Growth of B. napus plants under different illumination sources. A) Stem length (n = 24). B) Fresh weight of whole 24 and 41 days old plants; C) chlorophyl content of the same plants (n = 15). D) Relative transcription of PR1 gene (n = 3). The PR1 transcription was normalized to the reference gene for actin. In all cases error bars represent SD. Asterisks indicate statistically significant differences compared to plants grown under fluorescent lights (**P < 0.01, two tailed Student’s t-test).