ABSTRACT
Traditionally, potato crop is grown from tubers, often called seed tubers. This vegetative method of potato production has many advantages, including ease of planting, vigorous plant growth, and high yields of uniform produce. However, low multiplication rate, high storage and transportation costs, carryover of pathogens, and physiological degeneration are among the constraints associated with the use of seed tubers. Inevitably, crop performance declines as viruses accumulate, so that an elaborate and complex system of disease-free seed production is necessary. The costs of healthy planting material are therefore higher for a potato crop than for any other staple crop: an average of 20-30 percent of total production costs (Almekinders et al., 1996). In warm and developing regions of the world, the constraints of seed tuber-based potato production systems are more serious as quality seed tubers are either not easily available or priced too highly, and stocks degenerate quickly because of systemic as well as tuber-borne diseases (Malagamba and Monares, 1988). Healthy seed tubers under these conditions account for 50-70 percent of total production costs (Horton and Sawyer, 1985).
