Abstract
An experiment was conducted in 1990/91 and repeated in 1991/92 to study the effects of Fusarium graminearum the causal agent of foot and root rot and N-level on wheat grain yield, yield components, plant height and heading date. Four nitrogen levels; 0, 138, 276 and 414 kg N/ha were applied to soils noninfested or infested with the fungus. The presence of F. graminearum caused a remarkable root rot and significantly reduced wheat grain yield, yield components and plant height. On the other hand, heading date was not influenced by the fungal infection. N-level had significant effects on all studied characteristics in both seasons. The third level of N (276 kg/ha) maximized the grain yield. Concerning the interaction between the fungus and N-level, the highest grain yield losses were found when either higher N-level or no nitrogen were applied to wheat plants in the infested soil. The third and second N-levels were optimum in the noninfested and infested soils, respectively.
Based on the these results the common assumption that application of high N-level to overcome wheat grain yield losses caused by foot and root rot disease is not justified.