Figure 4.

Secondary metabolites in maca plants grown under UV-transmitting and -blocking filters. Concentration of benzylglucosinolate expressed in μmol g⁻¹ DW (a,b) and phenolic compounds in mg g⁻¹ DW (c,d) was determined in 4- and 7-month-old plants grown under mountain ecosystem. Total content of these secondary metabolites was also calculated. (e–h) Error bars represent the standard error of the mean (n = 6). The P-values indicate the significance of the effects of solar UV (UV), plant age (Age) and their interaction (UV*Age), all calculated from a two-way ANOVA. Differences between means are indicated by different letters (P < 0.05). BenzylGlc, benzylglucosinolate. Control, UV-transmitting filter. UV-block, UV-blocking filter. DW, dry weight.