Interspecific variations in seed germination and seedling emergence of three Setaria species

Setaria glauca (L.) Beauv., Setaria verticillata (L.) P. Beauv., and Setaria viridis (L.) P. Beauv. are summer annuals and problematic weeds of many annual and perennial summer crops and orchards in the north of Iran. There is no information about interspecific variations in responses to environmental factors. In this study, interspecific variations of the Setaria in response to temperature in light/dark and complete darkness regimes, pH, salt and osmotic stress, and seed sowing depth in the laboratory and greenhouse experiments were investigated. The optimum temperature of S. viridis and S. verticillata seed germination was 25/15 degrees C in light/dark regime, while germination of S. glauca at 20 degrees C was the maximum in both light/dark and complete darkness regimes. The maximum germination of the Setaria occurred at pH 7 (41-48 %) and no seed germinated at pH 11. S. verticillata and S. viridis were moderately tolerant to salt and osmotic stress, but S. glauca was more tolerant to higher levels of stress. The maximum seedling emergence occurred when the seeds were planted on the soil surface (88-94 %) and decreased as sowing depth increased. Seedling emergence of S. verticillata and S. viridis reached zero at depths of 6 cm, while 12.11 % of S. glauca seedlings emerged at a depth of 8 cm.