ارزيابي مراحل نموي ذرت متاثر از تراكم و دوره هاي مختلف تداخل سورگوم

Effect of Sorghum Density and Interferences on Maize Development and Grain Yield

In order to investigate the effects of sorghum densities and interference periods on development , grain yield and yield components of maize, a factorial experiment based on randomized complete block design with three replications was conducted in 2002 at the Research Field of Faculty of Agriculture, University of Tabriz, Iran. Factors were : sorghum densities (4 , 8, 12 plants /m2) and interference periods (0,14, 28, 42 days after emergence of seedlings and also during plant life of maize). Optimum maize density was 7.8 plants/m2. In maize monoculture, the rate of plant development (except coincidence of flowering), as measured by days after sowing, was increased. However, the rate of maize development was decreased, with increasing sorghum density and interference period .Increasing sorghum density and interference periods were resulted in increasing maize plant height and decreasing yield and yield components (except number of kernels per row). Maximum maize yield losses was 38% , which occurred at the highest sorghum density and interference .At this case, maize development period increased by a week, as compared to maize monoculture. Heat requirement, based on growth degree-days, for plant development (except for coincidence of flowering) in maize monoculture was decreased, but it was increased with increasing sorghum density and interference. It was, therefore, concluded that maize yield loss could be largely overcome by minimizing sorghum density and interference.