Sunflower (Helianthus annuus L.) Yield Performance under Additive Intercropping with Bean (Phaseolus vulgaris L.) and Different Tillage Systems

  Agricultural conservation technologies maintain water and soil, keep soil moisture and increase crop yield and soil quality, which are beneficial for sustainable development of agricultural production. Hence, conservation tillage may improve crop yield, among other economic benefits. Conservation tillage is a crop management system that increases the efficient use of nutrients and water. Conservation tillage includes any method of soil cultivation that leaves the previous seasons crops residues on fields before and after planting the next crop. Intercropping has been long practiced in many parts of the world and continues to be widely employed not only in tropical, but also in temperate regions. Compared to sole crops, intercropping system has higher utilization of resource i.e., nutrient use efficiency, water use efficiency, and land use efficiency.
Material and A split plot experiment was designed based on randomized complete blocks with three replications and implemented on a clay loam soil during the growing seasons of 2013 and 2014, at the Agricultural Research Station, Faculty of Agriculture, University of Bu-Ali Sina, Hamedan, Iran. Tillage (reduced tillage by chisel and disc and conventional tillage) as main factor and planting pattern (sole cropping of bean and sunflower and additive intercropping 30 and 60% bean with sunflower) were considered as sub-plot. Twenty days before planting, the soil was tilled by harrow for conventional tillage and by chisel and disc for minimum tillage. Sunflower and soybean were considered as main and secondary crops, respectively. The crops' seeds were simultaneously sown. Harvest operation was done on September 30, 2013 and September 27, 2014. After considering of border effect random samples 2 m2 areas was harvested by cutting the stems near ground level to determine the crops’ grain and straw yield. The land use efficiency (LUE) was calculated to measure efficiency of intercropping compared to pure cropping. Land use efficiency calculated as: LUE = (I1/P1) + (I2/P2). Grain oil percent and grain protein percent were determined by Soxhlet and Kjeldahl methods. SAS procedures and programs were used for analysis of variance (ANOVA) calculations. ANOVA indicated that bean biologic and grain yield was not significantly affected by the tillage but, bean biologic and grain yield was significantly (p> 0.01) affected by the planting pattern. Also, tillage × planting pattern effect was significant on these properties. Effect of planting pattern was significant on the most of traits, but the most properties were not affected by tillage. The highest grain yield, protein yield and oil yield of sunflower (356.22, 160.90, 77.27, respectively) were achieved at sole cropping treatment, but intercropping decreased these traits significantly. The highest total biological and grain yield (1189.40 and 437.28 g m-2, respectively) belonged to additive intercropping 60% bean + sunflower treatment. One of the important intercropping benefits is the higher productivity and profitability per unit area When the value of LUE is less than 1, the intercropping negatively affects the growth and yield of crops grown in mixtures but when the value of LUE is greater than 1, the intercropping favors the growth and yield of the crops. Land use efficiency at additive intercropping 60% bean + sunflower treatments with different tillage were more than one, so highest LUE was obtained at × 60% bean +sunflower. Moreover, the total land use efficiency was higher in intercropping system compared to the sole cropping system, indicating the advantage of intercropping over sole cropping in utilizing environmental resources for crop growth. In general, reduced tillage by chisel could say that additive intercropping 60% bean + sunflower had total yield in comparison to sole cropping of both two crops and increase land use efficiency. Acknowledgments
We would like to thank the funding from Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran