A field experiment was conducted at Haramaya and Hirna during the main cropping season of 2013 to determine the appropriate plant spacing for potato cultivars in relation to growth and yield. The treatments consisted of five seed tuber spacing (75 cm × 30 cm, 60 cm × 30 cm, 60 cm × 25 cm, 50 cm × 25 cm and 45 cm × 20 cm) and four potato varieties (Bubu, Badhassa, Zemen and Chiro). A randomised complete block design was used with three replications. The analyzed data results showed that the main effects of spacing and variety and the interaction effect significantly affected growth and yield parameters of the crop. The maximum marketable tuber yield at Haramaya (24.7 t ha-1) and Hirna (27.99 t ha-1) was recorded in response to seed tuber spacing of 60 cm × 30 cm whereas the maximum total tuber yield at Haramaya (34.29 t ha-1) and Hirna (42.07 t ha-1) was obtained from seed tuber spacing of 45 cm × 20 cm. Cultivar Bubu produced the maximum marketable tuber yields at Haramaya (29.91 t ha-1) and Hirna (30.01 t ha-1) and the same variety also produced the maximum total tuber yields at both locations.
Key words: Cultivar, growth, marketable yield, non-marketable yield, plant spacing, Solanum tuberosum L., total tuber yield.