Dark conditioning, cold stratification and a smoke-derived compound enhance the germination of Eucomis autumnalis subsp. autumnalis seeds

Seed germination requirements are important for the conservation and propagation of Eucomis autumnalis subsp. autumnalis, a threatened, yet widely utilized medicinal plant in southern Africa. In this study, conditions to maximize germination were investigated. The seeds of E. autumnalis were subjected to various environmental factors such as constant and alternating temperature regimes, cold stratification, temperature shifts and light/dark conditions. Effects of smoke–water and the newly identified smoke-compound (3-methyl-2H-furo[2,3-c]pyran-2-one) were tested on germination. At 20 °C and alternating temperature (30/15 °C) under a 16 : 8 h light / dark regime, germination was improved. The highest percentage germination (100%) was achieved with a mean germination time (MGT) of 30.6 ± 1.3 days, when the seeds were subjected to constant dark at room temperature (25 ± 0.5 °C). This indicates the negative photoblastic characteristic of E. autumnalis seeds. The species is associated with high-altitude regions. Cold stratification (5 °C) for 45 days significantly improved the percentage germination (90%) as compared to non-stratified controls (40%) when subsequently incubated at 25 ± 0.5 °C under a 16 : 8 h light / dark regime. Seeds treated with 3-methyl-2H-furo[2,3-c]pyran-2-one and incubated in constant light or a 16 : 8 h light : dark photoperiod germinated better (86.7% and 66.7%, respectively) compared to the controls (55% and 40%, respectively). This smoke-derived compound substituted for the dark and cold stratification requirements for the germination of E. autumnalis seeds.