Figure 1.

Median cycle threshold (Ct) values for fourteen candidate reference genes in switchgrass root and leaf samples under heavy metals stress conditions. The variation is displayed as medians values (lines across the box plot), 25th to 75th percentiles (boxes), and the maximum and minimum values (whiskers). Cadmium-treated leaves (CdL) and roots (CdR); lead-treated leaves (PbL) and roots (PbR); mercury-treated leaves (HgL) and roots (HgR); chromium-treated leaves (CrL) and roots (CrR); arsenic-treated leaves (AsL) and roots (AsR), the same below.