**2. Results**

lights (*p* ≤ 0.001).

**2. Results** 

#### *2.1. Seedling Height and Biomass* **Table 1.** Main effects of species (amaranth and turnip greens) and LED treatment (W = white, B = blue, R = red) on plant height, fresh biomass, and dry biomass percentage of microgreens.

*2.1. Seedling Height and Biomass* 

*Plants* **2021**, *10*, x FOR PEER REVIEW 3 of 19

Seedling height was influenced by species, light, and their interaction (Table 1, Figure 1). Seedlings of amaranth were significantly smaller than those of turnip greens, under all lights (*p* ≤ 0.001).  **Seedling Height (H, cm) Fresh Biomass (FW, mg·Plant<sup>−</sup>1) Dry Biomass (DW, %)**  Species (*S*) Amaranth 3.9 ± 0.2 b 18.5 ± 1.8 b 5.4 ± 0.4

Seedling height was influenced by species, light, and their interaction (Table 1, Figure 1). Seedlings of amaranth were significantly smaller than those of turnip greens, under all

**Table 1.** Main effects of species (amaranth and turnip greens) and LED treatment (W = white, B = blue, R = red) on plant height, fresh biomass, and dry biomass percentage of microgreens. Turnip greens 5.4 ± 0.2 a 66.4 ± 2.8 a 5.2 ± 0.3 LED treatments W 3.9 ± 0.4 c 37.1 ± 9.9 b 5.9 ± 0.3 a B 5.2 ± 0.4 a 50.1 ± 11.8 a 5.9 ± 0.3 a


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* ≤ 0.01 (\*\*) and 0.001 (\*\*\*). Three biological replicates were used for measurements (*n* = 3). height close to 6 cm; in this species, white light (W) adversely affected plant growth, leading to a final height < 5 cm (Figure 1).

**Figure 1.** Interaction effect of *species* × *light treatment* (W = white, B = blue, R = red) on seedling height (H, cm) of microgreens. Data are means ± standard error (*n* = 3). Three biological replicates were used for the measurements. Different letters indicate significance at *p* ≤ 0.05 according to Tukey's test. **Figure 1.** Interaction effect of *species* × *light treatment* (W = white, B = blue, R = red) on seedling height (H, cm) of microgreens. Data are means ± standard error (*n* = 3). Three biological replicates were used for the measurements. Different letters indicate significance at *p* ≤ 0.05 according to Tukey's test.

Fresh biomass of the single plant varied with species and light but not with their interaction. According to seedling height, turnip greens produced a fresh biomass more than threefold greater than that of amaranth (*p* ≤ 0.001) under the same experimental conditions, revealing a faster growth. Light also affected the biomass accumulation, and However, light exerted a different effect, depending on species (*S* × *L*, *p* ≤ 0.01). In amaranth, seedlings were almost 3 cm tall in W, whilst their height exceeded 4 cm in B and R. In turnip greens, blue light (B) promoted plant growth, resulting in a final seedling height close to 6 cm; in this species, white light (W) adversely affected plant growth, leading to a final height < 5 cm (Figure 1).

fresh weight of the single plant at harvest was significantly greater under blue light in both species (*L*, *p* ≤ 0.001; *S* × *L*, *p* ≥ 0.05). Fresh biomass produced in W and R did not differ at ANOVA. However, dry biomass was the lowest (<4.3%) under red light, in both species, indicating a greater plant water content under these growing conditions. Fresh biomass of the single plant varied with species and light but not with their interaction. According to seedling height, turnip greens produced a fresh biomass more than threefold greater than that of amaranth (*p* ≤ 0.001) under the same experimental conditions, revealing a faster growth. Light also affected the biomass accumulation, and fresh weight of the single plant at harvest was significantly greater under blue light in both species (*L*, *p* ≤ 0.001; *S* × *L*, *p* ≥ 0.05). Fresh biomass produced in W and R did not differ at ANOVA. However, dry biomass was the lowest (<4.3%) under red light, in both species, indicating a greater plant water content under these growing conditions.

When the height/dry biomass (cm·mg−<sup>1</sup> ) ratio was calculated, interesting results on plant morphology were obtained (Figure 2). While no differences among light treat-

ments were observed in turnip for the ratio (<2 cm·mg−<sup>1</sup> ), the significantly higher value (7 cm·mg−<sup>1</sup> ) calculated for amaranth (*S* × *L*, *p* ≤ 0.001) in R with respect to W and B (3.7 cm·mg−<sup>1</sup> , on average) indicates that the same dry matter was distributed over longer plants under red light, i.e., the hypocotyls were thinner under these experimental conditions, contributing to total plant biomass. were observed in turnip for the ratio (<2 cm·mg*−*1), the significantly higher value (7 cm·mg*−*1) calculated for amaranth (*S* × *L*, *p* ≤ 0.001) in R with respect to W and B (3.7 cm·mg*−*1, on average) indicates that the same dry matter was distributed over longer plants under red light, i.e., the hypocotyls were thinner under these experimental conditions, contributing to total plant biomass.

When the height/dry biomass (cm·mg*−*1) ratio was calculated, interesting results on plant morphology were obtained (Figure 2). While no differences among light treatments

*Plants* **2021**, *10*, x FOR PEER REVIEW 4 of 19

**Figure 2.** Interaction effect of *species* × *light treatment* (W = white, B = blue, R = red) on plant height/dry biomass ratio (H/DW, cm·mg<sup>−</sup>1) of microgreens. Data are means ± standard error (*n* = 3). Three biological replicates were used for the measurements. Different letters indicate significance at *p* ≤ 0.05 according to Tukey's test. **Figure 2.** Interaction effect of *species* × *light treatment* (W = white, B = blue, R = red) on plant height/dry biomass ratio (H/DW, cm·mg−<sup>1</sup> ) of microgreens. Data are means ± standard error (*n* = 3). Three biological replicates were used for the measurements. Different letters indicate significance at *p* ≤ 0.05 according to Tukey's test.
