Development of the Sweet Potato for Increased Usage in the Caribbean Franklin W. Martin Tropical Agriculture Research Station Southern Region, ARS/USDA Mayaguez, Puerto Rico Inexpensive, efficient food crops that are attractive, tasty, nutritious, and versatile are needed in the Caribbean. The sweet potato has the advantage that it can be produced and harvested throughout the year. Usage of the sweet potato can be increased by breeding better varieties, especially those with little or no sweetness and bland flavors, and by better methods of preparation. A diffusion process was developed, which im- proves the acceptability even of the worst sweet potatoes. A household type process for making flour was developed; flours can be used in partial substitution for wheat flour. Insect resistance and stress tolerances are needed. Progress has been rapid, using mass selection as a tool. Varieties with new characteristics are available and need regional testing. Progress is being made in developing improved horticultural tech- niques and short cuts for testing adaptability. "Our daily bread" is a beautiful fragment of a prayer which ex- presses a truth: most people in this world tend to fill a great part of their food needs with a single staple food. Staple foods are great foods. If you begin to enumerate the great foods of the world, the list, in order of importance, would be wheat, rice, corn, potatoes, barley, and tied in sixth and seventh places, cassava and sweet potatoes. Note that four of these crops are cereal grains, and three are roots or tubers. This paper concerns the sweet potato. Two-thirds of the world's sweet potatoes are grown in China where sweet potato is a great food. In very few other places in the world, however, can sweet potato be said to be "Our daily bread." The sweet potato is a crop of the Caribbean. While its origin is somewhere in the American tropics, we cannot be sure how it originated and spread. But a significant fact is clear: sweet potato was in the Caribbean before Columbus arrived. It was carried from place to place by the original peoples, and it is highly pro- bable that it continued to evolve in the Caribbean. It is still an important food, and still represented by hundreds of ancient varieties. For just a moment let us contrast the sweet potato to other starchy crops which are its rivals in the tropics (Table 1). Its season is quite short, just a little longer than that of potatoes, and it can be planted or harvested any time of the year. The propagating material is the stem, useful as feed but not as food, and thus the principal edible portion is not sacrificed when a new crop is planted. Its level of culture is relatively simple, and it can be pro- duced in anyone's backyard. But the crop can also be mechan- ized. Its food value (chiefly in terms of calories, vitamin C, and in yellow-fleshed types, vitamin A) is medium to high, sometimes a little better, sometimes a little less than other root crops. Finally, all parts of the sweet potato plant can be used as feed for animals. It appears that the combination of favorable characteristics of the sweet potatoes give it an appreciable edge over other crops that TABLE 1. Principal starchy crops of the tropics (excluding grains) and some of their characteristics. MINIMUM TIME TO PRODUCE (MONTHS) PROPAGATING MATERIAL RELATIVE EASE OF CIILTIURE NUTRITIONAL VAL IIF SWEET POTATO STEM EASY MEDIUM-HIGH EDIBLE PORTION STEM EDIBLE PORTION VARIOUS PARTS VARIOUS PARTS RHIZOME RHIZOME DIFFICULT EASY MEDIUM MEDIUM MEDIUM EASY MEDIUM MEDIUM-HIGH NO LOW MEDIUM MEDIUM MEDIUM LIMITED NO- LIMITED LIMITED LOW-MEDIUM LIMITED LOW-MEDIUM LIMITED PROCEEDINGS of the CARIBBEAN FOOD CROPS SOCIETY-VOL. XX CROP POTATO CASSAVA RESIDUES A. FFFD YES YAM TARO TANIER BAANAN PLANTAIN 10 8 10 10 10 12 ~ --- 202