VARIETAL RESPONSE OF IRISH POTATOES TO IRRIGATION SCHEDULING IN THE NORTHERN GUINEA SAVANNAH ZONE OF NIGERIA

The effects of cumulative pan evaporation (CPE)-based irrigation scheduling on growth, yield, crop water use and crop water use efficiency of Irish potatoes (Solannum tuberosum L.) were studied. Irrigation scheduling was at CPE of 20 mm, 30 mm, 40 mm and irrigating at 7-days rotation (Control). Net depth of 50 mm was used. Pakistan, Nicola, SP and Dual were the four varieties of Irish potatoes used for the study. Irrigating at 20 mm resulted in early flowering, early germination, highest total yield at harvest, largest tuber sizes, heaviest tubers, and largest total number of tubers. Seasonal crop water use and crop water use efficiency were found to be 551 mm and 48.85 X10^-3.  Dual exhibited best performance in terms of early germination, total number of tubers and tuber weights; but the largest tuber sizes were produced by variety Pakistan. The 7-day rotational irrigation which is the conventional irrigation interval for the crop in this region did not turn to favor the growth and yield of the crop. Irrigation interval of not more than four days is therefore recommended for the growth and production of the crop in this region when a net depth of 50 mm is used on a loamy soil.