*2.2. Chlorophyll (a, b, and Total) and Carotenoids*

*2.2. Chlorophyll (a, b, and Total) and Carotenoids*  The content of Chl *a* exhibited a different pattern in relation to species and light. Overall, greater contents were measured in shoots of amaranth (Table 2, Figure 3a). In this species, Chl *a* was maximized in B, whereas, in turnip greens, Chl *a* content did not differ with light (*S* × *L*, *p* ≤ 0.01). No effect of species and light was observed according to ANOVA on Chl *b* content (*S*, *L*, *S* × *L*, *p* ≥ 0.05) (Table 2, Figure 3b). As a result, *total* Chl content followed the same pattern of Chl *a*, being higher in amaranth. In this species, as for Chl *a*, total Chl peaked under blue light, whereas it did not change with light in turnip greens (*S* × *L*, *p* ≤ 0.05) (Table 2, Figure 3c). The content of Chl *a* exhibited a different pattern in relation to species and light. Overall, greater contents were measured in shoots of amaranth (Table 2, Figure 3a). In this species, Chl *a* was maximized in B, whereas, in turnip greens, Chl *a* content did not differ with light (*S* × *L*, *p* ≤ 0.01). No effect of species and light was observed according to ANOVA on Chl *b* content (*S*, *L*, *S* × *L*, *p* ≥ 0.05) (Table 2, Figure 3b). As a result, *total* Chl content followed the same pattern of Chl *a*, being higher in amaranth. In this species, as for Chl *a*, total Chl peaked under blue light, whereas it did not change with light in turnip greens (*S* × *L*, *p* ≤ 0.05) (Table 2, Figure 3c).


Carotenoids were accumulated in a larger amount in microgreens of amaranth (0.10 mg·g**−**1 FW, against 0.08 mg·g**−**1 in turnip greens, *p* ≤ 0.01). They exhibited opposite trends in the two species, in response to light (*S* × *L*, *p* ≤ 0.01) (Table 2, Figure 3d). In amaranth, **Table 2.** Main effects of species (amaranth and turnip greens) and LED treatment (W = white, B = blue, R = red) on chlorophyll *a*, *b*, chlorophyll *a*/*b* ratio (Chl *a*/Chl *b*), total chlorophyll, carotenoids, and chlorophyll/carotenoid ratio (Chl/Car) of microgreens.

Values (mean ± *se*) within each column, followed by the same letter, do not significantly differ at *p* ≤ 0.05 according to Tukey's test; ns = not significant; significant at *p* ≤ 0.05 (\*), 0.01 (\*\*), and 0.001 (\*\*\*). Three biological replicates were used for the analysis (*n* = 3).

for the analysis (*n* = 3).

LED treatment (*L*)

*Significance*

(Chl/Car) of microgreens.

 **Chl** *a*

**(mg·g−1 FW)** 

**Table 2.** Main effects of species (amaranth and turnip greens) and LED treatment (W = white, B = blue, R = red) on chlorophyll *a*, *b*, chlorophyll *a*/*b* ratio (Chl *a*/Chl *b*), total chlorophyll, carotenoids, and chlorophyll/carotenoid ratio

Species (*S*) Amaranth 0.41 ± 0.0 a 0.11 ± 0.0 a 3.79 ± 0.18 a 0.51 ± 0.0 a 0.10 ± 0.00 a 5.1 ± 0.1

**Chl** *a***/Chl** *b* **(mg·g−1 FW)** 

Turnip greens 0.32 ± 0.0 b 0.10 ± 0.0 b 3.20 ± 0.20 b 0.43 ± 0.0 b 0.08 ± 0.00 b 5.2 ± 0.1

W 0.34 ± 0.1 0.11 ± 0.0 3.18 ± 0.11 b 0.45 ± 0.0 b 0.08 ± 0.00 b 5.3 ± 0.1 B 0.40 ± 0.0 0.11 ± 0.0 3.74 ± 0.33 a 0.51 ± 0.0 a 0.10 ± 0.01 a 5.1 ± 0.2 R 0.35 ± 0.0 0.10 ± 0.0 3.49 ± 0.08 ab 0.45 ± 0.0 b 0.09 ± 0.00 b 5.1 ± 0.1

*S* \*\*\* \*\*\* \*\*\* \*\*\* \*\*\* ns *L* ns ns \*\* \*\* \*\* ns *S* × *L* \*\*\* ns ns \* \*\* ns

**Total Chl (mg·g−1 FW)**  **Carotenoids (mg·g−1 FW)** 

**Chl/Car (mg·g−1 FW)** 

**Chl** *b* **(mg·g−1 FW)** 

**Figure 3.** Interaction effect of *species* × *light treatment* (W = white, B = blue, R = red) on chlorophyll (*a*  (**a**), *b* (**b**), and total (**c**)) and carotenoids (**d**) of microgreens. Data are means ± standard error (*n* = 3). Different letters indicate significance at *p* ≤ 0.05 according to Tukey's test. **Figure 3.** Interaction effect of *species* × *light treatment* (W = white, B = blue, R = red) on chlorophyll (*a* (**a**), *b* (**b**), and total (**c**)) and carotenoids (**d**) of microgreens. Data are means ± standard error (*n* = 3). Different letters indicate significance at *p* ≤ 0.05 according to Tukey's test.

*2.3. Sugar Content*  Sugar content varied with the species, being more than 40% greater in turnip greens (>1.3 mg·g**−**1 FW) than in amaranth (<0.7 mg·g**−**1 FW) (Table 3). Light did not exert any clear effect on this trait (*L*, *p* ≥ 0.05), while the interactive effect with species was not significant (*S* × *L*, *p* ≥ 0.05). Carotenoids were accumulated in a larger amount in microgreens of amaranth (0.10 mg·g <sup>−</sup><sup>1</sup> FW, against 0.08 mg·<sup>g</sup> −1 in turnip greens, *p* ≤ 0.01). They exhibited opposite trends in the two species, in response to light (*S* × *L*, *p* ≤ 0.01) (Table 2, Figure 3d). In amaranth, blue light (B) promoted the biosynthesis of carotenoids, whose content was almost the 30% higher than that in W and R. Such differences were not evidenced in turnip greens, where the content of carotenoids did not change with the light conditions of growth. The chlorophyll *a*/*b* ratio showed that W treatment provided a lower value while the highest ratio was found in the B light treatment. The relationship between total chlorophyll and carotenoids expressed as a ratio did not show any significant difference (Table 2).
