The high cost of seed yam is a serious constraint to water yam production. Therefore a two-year field trial was conducted at the University of Uyo Teaching and Research Farm to evaluate dry matter accumulation and partitioning among various plant parts in water yam (Dioscorea alata L.) minisetts as influenced by portion of tuber planted and time of harvesting. The experiment was laid out in a randomised complete block design with a split-plot arrangement. The main-treatments were portions of tuber planted (head, middle and tail) and the sub-treatments were time of harvesting (90, 180 and 270 days after planting DAP). The results showed that portions of tuber planted had no significant effect on dry matter accumulation within leaves, vines, roots and tuber. Early in the season (i.e. 90 DAP), leaves, vines and roots collectively accounted for 67, 62 and 57% of the total plant dry matter for the head, middle, and tail portions, respectively; thereafter the dry matter content declined. However, as the plant matured, the partitioning ratios decreased for leaves, vines and roots, but increased for tubers. Similarly, dry matter accumulation differed significantly (p<0.05) among times of harvesting. The highest dry matter accumulation was attained at 270 DAP. Therefore, it is recommended that any of the tuber portions could be conveniently used to raise seed yam, while harvesting should not be done before 270 DAP for maximum dry matter accumulation.
Key Words: Water yam, Minisett, Dry matter accumulation.
(Global Journal of Pure and Applied Sciences: 2002 8(3): 287-294)