Potential Utilization of Coconut Water as a Natural Substitute to Plant Growth Regulators for In Vitro Propagation of Hibiscus sabdariffa

Abstract

Hibiscus sabdariffa L. possesses various parts like seeds, leaves and calyces that hold economic importance due to their multi purpose. Its benefits can be fully tapped into using in vitro propagation, especially by incorporating organic additives into the media. This study established the sterilization protocol and the response of H. sabdariffa to various concentrations of coconut water as a natural plant growth regulator. Seeds were surface-sterilized using calcium hypochlorite solution in combination with 70% ethanol, with or without hot water pre-treatment, and cultured on Murashige and Skoog (MS) basal media. Ten days after culture, hypocotyl, cotyledon and cotyledonary node explants excised from in vitro-grown seedlings were cultured on MS medium supplemented with varying concentrations of coconut water (0, 5, 10, 15, 20 and 25% v/v). The cultures were monitored for callus induction, morphology, and colour of the callus, as well as shoot and root formation. The result showed that the seeds sterilized in 70% ethanol (20 s) and 5% calcium hypochlorite for 20 min resulted in the highest percentage of clean culture and germination. By day 28, all the explants in the different coconut water treatments had formed callus. Leaf formation was observed from all cotyledonary nodes in the various treatments. Multiple shoots were observed on cotyledon explants in MS medium supplemented with 15% coconut water. Root formation was observed on all the treatments. Further research is recommended to ascertain the effect of coconut water on the morphogenesis of the plant.