Development and comparative analysis of initiation ability in large-scale Heuchera propagation using tissue culture versus cuttings

The Heuchera genus, a member of the Saxifragaceae family, encompasses a wide array of varieties and hybrids, serving both traditional medicinal and ornamental purposes. However, a significant knowledge gap persists in achieving efficient mass propagation of diverse Heuchera cultivars creating a substantial market void. To address this, our study focuses on expedited seedling regeneration by investigating leaf cutting and tissue culture techniques to offer novel insights to cultivators. Herein, we successfully rooted thirteen distinct cultivars from the Heuchera and Heucherella (Heuchera × Tiarella) genera through cutting. Moreover, in vitro culture experiments led to the successful induction of calli and shoots from petiole samples. Notably, variations in measured parameters were observed across cultivars in both cutting and tissue culture methodologies. When petiole explants were exposed to cytokinin 6-benzylaminopurine (BA) at concentrations of 0.5, 1.0, and 2.0 mg/L along with auxin α-naphthaleneacetic acid (NAA) at 0.5 mg/L, shoots were produced either directly or indirectly during the primary culture. Exposure to darkness and the application of 2,4-dichlorophenoxyacetic acid (2,4-D) did not promote shoot formation but were beneficial for callus stimulation. Interestingly, a negative correlation was observed between the ease of initiating cutting recovery and inducting tissue culture regeneration, suggesting that cultivars that easily regenerate through cutting might encounter difficulties during induction by tissue culture. In light of these findings, we devised a streamlined and effective protocol for rapid Heuchera propagation. This protocol involves micropropagation, directly acquiring adventitious shoots from primary cultures supplemented by cutting-based propagation methods.