ABSTRACT
The objective of this research was to evaluate the effects of temperature and light on germination of barnyardgrass in different periods of seed storage after dispersal. The research was divided into two studies: in the first it was evaluated the effect of three temperatures (15, 25 and 35 °C) and two light conditions (presence and absence), on germination percentage, hypocotyl length and radicle length; and, in the second, it was evaluated the effect of three temperatures (15, 25 and 35 oC) on the germination speed index and germination speed. The seeds were collected in the field shortly after the start of natural seed dispersal. The studies were performed at 30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330 and 360 days after seed harvest. At 30 days after seed harvest, there was no germination regardless of light conditions and temperature. At 60 days after seed harvest, the seeds germinated both in the presence and absence of light. The absence of light increased hypocotyl length, regardless of temperature. Under 15 oC temperature condition and absence of light, the seeds showed higher radicle length. The increase in temperature caused an increase on the germination speed index and germination speed of the seeds. The knowledge of factors that affect barnyardgrass germination contribute to develop crop management practices of this important weed that interferes in some crops, including the soybean grown in rotation with rice paddy.
Echinochloa crusgalli; germination test; germination biology
