Effects of red and blue LED light sources on the growth of SRPs
The light treatment had significant (p < 0.001) effects
on the shoot length and root differentiation of the SRPs. The shoot
length of SRPs was significantly (p < 0.05) increased
under the blue light treatment, while the needles were light green in
contrast to the CK treatment. Additionally, the root differentiation was
significantly (p < 0.05) promoted under the R, 7R3B,
and 8R2B treatments (Fig. 4). With further statistical analysis, the
greatest shoot length (3.56 cm) was obtained under the blue light
treatment (Fig. 4 A). In terms of root differentiation, the total length
of roots, their volume, and the number of root tips all reached the peak
under the 8R2B treatment (Figs. 4 B, D, E). However, the root surface
area and average diameter reached their peak under the R treatment (Fig.
4 C, F). In general, the blue light promoted the longitudinal growth of
the shoots, whereas the red light was beneficial for root development.
In addition, the optimal combination for the enhancement of the SRP was
8R2B.