The varieties of Strawberries
In the realm of seasonal fruit, in particular in that of spring fruit, strawberry is the undisputed queen.
There are many species of varieties of strawberries, including: Fragaria chiloensis, from South America, Fragaria virginiana, native to the south of the United States and Fragaria ovalis, native to the Kurile Islands. All species of non-European origin are octoploid, while Fragaria vesca is diploid. The cultivated varieties are almost all crosses between Fragaria chiloensis and Fragaria virginiana.
In general, the plants of strawberries can be classified into:
- june-bearing or spring-bearing strawberries or short-days: buds form with less than 12 hours of daylight and with a sufficient temperature range. Buds form from September up to the first frosts and fruits ripe in spring during about 4 weeks. Some june-bearing varieties can, sometimes become ever-bearing.
- ever-bearing or long-days:buds form with more than 14 hours of daylight and produce strawberries from Sring to Fall. They have never been widespread at industrial level, but are used almost exclusively in families for their slowness in breeding: they produce few runners and multiply mainly by plant division;
- day neutral : buds form under any daylight condition, as long as the temperature range is observed.
Based on season of ripening, the varieties of strawberries are diveded into: early season, midseason, late midsesason and late season; starting from early strawberries to the late season, some varieties of strawberries are: Alba, Queen Elisa, Clery, Irma, Adria, Record Argentera and Sveva. In the south of Italy the most important varieties are: Ventana, Nora, Kilo, Camarosa and Candonga Sabrosa.
Strawberries prefer temperate climate and a good exposure to sun: they grow wild in woods, brush and fresh places all over peninsular Italy, but they can easily be cultivated. For botanists, strawberries are not exactly fruits, but rather a kind of weed, and in Europe three spontaneous species of strawberries are known: vesca, moscata and viridis.
The spontaneous variety of strawberries, vesca, is formed by a bush, which can be 10 up to 30 cm tall, with trifoliate, toothed leaves: the plants of strawberries belonging to this variety are usually dark green on the upper side of leaves and silver-grey on the lower side. Flowers of strawberries, grouped in 5-8, have always five white petals with many stamens. The runners (stolons) produce radicles that give birth to new seedlings.
This variety of strawberris is better known as woodland strawberry, just because it grows wild especially in woods of mountain environments: it is characterized by small and fragrant fruits, which are harvested from June to Semptember; this variety of strawberry is cultivated above all in the Italian region Trentino.
Strawberries ripe from May to July, according to the areas in which they are cultivated, however, technically, real fruits are those tiny grains on receptacle, while the short hair among them is the rest of pistils.
Less widespread are instead: the variety of strawberry moscata, recognisable from erected and quite tall flowering stems, which grow above leaves ad small pear-shaped fruits at the base, and the variety viridis, with short flowering stems, leaves bright as silk and smaller fruits.
Strawberries are extolled as spring seasonal fruit and for their nutritional, refreshing, astringent, diuretic, antigottose properties and their beneficial depurative action on blood. Rich in vitamin A, B1, B2 and C, sugars, phosphorus, calcium, iron, flavoinoids and salicylic acid, the strawberry is a very valuable fresh fruit, even though it can cause allergy in predisposed people: in fact, strawberries are usually not recommended to patients already suffering from eczeme and hives, to diabetics, obese people and dispeptics. Many virtues are assigned to strawberries and they can be helpful in curing some deseases, such as rheumatisms and high blood pressure, because they stimulate the production of hormones that regulate the nervous system. Strawberries have a refreshing, depurative ad duretic action on the organism, thanks to the presence of potassium. Furthermore, strawberries are a dietic fruit, as they are low in calories: 100 gr of strawberries contain only 24 kcal and they are also low in minerals.
The most cultivated species, Fragaria x ananassa, comes froms several crosses between Fragaria chiloensis and Fragaria virginiana.
Presently, there is a progressive increase in the acreage of strawberries cultivated in greenhouse-tunnel and a parallel decrease in open field cultivation, even though early productions are not required: this choice is motivated by the fact that farmers want to avoid the risk of damage due to bad weather, given the great investment that this cultivation involves and harvesting periods always at risk of rain, hail, frost, etc.
Moreover, new techniques for the cultivation of strawberries and "offseason" production, were recently developed: these cultivation require a different kind of "enlarged plants".
"Enlarged plants" are used in "offseason" cultivation, both for fall productions, and for summer mountain production, as they are able to produce a sufficient number of flowers to ensure a good production already after 50-70 days from plantation. They are also the only plants that can be used in the "soilless" cultivation, a technique developed in Belgium and Holland that is cosidered more and more interesting also in Italy, where is sometimes applied. It is a very sophisticate and expensive technique that consists in cultivating the plants of strawberries in bags of fertilized peat, placed on supports at 1.20 to 1.50 m from the ground in greenhouses with irrigation systems.
"Enlarged plants" allow two production cycles, the first at 60-70 days after transplanting and the second, normal in Spring.
Varieties of strawberries that can be stored in refrigerators or cultivate fresh include:
STRAWBERRIES WAITING BED (WB): plants stored in refrigerators after an enlargement done in beds with 2 or more buds per flower.
STRAWBERRIES TRAYPLANT (TP): plants stored in refrigerators with part of the flowers obtained by runners that had radicated and afterwards enlarged in special receptacles and in protected environments.
STRAWBERRIES A+ : plants stored in refrigerator selected with a calibre higher than 14 mm.
STRAWBERRIES WITH ROOTED TOPS: fresh plants derived from young runners, with small roots, rooted in polystyrene trays, with 50-80 alveoli and sold ready for transplant.
STRAWBERRY PLANTS IN POTS: fresh plants that may have originated from plants of small diameters (AA) stored in refrigerators or from fresh runners more or less rooted and put in plastic pots to complete rooting. Fresh plants rooted in pots permit to anticipate the plantation of about one month compared to the fresh Spanish plants, done in the South of Italy, with undoubtful advantages as to increase in the production and earlyness of the fresh plant has compared to the one stored in refrigerators.
ANTEA STRAWBERRIES*: Early midseason variety that suits to any European environment. Fruits, regular and alongated, are homogeneous, attractive, bright red also when completely ripe. Flesh and skin are very resistant to manipulations and to the transport. Variety characterized by excellent trading and gastronomic qualities.
CANDONGA STRAWBERRIES: Variety selected in Spain. It is a very rustic and vigorous plant. It suits well to organic and integrated cultivation. This variety differs from the others for its organoleptic characteristics. The fruit is medium-large, cone shaped and bright red. The flesh is red, compact and very sugary. The skin id very resistant to harvesting and transport. Very interesting cultivation for its good and constant productivity during all the period of harvesting.
CHIFLONA STRAWBERRIES: Selected in Spain, is a popular variety for its earlyness that allows to obtain a good production in the early months of the season, It's a plant of medium vigour. The fruits are wedged cone-shaped and bright red. The fruit size is medium-large and it is constant until the end of harvesting. The flesh is homogeneous and red, aromatic and slightly acid. The skin is elastic and resistant to damage from handling and transport. It suits to Mediterranean environments and it is not sensitive to changes in climate.
CLERY STRAWBERRIES: Very early variety that suits to European temperate environments. It is characterized by excellent productivity, trading and organoleptic qualities. The fruit is bright crimson red, cone shaped, regular already in the first harvestings. Organoleptic qualities are high, as well as taste characteristic of aroma and intense flavour. Excellent resistance to handling and transports.
CRISTAL HIDROP STRAWBERRIES: Ever bearing variety that has a high production level and that suits very well to areas perfect for strawberries and is particularly suitable for the fall and winter production. Fruits are bright red, with a compact, sugary and aromatic flesh. Cristal is a patented variety and reproduction without authorization from Planasa S.A. is forbidden.
ELSEGARDE® STRAWBERRIES civr 30*: It is an everbearing variety that suits well to European continental environments, with a constant production throughout all the growing season. The fruit is very attractive, cone shaped, large sized, bright red and with excellent organoleptic characteristics.
ELSINORE® STRAWBERRIES civr 30*:: Fruit with the form of a cone or a truncated cone, large sized and with a red-orange uniform colour.The flesh is red, firm and good tasting. It is an everbearing variety that suits well to continental environments and that, for its excellent organoleptic and aesthetical characteristics, is one of the most interesting varieties on the market.
DELY* STRAWBERRIES: Recently introducted, it is an early variety that suits to continenatl areas. Its fruits are good-sized, bright red and have a high "brix" degree. Taste, flavour and fragrance are inspired to woodland strawberries, being for this reason at the top of gastronomic qualities.
JOLY* STRAWBERRIES: It is a late midseason variety, very productive and suitable to continental areas. Recently introduced, it has a cone ore truncated cone shape, a big size, which remains homogeneous throughout all the harvesting period. The flesh has the same colour of the skin and taste is very sweet, with a delicious aroma and excellent organoleptic qualities.
NAIAD® STRAWBERRIES civr 35*: Early mid season variety, with a great productivity level. The fruits are attractive, tasty and are quite resistat thanks to the texture of their flesh. The fruits have the shape of an alongated cone and are medium/big sized and uniform, their skin is intense red and their flesh, also red is really tasty.
SIBA* STRAWBERRIES: Early season variety with a good productivity level, whose fruits have the shape of an alongated cone and are big-sized, they are very attractive, bright red and have a great texture. The flesh, intense red, is very sweet, has a good flavour and is really tasty.
TUDNEW® STRAWBERRIES: Variety selected in Spain and cultivated in areas with a Mediterranean climate, both as a plant stored in refrigerators or fresh. It is a very interesting variety for its great productivity level and the exellent quality of its fruits. Fruits are cone shaped and of a big size that remains the same for the entire season. The bright red skin of fruits has a great resistance to harvesting and to transport. The flesh, also bright red is compact, tasty and has an excellent flavour. These characteristics fulfill the requirements of Italian and foreign markets.
CHANDLER STRAWBERRIES: variety, whose fruits are cone shaped and a bit flat; they are cultivated in Sicily, but are native to California. The flesh is red and has a good flavour and fruits are particularly resistant to transport.
MIRANDA STRAWBERRIES: native to Italy, this variety grows in the Centre and south of Italy. The fruits are red-orange and are very big.
PAJARO® STRAWBERRIES: this variety is native to California and can be cultivated only with authorization. The plant is very vigorous and productive and fruits are big and bright red. Their size and qualtity remains steady throughout the period of harvesting.
TUDLA® STRAWBERRIES: native to Spain, this variety is cultivated also in Italy with specific authorization. It is a very early season variety, fruits are incredibly big, red verging to dark red and very juicy; it is produced mainly in Sicily.
IDEA STRAWBERRIES: plants become very big, vigorous and thick. Its fruits are sweet and the flesh is red-orange. It is cultivated in the North of Italy and is the most late season variety among those there cutivated.
The necessity to improve strawberries characteristics has pushed private farmers and institutions to actuate importat breeding programms, in order to find new varieties. Since 1980, this activity has become increasingly intense and now involves 40 countries, of which 35 have found new varieties. (Mourgueset al., 2000). As a whole 750 varieties of strawberries have been created: they mainly belong to the species Fragaria x ananassa and only minimally to the decaploid species Fragaria x potentilla and Fragaria vesca.
The main genetic improvement programs are concentrated in North America (35 programs, of which 13 private), in the EU (34 programs, of which 16 private), in the non-EU countries (17 program of which 2 private) and in Asia (19 program of which 1 private), for a total of 79 public programs and 32 private.
Starting from the mid-Nineties on, the quantity of varieties of strawberies doubled compared to the previous 15 years: this is due to the intense genetic improvement activity of privates, who until that moment were not active compared to the public institutions. Several genetic improvement programs had a great success in the last two decades. This allowed the diffusion of varieties that have a great adaptability to different environments and completely fulfill the requirements of producers and consumers all over the world. For example, the program of the University of California (UC) that produced a lot of successful varieties, such as Camarosa, Chandler, Seascape and Pajaro. Altogether, the UC varieties represent more than 50% of the surface assigned to the production of strawberries in the world (Larson, 2000). Private genetic improvement programs had more and more impulse: these programs aim at being financed with the royalties given by patents.