PHYTOCHROME-MEDIATED AMARANTHUS GERMINATION I - EFFECT OF SEED BURIALAND GERMINATION TEMPERATURE

This research was conducted to evaluate the light requirement for redr oot and smooth pigweed germination in soil, and how this requirement i s affected by germination temperature and seasonal periodicity in seed dormancy. Seed enclosed in nylon mesh bags was buried in the field in December 1993 and 1994 and was recovered throughout the spring and su mmer of the following year, respectively. Germination was highest with red light or at 30 C. The requirement for red light was more pronounc ed at 20 vs. 30 C. The saturating fluence of red light was as low as 3 mu mol m(-2) in buried seed and 1,000 mu mol m(-2) in unburied contro l seed, depending on germination temperature. The effect of light and germination temperature pigweed germination also changed throughout th e growing season. Our results indicate that light may be a requirement for germination in only the most dormant weed seed in the soil seedba nk.