Polypogon fugax is a malignant weed that has caused great damage to rape (Brassica napus) fields in Dongting Lake District, China.Growth chamber experiments were conducted to determine the influence of environmental factors on seed germination and the emergence of Polypogon fugax.The optimum temperature for seed germination was a constant temperature of 20 C or an alternating temperature of 22/15 C.Seeds could germinate in the dark, but light exposure significantly enhanced the germination rate.