Aronia is a genus of deciduous shrubs, the chokeberries, in the family Rosaceae native to eastern North America and most commonly found in wet woods and swamps. The genus Aronia is considered to have 3 species. The most common and widely used is Aronia melanocarpa (black chokeberry) which emerged from Eastern North America. The lesser known Aronia arbutifolia (red chokeberry) and the hybrid form of the above mentioned species called Aronia prunifolia (purple chokeberry) were first cultivated in Central and Eastern North America. In the eighteenth century, the first shrubs of the best-known species Aronia melanocarpa reached Europe where they were first cultivated in Scandinavia and Russia.
Chokeberries are cultivated as an ornamental plant and as a food plant. The bitter berries, or aronia berries, can be eaten fresh off the bush, but are more frequently processed. They can be used to make wine, jam, syrup, juice, soft spreads, tea, salsa, extracts, beer, ice cream, gummies, and tinctures. The name "chokeberry" comes from the astringency of the fruits, which create the sensation of making one's mouth pucker.
Chokeberries are often mistakenly called chokecherries, the common name for Prunus virginiana. Further adding to the ambiguity, a variety of Prunus virginiana is melanocarpa, and readily confused with black chokeberry because it is commonly referred to as "black chokeberry" or "aronia". Aronia berries and chokecherries both contain polyphenolic compounds, such as anthocyanins, yet the two plants are somewhat distantly related within the Amygdaloideae subfamily. Black chokeberry is grown as a common shrub in Central Europe where it is mainly used for food production.
Identification and taxonomy The leaves are alternate, simple, and oblanceolate with crenate margins and pinnate venation; in autumn, the leaves turn a bold red color. Dark trichomes are present on the upper midrib surface. The flowers are small, with five petals and five sepals, and produced in corymbs of 10–25 together. The hypanthium is urn-shaped. The fruit is a small pome, with an astringent flavor.
Aronia has been thought to be closely related to Photinia, and has been included in that genus in some classifications, but botanist Cornelis Kalkman observed that a combined genus should be under the older name Aronia. The combined genus contains about 65 species. In 2004, Kalkman expressed doubt about the monophyly of the combined group, and new molecular studies confirm this. [Referring to the subfamily by the name "Spiraeoideae"] They do not place these two genera together or even near one another.
In eastern North America, two well-known species are named after their fruit color, red chokeberry and black chokeberry, plus a purple chokeberry whose origin is a natural hybrid of the two. What has been regarded as a fourth species, Aronia mitschurinii, that apparently originated in cultivation, is now treated as × Sorbaronia fallax. Flowers Fruit Scientific name Common nameDescriptionDistribution Aronia arbutifolia (Photinia pyrifolia) Red chokeberrygrows to 2–4m (6.5–13 ft) tall, rarely up to 6 m (19.6 ft) and 1–2 m (3-6.5 ft) wide. Leaves are 5–8 cm wide and densely pubescent on the underside. The flowers are white or pale pink, 1 cm wide, with glandular sepals. The fruit is red, 4–10 mm wide, persisting into winter. Eastern Canada and to the eastern and central United States, from eastern Texas to Nova Scotia inland to Ontario, Ohio, Kentucky, and Oklahoma Aronia melanocarpa (Photinia melanocarpa), Black chokeberrytends to be smaller, rarely exceeding 1–2 m (3–6 ft) tall and wide, and spreads readily by root sprouts. The leaves are smaller, not more than 6-cm wide, with terminal glands on leaf teeth and a glabrous underside. The flowers are white, 1.5 cm wide, with glabrous sepals. The fruit is black, 6–9 mm wide, not persisting into winter. Eastern North America, ranging from Canada to the central United States, from Newfoundland west to Ontario and Minnesota, south as far as Arkansas, Alabama, and Georgia Aronia × prunifolia (Photinia floribunda) Purple chokeberryapparently originated as a hybrid of the black and red chokeberries but might be more accurately considered a distinct species than a hybrid (see also nothospecies). Leaves are moderately pubescent on the underside. Few to no glands are present on the sepal surface. The fruit is dark purple to black, 7–10 mm in width, not persisting into winter. There are purple chokeberry populations which seem to be self-sustaining independent of the two parent species – including an introduced one in northern Germany where neither parent species occurs – leading botanist Alan Weakley to consider it a full species rather than a hybrid. The range of the purple chokeberry is roughly that of the black chokeberry; it is found in areas (such as Michigan and Missouri), where the red chokeberry is not. Eastern Canada and to the eastern and central United States, from Nova Scotia west to Ontario and Wisconsin, south as far as western South Carolina, with an isolated population reported in southern Alabama
Nutrition +NutrientMass in fruit [g/100g]Mass in pomace [g/100g]Total sugars6.21–42.1—Fructose2.2–15.8—Total fiber—57.8–71.6Dietary fiber—43.8–61.7Lignin—22.68Cellulose—34.56Pectin—7.52Protein0.7—Fat0.14%—Vitamins[mg/100g][mg/100g]Vitamin C7.25–98.75—Vitamin A0.77—Vitamin B52.845—Vitamin B61.132—Minerals[mg/100g][mg/100g]Na0.427–1.18—K135–679—Ca11.9–116.7—Mg8.3–66.9—P23.9–95.6—Organic compounds[mg/100g][mg/100g]Anthocyanins284–631—Proanthocyanidin522–1,0006,200–9,720Flavonols3.9–61.722.7–43.7
Cultivation
Soil and climate requirements The chokeberry is a characteristic shrub of the northern hemisphere. Its climatic requirements are temperate and cool temperatures. The shrubs are extremely winter hardy and can survive temperatures down to −30 °C without damage if they are in winter dormancy. After flowers form in late April/early May, the plants become sensitive to frost. Chokeberries are usually planted in early spring after thaw but autumn is also possible if the plantation is mulched or snow covered during frost.
The chokeberry has a shallow and compact root system and thrives in humus and nutrient rich soils that are frost free, unflooded and with a rather low groundwater level. While the plant is moisture-loving, it also tolerates dry periods. Depending on the timing and intensity, these dry periods are yield limiting. While the crop needs more than 500 mm of precipitation, good yields can be obtained at 700–800 mm. Furthermore, chokeberries are sun loving and usually thrive better under direct sunlight rather than in shade.
Seedbed requirements and sowing Chokeberries grows on medium-heavy soils, which can be neutral to slightly acidic. Before planting, it is advisable to promote soil structure and humus formation, which can be enhanced by green manuring using organic fertilizers and deep tillage of the soil. Planting chokeberries in an existing grass plot is not recommended, due to the strong competition of weeds in the understock area. Commonly, two-to-three-year-old bare-root plants are set between October and November. Machine planting places about 3000 seedlings per hectare, each 20–25 cm deep into the soil. Plant distance is 60 cm and row distance is given by the harvest machine.
Crop sequence requirements If chokeberries are planted directly after a previous cultivation of other Rosaceae, an intercrop such as cereals is recommended, as well as staggered row planting, since chokeberries might suffer from a replant disease (also: soil fatigue).
Cultivation management For the first two years, much attention should be given to keeping the understock area clear during maintenance. The understock maintenance can be done by machine hacking or by using a string trimmer with protection. Covering the plant strip with mulch also helps to minimize weeds. When maintaining the alley, it is important to cut it every 3–4 weeks. The young plants are sensitive to drought stress, so proper watering should be guaranteed. At the beginning the plant needs to put its energy into vegetative growth, therefore it helps to remove flower buds. In order to achieve a balanced fruit quality in the long term, the plant, which grows as a shrub, should be trimmed regularly. Furthermore, uniform plant stands are easier to manage and harvest by machine. As a rule, chokeberry branches achieve the highest yields in the 5-6 year period, so cutting is not done again until the 7th year.
The aim of both the mechanical and the manual cutting system, is to let the shrubs grow into a closed hedge. While in the mechanical cutting the whole plant is cut back to a few centimeters above the ground every 6th year during the winter dormancy. The manual cutting removes the oldest shoots, the weak annual shoots and those shoots that are inside the cane slightly above the base of the cane in the winter dormancy. In the case of manual cutting, the ages of 1-6 year old shoots should be present in equal proportions after cutting, thus the chokeberry forms robust shoots and allows uniform harvests from year to year.
Fertilization requirements For optimal fertilization, collecting soil samples before the planting of the seedlings is required. The soil analysis enables planning of effective fertilizer applications. In the first two years, after planting the seedlings, there must be enough nutrients in the soil so that the seedlings can grow optimally, including phosphate (P), potassium (K) and magnesium (Mg) and, therefore, they should be present at the beginning of vegetation period. When potassium levels in the soil are low, the nutrients can be supplied via cattle manure and cattle slurry. If the potassium content in the soil is high, it is better to use compost, since a too high potassium concentration inhibits the uptake of magnesium, calcium and ammonium. However, there is no need to be too sensitive about potassium levels in the first few years, since a high amount is basically needed. It is clear that nitrogen fertilization is necessary. Often, one half is applied at the beginning of vegetation period and the other half at flowering. Since the plant already has a greater growth potential in the second year, the amounts of fertilizer can be increased a little. From the third year on, the chokeberry has the full nutrient requirement. Depending on the vigor, wood maturity and yield, the fertilizer quantities can be slightly adjusted upwards or downwards. Through the targeted strip fertilization, the amount of fertilizer can be reduced by 1/3, which may be of economic interest to the cultivator.
Breeding One part of the breeding efforts focuses on improving red chokeberries for their use as ornamental plants. Breeding goals include the reduction of the plants stature, reduction of its tendency towards legginess, increasing the fruit size and improving leaf retention for a longer lasting fall foliage. Breeding of the red chokeberry is difficult, because the available accessions are tetraploid plants and thus, are likely to produce apomictic seeds. Furthermore, the breeding of polyploids makes mutation breeding more challenging because the additional sets of chromosome can mask incomplete mutations. If breeders had access to a wild diploid A. arbutifolia breeding would arguably become more successful.
The breeding success of the black chokeberry for food production in Europe and Russia has been restricted because the genetic pool of the domesticated Russian plants is homogeneous. Breeding efforts aim to increase the content of polyphenol compounds while maintaining or increasing the fruit size. Further breeding targets are improvement of flavor.
Harvest and post-harvest treatment