*2.3. E*ff*ect of Growth Periods on C-glycosylflavones and Policosanol Content in Young Barley and Wheat Seedlings*

To understand the effect of sprout growth periods (3–9 days) on the metabolite content (saponarin, isoorientin, isoschaftoside, hexacosanol, and octacosanol) under fluorescent and LED light irradiation, we conducted a further investigation. Of all the growth times, the saponarin content of barley and isoorientin/isoschaftoside contents of wheat seedlings were found to be the highest on the 3rd day of the treatment (Figure S3A–C). The contents of these *C*-glycosylflavones showed a declining trend with an increase in growth times (i.e., after 5, 7, and 9 days) in barley and wheat seedlings (Figure S3A–C). However, the magnitude of reduction in metabolite content varied with different light qualities and metabolites in these sprouts. The saponarin content of barley was reduced by 37.96%, 43.58%, 39.43%, and 45.93% for FL, white, blue, and red LED light irradiation, respectively, after the further growth

period of 9 days. A statistically significant negative correlation (−0.93 to −0.99) between saponarin content and sprout growth period was observed during FL and LED light (white, blue, and red) irradiation (Table 1). A similar attempt to establish relationships between isoorientin content and growth periods in wheat sprouts under FL and LED treatment showed that isoorientin accumulation was negatively correlated with growth periods under specific light (FL, white, and red) treatments. Furthermore, isoschaftoside accumulation is negatively regulated under white and red LED light treatments across growth periods. Nonetheless, their relationships in blue LED irradiated sprouts were inconclusive. *Plants* **2020**, *9*, x FOR PEER REVIEW 5 of 15

**Figure 2.** Policosanol content (μg/g DW) in barley and wheat seedlings during different growth periods and light conditions. (**A**) denotes hexacosanol (major policosanol) content in barley sprouts, whereas (**B**) denotes octacosanol content in wheat sprouts. \* (*p* < 0.05), and \*\*\* (*p* < 0.0001) indicate the statistical significance. **Figure 2.** Policosanol content (µg/g DW) in barley and wheat seedlings during different growth periods and light conditions. (**A**) denotes hexacosanol (major policosanol) content in barley sprouts, whereas (**B**) denotes octacosanol content in wheat sprouts. \* (*p* < 0.05), and \*\*\* (*p* < 0.0001) indicate the statistical significance.


*2.3. Effect of Growth Periods on C-glycosylflavones and Policosanol Content in Young Barley and Wheat*  **Table 1.** Analysis of correlation statistics (Pearson correlation) among metabolite content, growth periods, and their respective biosynthesis-related gene expression patterns across different light qualities.

content and growth periods in wheat sprouts under FL and LED treatment showed that isoorientin accumulation was negatively correlated with growth periods under specific light (FL, white, and red) \* *p* < 0.05, \*\* *p* < 0.001, \*\*\* *p* < 0.0001, \*\*\*\* *p* < 0.00001 indicates statistical significance (replicates were included for measuring Pearson correlation).

treatments. Furthermore, isoschaftoside accumulation is negatively regulated under white and red LED light treatments across growth periods. Nonetheless, their relationships in blue LED irradiated sprouts were inconclusive. In contrast to *C*-glycosylflavone content, the hexacosanol content in barley sprouts gradually increased with the extension of the growth period. In fact, the highest accumulation of hexacosanol was observed in barley sprouts after 9 days of FL and LED light (white, blue, and red) irradiation treatments (Figure S3D). The correlation coefficient (Pearson) analysis showed that positive In contrast to *C*-glycosylflavone content, the hexacosanol content in barley sprouts gradually increased with the extension of the growth period. In fact, the highest accumulation of hexacosanol was observed in barley sprouts after 9 days of FL and LED light (white, blue, and red) irradiation treatments (Figure S3D). The correlation coefficient (Pearson) analysis showed that positive correlations (0.69 to 0.91) existed between hexacosanol content and growth period, which was statistically significant in both FL and LED irradiated seedlings (Table 1). Unlike hexacosanol, the positive relationship between octacosanol content and wheat growth period was not clear (Figure S3E). As indicated in Figure S3E,

octacosanol concentration in wheat sprouts.

comparison of growth periods under white LED irradiation showed significant differences in

correlations (0.69 to 0.91) existed between hexacosanol content and growth period, which was statistically significant in both FL and LED irradiated seedlings (Table 1). Unlike hexacosanol, the positive relationship between octacosanol content and wheat growth period was not clear (Figure the growth period did not impose any significant effect on octacosanol content under white, red, and blue LED or FL light irradiation. Nonetheless, a comparison of growth periods under white LED irradiation showed significant differences in octacosanol concentration in wheat sprouts.
