Effect of planting patterns of sunflower on yield and extinction coefficient

Abstract - We studied the effect of different planting patterns and density of sunflower on yield and on extinction coefficient. The experiment was conducted in the field at the Seed and Plant Improvement Institute, Karaj, Iran on a loamy clay. Planting patterns included wide rows, conventional rows, twin rectangular rows and twin zigzag rows. Populations of plants were at 3 levels including 6, 8 and 10 plants per square meter. The results show that different planting patterns sometimes produced higher yield, but not always. Furthermore, equidistant plant distribution at equal plant densities produced a higher radiation interception and extinction coefficient. Moreover, when row spacing was reduced, grain yield increased. The greatest increase in radiation interception and in the extinction coefficient in response to planting patterns and plant densities was observed in twin zigzag rows of 8 plants m^-2. Twin zigzag rows of 8 plants m^-2 and conventional rows of 8 plants m^-2 produced the highest yield.