Germination, emergence, and growth of giant foxtail (Setaria faberi) and fall panicum (Panicum dichotomiflorum)

Abstract

Controlled environment experiments were completed to determine the effect of temperature on giant foxtail and fall panicum germination, emergence, and growth. Giant foxtail seed germination decreased when exposed to a constant 30 C compared to 20 C. Germination also decreased in the alternating 20/30 C temperature regime when the hours of exposure to 30 C as compared to 20 C increased. Fall panicum required alternating temperatures of 14 C (9 h)/28 C (15 h) to germinate. Giant foxtail seed germination exceeded 60% 4 d after exposure to an alternating temperature of 7 C (9.4 h)/20 C (14.6 h). Conversely, fall panicum seed did not germinate at the 7 C (9.4 h)/20 C (14.6 h) temperature regime and required a minimum of 7 d exposure to alternating temperatures of 13 C (8.7 h)/26 C (15.3 h) for 88% of the seed to germinate. The greatest emergence of giant foxtail and fall panicum was from 1 cm and 1 to 2.5 cm, respectively. Less than 5% of the giant foxtail and fall panicum seed emerged from 7.5 cm. The growth of giant foxtail seedlings was five times greater than that of fall panicum at each temperature regime tested. Incorporation of this information into bioeconomic models could result in accurate predictions of weed germination for effective weed management strategies.