Solanum juzepczukii

Solanum juzepczukii, known as rucki, is a perennial potato. It belongs to the nightshade family, Solanaceae. Its native range runs from Peru to western Bolivia. Growers raise it for food in the high Andes. Plants occur in fields at 12,140–13,450 feet [3,700–4,100 metres]. Plants For A Future reports no known wild habitat. The Ferns describes it as a triploid potato form. Its account also notes that potato classification remains unsettled.

Young plants form a low rosette near the ground. As they grow, the stems take a partly upright form. These stems rise from a rootstock that bears tubers. The listed plant height is about 2 feet [0.6 metres]. Stems measure about 1.3–2.6 feet [0.4–0.8 metres] long. This is a herbaceous plant, rather than a woody shrub. Its flowers have both male and female organs.

Rucki suits cool growing conditions at high elevations. The Ferns gives its best daytime range as 6–14°C. It reports tolerance of temperatures from 3–18°C. Andean growers plant it as insurance against cold weather. Yet its hardiness reports do not fully agree. Both sources describe strong frost resistance in their cultivation notes. They cite regions with frost on 300 days each year. In contrast, the brief PFAF profile calls it frost tender. These accounts do not establish a firm garden hardiness zone.

Choose a sunny site with fertile soil rich in humus. PFAF also lists light shade as suitable. The plant prefers moist soil, but dislikes wet ground. Heavy clay is also a poor choice. A medium-textured soil gives the best results. Slightly acid to neutral soil suits it best. Lime-rich soil or too little humus can promote tuber scab. PFAF suggests planting tubers in spring and harvesting in autumn. Its storage guidance calls for cool conditions without frost. Seed propagation starts in a warm greenhouse in early spring.

The tubers contain starch, but their taste is bitter. Traditional freeze-drying turns them into a food called chuño. This process removes the bitterness described by PFAF. The Ferns warns that the tubers contain glycoalkaloids. It states that they need cooking or freezing before eating. They should therefore not be treated as a raw food. Yields are low, despite the crop's value in cold areas. PFAF lists no known medicinal or other non-food uses.