Alpha

Key Characteristics

Alpha is a variety of American origin, introduced to the Primorsky Krai in 1937. It belongs to the group of mid-season ripening varieties. In the Primorsky Krai, full ripening of the berries is observed from September 15 to 20, and in the Moscow Region from September 25 to 30. The vegetative period lasts 140–145 days, requiring a sum of active temperatures of 2100–2400 °C. Under advanced agricultural practices, the yield in the Primorsky Krai reaches approximately 60–90 centners per hectare. The clusters are of medium size (13–15 cm long, 8–10 cm wide), with a mass of 100–350 grams. The berries are medium-sized (16×16 mm), round, black with a violet tint, and covered with an abundant waxy bloom that gives them a glaucous shade. The skin is firm and dense, easily separating from the pulp. The pulp is mucilaginous and separates poorly from the seeds. The taste is refreshing and sweet-sour, with a distinct foxy flavor. The organoleptic evaluation score of the Alpha grape variety is 6 out of 10 points.

Morphological Description

• Young shoot tip: Greenish-yellow with a bronze tint, featuring a weak bristly pubescence.
• Annual shoot: Dark brown with a reddish tint that intensifies at the nodes. The ripening of the shoots is good.
• Mature leaf: Large, three-lobed, slightly dissected, and round. The leaf blade is shiny, smooth, or net-wrinkled.
• Leaf sinuses: Upper sinuses are open and shallow, forming an incoming angle (sometimes barely marked); lower sinuses are absent.
• Petiolar sinus: Open, deep, and V-shaped, with a sharp or rounded base.
• Leaf teeth: Large, narrow-triangular, and extended into a sharp point at the ends of the lobes.
• Leaf pubescence: The lower surface has weak, bristly pubescence, which is more pronounced along the veins.
• Flower: Hermaphrodite.
• Cluster: Cylindric-conical or cylindrical, ranging from medium density to dense.

Agricultural Features

The vines are characterized by vigorous growth. Shoot maturity remains good even in years with unfavorable combinations of meteorological factors. This grape variety enters bearing in the 3rd or 4th year after planting. It bears fruit better with long canes pruning (to 12–15 buds) and a total load of 35–40 fruiting shoots. Compared to European and Far Eastern varieties, it is minorly damaged by downy mildew. In recent years, susceptibility to chlorosis and brown spot has been recorded. The root system possesses high frost resistance; for wintering, the vines are covered with a soil layer 20–30 cm thick. The Alpha variety is successfully used as a frost-resistant rootstock with fast and good rooting capacity. The variety is officially approved for cultivation across all zones of the Russian Far East.

Winemaking and Product Characteristics

The Alpha grape variety is characterized by high titratable acidity of the juice (20–24 g/L) and a low sugar content (14–20%). Sugar accumulation occurs most intensively during the second half of September. The grapes are suitable for the preparation of wine and juices. In the Primorsky Krai, the variety is also utilized for fresh local consumption.

* VINEYARD Note: In the source material, the Alpha grape variety is evaluated under the severe climatic conditions of the Russian Far East.