both species are considered. In the future, problems will be expected for flower initiation of June-bearing raspberry and for breaking of dormancy of strawberry and raspberry cultivars with high chilling requirement. The predicted temperature increase will lead to early flowering and cropping of the berries.     

Promoting Second Cropping in Strawberry by Avoiding Chilling or Advancing Spring Growth

Second crops of the cultivar Redgauntlet were greatly increased in size and advanced in season from September and October to July and August by two methods. In the first, plants were potted in January or early February and grown in a cool glasshouse before being planted outdoors in March. In the second method, chilling was avoided by overwintering plants in cool glasshouses and again planting them outdoors in March. The relation between winter temperatures and the subsequent growth and fruiting of the plants is discussed.     

Class II chitinase accumulated in the bark tissue involves with the cold hardiness of shoot stems in highbush blueberry (Vaccinium corymbosum L.)

To understand the development of cold hardiness in highbush blueberry plants (Vaccinium corymbosum L.), we investigated seasonal changes in the protein compositions of current-year and overwintered shoots. Electrophoresis using SDS-polyacrylamide gels indicated that the amounts of a few proteins increased in autumn, in association with an enhancement of cold hardiness. Of these proteins, 65- and 60-kDa proteins were confirmed to be dehydrins by western blotting. While the levels of most of the accumulated proteins decreased in April, a 27-kDa protein maintained its level in the overwintered stem during spring. The amino acid sequence deduced from a cDNA for this protein showed significant similarities with known chitinases. The stem segments from overwintered shoots sampled in July showed higher cold hardiness against sub-zero temperature than those from current-year shoots, and the bark tissue of overwintered shoots had higher cold resistance than that of current-year shoots. The 27-kDa protein (BC27) was mostly found in the bark tissue of stems. Appreciable accumulation of this protein in floral buds was not detected. The purified BC27 protein exerted a cryoprotective effect on protoplasts subjected to a freeze–thaw treatment. These results suggest that the stems of highbush blueberry develop a system of cold hardiness different from that of the buds and apices, and that the accumulation of chitinase is involved in tolerance to low temperature in winter or unseasonably low temperature in spring.     

Effect of temperature on dormancy in strawberry

Early in autumn, at the end of September or at the beginning of October, strawberry plants of the cultivars ‘Glasa’ and ‘Tioga’ were transferred from outdoors to separate phytotron glasshouses at constant temperatures of 10° and 14°C. In November a number of these plants were chilled at 3°C for 0 to 4 weeks and subsequently forced; the rest remained at 10° and 14°C until June.The plants kept at 10°C and subsequently chilled and forced, grew faster and more vigorously than those pretreated at 14°C. The 14° plants showed more pronounced growth differences resulting from the length of the chilling treatments than did the 10° plants. Those remaining continuously at 10° developed vigorously from March onwards, while those at 14°C retained their flat appearance into June. These results showed that a continuous temperature as high as 10°C was still able to break dormancy in the strawberry plants, while 14°C was ineffective.     

Relationships between yield components in first cropping year and average yield of short-day strawberries over two main seasons

Fruit productivity of the garden strawberry, Fragaria × ananassa Duch., is a result of interrelationship of yield components contributing to it directly or indirectly. The main aim of the investigation was to find out whether there exists any general regularity, connecting relationships between main yield components in first cropping year to average yield of two main seasons. Two successive studies which primarily included 23 genotypes, differing in yield components and productivity, each, were planted in field conditions in spring 1999 and in spring 2000, respectively, and used for data collection to explore the material obtained in them. Four key yield components and average yields were measured in both cropping years, after which all possible ratios between the components were calculated to find out: first, the relationships to be influential on average yield of the two main seasons; second, type of the probable yield dependence upon the ratios; and, third, their values leading to high yields. Two ratios between the key yield components in first season, i.e.: inflorescence number per plant to branch crown number per plant, named ratio 1, and fruit weight (g) to flower count per inflorescence, named ratio 2, have been found to be related to average yield. An irregular surface, with a single peak falling approximately in its centre, describes average yield dependence upon the ratios. Values of the two ratios falling in the range of 1.0–1.6 each, provided that they are close, have enabled plants to produce high yields cumulatively over two first years. The paper highlights the most important differences in plant behaviour and yield dynamics of strawberry genotypes, depending on combinations of the ratios in first year, discerning those, which have been particularly advantageous to obtain very high yields, and are influenced by negative environmental factors least of all. Based on the findings, a method of predicting of average yield has been developed. Following this, usefulness of the method and possibilities of its using in strawberry breeding and variety trial are discussed.     

缺钾胁迫对连作草莓生长和土传病害的影响

 以草莓‘红颜’品种为试材,设缺K（K+ 48.75 mg · L^-1,缺量水平）、1/2K（K+ 415.58 mg · L^-1, 半量水平）和全量K（K+ 782.41 mg · L^-1,正常水平）营养液处理,对缺钾胁迫与草莓连作障碍的关系进 行了探讨。结果表明,缺钾处理显著抑制二茬草莓植株地下部分和地上部分的生长,其中缺K 的长势最 弱,1/2K 比全量K 的长势强;缺K 二茬植株根系分泌物对草莓组培苗生长有显著影响,表现为低浓度（1%、 2%）根系分泌物促进幼苗侧根和茎叶生长,高浓度（4%）则抑制根系生长。不同浓度钾营养液处理的三 茬植株分别接种尖孢镰刀菌和大丽轮枝菌后,在不同时期比未经过连作的基质对照发病都严重。缺K 三 茬植株发病最重,接菌后10 d 时病情指数就高达75,全量K 三茬植株发病次之,1/2K 三茬植株发病相 对较轻。因此,缺K 环境会加重草莓的连作障碍,适宜的K 量对草莓连作障碍的防治有重要意义。     

西北冷凉区草莓温室栽培试验

受气候条件的影响,草莓在高海拔冷凉地带的栽培,采收期短,产量低。试验表明,设施栽培可以延长花芽分化及发育时间,使果实的采收期延长,还能抑制匍匐茎的发生,从而提高草莓产量。温室反季节栽培是该类地区草莓生产比较合理的方式。     

冬春大棚有棱丝瓜高效丰产栽培技术

为有效缓解广州地区冬春季节瓜果蔬菜的供给不足,保障蔬菜质量安全,提高种植经济效益,满足居民对优质安全、绿色无公害蔬菜的需求,大面积推广有棱丝瓜标准化高效丰产栽培技术具有重大意义。在充分利用有棱丝瓜这一地方品种耐湿、抗寒特性的基础上,于秋冬季塑料大棚内,采用薄膜覆盖简易生产技术,促使有棱丝瓜延后成熟、连续结瓜,并且结合陆续采收的方式,延长市场供应时间;同时采取品种选择、温汤浸种、低温炼苗、高畦整地、双株定植、田间管理、采收留种等措施,对解决春节期间丝瓜的市场需求和打破常规生产中出现的连作障碍具有明显改善作用。     

草莓微繁殖苗移栽后开花结果的研究

以草莓品种丰香、吐德拉、全明星、北辉为试材,研究了移栽时期、生根方式对草莓微繁殖苗移栽后开花结果的影响。草莓微繁殖苗在春季移栽时期对开花结果习性具有重要影响,2月份移栽,4个品种都开花结果,成熟期比露地栽培草莓大约晚20d,全明星、吐德拉和丰香3个品种的产量与普通苗露地栽培的产量相近;3月份移栽,虽然有开花结果,但并无经济学产量;4月份移栽,4个品种均未开花。不同品种的微繁殖苗在开花株率、单株产量等指标上差异显著,其中全明星微繁殖苗的开花结果能力最强,2月份移栽的微繁殖苗的开花株率达89.3%,单株产量达98.2g。在花序数上,培养基中不含植物生长调节剂处理显著高于附加植物生长调节剂的处理。     

Evaluation of three methods to assess winter hardiness of strawberry genotypes

Summary

In northern regions, winter injury is a frequent problem in strawberry (Fragaria X ananassa Duch.) production. Controlled freezing tests provide an option for screening of winter survival potential in different genotypes. In this study, winter hardiness of strawberry genotypes was evaluated by three low-temperature procedures: an artificial hardening-dehardening-rehardening programme accompanied by freezing tests, prolonged freezing test, and laboratory cold hardiness measurements of field-grown plants. Rooted runner cuttings of five June-bearing strawberry cultivars and three new selections were tested in the course of two years. Relative winter hardiness of the genotypes could not be predicted by the hardening-dehardening-rehardening programme employed in the present study. Prolonged freezing at –6?C yielded promising results, whereas storage at _4?C and –8?C failed in discrimination between genotypes. Field-grown plants were sampled for cold hardiness measurements in January, March and April. The genotypes were best differentiated in January, at a fully acclimated state. The results indicate that strawberry winter hardiness can be evaluated by testing differences in the ability to survive lengthy exposure to sub-lethal low temperatures, or by applying conventional freezing tests to measure cold hardiness in different genotypes after field acclimation.