Freshly matured seeds used for the light experiments
were harvested from multiple plants in a crop production
field at the Clemson University campus in SC, USA, in early
November 2004 and 2006. The PVC pipes were established in the
field at the Clemson University Simpson Research Center in Pendleton,
SC, USA, similar to the temperature study; burial and retrieval
of the seed bags at 0, 3, 6, 9, and 12 month(s) after seed maturation
were conducted using the same procedure described previously.