Effects of smoke water on germination, seedling vigour and growth of Sceletium tortuosum

Abstract

Sceletium tortuosum (L.) N. E. Br. is a South African protected species widely utilized in traditional medicine. The plants' mesembrine-type alkaloids have immense potential in modern pharmacology as treatments for numerous medical and psychological disorders. Fresh plant material is paramount for researchers and pharmaceutical companies as it is presently the only available alkaloid source. Although S. tortuosum is a conservation concern and valuable to the pharmaceutical industry, information on germination behaviours of this species is scant. This study highlights the effects of the bio-stimulant smoke water (SW) on germination, seedling vigour and growth of Sceletium tortuosum in vitro. A standardized smoke extract was diluted to concentrations of 1:500, 1:1000, 1:1500, 1:2000, 1:2500 (v/v). Seeds were pulse-treated with SW solutions for 1, 2, 8 and 24 h. The study included positive and negative control treatments. The highest mean germination percentage and germination rate were recorded for 1:1000 SW for 24 h (83 ± 1.9%) and 1:2500 SW for 24 h (6.35 seeds germinated/day). Vigour index was highest for 1:1000 SW (24 h). Smoke water only improved seedling growth when germination occurred slowly. Although mean shoot length was optimal for 1:2500 (1 h) – 4.19 ± 0.15 mm – mean root length and seedling size were highest in the negative and positive (1 h) control treatments. This investigation showed that SW effectively improved germination and seedling vigour of S. tortuosum, however, alternatives must be investigated to optimize seedling growth when this biostimulant is applied.