Effect of density on weeds seed production and biomass and sorghum yield rotated with different plants

摘要

The present study aimed at evaluating effect of crop rotation and planting density on sorghum yield, weed seed production and biomass. The experiment was conducted as split plots using completely randomized blocks design with three replications. The factors included prior cultivation at five levels: lentil, maize, wheat, bean, and rapeseed as main factor and sorghum density as secondary factor at four levels including 50 plants/m² (row spacing = 4 cm), 25 plants/m² (row spacing = 8 cm), 17 plants/m² (row spacing = 12 cm), and 12 plants/m² (row spacing = 16 cm). According to the results, maximum length of panicle, 1000 kernel weight, and biomass of sorghum was seen in densities of 12 and 17 plants/m². In these treatments, there was not any significant difference between densities of 12 and 17 plants/m². However, more density resulted in significantly decrease of these traits. Sorghum biomass in densities of 25 plants/m² and 50 plants/m² was 37.3% and 34.4% less than that of 12 plants/m², respectively. The highest biomass per area unit (1636g/m²) was seen in wheat rotation and density of 50 plants/m². After this treatment, maximum biomass (1213 and 1170 g/m²), was seen in bean and rapeseed rotations in the density of 50 plants/m².