Effects of Aloe vera extract as a natural plant growth regulator on the In Vitro Growth of Dendrobium spectabile (Blume) Miq. plantlets

Dendrobium spectabile (Blume) Miq. is an ornamental orchid with high aesthetic and commercial value; however, its natural populations continue to decline due to habitat destruction and excessive exploitation. In vitro propagation offers an effective strategy for the large-scale production and conservation of this species. Natural plant growth regulators (PGRs), such as Aloe vera extract, have attracted increasing attention as environmentally friendly and cost-effective alternatives to synthetic PGRs because they contain naturally occurring auxins, cytokinins, vitamins, amino acids, and minerals that promote plant growth. This study aimed to evaluate the effects of different concentrations of Aloe vera extract on the in vitro regeneration and growth of D. spectabile plantlets. A Completely Randomized Design (CRD) with five treatments (0, 15, 30, 45, and 60 g L⁻¹ of Aloe vera extract) was applied using Vacin and Went (VW) medium, with five replications per treatment. Plantlet survival, height, root length, number of leaves, shoots, roots, and fresh weight were evaluated 15 days after inoculation. Quantitative data were analyzed using one-way analysis of variance (ANOVA), followed by Tukey's Honest Significant Difference (HSD) test at the 5% significance level. All treatments maintained a 100% plantlet survival rate throughout the experimental period. The addition of Aloe vera extract significantly affected all growth parameters, with the 45 g L⁻¹ treatment producing the greatest plantlet height (3.26 ± 0.26 cm), root length (1.58 ± 0.09 cm), number of leaves (4.00 ± 0.45), number of shoots (4.80 ± 0.58), number of roots (3.60 ± 0.51), and fresh weight (0.132 ± 0.009 g). These findings demonstrate that Aloe vera extract can serve as an effective natural plant growth regulator for the in vitro propagation of D. spectabile, with 45 g L⁻¹ identified as the optimum concentration for promoting plantlet regeneration and vegetative growth.