Wheat-Lolium multiflorum competence: effect of nitrogen application onto Argentinean varieties aggressivity

The objective of this study was to establish the competitive ability of Argentinean wheat (Triticum aestivum L) varieties in competence with Lolium multiflorum, and to determine the nitrogen level influence in the competitive process. Fields experiments were conducted at the La Plata National University Experimental Station (34°S, 58°W) La Plata (Argentina) during 1997 and 1998. Two wheat varieties (Klein Cacique and Pro Inta Super) and a local ecotype of L.multiflorum were used. The aggressivity index for above dry matter and grain yield and relative yield total were used as a measure of competitive ability and complementary resources, respectively. The aggressivity index variation due varieties was significant (p