Background: Daylilies are a lucrative crop used for its floral beauty, medicinal proprieties, landscaping, fire prevention, nutritional value, and research. Despite the importance, daylilies remain extremely challenging for multiplying in vitro. The response difficulty is exacerbated because a few good protocols for daylilies micropropagation are generally difficult to reproduce across genotypes. An efficient strategy, currently applied at Langston University, is to systematically explore individual tissues or organs for their potential to micropropagation. This article is a partial report of the investigation carried out under room environmental conditions and focuses on developing an efficient daylilies in vitro propagation protocol that uses the stem tissue as the principal explant. Results: In less than three months, using thidiazuron, the use of the stem tissue as the in vitro experimental explant was successful in inducing multiple shoots several folds greater than current daylilies shoot organogenesis protocols. The study showed that tissue culture can be conducted successfully under unrestricted room environmental conditions as well as under the controlled environment of a growth chamber. It also showed that splitting lengthwise stem explants formed multiple shoots several folds greater than cross-sectioned and inverted explants. Shoot conversion rate was mostly independent of the number of shoots formed per explants. The overall response was explant and genotype-dependent. Efficient responses were observed in all thidiazuron treatments. Conclusion: An efficient protocol, which can be applied for mass multiple shoots formation using the daylilies stem tissue as the main explant, was successfully developed. This could lead to a broad and rapid propagation of the crop under an array of environmental conditions to meet the market demand and hasten exogenous gene transfer and breeding selection processes.

A bract is a non-inflorescence structure that exists in many plant species. In daylilies, the bract is biologically functional and is the object of the present tissue culture study. After sterilization, bract explants were treated with 6-benzylaminopurine (BA) and thidiazuron (TDZ) that were used individually or in combination in Murashige and Skoog (MS) nutrients medium, under room environmental conditions, to study its capacity to induce shoots in vitro. The results were successful. Both direct and indirect shoot organogenesis were observed. Although variably, all nineteen cultivars that were investigated induced multiple shoots. TDZ was the most potent chemical stimulus for shoot organogenesis. The results also showed no significant correlation between shoot conversion potential and genotype or treatment.