The effect of sowing date and seed pretreatments on establishment of the energy plant Silphium perfoliatum by sowing

Silphium perfoliatum shows great potential in biomass production. Until now, stand establishment has been done by cost- and labour-intensive planting of seedlings. Sowing is impeded by seeds with low field emergence and unfavourable seed flow characteristics. An experiment with five different sowing dates and eight different pretreatments of seeds to break physiological dormancy in S. perfoliatum seeds was conducted. To monitor the establishment of the crop, field emergence, leaf area index and ground cover were measured in the first growing season and the biomass yield in the second growing season.

Seeds treated with gibberellic acid or potassium nitrate, and cold-stratified seeds showed a significantly higher field emergence than the untreated control group. Germination experiments under controlled conditions in the laboratory confirmed the significant positive effect of seed pretreatments on germination. Mean field emergence decreased as the growing season advanced. Field emergence correlated with leaf area index and ground cover. Pelleted seeds were able to overcome the unfavourable seed flow characteristics. In conclusion, stand establishment of S. perfoliatum in Central Europe by sowing is feasible when using pelleted seeds implemented with gibberellic acid and adhering to a sowing date at the end of April.