Comparative Analysis of Tuber Development in Six Sweet Potato (Ipomoea batatas (L.) Lam) Cultivars

Abstract

Differences in tuber initiation, tuber growth and partition of assimilate during development were investigated in six local sweet potato cultivars. Study of the quantitative morphogenesis of root types in the sweet potato root system indicated that tuber initiation was completed by 8 weeks after planting in most cultivars and frustrated thereafter. Subsequent differences in patterns of tuber development were not obviously related to final tuber yield. Thus, high yield resulted either from a short period of rapid tuber growth or a longer period of slower tuber growth. Maximum shoot growth was achieved by week 12 in all except one cultivar, and the cessation of shoot growth resulted in either increases or decreases in tuber growth rate or had no affect on the rate of tuber growth (cv. A28/7). The partition of assimilate to tubers at final harvest was the parameter most closely related to the yield of the six cultivars studied, but there was some evidence that such partition was related to total dry weight. It is suggested that limiting factors in sweet potato tuber yield, e.g. assimilate production and transport or capacity for tuber growth varied with the cultivar studied.