Application of chitosan nanoemulsion and Indole-3-butyric acid in the propagation of medicinal-ornamental Rosa damascena Mill.

Rosa damascena Mill., a member of the Rosaceae family, is an important medicinal and ornamental species globally known for its essential oil. However, despite its high economic value, this plant is considered difficult to root. One of the most critical parameters in rooting evaluation is the increase in rooting percentage and the number of roots during the cutting period. This study employed a factorial arrangement within a completely randomized design to develop a novel procedure for the vegetative propagation of Rosa damascena , applying five concentrations of Indole‑3‑Butyric Acid (up to 4000 mgL -1 ) and Chitosan nanoemulsion (up to 2% v/v) to hardwood stem cuttings. Fourteen morphological traits (leaf characteristics, callus formation, shoots, roots, and root fresh and dry weight) were evaluated on in R. damascena cuttings during winter. The results demonstrated that treatment with 1000 mgL -1 IBA was the most effective, significantly improving the majority of traits, including rooting percentage and diameter, root fresh and dry weight, and survival rate. Application of 1000 mgL -1 IBA increased the rooting percentage by 40% compared with the control. No root or leaf formation was reported at the highest concentration of IBA, alone and/or with chitosan nanoemulsion. Furthermore, treatments with 0.2 and 0.5% chitosan nanoemulsion and the combined application of 1000 mgL -1 IBA with 0.2% chitosan nanoemulsion were reported as the most effective. This combination significantly improved rooting percentage, chlorophyll index, length of the longest root, and the number of roots, shoots, and leaves. The findings demonstrate that the combination of chitosan nanoemulsion and IBA at lower concentrations is efficient for the propagation of R. damascena through stem cuttings. Thus, this cost-effective and innovative protocol offers a practical approach for the vegetative propagation of R. damascena . • Increasing rooting percentage and the number of roots during cutting time is one of the most important traits in the rooting evaluation of Rosa damascena Mill. • The current study demonstrated that Rosa damascene is a hard-to-root medicinal-ornamental plant. • The application of chitosan nanoemulsion (0.2%) and/or IBA (1000 mgL -1 ) at lower levels and their combinations firstly improved rooting parameters and subsequently shoot and leaves growth. • The finding of this study indicated that the applying of chitosan nanoemulsion in stem cutting of Damask rose might be a simple and effective way to improving the rooting and survival problem in this economical valuable plant.