Rooting and growth of root cuttings of two old rose cultivars ‘Harison’s Yellow’ and ‘Poppius’ treated with IBA and biostimulants

Propagation by root cuttings is an easy and low-cost method for plant taxa with an ability to produce rhizomes or suckers. This research examined the possibility of using root/rhizome cuttings in the propagation of two difficult-to-root old rose cultivars, ‘Harison’s Yellow’ and ‘Poppius’. A plant-based preparation (Root Juice), titanium (Tytanit), and IBA (Chryzotop Green 0.25% IBA, Rhizopon AA 020 XX 2.00% IBA) were tested as rooting and growth enhancers for thick, medium, and thin rhizome/root cuttings. Additionally, observations were made to identify the site of the initial root and shoot formation. Shoots appeared before roots, without polarity. The visible swellings differentiating in new root/shoot buds in these two rose cultivars were placed along the rhizome. The primordia of root and shoot buds were situated near the pith rays and the vascular cambial zone. The trial reported here showed significant effects of the thickness of root cuttings and the preparations used in terms of rooting success and growth characteristics. Medium-sized cuttings of rose ‘Harison’s Yellow’ (45.0%), and thin cuttings of ‘Poppius’ (74.3%) achieved the highest rooting percentages. The most effective treatment was with Chryzotop Green, but Root Juice 0.01% and Tytanit 0.04% (‘Poppius’) and 0.02% (both cultivars) also had positive activity. Root Juice and Tytanit can be suggested for rooting cuttings of these roses as eco-friendly preparations.