Evaluation of Roselle (Hibiscus Sabdariffa) Accessions on Disease Resistance, Horticultural and Anti-Microbial Properties

NON-TECHNICAL SUMMARY: This project collaborates with USDA/ARS and other public and private agencies to screen for adaptable roselle accessions for production by limited resource farmers both in Louisiana and the southeast region of the U.S. To ensure the survivability of roselle enterprise in the region, preventive measures such as appropriate roselle accessions with good calyce quality and soil-borne disease resistance must be naturally selected and developed through micrografting technique. The novel application of roselle calyces as an antimicrobial component against food-borne pathogens in foods at pre-and post-harvest level will also be evaluated. The success of this project will promote roselle niche market production and enterprise development in the state of Louisiana because of the availability of adaptable and soil-borne disease resistant roselle accessions. The knowledge- base information of roselle as natural plant products for farmers, scientific communities and USDA/ARS database will be broadened.

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APPROACH: Roselle (Hibiscus sabdariffa) accessions from various sources including ARS roselle germplasm pool will be field tested for disease occurrence, earliness of flowering and fruit production, horticultural and anti-microbial activities. The quality evaluation of calyces includes total flavonoids and phenolic acids, color, elemental composition. Selected roselle accessions from Objective 1 will be used to develop new soil-borne disease resistant roselle accessions through micrografting technique (pin graft). A two-leaf-stage roselle seedling shoot tip will be interfaced with soil-borne disease resistant okra rootstock with an aid of a ceramic pin. Grafted roselle seedlings will be maintained under humid condition and partial shade to ensure successful graft unions from desiccation and survivability of the grafted plant. Grafted roselle will be field tested along with non-grafted roselle plants. The experimental design will be randomized complete block design with factoral arrangement of treatments (grafted and non-grafted). The data will be analyzed as a linear fixed effects model with binomial distribution. The calyces of selected roselle accessions from Objective 1 and 2 will be used to quantify their antimicrobial activities against food-borne pathogens in food at pre- and post- harvest levels.