Blueberry Yields, Quality, Consumption

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Harvesting 

After planting the three-year-old seedlings, the first bunches of berries ripen. However, for the first two years, it is advisable not to allow harvesting, and if flower buds form, they and the flowers should be picked off in order to make the bushes grow stronger. In the third and fourth years, the first large crop is produced, and in the fifth and sixth years, the berry bushes produce excellent yields, depending on the variety, cultivation, and weather conditions, of around 3,5-12 kg per bush. The average yield per hectare is 5-8 tonnes of berries, and around 10 tonnes when weather conditions are particularly favorable. The plantation is long-lived and produces fruit for 25-30 years, sometimes for up to 50 years.

It takes about a month to ripen in a bunch, but not all at the same time, which is why they are picked several times. Some varieties – ‘Earliblue’, ‘Bluetta’, ‘Brigita Blue’, ‘Collins’, ‘Denise Blue’ – have a relatively short ripening period, while others: ‘Blueray’, ‘Duke’, ‘Spartan’, ‘Northland’ are longer and ‘Bluecrop’, ‘Herbert’, ‘Coville’ are longer so that they are picked as often as 3-4 times (approximately every two weeks). The first picking is done when about one-third of the crop is ripe. As the berries ripen, the skin first turns blue. Later, the purple shade is replaced by a pure blue color. The berries are still growing at this time, with an increase in weight of about 20 %. The berries are fully ripe when they turn dark blue, after which it takes about 7-10 days. These berries have the right ratio of sugar to acid, are very tasty, and can be eaten fresh or processed. Unripe fresh berries are not palatable, but they keep much better. Overripe berries have a significant increase in sugars.

In many countries, lists of varieties are given according to the ripeness of the berries. The size, color, waxy coating, flavor, aroma, and size of the fruit scar vary from variety to variety.

Some varieties are wet when they break away from the fruit stem. This depends on the size of the fruit scar. The smaller the scar, the faster the ripening, the better the preservation, and the more resistant to rot. The smallest scar is found on ‘Bluecrop’, ‘Toro’ and ‘Bluegold’, while the largest scar is found on ‘Jersy’, etc. Not all ripe berries and the fruit are the same color, some varieties have a pinkish tinge.

It is therefore important to know at the time of planting what the berries will be used for fresh consumption, long-distance transport, or processing. The large berries are best for fresh consumption

The varieties that have an excellent flavor and an intense waxy coating on the skin are usually hand-picked.

Mechanical harvesting is determined by the difference in the bulkiness of the ripe and green berries, which is influenced by the size of the scar on the fruit tree. The most suitable varieties for mechanical harvesting are: ‘Coville’, ‘Bluehaven’, ‘Elliot’, ‘Rubel’, ‘Concord’, ‘Atlantic.

Some varieties such as ‘Nui’, ‘Puru’, ‘Bluegold’ keep well in storage and can be kept fresh for 4-6 weeks in refrigerators at 0 °C. ‘Earliblue’, ‘Rubel’, ‘Rancocas’, ‘Puru’ can withstand transport well. There are varieties of blueberries such as ‘Bluecrop’, ‘Blueray’, ‘Berkeley’, which are resistant to cracking after prolonged and heavy rain.

The yield of berries depends on the variety, the agrotechnique, the age of the plant, and the meteorological conditions. There are high-yielding varieties such as ‘Bluecrop’, ‘Patriot’, ‘Weymouth’, ‘Improved Stanley’, ‘Bluehaven’, high-yielding varieties such as ‘Coville’, ‘Bluejay’, ‘Ama’, ‘Heerma’, ‘Gretha’ and lower-yielding varieties such as ‘Berkeley’, ‘Herbert’, ‘Northblue’, ‘Dixi’, ‘Meaderveisle’.

The most widely grown variety in the world and the most suitable for plantations, ‘Bluecrop’, produces 8-12 kg berries per bush. The New Zealand varieties ‘Reka’, ‘Nui’, ‘Puru’, which are very prolific in New Zealand, produce high yields of about 12-15 t of berries per hectare.

Many of the plantations do not drop off the bush when ripe and can be kept on the shelves for longer than any other berry.

Hand-picking The most common method of picking rosehips is by hand, especially if they are to be eaten fresh. On average, 60-70 kg of berries is picked by one person per working day, directly into small plastic or wicker boxes of 0,25-0,5 kg. It takes 10 pickers per hectare per season to pick the berries.

Blueberries
Blueberries

Mechanized harvesting

In the USA and European countries, some of the orchard blueberries are harvested with harvesters. They are available in different types, with combing and suction principles.

Mechanical harvesting of rose hips results in a large number of green berries among the ripe berries, as well as leaves and small forks. Once the berries have been picked, they need to be sorted, some of which are suitable for fresh consumption and others for processing.

Conveyors for sorting and transporting the berries, packaging equipment, and industrial refrigerators are as important to large blueberry farms as mechanical harvesting machines. All equipment must be carefully maintained on a daily basis, as it can spread parasitic fungal spores.

Berry harvesters, sorting and other equipments are very expensive, so the blueberries.

Blueberries
Blueberries

THE EXPERIENCE OF GERMAN AND DUTCH BLUEBERRY GROWERS

Early harvesting Like farmers of other crops such as vegetables, flowers, and strawberries, growers of blueberries can bring forward the harvest of blueberries. If you want to harvest planted rosehips earlier than conventional cultivation, they can be grown under cover or in greenhouses. A polytunnel is suitable and can be easily erected in spring. The blueberry bushes are warmer in the tunnel than outdoors, so they start to fruit earlier.

The film cover protects the plants from prolonged rain, hail, pests, and birds. It is also possible to grow chanterelles in a greenhouse, but the cost of building one is much higher than building a polytunnel.

In the Netherlands, it is popular to grow blueberries in glass greenhouses. In December, the blueberries are brought into the greenhouse after being planted in containers, where they are kept at a constant temperature of 20 °C and at the right humidity. In February, bee or bumblebee hives are brought into the greenhouse to pollinate the blossom. This method of cultivation can produce a crop of berries as early as April.

In the Netherlands, another method of early fruiting is the selection of varieties and the storage of the berries at a low temperature before flowering until the flower buds form. The duration of the cold storage depends on the variety of rosehip. The earliest cultivar ‘Nui’, which is grown in heated greenhouses, is the earliest to fruit and the most expensive. It is also profitable to bring forward the ripening of Duke’.

Incidentally, the berries of greenhouse-grown rosehips are not the bright dark blue color of the same shrubs grown outdoors.

Harvest delays The late variety ‘Elliot’ does not ripen every year in northern Germany, but in southern Germany, the Netherlands, and Belgium it ripens every year, which means that large areas of the variety are grown.

The fruiting period of ‘Elliot’ can be extended. To ensure that all the berries ripen, a sunroof is built to let in sunlight and protect against rain. Late varieties may take longer to fruit if the plantation is covered from rain and sited at an altitude above 600 m above sea level. Late varieties of blueberries continue to produce until the weather cools down.

Green blueberries
Green blueberries

RETENTION OF BERRIES

Fresh elderberries should be kept dry and cool. On larger blueberry farms the berries are stored in refrigerators.

A temperature of 12-15 °C is required for short storage (1-3 days). Large temperature differences (around 10 °C) between the outside and the fridge should be avoided as this creates moisture which will dampen the berries. The moisture can evaporate through wooden containers or wicker boxes, but not through plastic packaging. The most suitable storage container for blueberries is a wicker box, which allows the berries to breathe and does not generate moisture.

For longer storage (up to 3 weeks), it is suggested to maintain a temperature of 2-4 °C in cold storage. Care should be taken to ensure that the refrigeration equipment’s instruments indicate the correct temperature. Some varieties of berries keep well for 16 weeks at 0 °C in refrigerators. Long-term storage (up to 12 weeks) is recommended under a controlled atmosphere (CA). When the correct ratio of carbon dioxide to it is established and the gas is metered from the gas tanks into the storage room, the ripening of the berries is stopped. This storage method is particularly suitable for the varieties ‘Elliot’ and ‘Pricita Blue’, whose ripe berries are more acidic. Other late varieties should also be stored in this way.

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