Field experiments were conducted in the Sudan savannah zone of Nigeria during the 2015/2016 dry season. The Research Farm of Audu Bako Collage of Agriculture, Danbatta (12° 44′ N and 8° 51′ E) and Federal Collage of Education Technical, Bichi (12º24′N and 8.24′E) represented the two locations. Subjects of interest were to determine the effect of variety and sowing date on yield of Irish potato. Treatment combinations were five certified varieties (Nicola YL, Nicola GL, Bertita, Ditta and Marabel) and four levels of sowing date (early November, middle of November, end of November and middle December), respectively. In three replications, treatments were laid down in a split plot design with varieties in main plots and sowing dates in sub plots. All cultural practices for dry season production of Irish potato and determination in physico-chemical properties of soil samples were observed. Data collected on yield components were analyzed using a trial version (statistix-version 10). Statistically the results obtained from measured yield and yield parameters were taken from sampled plants. The parameters include: number of tubers per plant, tuber weight per plant (kg), tuber yield in kg/ha, unmarketable tuber yield in kg/ha and unmarketable tuber yield per plant (%). The results based on a comparison between five varieties of Irish potato and four levels of sowing dates show that variety and sowing date have statistically significant effects. Variety Nicola GL and Nicola YL, when sown in the middle of November, were higher in yield.
Keywords: Sudan savannah, Irish potato varieties, sowing dates and yield