IN VITRO PROPAGATION OF SA PA AND VAN KHOI ANCIENT ROSE (Rosa spp.) CULTIVARS USING PLANT TISSUE CULTURE

Abstract

Sa Pa and Van Khoi ancient rose varieties are currently overexploited, leading to a shortage of high-quality plant materials. This study aimed to develop an in vitro propagation protocol for these two valuable rose cultivars. The most effective surface sterilization treatment for Sa Pa rose stem segments was immersion in 70% ethanol for 15 minutes, followed by 5% sodium hypochlorite for 10 minutes and 0.1% HgCl₂ for 5 minutes, resulting in 81.1% clean and viable explants. For Van Khoi rose, reducing ethanol exposure to 10 minutes achieved 75.6% clean and viable explants. Shoot induction was optimal on MS medium supplemented with 1.5 mg/l BAP, producing shoots 1.8 - 2.0 cm in height, with an average of 1.8 shoots/node and 4.0 - 5.3 leaves/shoot after 6 weeks. The most effective shoot multiplication medium was MS supplemented with 1 mg/l BAP, 0.5 mg/l kinetin and 0.3 mg/l α- NAA, yielding 91.1 - 92.2% shoot cluster formation and a multiplication rate of 2.8 - 2.9 times after 8 weeks. Rooting was best achieved on MS medium supplemented with 0.5 mg/l IBA, with a rooting rate of 88.9 - 94.4%, averaging 3.6 - 3.7 roots per shoot. In the nursery stage, a substrate composed of 50% soil, 25% vermicompost and 25% rice husk biochar supported a survival rate of 78.9 - 82.1%, plantlet height of 5.9 - 6.8 cm and 9.7 - 10.5 leaves per plantlet. Foliar application of Vinaf 30-20-10+TE fertilizer increased survival rates to 85.6 - 87.7%, plantlet height to 6.5 - 7.1 cm, and leaf number to 9.7 - 11.0 leaves per plantlet. This protocol provides a reliable foundation for large-scale production of disease-free, genetically uniform, and high-quality ancient rose plants.