Evaluation of sweet potato (Ipomoea batatas (L.) Lam.) germplasm for yield and storage characteristics.

A sweet potato germplasm collection (155 accessions) in Trinidad and Tobago was evaluated. Three groups of varieties were identified on the basis of tuber yield at 20 tons/ha and above, 15-20 tons/ha and 6.5-15 tons/ha as high yielding, medium yielding and low yielding groups respectively. The dry matter percentage of the varieties ranged from 25.6 % in variety TIB 5(61) to 48.5 % in variety 11/59. There was a considerable variation in sprouting behaviour of different sweet potato varieties. On the basis of percentage weight loss in the first fortnight in storage, sweet potato varieties were grouped into those which lost < 5 %, 5 to 10 %, 10 to 15 %, 15-20 % and > 20 %. The varieties A28/7, AI 271, TIB 5(61), 33/57 and 03/58/18 did not lose weight due to decay in both experiments. The percentage dry weight lost ranged from 1.3 to 31.7 % and from 0.24 to 20.3 % for the varieties which store without rotting for 5 weeks in Experiments 1 and 2 respectively. The percentage dry weight loss ranged from 0.35 to 16.4 % for the varieties which store without rotting for 9 weeks in Experiment 2 only. There was considerable variation in both starch and total sugar content of different varieties both at weeks one and five. The total sugar content of tubers increased in storage while the starch content decreased. Significant negative correlation coefficients were obtained for the association between dry matter yield and flesh colour; total sugar content and dry matter percentage; and starch and total sugar content. Significant positive correlation coefficients were obtained between dry matter yield and skin colour; starch content and percentage dry matter; dry matter percentage and percentage sprouting after five weeks of storage; and skin colour and percentage sprouting after five weeks of storage. The implication of the results for identification of high yielding sweet potato varieties wi.