Seed potential and germination dynamic of Abutilon theophrasti in subsequent crops
Abutilon theophrasti (Medic.) is native in China or India and primarily known in Germany as a weed in sugar beets. Due to the increased demand for renewable raw materials, A. theophrasti as a fibre plant could be of particular interest to the automotive industry in Germany. The possibilities and potential of cultivation of A.theophrasti in Germany are still under investigation. However, the high production of persistent seeds could be a problem in cultivation. The emergence of the seeds in the following growing season can lead to yield loss in the subsequent crop. In order to investigate and quantify the seed potential in the soil and the dynamics of germination of A. theophrasti, field trials were carried out in 2015 and 2016, where winter wheat (Triticum aestivum) and sorghum (Sorghum bicolor) were cultivated after A. theophrasti, in 2017 followed by maize (Zea mays). The seed potential in the soil and the number of emergent plants was continuously determined. After harvest of A. theophrasti, a soil seed bank of over 10,000 seeds m-2 in 2015 and 6,000 seeds m-2 in 2016 was determined. Within 2 years after the cultivation of A. theophrasti and winter wheat the number of seeds in the soil decreased by 77 to 82%. But 1 year after cultivation of A. theophrasti and subsequent crop still 1,973 to 3,096 seeds m-2 in the soil were present. The dynamics of germination showed that the majority of the seeds in the soil only emerge before sowing sorghum and after harvest of sorghum or winter wheat. The comparison of A. theophrasti with Camelina sativa as a pre-crop showed that there were no significant differences in yield of sorghum or winter wheat.