Factors influencing seed germination, emergence and mortality in soil seed bank of Bromus sterilis L.

Bromus sterilis L. (barren brome) spreads rapidly in many European regions. In the Czech Republic, its importance has increased dramatically over the past 10 years. Barren brome is reported as a problem weed in winter crops such as winter wheat, winter barley and oil seed rape, in vineyards and in other cultivated places. Barren brome has been becoming troublesome weed of winter cereals mainly in reduced soil tillage systems. The factors, that are important for its spreading and adaptability under different environmental conditions, are dormancy and germination. Optimal timing for seed germination varies with respect to natural conditions and it is determining for plant development. These traits are adapted to different conditions and habitats; therefore the dormancy and germination response patterns to those conditions vary significantly. Recently there are not many information available on germination behaviour, therefore this study was focused on seeds of barren brome and its characteristics, which were collected in different regions of the Czech Republic. Seeds were investigated under different temperatures, light regimes and water stress in a wide range of conditions. The following characteristics of seeds were studied the dormancy, the dynamics of germination, the temperature optimum, the age of seeds and dynamics of emergence from different depths and persistence in the soil profile under field conditions. Dormancy and germination are influenced by external conditions. The dormancy of seeds barren brome is very short or missing. The germination is influenced by light; the seeds germinated better under darkness than under light regime. The primary dormancy of B. sterilis was short and the seeds needed only three weeks for after-ripening. The seeds of B. sterilis showed broad ecological valence to hydrothermal factors germinating in the wide range of 3 to 35 °C. The temperature optimum is 5-23°C. The germination was only slightly influenced in an environment with low water potential. Germination was limited under water stress only at lower temperatures under 10°C. The response to light at various temperatures showed that seeds germinated better in darkness in all temperatures regimes, than in alternating light regime, especially at lower temperatures. The emergence declined significantly with burial depth (under 40 mm). The seeds were not able to survive in the soil seed bank for a longer time and fall seeds lost viability after 1 year burial in soil profile. These results may be of value for development of predictive models and understanding period when weed control may be most feasible