Seed germination and vegetative propagation of Helichrysum odoratissimum

Abstract

Helichrysum odoratissimum is a popular indigenous herb of South Africa, well known for its aromaticity. It offers potential as a source of extracts for the development of cosmeceutical products as it has been reported to be a natural antibiotic, and has antifungal, antimicrobial, antioxidant and antiviral properties. In order to be commercialized, a sustainable production system is required to ensure a consistent supply of good quality material. Therefore, the production of H. odoratissimum by seed and stem cutting was evaluated. The interactive effect of different seed priming methods and temperature levels were investigated on germination indices of H. odoratissimum seeds. A randomized complete block design with three replicates was used to evaluate the effect of season, cutting position, rooting hormone and growth media on survival percentage, number of buds, number of leaves, rooting percentage, number of roots per cutting and root length of H. odoratissimum stem cuttings. Data for both aspects was analysed using ANOVA and means with significant differences were separated with a t-test at 5% level of significance. Smoke treated seeds incubated at 20 °C had a significantly higher germination percentage (91,7%), mean germination rate (0.59) and coefficient velocity of germination (59.5) compared to most other treatments. Almost all factors tested in vegetative propagation significantly affected parameters measured. Apical cuttings taken during autumn resulted in significantly higher survival (78.5) and rooting percentages (71.1%) compared to other seasons. Cuttings planted in a perlite, vermiculite and sand mixture during autumn significantly outperformed all other season/media combinations with regards to rooting percentage (75%). PGR application improved the number of roots obtained significantly in autumn and winter, but not in summer and spring, compared to the control. It was therefore concluded that, for higher seed germination H. odoratissimum seeds must be primed with smoke water and incubated at 15–20 °C and cuttings may be taken autumn for higher rooting and survival rates as well as improved root length. A PGR application can be beneficial depending on the type of medium used.