Breaking seed dormancy in Lobostemon fruticosus

Lobostemon fruticosus (Boraginaceae) is one of the most important South African endangered medicinal plants, which is rare in nature due to over exploitation and poor seed germination. Natural regeneration of the crop is furthermore limited by over exploitation of the root system in nature. In an effort to improve and promote the cultivation of this plant by means of seed, the effects of four temperatures (15, 20, 25 and 30°C), exogenous gibberellic acid (GA3) (100 and 200 ppm) and water extracts of smoked paper (extracted in 10 and 5% concentration) were investigated on dormancy breaking and germination. The treatments were arranged in a factorial experiment (randomized complete block design) with three replicates of 25 seeds each on a double layer of filter paper (Whatman No. 1) in Petri dishes (90-mm sterile). The highest germination rates obtained were 80 and 76% for 100 ppm GA3 and smoke water (extracted in 10% concentration) treatments respectively, after 4 days, at 25°C compared to the control (46%) under similar conditions. The GA3 and smoke water treatments were easy to apply, and can therefore be recommended to growers for breaking dormancy in L. fruticosus seeds. The findings of this research will promote the cultivation of L. fruticosus by means of seed and significantly contribute to the conservation of this important and over exploited medicinal plant species.