"Blueberries: The Global Fruit of a Globalizing World"

Blueberries: The Global Fruit of a Globalizing World Blueberry is a perennial shrub species belonging to the genus Vaccinium in the Ericaceae family, producing berry-like fruits. Two species grow naturally in the Black Sea Region: Vaccinium arctostaphylos (bear's grape, Trabzon tea, tea grape, hunter's grape, Likarpa, Likapa, Lifar) and Vaccinium myrtillus (shepherd's grape, shrub strawberry, highland likapası, ground liforu). However, small amounts of Vaccinium vitis idaea and Vaccinium uliginosum have also been reported. [caption id="attachment_127943" align="aligncenter"] Image 1: Flowers, fruits and leaves of Vaccinium species growing naturally in the Black Sea Region ((A) Vaccinium vitis idea L. (B) Vaccinium myrtillus L. (C) Vaccinium uliginosum L. (D) Vaccinium arctostaphylos L.)[/caption] Because blueberries, which originated in America, became quite popular, the first selection work was initiated by Dr. F.C. Coville starting from 1906. In European countries, the cultivation of blueberries became a focus of interest when North America began growing high-bush blueberries in the early 20th century. The first plantation was established by Bergesius in 1923 in the city of Assen, Netherlands, covering an area of 10 hectares. Dr. Piotr Hoser imported some blueberry plants to Poland in 1924. However, these plants were destroyed during the winter of 1929. That same year, German Dr. Walter Heerman imported blueberry plants from America and began cultivating and producing them. Dr. Walter Heerman, E. White and Dr. F.V. Coville continued blueberry production using seeds and hybrids from North America. Subsequently, Dr. Heerman's work continued specifically until 1934. As a result of these studies, a plantation covering 50 hectares was established in 1951. However, blueberries gained real attention in the world market after World War II. Today, rapid developments in forestry and agricultural technologies and increased demand for functional foods have made blueberry fruits a sought-after product on the market.

Blueberry Varieties Commercially Produced in the World

Blueberries grow wild naturally in their natural environments, and since the 1900s, through breeding work initiated with certain species and their varieties, as well as mixed hybridization efforts, many new varieties have been obtained and are now cultivated. Because blueberries are highly demanded products on the world market, breeding work has been conducted to improve certain characteristics such as harvest season, yield, annual production intensity, fruit quality, disease resistance and winter hardiness. Many varieties traded worldwide have been bred from the following species. These are: 1. Lowbush blueberry (Vaccinium angustifolium). 2. Highbush blueberry (Vaccinium corymbosum). a) Northern origin blueberry species. b) Southern origin blueberry species. 3. Half-high blueberry species. 4. Rabbiteye blueberry (Vaccinium ashei). Although blueberries growing wild in forests and open areas in the Eastern Black Sea Region are consumed naturally by the local population, their importance was not recognized by regional inhabitants and consumption was limited to local use. In the 2000s, when the first varieties arrived in the region, adaptation trials were conducted and it was determined that northern origin high-bush blueberries were suitable for the region, so varieties derived from these species were generally brought in. However, trials of southern origin high-bush blueberries continue in some areas. Personal and commercial production continues in the provinces of Artvin, Rize, Trabzon, Ordu, Giresun and Samsun in the Eastern Black Sea Region. The harvest times of northern origin high-bush blueberry species, like other blueberry species, differ after the plants reach full maturity. These times vary due to changing climatic conditions from region to region, but are generally named as follows: Early Season Ripening Varieties: Varieties that ripen at any time period during June and July. Mid-Season Ripening Varieties: Varieties that ripen beginning from the second week of July through any time period in early August. Mid-Late Season Ripening Varieties: Varieties that ripen beginning from mid-July through any time period in mid-August. Late Season Ripening Varieties: Varieties that ripen beginning from August through any time period up to the second week of September at the latest. At the same time, fruit yields from varieties vary depending on climatic and environmental conditions.

Lowbush Blueberries

Lowbush blueberries, as the name suggests, are a type that does not grow very tall and spread primarily by forming rhizomes underground. Only rarely do they exceed 1.5 meters. Mature plants can densely cover the ground surface. This species is suited to acidic soils with abundant sunlight and good drainage. The soil should contain high levels of organic matter, but the amount of mineral matter available to the plant may be low. The desired soil pH for this species is between 4.2 and 5.2. It is a highly resistant species to acid rain. It is a species adapted to temperate climates. Commercially cultivated varieties of this type include: Brunswick, Blomidon, Cumberland, Burgundy, Fundy, Augusta, Claret, Jonesboro, North Country, Northsky, Pretty Yellow, Spring, and Verde. Among these varieties, industrially widely used varieties are Blomidon and Burgundy and Highbush Blueberry (Vaccinium Corymbosum). [caption id="attachment_127944" align="aligncenter"] Image 2: Lowbush blueberry fruit and general appearance[/caption] Today, a large portion of the varieties used in blueberry plantations are included within these cultivated types. Highbush blueberries are suitable for both small-scale and very large commercial production. The best locations for highbush blueberries are sandy-clay soils with pH between 4.5-5.0. Good drainage of soils at the growing site is of vital importance, and they especially require high moisture during summer months. Highbush blueberries are divided into two categories among themselves. These are northern origin blueberry species and southern origin blueberry species. Northern origin blueberry species are plants that can reach heights of 1.5 to 3 meters. For the first time in the early 1920s, a species selected from the wild and named "Rubel" was planted. Today, many species have been developed and continue to be developed. Northern origin blueberry species are productive types. They have achieved quite good adaptation in mountainous areas. They are types that prefer cold regions. While some sources report that temperatures below -20°C can be tolerated by these species, other sources state that some varieties can suffer damage when winter temperatures drop below -30°C. They are also resistant to many fruit diseases. As a result of experimental studies, it has been determined that the minimum chilling requirement for increasing the yield of northern origin high-bush blueberry species is 800 hours. Northern origin high-bush blueberries have approximately over 100 cultivars. To increase fruit yield in areas to be commercially planted, it would be beneficial to plant more than one cultivar type in the planting area. Some northern origin blueberry varieties traded commercially can be listed as: Earliblue, Bluecrop, Bluegold, Torro, Jersey, Brigitta, Bluejay, Aurora, Bluetta, Blueray, Chandler, Coville, Collins, Croatan, Darrow, Draper, Duke, Echota, Elliott, Hardyblue, Ivanhoe, Lateblue, Liberty, Nelson, Northland, Nui, Olympia, Patriot, Reka, Rubel, Spartan. [caption id="attachment_127945" align="aligncenter"] Image 3: Northern origin highbush blueberry flower and fruit (Talisman variety)[/caption] Southern origin blueberry species are heat-loving, extreme winter condition-intolerant types. Their chilling requirements are quite low; average chilling periods of 200-300 hours are sufficient for these species. These species can reach heights of 2-4 meters. The cultivation of these species is somewhat more difficult than other types. Some types ripen quite early, with types reported to ripen even in April. However, they are quite susceptible to spring frosts. They adapt well to soils with low organic content. Some southern origin blueberry varieties traded commercially include: Oneil, Sharpblue, Jubile, Ozarkblue, Misty, Snowchaser, Primadonna, Springhigh, Jewel, Rebel, Sapphire, Millennia, Star, Abudance, Windsor, Southern Belle, Emerald, Palmetto, Camellia, Santa Fe, Bladen, Bluecrisp, Reveille, Pamlico, Lenoir, Craven, Marimba, Southmoon, Avonblue, Gulfcoast, Georgian, Cooper, Sampson, Biloxi, Capefear, Flordablue, Magnolia, Blueridge, Pearl River, Half-High Blueberries (V. corymbosum x V. Angustifolium). [caption id="attachment_127946" align="aligncenter"] Image 4: Southern origin highbush blueberry general appearance and fruit (Gumbo variety)[/caption] Half-high blueberry species are generally obtained through crosses between highbush blueberries and lowbush blueberries (V. corymbosum x V. angustifolium). Half-high blueberries are resistant to extreme winter cold. Indeed, while northern species can suffer serious damage when temperatures drop below -30°C, half-high blueberry species can tolerate temperatures between -37 and -43°C. However, they may not be as productive as northern species. Because some varieties have low or moderate yields, in areas where commercial plantations are established, if northern origin highbush blueberry varieties can be cultivated, they are preferred. However, this does not mean that commercial production of these does not take place. Heavy commercial production occurs in cold regions. Some half-high blueberry varieties traded commercially include: Tophat, Northsky, Chippewa, Northblue, Polaris, Northcountry and Friendship. [caption id="attachment_127947" align="aligncenter"] Image 5: Half-high blueberry general appearance and fruit (Top Hat variety)[/caption]

Rabbiteye Blueberries (Vaccinium Ashei)

Cultivation of this species began in the 1940s. Because they flower early, they are not suitable for cultivation in mountainous areas. Chilling periods range from 450-600 hours. Compared to northern origin high-bush blueberries, their tolerance to cold is low. These species grow in diverse acidic soils and soils with low organic matter content (1-2%). However, they are very susceptible to frost. Another problem is that they are self-infertile. This makes pollination with other rabbiteye blueberry species necessary. For this reason, compatible rabbiteye blueberry varieties must be identified and planted together in the region where this species will be cultivated to facilitate pollination. Some trials of rabbiteye blueberries established in areas with drought problems have yielded interesting results. Some rabbiteye blueberry varieties traded commercially include: Powderblue, Ochlockonee, Tifblue, Yadkin, Baldwin, Alapaha, Climax, Premier, Montgomery, Ira, Brightwell, Onslow, Windy, Snowflake, Savory, Beckyblue, Aliceblue, Vernon, Bonita, Bluegem, Woodard, Chaucer, Bluebelle, Briteblue, Choice, Columbus, Delite, Centurion. [caption id="attachment_127948" align="aligncenter"] Image 6: Rabbiteye blueberry general appearance and fruit (Desoto variety)[/caption]

Medical and Chemical Properties of Blueberries

The bioactive compounds found in blueberries give products derived from these fruits medical and biological properties. Extracts obtained from blueberries have been reported to possess many pharmacological activities. Some of these include wound healing properties, anti-ulcer, anti-atherosclerotic and vasoprotective effects. Furthermore, it is highly effective in regulating the body's circulatory system. Anthocyanins found in blueberries increase the permeability and elasticity of capillaries in the eye globe, thus enhancing microcirculation and improving night vision. Because of these properties, extracts from blueberries are used in the preparation of eye-related pharmaceuticals. Besides these, some Vaccinium species have been reported to possess antidiabetic properties. These species are widely used in traditional medicine in the treatment of diabetic patients. The lifespan effect of many plant extracts has been studied on C. elegans. Extract obtained from V. angustifolium was shown to extend the average lifespan of C. elegans by 28%. The presence of flavonoids, phenolic acids, Vitamin C, Vitamin E, carotenoids and various minerals in blueberry composition makes them a rich source of antioxidants. Low calorie and sodium content and being a major source of fiber places this plant among important nutrients. The therapeutic role of blueberries stems from the phenolic compounds in its structure. Therefore, fruit type and the plant's cultivation conditions have a significant impact on the formation of this type of chemical composition in the fruit.

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[caption id="attachment_127950" align="alignnone"] Assoc. Prof. Dr. Onur Tolga Okan Karadeniz Technical University Maçka Vocational School – Chemistry and Chemical Processing Technology Department[/caption]