yield and relative advantage of sunflower intercropping at different patterns with soybean and corn

in order to evaluate the yield and advantage of two- and three-species intercropping of sunflower with corn and soybean, an experiment was conducted at the research farm of faculty of agriculture of tabriz university in tabriz, iran 2011. the experiment was arranged based on randomized completely block design with 6 treatments and three replications. treatments were included the pure stand of sunflower, replacement intercropping including two-species intercropping of sunflower and corn in ratio of 3:3, sunflower and soybean in ratio of 3:4, three-species intercropping of sunflower -soybean– corn at ratio of 3:4:3, three-species intercropping of sunflower- soybean-corn-soybean at ratio of 4:3:4:3, respectively; and additive intercropping of sunflower with soybean in ratios of 100: 20. results indicated there were not significant differences for plant height, chlorophyll content, seed weight and biological yield of sunflower between pure stand and intercroppings. the leaf number of sunflower was affected significantly by planting pattern and in intercropping treatments was greater than that of sunflower pure stand. the head diameter, number of seeds per head, seed yield and harvest index of sunflower in intercropping of sunflower-maize were lower than them in pure stand and other intercropping treatments. the two-species intercropping of sunflower-soybean had higher grain yield and harvest index than three-species intercropping of sunflower-soybean-corn. the highest and lowest values of land equivalent ratio (ler) were obtained in additive intercropping of sunflower–soybean (1.37) and replacement corn-sunflower (0.87). the three-species intercropping of sunflower-soybean-corn-soybean had greater ler (1.01) than intercropping of sunflower-soybean-corn (0.94). using three crops in intercropping causes increase in yield and also sustainability in agro-ecosystem.