LAUSR

Adjustment of seeding schemes is one of the crop management techniques that most influences grain yield. A field study was undertaken to evaluate the effects of densities on optimum wheat grain yield, biological yield and harvest index by using of reciprocal model. The treatments comprised nine wheat cultivars and five densities (200, 250, 300, 350 and 400 plants m-2 ). Evaluation analysis showed that the performance of the model was reasonable as indicated by close correspondence of simulated biomass accumulation, grain yield and harvest index with measured data. Optimum wheat density based on maximum grain yield was almost 400 plant m-2 for ‘Rasad’, ‘Azar2’, ‘Homa’, ‘Saji’, ‘Koohdasht’, ‘Gohar’ and ‘Ohadi’; however, the optimum density was of 370 and 500 plant m-2 for ‘Nicknejad’ and ‘Zagros’ respectively. As an average, the highest of grain yield belonged to ‘Azar2’ by 414 g/m-2 . Biological and grain yields were dependent on the plant density, and increased when wheat density enhanced from 200 to 400 plants/m-2.