Strawberry
The garden strawberry is a widely grown hybrid plant cultivated worldwide for its fruit. The genus Fragaria, the strawberries, is in the rose family, Rosaceae. The fruit is appreciated for its aroma, bright red colour, juicy texture, and sweetness. It is eaten either fresh or in prepared foods such as jam, ice cream, and chocolates. Artificial strawberry flavourings and aromas are widely used in commercial products. Botanically, the strawberry is not a berry, but an aggregate accessory fruit. Each apparent 'seed' on the outside of the strawberry is actually an achene, a botanical fruit with a seed inside it.
The garden strawberry was first bred in Brittany, France, in the 1750s via a cross of F. virginiana from eastern North America and F. chiloensis, which was brought from Chile by Amédée-François Frézier in 1714. Cultivars of F. × ananassa have replaced the woodland strawberry F. vesca in commercial production. In 2023, world production of strawberries exceeded ten million tons, led by China with 40% of the total.
Strawberries have appeared in literature and art from Roman times; Virgil wrote about the snake lurking beneath the strawberry, an image reinterpreted by later writers including Shakespeare. Strawberries appear in Italian, Flemish, and German paintings, including Hieronymus Bosch's The Garden of Earthly Delights. It has been understood to symbolise the ephemerality of earthly joys or the benefit that blessed souls get from religion, or to allegorise death and resurrection. By the late 20th century, its meaning had shifted: it symbolised female sexuality.
Evolution
History and taxonomy
In Europe, until the 17th century cultivated plants were obtained by transplanting strawberries from the forests; the plants were propagated asexually by pegging down the runners, allowing them to root, and then separating the new plants. F. virginiana, the Virginia strawberry, was brought to Europe from eastern North America; F. chiloensis, the Chilean strawberry, was brought from Chile by Amédée-François Frézier in 1714. At first introduction to Europe, the Chilean strawberry plants grew vigorously, but produced no fruit. French gardeners in Brittany in the 1750s noticed that the Chilean plants bore only female flowers. They planted the wild woodland strawberry F. vesca among the Chilean plants to provide pollen; the Chilean strawberry plants then bore abundant fruits.In 1759, Philip Miller recorded the 'pine strawberry' in Chelsea, England. In the gardens of the Palace of Versailles, France, Antoine Nicolas Duchesne found in 1766 that F. ananassa was a hybrid of the recently arrived F. chiloensis and F. virginiana. In 1806, Michael Keens of Isleworth, England selected the Keens Imperial cultivar from many hybrids, winning the Royal Horticultural Society's Silver Cup. Both the names 'pine' and 'ananassa' meant "pineapple", for the fruit's flavour. Modern strawberries and both parent species are octoploid. The genome sequence of the garden strawberry was published in 2019.
Further breeding in the following centuries produced varieties with a longer cropping season and more fruit. During the Green Revolution of the 1950s, agronomists used selective breeding to expand phenotypic diversity of the garden strawberry. Adoption of perpetual flowering hybrids not sensitive to changes in photoperiod gave higher yields and enabled production in California to expand.
Phylogeny
The phylogeny of the cultivated strawberry within the genus Fragaria of the Rosaceae family was determined by chloroplast genomics in 2021. The polyploidy is shown as "2N" etc. by each species.Description
In culinary terms, a strawberry is an edible fruit. From a botanical point of view, it is not a berry but an aggregate accessory fruit, because the fleshy part is derived from the receptacle. Each apparent seed on the outside of the strawberry is actually an achene, a botanical fruit with a seed inside it.Composition
Nutrition
Raw strawberries are 91% water, 8% carbohydrates, 1% protein, and contain negligible fat. A reference amount of supplies 33 kilocalories, is a rich source of vitamin C, and a good source of manganese, with no other micronutrients in significant content. Strawberries contain a modest amount of essential unsaturated fatty acids in the achene oil.Phytochemicals
Garden strawberries contain diverse phytochemicals, including the dimeric ellagitannin agrimoniin, which is an isomer of sanguiin H-6. Other polyphenols present include flavonoids, such as anthocyanins, flavanols, flavonols and phenolic acids, such as hydroxybenzoic acid and hydroxycinnamic acid. Although achenes comprise only about 1% of the total fresh weight of a strawberry, they contribute 11% of all polyphenols in the whole fruit; achene phytochemicals include ellagic acid, ellagic acid glycosides, and ellagitannins.Pelargonidin-3-glucoside is the major anthocyanin pigment in strawberries, giving them their red colour, with cyanidin-3-glucoside in smaller amounts. Strawberries also contain purple minor pigments, such as dimeric anthocyanins.
Flavour and fragrance
Sweetness, fragrance and complex flavour are important attributes of strawberries. In plant breeding and farming, emphasis is placed on sugars, acids, and volatile compounds, which improve the taste and fragrance of the ripe fruit. Esters, terpenes, and furans are the chemical compounds having the strongest relationships to strawberry flavour, sweetness and fragrance, with a total of 31 out of some 360 volatile compounds significantly correlated to desirable flavour and fragrance. In breeding strawberries for the commercial market in the United States, the volatile compounds methyl anthranilate and gamma-decalactone, prominent in aromatic wild strawberries, are especially desired for their "sweet and fruity" aroma characteristics. As strawberry flavour and fragrance appeal to consumers, they are used widely in manufacturing, including foods, beverages, perfumes and cosmetics.Allergy
Some people experience an anaphylactoid reaction to eating strawberries. The most common form of this reaction is oral allergy syndrome, but symptoms may also mimic hay fever or include dermatitis or hives, and, in severe cases, may cause breathing problems. Proteomic studies indicate that the allergen may be tied to a protein for the red anthocyanin biosynthesis expressed in strawberry ripening, named Fra a1. White-fruited strawberry cultivars, lacking Fra a1, may be an option for people allergic to strawberries. They ripen but remain pale, appearing like immature berries. A virtually allergen-free cultivar named 'Sofar' is available.Varieties
Strawberries are often grouped according to their flowering habit. Strawberries occur in three basic flowering habits: short-day, long-day, and day-neutral. These describe the day-length sensitivity of the plant and the type of photoperiod that induces flower formation. Day-neutral cultivars produce flowers regardless of the photoperiod. Strawberry cultivars vary widely in attributes such as disease resistance, dessert and freezing quality, yield, and season of ripening.Cultivation
Production
In 2023, world production of strawberries was 10.5million tonnes, led by China with 40% of the total; the United States was the main secondary producer.For commercial production, plants can be propagated from bare root plants or plugs. One method of cultivation uses annual plasticulture; another is a perennial system of matted rows or mounds which has been used in cold growing regions for many years. In some areas, greenhouses are used; in principle they can provide strawberries during the off season for field crops.
In the plasticulture system, raised beds are covered with plastic to prevent weed growth and erosion. Plants are planted through holes punched in this covering. Irrigation tubing can be run underneath if necessary.
Another method uses a compost sock. Plants grown in compost socks have been shown to produce significantly more flavonoids, anthocyanins, fructose, glucose, sucrose, malic acid, and citric acid than fruit produced in the black plastic mulch or matted row systems. An earlier study by the United States Department of Agriculture confirms the value of compost.
Strawberries may be propagated by seed. Strawberries can be grown indoors in pots. Strawberries will not grow indoors in winter though an experiment using a combination of blue and red LED lamps shows that this could be achieved in principle. In Florida, winter is the natural growing season and harvesting begins in mid-November.
Domestic cultivation
Strawberries are popular in home gardens, and numerous cultivars have been selected for consumption and for exhibition purposes. The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:- 'Cambridge Favourite'
- 'Hapil'
- 'Honeoye'
- 'Pegasus'
- 'Rhapsody'
- 'Symphony'
Pests and diseases
Strawberry plants are subject to many diseases, especially when subjected to stress. The leaves may be infected by powdery mildew, leaf spot, leaf blight, and by a variety of slime molds. The crown and roots may fall victim to red stele, verticillium wilt, black root rot, and nematodes. The fruits are subject to damage from gray mold, rhizopus rot, and leather rot.