are nearly spherical (occasionally oval), and range between 0.5 and 0.9 cm in diameter. Different strains have diverse coloration—white, yellow, gray, blue, purple, red, brown, black, and mixed.
Horticultural Strains. In the northern Peruvian Andes, where nuñas are almost a staple, the most common color forms marketed are gray and white speckled (nuña pava), light red (nuña mani), dark blue (nuña azul) and gray (nuña ploma). Within the vicinity of Cajabamba (near Cajamarca) and Huamachuco (La Libertad), there are scores of distinct types differing in seed size, shape, and color.
Although there are no discernible differences in taste between different types of nuñas, there is variation in the capacity to “pop.” This quality is recognized by farmers and consumers: strains that pop the best are valued the most in the markets. The nuña pava (also called “coneja”) is held in particularly high regard.12 There is a white nuña at Cajabamba called “huevo de paloma” (pigeon egg), which is outstanding in popping ability, taste, and crunchiness. In Cajabamba there is also a red and white mottled nufia called “parcollana.”13
In the southern Andes of Peru, several strains of Phaseolus vulgaris appear to be closely related to the nuña. These are usually roasted (15–30 minutes) in either gypsum pebbles (pachas) or sand, rather than oil. They are called “poroto de Puno” and are found only in certain valleys, certain markets, and on special days. They do not pop, but the seed coat breaks open, and the shell comes off to leave a very dry, but tasty, product.
Daylength. As noted, certain nuña types are highly photoperiod sensitive. This sensitivity increases with growing temperature.
Rainfall. 500–1,300 mm throughout the growing season.
Altitude. 1,800–3,000 m in Peru
Low Temperature. 2–5°C; frost susceptible
High Temperature. About 25°C; may be intolerant of even moderately hot conditions.
Soil Type. As with modern beans. Nitrogen-fixing is more effective in light, well-drained soils because of better Rhizobium growth.