부산대학교 도서관

Sorghum is one of the most promising new options for the diversification of land use and for the replacement of maize in energy cropping systems. In on-farm experiments in three different regions of Germany (Thuringian Basin, East Brandenburg and the Lake District of Mecklenburg) between 2008 and 2010, we investigated if and how the cultivation of sorghum affects weed abundances and biodiversity aspects under real farming conditions. Energy maize was used as reference crop for the comparisons with sorghum. Special regard was given to test the hypothesis that differences in the weed flora between both crops can be explained by structural and temporal characteristics of the crop stands.In the field experiments, we found crop stands of sorghum and maize to have varying temporal (sowing time, growth dynamism) and structural traits (crop stands height and coverage). Hence, although sorghum shows a growth habit similar to that of maize, it is differing mainly in:i) the at least 3-4 week delayed sowing time,ii) a slow development during early growth stages,iii) a higher crop stand density and more intense shadowing at the end of the growing period.According to these particularities, we found sorghum to be very sensitive to early weed infestations. The height of early weed infestation level were in dependence of the weather conditions. The weed flora (species richness and species composition) in sorghum did not differ much from that of maize. Species composition was mainly affected by the modified sowing time. The weed species composition of the later sown sorghum differed mainly in the dominance of single weed species and the share of different ecological groups. Late summer or whole year germinating weed species like e.g. species of the Polygonaceae family may benefit specifically while Asteraceae species tend to be restricted.