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Submitted to: African Journal of Biotechnology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/24/2009 Publication Date: 11/16/2009 Citation: Sakhanokho, H.F. 2009. Sulfuric acid and hot water treatments enhance ex vitro germination of Hibiscus seed. African Journal of Biotechnology. 8:6185-6190. Interpretive Summary: The genus Hibiscus includes about 300 species. Among them are Hibiscus acetosella and H. dasycalyx. H. acetosella is edible but also grown as an annual ornamental for the attractiveness of its deep burgundy red, maple-like leaves. H. dasycalyx is a federally listed candidate endangered ornamental species that is native to North America and can only be found in three wetlands in Eastern Texas. The objective of the study was to establish protocols that promote rapid and uniform seed germination in vitro and ex vitro for H. dasycalyx and the two variants of H. acetosella. Sulfuric acid scarification was very effective for in vitro and ex vitro germination of both forms of H. acetosella seeds. Acid scarification of Hibiscus acetosella seeds for 10 and 15 min resulted in 99 and 100% germination rate within a week for the green and red form, respectively. A 72% in vitro seed germination was achieved with Hibiscus dasycalyx within a week after a 20 min acid scarification, compared to zero percent in 21 days for the non-treated seeds. Hot water scarification was ineffective for Hibiscus acetosella seeds (both in vitro and ex vitro) as it appeared to result in severe injury or death of the embryos. However, it was effective for seed germination in H. dasycalyx under both in vitro and ex vitro conditions. The protocols described here constitute rapid, reliable, and simple methods to germinate H. acetosella and H. dasycalyx seeds in vitro and ex vitro. Technical Abstract: Seeds of Hibiscus dasycalyx S. F. Blake & Shiller, a federally listed candidate endangered species and native to North America, and two variants of Hibiscus acetosella Welw. ex. Hiern were scarified using sulfuric acid and hot water. The effects of the scarification methods on in vitro and ex vitro germination in both species were evaluated. Sulfuric acid scarification was very effective for in vitro and ex vitro germination of both forms of H. acetosella seeds by dramatically increasing germination rate and decreasing germination time. Acid scarification of Hibiscus acetosella seeds for 10 and 15 min resulted in 99 and 100% germination rate within a week for the green and red form, respectively, of this species. A 72% in vitro seed germination was achieved with Hibiscus dasycalyx within a week after a 20 min scarification, compared to zero percent in 21 days for the non-treated seeds. Hot water scarification was ineffective for Hibiscus acetosella seeds (both in vitro and ex vitro) as it appeared to result in severe injury or death of the embryos. However, in vitro seed germination in H. dasycalyx improved from zero percent (non-treated seeds) to 65% in vitro and from 6% (control seeds) to 72% ex vitro. |
