Blackgrass (Alopecurus myosuroides Huds.) seed dispersal from a single plant and its consequences on weed infestation

Blackgrass (Alopecurus myosuroides Huds.) seed dispersal from single mother-plants was studied in two experiments. For the first experiment, eight blackgrass plants of different heights and number of ears were produced in a greenhouse with the help of different in sowing densities and nitrogen nutrition levels. At the beginning of seed shedding, the plants were placed outside, and seeds were gathered daily. Daily seed dispersal was analysed by fitting a Weibull equation to the number of seeds as a function of distance to the mother-plant. The second experiment was carried out in a field comprising winter barley and spring barley plots as well as bare soil. In each of these three parts, two isolated blackgrass plants were selected and seeds gathered with the help of small pots located along and across the crop rows at growing distances from the mother-plants. For both experiments, total seed dispersal was analysed by fitting a sum of two Weibull equations and analysing the estimated parameters as a function of blackgrass characteristics (plant height, number of ears per plants), seed characteristics (weight, presence of caryopsis, germination ability), crop cover (winter barley, spring barley, no crop) and direction (along or across crop rows). The dispersal equations were then introduced into a weed demography model, and blackgrass spread in time and in space was simulated for a field cultivated with different crops.