Yam bean is a tropical tuber and grain legume that needs to be better known as a crop for human consumption and animal feed. The seeds are poisonous but can be used for planting. The tuber is edible and can be eaten as a fresh vegetable or cooked. Large tubers and better fruiting occurred when the growing season coincided with long days, but marketable tubers were produced, especially under short days. In all cases tuber production competes with seed production. Investigations were undertaken to study the effects of foliar application of GA3 and CCC on growth, sugar composition and tuber yield of yam bean under short days. GA3 promoted shoot growth, tuber enlargement,. yield increase, sucrose accumulation and starch content increase. CCC did not consistently affect growth, but reduced tuber size, increased starch content, therefore reduced tuber and starch yields per plant. Foliar applications of GA3 might be used to increase tuber and starch yields per plant under short days. This result was obtained because of a partial or total inhibition of flowering and seed set by that growth substance.