The effects of different rates of Nitrogen (0, 30, 60, 90 and 120 kg N/ha) on the reaction of five (FARO 46, FARO 11, FARO 45, FARO 48 and FARO 38) and seven (FARO 46, FARO 11, FARO 45, FARO 48, FARO 38, FARO 40 and WAB 56-50) varieties of upland rice were studied in field trials conducted in both the dry and wet seasons of 1997 and 1998. The trials ware laid up in split plot design with three replications. The upland rice varieties formed the main plot treatments while the nitrogen levels were the subplot treatments. FARO 40 and WAB 56-50 did not support Striga emergence, and thus exhibited resistance to Striga hermonthica. FARO 48, a variety normally susceptible to S. hermonthica, supported delayed and low Striga emergence, exhibiting enhanced resistance. In spite of support for early and high Striga infestation, FARO 11 exhibited tolerance. All other varieties FARO 45, FARO 46 and FARO 38 exhibited susceptibility to S. hermonthica. In the study, the application of 90 and 120kg N/ha delayed and reduced Striga emergence on the crop, induced low crop reaction score which resulted into grain yield that were the maximum or significantly higher than the least. The lower rates of nitrogen (30 and 60 kg N/ha), which caused similar Striga incidence however, resulted in significantly lower yield than 90 and 120 Kg N/ha. The interaction of upland rice varieties and nitrogen was significant on the number of days to first Striga emergence, crop reaction syndrome and number of days to 50% flowering of rice, indicating that host plant resistance alone may also not be adequate for Striga management in upland rice.
[Niger Agric. J. 33 (2002): 119-127]