Figure 4.

Effects of low blue light conditions on the growth rates and xyloglucan-degrading activity in the alpine and prairie ecotypes. A, Representative ramets from the alpine and prairie plants after 1 week in the indicated treatments. Control plants were grown in light with an unaltered spectral composition. Each bar on the scale = 1 cm. B and C, Ramet elongation rate for alpine (B) and prairie (C) plants grown under low blue light (white circles) and control (black circles) conditions for 1 week. Data points represent means ± se (n = 30–35). Ramet length measurements were made using a digital caliper. Growth rate differences between control and low blue light treatments were statistically significant at all time points (P < 0.05, Student's t test). D and E, Xyloglucan-degrading activity measured in the top internodes of alpine (D) and prairie (E) plants grown for 3 d under low blue light conditions. Controls refer to data from plants grown under normal light conditions (unaltered spectral composition). Data points represent means ± se (n = 3); each biological replicate consisted of internodes pooled from different ramets from different pots. Different letters above each bar indicate statistically significant differences (P < 0.05, Tukey's b test). Experiments were repeated twice with similar results. [See online article for color version of this figure.]