P. Demo, M.O. Akoroda, J. Koi, V. Deffo, D. Njualem & S.F. Nana
In 1995/96, two field experiments were conducted in Bambui, Cameroon in order to investigate the effects of 10 different seed tuber sizes ranging in diameter from <5 mm to 45-50 mm on tuber yield of potato. The objectives of the study were (1) to determine the minimum adequate and the optimum seed tuber sizes for potato production and (2) to generate agronomic data required for an objective determination of seed potato price per size grade. Tuber yield, average weight per tuber, and tuber size distribution after harvests were compared. Tuber yield per plant increased significantly with increasing seed size. This yield varied from 308.1 g/plant for <5 mm seed to 663.9 g/plant for 35-40 mm seed in the first experiment and from 256.5 g/plant to 741.5 g/plant for <5 mm and 45-50 mm seed respectively, in the second trial. All seed sizes tested consistently yielded at least 10 tubers per plant. Seed tubers $30-35 mm consistently gave similar and highest tuber yield per plant. Smaller seed tubers were more efficient in converting their unit weight into tuber yield than larger ones. It was concluded that (a) the minimum adequate seed sizes for seed and ware potato production are 5-10 mm (1.31 g) and 10-15 mm (3.03 g), respectively; (b) the optimum seed size for potato production is 30-35 mm (25.51 g). Seed tubers <5 mm diameter
(0.56 g) produce >10 tubers per plant in the field but their management is very difficult.