SRP survival rate
The treatments that effectively promoted the growth of SRPs also contributed to the survival rate of the transplanted plants. For example, the SRPs treated with 20 g/L sucrose obtained the highest survival rate (85.2 %). Similarly, following the liquid medium and transplantation stroma treatments, the highest survival rate was obtained in the 1/2 WPM and mixture of vermiculite and perlite (1:1 (v/v)). Thus, the optimal enhancement for P. thunbergii SRPs was 20 g/L sucrose, 1/2 WPM liquid medium, and a transplantation stroma of vermiculite and perlite (1:1 (v/v)). Among the spectral treatments, the highest survival rate occurred under the 8R2B, while the lowest survival rate was under the B treatment. Furthermore, the survival rate of SRPs was significantly promoted in the rooting medium with 1 µg/L BR (Fig. 5). As for the ratio of roots to shoots (R/S), the results revealed that when the ratio of roots to shoots < 4cm, there was no relationship with survival rate. When the ratio of roots to shoots > 4cm, it was positively related to survival rate (Fig. 6). Among all treatments, those under the light spectrum had the highest survival rate. Thus, based on the light spectrum treatments, principal component analysis showed that the factor that had the greatest influence on the survival rate was the tips (Fig. S1). Moreover, the correlation analysis also showed that the correlation coefficient of the root tips on survival was the greatest (p< 0.001; r=0.53), while the highest correlation with the root tips was the root volume (p < 0.001; r=0.38). The root length had the lowest correlation coefficient (p < 0.05; r = 0.18) for the survival rate compared to the root tips, surface area, volume, and diameter, (Fig. 7).