Blueberry

Blueberries are fruits that belong to the genus Vaccinium of the Ericaceae family and constitute a group of species widely distributed throughout the Northern Hemisphere, especially in North America, Central Europe and Eurasia, also found in South America and a few species in Africa and Madagascar. In addition to being eaten fresh, it is mainly consumed in jams, cakes and as an accompaniment to various dishes. It is a food rich in vitamins that provides few calories to the body.

Two large groups are distinguished, the cranberry and the blueberry, the latter being the only one used for fresh consumption.

Blueberries have been one of the last species domesticated by man. The first shrub selection and propagation techniques programs began in North America in the early 1900s. There are different varieties of common blueberry that differ in their ripening moment.

In the first decade of the 20th century, two botanists Elizabeth Coleman White and Frederick Vernon Coville, created the first varieties of great commercial interest, called "the magnificent 8" from which all other varieties have been obtained. These varieties are: Earlyblue, Bluecrop, Blueray, Berkley, Collins, Coville, Ivanhoe and Herbert.

The main producer of blueberries is North America, with the United States and Canada in the lead, followed by Poland, Spain and Germany in the northern hemisphere. In the Southern Hemisphere the main producers are Chile, Argentina and Peru.

In Europe, there are 2 production areas, the south, which includes almost exclusively the province of Huelva, with winter-spring production and the rest with countries such as Germany, Poland, Holland, England and the area of the North of Spain. They produce throughout the summer and early fall.

In recent years, the cultivation of blueberries has seen significant growth throughout the world. Specifically in Asturias (North of Spain where we are), it has gone from only 5 ha and about 5 professional farms to the current 150 ha distributed among about 70 producers in the last 10 years.

80% of the cultivated species are highbush, followed by V. ashei (rabbiteye) species with a proportion of around 14%.

To become familiar with this fruit, there are some terms related to the different types of blueberries most used for cultivation, which are important to know when starting a commercial plantation, in relation to the climatic zone where they will be installed and are the following:

• Highbush: it is a kind of blueberry with a height between 1.5 to 7 meters; it was the first domesticated species for cultivation. Native to the east coast of North America. There are more than 50 varieties improved from it and produced in the United States. Between them:
• Vaccinium Corymbosum: Known as "Northern Highbush", native to the northeast of North America, with requirements in winter cold above 800 chill hours, which can reach a height of between 1.5 to 3 meters. The varieties of this species are the most interesting for growing in cold areas. They have a very good fruit quality.
• Southern Highbush: It is a group of interspecific varieties, which do not exist in the wild in nature. They were developed mainly from V. Corymbosum and other species native to the southern United States, with very low chill needs. In this way, the first varieties were obtained with very low winter cold requirements, less than 400 chill hours. Ideal for growing in areas such as Florida in the United States or Huelva in Spain.
• Vaccinium Ashei: The varieties of this species are also known as "Rabbiteye", because the shape of the corolla of the fruit gives it this appearance. Its cultivation is less important, because its fruit is of lower quality. It has intermediate winter cold requirements between the previous two, 500-600 chill hours. These plants are larger than all those others grown, and can exceed 5 meters in the wild.
• Northern varieties: Originally from Michigan, these are varieties that require many chill hours. The main varieties are Earlyblue, Bluetta, Duke, Bluecrop, Berkeley, Legacy, Ozarkblue, Liberty, Elliot and Aurora.
• Southern varieties: native to the southeastern United States, they are varieties with low requirements of chill hours. Its commercial use is more recent.

There are 30 species that constitute the genus Vaccinium, but only a few are of commercial interest. For the northern area of Spain, there are 2 species that are much more important than the rest from the economic point of view: V. ashei Reade and V. corymbosum L.

Currently V. corymbosum L. is the most important, representing more than 80% of the cultivated area. Its main characteristics are described below:

• Root: The root system is superficial, 80% being located in the first 40 cm of depth; It has fibrous roots, thin and without absorbent hairs. It is sensitive to waterlogging in heavy soils.
• Leaves: Simple, alternate, little pedicellate, elliptical-lanceolate in shape and about 5 cm long, deciduous, of a pale to very intense green color depending on cultivars, slightly toothed and finely veined on the underside.
• Flowers: Axillary or terminal, in clusters of 6 to 10 flowers in each bud. Persistent sepals. White bell-shaped corolla with pink tones in some cultivars, formed by 4-5 fused petals. 8 to 10 stamens with anthers pointed or not. A simple pistil. Inferus ovary with 4 to 10 locules.
• Fruit: It is a blue spherical berry 1 to 3 cm in diameter, weighing 0.5 to 4 grams and several seeds inside.