Determining the Best Width of Strip in Row Intercropping of Sesame (Sesamum indicum L.) and Flax (Linum usitatissimum L.) and Its Effect on Yield, Yield Components and Weed Density

Providing food for the rising world population is one of the first human needs. In recent years, there has been increased interest in agricultural production systems in order to achieve high productivity and promote sustainability over time. Intercropping is one of the methods that simultaneously can increase the agricultural system productivity and also reduce their side effects on the environment.  Intercropping can provide numerous benefits to cropping systems through increasing the total yield and land-use efficiency by enhancing the use of light, water, and nutrient, as well as improving soil conservation and declining the economic damage of agricultural pests, diseases, and weeds.Several factors can influence the growth and yield of the species used in the intercropping, including the kind of selected crops, sowing ratio, and competition between the mixture components. Therefore, the present study, to compare the different intercropping patterns of sesame and flax and their effects on the yield and the weed density.

In order to determine the best width of strip in row intercropping of sesame (Sesamum indicum L.) and flax (Linum usitatissimum L.) a two-year field study based on a randomized complete block design with three replications was conducted during the growing seasons of 2009-2010 and 2010-2011 in the Agriculture Research Station of Ferdowsi University of Mashhad. Treatments were four patterns of sesame-flax row intercropping including one row of sesame + one row of flax (1:1), two rows of sesame + two rows of flax (2:2), three rows of sesame + three rows of flax (3:3), four rows of sesame + four rows of flax (4:4) and monoculture of sesame and monoculture of flax. The crops were sown simultaneously on 1 and 5 May in 2009 and 2010, respectively. The crops were irrigated after sowing and thinned out in the 4-6 leaf stage. In the first month after sowing, all plots were weeded by hand and after that, we did not use any method for controlling of weeds and the density and dry weight of weeds were evaluated in four sampling dates. At the end of the experiment, the yield and yield components of both crops were measured and the land equivalent ratio (LER) was calculated based on the yield of each crop in monoculture and in intercropping patterns.

The results showed a significant difference among different intercropping patterns based on the density and dry weight of weeds. The highest and lowest dry weight of weeds were observed in flax monoculture (832.1 g.m-2) and 2:2 pattern (41.66 g.m-2), respectively. On the other hand, improving diversity by using intercropping had a negative effect on the density and dry weight of weeds. The maximum amount of biological yield of sesame was recorded in monoculture (9508.7 kg.ha-1) and for flax was recorded in monoculture and the pattern of 2:2 (3987.3 and 3521.7 kg.ha-1, respectively). Besides, the highest seed yield of the two crops was gained in monoculture (4876.3 and 2122.12 kg.ha-1 for sesame and flax, respectively). The land equivalent ratio (LER) for different patterns ranged from 0.68-1.34 and the maximum LER belonged to the pattern of 2:2. In general, the best result was obtained in the pattern of two rows of sesame+ two rows of flax (2:2). 

Overall, our results indicated that in intercropping, planting pattern with two or three rows of flax among the sesame rows had the best planting composition to achieve the highest yields for the two crops. In addition, the land equivalent ratio in these patterns was calculated more than one. One of the other effects of intercropping in our study was reducing the density and biomass of weeds. As a result, choosing the right pattern in the intercropping not only can be effective on the crop yield, but also by reducing the density of weeds can decrease the environmental impact of agricultural production systems by diminishing the use of chemical herbicides.