Competition and niche differentiation in barley (Hordeum vulgare) and wheat (Triticum aestivum) mixtures under rainfed conditions in the Central Highlands of Eritrea

Barley and wheat mixtures were grown in the field using additive and replac ement ratios at two locations (Halhale and Mendefera) in Eritrea during the 1997 and 1998 seasons. The aim was to assess yield advantage and to analys e competition and niche differentiation using a hyperbolic regression model . It proved advantageous to grow barley and wheat in mixtures because more land area was required to obtain the same yield in sole crops. The hyperbol ic regression approach confirmed that barley and wheat grown in mixtures re sulted in yield advantages as a result of complementary use of resources. B arley showed greater competitive ability than wheat. for wheat, interspecif ic competition was larger than the intraspecific competition while for barl ey the intraspecific competition was greater than the interspecific competi tion. Niche differentiation indices were always above 1.0 indicating that t he component crops did not inhibit each other from sharing resources in a c omplementary way.