Controlled environmental chamber experiments were conducted for a 14-d
incubation period to measure the effect of temperature, light, light
intensity, water potential, and pH on eclipta seed germination. In ful
l light, seed germinated over a range of 10 to 35 C; however, germinat
ion was highest at 83% at 35 C. Seeds were strongly photoblastic with
none germinating in the dark. Seeds germinated in light intensities be
tween 6 and 100% of full light. Seeds germinated 78 to 88% in water po
tentials of 0.0, -0.1, and -0.2 MPa. In distilled water (pH similar to
5.5) and a buffered solution pH 6 and 7, seeds germinated 85 to 89%;
however, some seeds germinated in a buffered solution pH range of 5 to
8. After the first 14-d incubation period, ungerminated seeds were tr
ansferred to distilled water and incubated at 35 C in full light for 4
to 6 d as a second incubation period. Seeds germinated 89 to 96% afte
r this second incubation period when first incubation was at temperatu
res 10 to 35 C in full light or darkness, light intensities 0 to 100%
of full light, water potentials 0.0 to -0.8 MPa, and buffered solution
pH levels of 5.5 to 7.