Factors affecting seed germination and emergence of Gomphrena perennis

Controlled growth chamber experiments were conducted to determine factors affecting seed germination and emergence of the troublesome weed Gomphrena perennis. The objective of this research was to examine the effects of temperature, light, moist chilling, osmotic potential, dry storage and depth of seed burial on G. perennis germination and emergence. The optimum temperature for germination was around 1520 degrees C. Seeds showed germination rates above 90% under 20/10 and 25/15 degrees C temperature regimes. The minimum exposure to light needed to stimulate germination was 1 min. However, the light requirement was reduced after a long storage period. Furthermore, germination was high (>90%) in all moist-chilling treatments tested. Germination was highly sensitive to increasing osmotic stress. The highest germination percentage (94%) was achieved at 0 MPa, and decreasing osmotic potential from 0 to -0.3 MPa reduced germination to 11%. The highest seedling emergence occurred for seeds placed from 0 to 1 cm deep, and no seedlings emerged from a 5-cm burial depth. Gomphrena perennis has a suitable environment in a no-till soybean field, where seeds remaining on the surface have the required temperature, light and depth needed for germination.