Assessment of intra- and inter-specific competition between wheat (Triticum aestivum) and wild oat (Avena fatua) by reciprocal yield model and competition indices

To determine intra- and inter-specific competition between wheat and wild oat by reciprocal yield model and other competition indices, a pot factorial experiment based on completely randomized design with 4 replications was carried out. The treatments were including four densities of wheat and wild oat as additive series (0, 2, 5 and 8 plants/pot). Results showed that interspecific competition coefficient of wild oat on wheat was greater than that of wheat on wild oat. Both species had low intraspecific competition effects relative to interspecific effects. Wheat plants were more susceptible to intraspecific competition than wild oat and relative competitive ability of wheat was lower than wild oat. Therefore, wheat plants were more affected by wild oat plants comparing to wheat plants. Relative yield in studied mixed relations was less than 1 or equal 1 indicating that wild oat and wheat plants compete on the same resources. Based on relative crowding coefficients analysis, wild oat was competitor than wheat. According to relative competitive effects, competitive ability of wild oat regard to biological and grain yield were 3.48 and 2.9 times of wheat, respectively.