Production of blueberry seedlings

Cultivated basically in the states of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo and Minas Gerais, blueberries have great potential for expansion in Brazil. For the installation of new production areas to offer good results, it is essential that the producer pays attention to the quality of the seedlings and carefully chooses the variety to be implemented.

There are several types of blueberries. Those in the lowbush group include low bushes, with a maximum height of 50 centimeters and high cold requirements (approximately 650 hours to 850 hours per year below 7,2º C). In the highbush group, the bushes reach up to two meters in height and have high cold requirements (between 650 hours and 850 hours annually). Within this group, there is a subgroup called Southern highbush represented by tall plants, with little need for cold, productive, early maturing and a more concentrated harvest. The group of Rabbiteye blueberries, or “rabbit's eye”, includes plants between 2 meters and 4 meters in height, with low cold requirements, between 300 hours and 400 hours. 
The most planted varieties in Brazil are Aliceblue, Bluebelle, Bluegem, Briteblue, Climax, Delite, Powderblue and Woodard from the Rabbiteye group, and Misty, O'Neal and Georgiagem from the Southern highbush type, but they are no longer planted in countries in the Northern Hemisphere for have lower productivity, late production, long harvests and lower fruit quality. 

The new varieties of the Southern highbush group: Star, Jewel, Emerald, Millenia, Primadonna and Snowchaser, which were developed by the University of Florida, have been introduced in Brazil with the aim of gradually replacing the cultivation of old varieties. The main advantage of these varieties is that their production is possible in places with a low incidence of winter cold, which makes it possible to expand the blueberry growing regions in Brazil.
When you intend to install a new production area, you must take into consideration not only the potential of the variety to be implemented, but also the quality of the seedlings that will be used in planting. 
The production of blueberry seedlings is carried out using a well-known propagation method, cuttings, which consists of rooting parts of the plant, mainly branches, taken from a mother plant that represents the variety in terms of productive potential and good health. . Herbaceous cuttings measuring 10cm to 15cm are used, which have tender, green tissues and are taken from the apical part of the branches in the spring/summer period, times when vegetative growth occurs. As this material is very sensitive to dehydration, collection is preferably done in the morning, leaving at least one pair of leaves, which will be responsible for the continuation of the photosynthetic process that will provide photoassimilates both for the maintenance of the cutting and for root formation.

Semi-hardwood and hardwood cuttings can also be used in the production of blueberry seedlings and must be obtained from partially or fully lignified branches. It is recommended to remove these cuttings during the vegetative rest period, being obtained from material discarded during winter pruning. Only semi-hardwood cuttings should remain with a pair of leaves. 

After collecting the cuttings from the mother plant, they are prepared, placing them for rooting in a suitable substrate that has good water retention capacity, satisfactory drainage and is free from soil pathogens, weeds and nematodes. In Brazil, the main substrate used for rooting these cuttings is sand and in Chile a mixture of peat (50%) and perlite (50%) is used. At this stage it is important to ensure that the substrate can adhere well to the stake. Then the substrate is lightly compacted around the cuttings, to avoid air pockets remaining at their base.  

Plant regulators, mainly synthetic auxins, are widely used to aid rooting and as they are difficult to dilute in water, they can be dissolved in an alcohol or potassium hydroxide solution to be applied in liquid form or mixed in talc for powder application. Herbaceous blueberry cuttings must be treated with indolebutyric acid (IBA) at a concentration of 2000mg/L to 2500mg/L.

Once ready, the cuttings are taken to environments suitable for rooting. Herbaceous and semi-woody cuttings must be placed in an intermittent misting chamber, which allows small droplets of water to be emitted into the environment, from time to time, keeping the surface of the leaves wet. This environment is conducive to rooting, as it prevents dehydration and waterlogging of the cuttings. In the case of wood cuttings, these installations are not necessary and can be placed in beds of sand or bags containing substrate in a covered environment with at most one shading screen, to avoid the effects of excess solar radiation and rain. 

After a period of approximately 90 to 120 days, the cuttings must be removed from the rooting environment and transplanted into 3 to 4 liter plastic bags, placed in an environment covered by plastic or shade. In Brazil, pine bark is used as a substrate and in Chile a mixture of 2/3 of pine needles (pine leaves) mixed with 1/3 of pine sawdust is used. It is common to cover the soil inside the nursery with plastic sheeting to avoid competition with weeds. The seedlings will develop and when they are approximately 12 months old, they can be sold. Some nurseries lower the seedlings to a height of 20cm before sending them to the producer, a recommended practice for plant formation both in field plantings and in pots or plastic bags. The steps for producing blueberry seedlings using herbaceous cuttings are illustrated in Figure 1.

Blueberry seedlings can also be obtained by "in vitro" propagation or micropropagation, which consists of applying the tissue culture technique to produce plants identical to the parent plant. This type of propagation allows the production of seedlings with high genetic and phytosanitary quality. It is made in laboratories from pieces of plant tissue. These fragments taken from plants are called explants and are multiplied in an artificial culture medium (without soil), which provide nutrients and other substances necessary for the multiplication and regeneration of new plants. “In vitro” propagation techniques allow the production of a large number of plants from a single explant, in a shorter time, in addition to enabling the production of seedlings free of disease-causing pathogens that conventional propagation methods can cause. be transmitted by seedlings.

First, explants are obtained and must remain in the culture medium for a period of 2 to 3 months. Then, these explants are removed from the medium and placed in special structures for acclimatization, to develop roots and leaves, for 3 to 4 months. After this period, small seedlings measuring 10cm to 15cm long are obtained, with few roots and approximately 2 to 4 shoots, which will be transplanted into plastic bags containing substrate until they reach a height of 40cm-50cm where they will be ready to be planted in the field. .

Seedlings today represent 27% of the costs of establishing a blueberry orchard, including old varieties. These costs increase to 42% if the seedlings come from varieties obtained through the Florida Breeding Program.

The quality of the seedlings is fundamental to the success of the business and Brazil has enormous potential for the development of the crop considering the favorable environmental conditions that allow the production of fruits in the off-season in the Northern Hemisphere, in addition to the availability of water, the presence of acidic soils required by the culture, the shorter distance to European purchasing markets compared to competitors in South America and the global trend of increasing consumption of blueberries.

Blueberry cultivation

Blueberries (Vaccinium spp.) are a fruit species native to the “temperate” forests of North America, as well as regions of northern Europe. In addition to the exotic flavor, the fruit contains anthocyanins and polyphenols, natural antioxidants that help prevent cancer, cardiovascular diseases, vision diseases such as cataracts and macular degeneration, as well as promoting improvements in blood circulation and, consequently, problems such as hemorrhoids, varicose veins, edema and wounds. Due to its properties, blueberries are also known as the “longevity” fruit.

Global blueberry production has grown every year, mainly due to its functional and nutraceutical properties. It is estimated that the global production volume is around 331 thousand tons in an area of ​​74 thousand hectares. Highlights include the United States and Canada, which together account for approximately 83% of production, and also Germany and Poland in Europe and Chile and Argentina in South America.

Although Brazil imports 90% of the blueberries it consumes, it has great growth potential mainly because it produces in the off-season in the Northern Hemisphere, which guarantees the profitability of producers seeking to diversify their orchards. Furthermore, the introduction of varieties obtained from the University of Florida's Genetic Improvement Program, with lower cold requirements and early harvest, between the months of October and November, guarantees the best market prices, as there is no supply of fruit during this period. from other countries in the Southern Hemisphere. 

In Brazil, blueberries are produced in the states of Rio Grande do Sul, Santa Catarina, Paraná, São Paulo and Minas Gerais and although there are no official data, it is estimated that the planted area is 250 hectares, with small plantations, smaller than two hectares.

Simone Rodrigues da Silva, Ricardo Bordignom Medina, Katia Fernanda D. Rodrigues and Tatiana Cantuarias Avilés, Esalq, USP, Piracicaba/SP

Article published in issue 80 of Cultivar Hortaliças e Frutas