Effect of nitrogen and phosphorus levels on barley cultivars grown in semiarid conditions

Most farmers in the rainfed parts of Jordan who use fertilizers use less than optimum rates of N and P because of the uncertainties associated with rainfall. Research results obtained by the national program indicated that the use of improved barley cultivars and fertilizers would result in substantial yield increases. The objective of the present investigation was to determine the optimum combination level of N and P for newly promising cultivars. The effect of 0-0, 5-10, 10-20 and 15-30 kg.ha(-1) of nitrogen (N) and phosphorus (P) levels on barley cultivars Rum, Giza, Fun, Harmel and Arta under rainfed conditions in the Mediterranean climate was studied during two cropping seasons, 1994-95 and 1995-96. Increased grain and straw yields, total N and P uptake and RUE were recorded with increasing N and P levels for almost all cultivars. Rum was significantly (P = 0.05) the highest grain and straw producer and highest RUE at the 10 N- and 20 P kg.ha(-1) level. The cultivar x fertility level (N-P) interactions were not significant for both grain and straw yields and for total N and P uptake.