Sea kale (Crambe maritima L.) is a wild edible plant with forgotten and undiscovered potential as a field vegetable. Its natural habitat is gravel beaches in northern Europe and the Black Sea. Three experiments were conducted to find the effect of temperature on seed germination and to determine plant growth response to organic fertilizer and soil types. Germination rates were estimated at three temperatures. Plant growth responses were conducted with application of two fertilizer concentrations [15 and 30 kg plant-available nitrogen (PAN)/ha] and by using four distinct soil types. Seeds sown at 20 and 15 °C reached a significantly greater germination rate after 32 days (48.0% and 40.4%, respectively) than seeds sown at 10 °C (16.6%). The number of days when 50% of the seeds that germinated during the experiment had germinated (T50) were 12.0, 11.8, and 16.8 days for 20, 15, and 10 °C, respectively. Application of 15 or 30 kg·ha−1 PAN did not result in any significant differences in plant size or biomass within 2 months of growth in sandy loam, but substantial plant heterogeneity was observed. Soil composition had a significant effect (P ≤ 0.05) on plant biomass. Plants grown in fine or loamy sand had the greatest growth and biomass. Sea kale seems to have a potential to become a field vegetable, because it grows well on other soil types than gravel. However, domestication processes of the species are required to obtain homogenous plants for future propagation.
Jonas Christensen, Uffe Bjerre Lauridsen, Christian Andreasen, and Henrik Lütken
Lívia Lopes Coelho, Amalia Fkiara, Kathryn Kuligowska Mackenzie, Renate Müller, and Henrik Lütken
Kalanchoë is an economically important genus comprising numerous potted plants and recently is also emerging as cut flowers. However, the lack of information about flower-inducing factors limits the number of species that can be used in commercial production and breeding programs. Therefore, the aim of this study was to investigate the effects of exogenous application of gibberellic acid (GA3) on flower induction and flowering quality of Kalanchoë longiflora and Kalanchoë pinnata. The experiment was conducted under a short day (SD) photoperiod with a day temperature of 22 °C and a night temperature of 15 °C for 8 weeks. The treatments consisted of four applications of either 0.25 or 0.50 μg of GA3 per plant per week, providing a total of 100 μg or 200 μg/plant and 0 μg/plant for the control. The volume of 100 μL of GA3 solution containing 1% agarose was applied to the shoot apex using a pipette. For both species, flowering was enhanced by the GA3 treatments compared with the control plants. Gibberellin-treated plants flowered earlier, produced more inflorescences, and exhibited an increased number of flowers compared with the control plants. Moreover, the GA3 treatments in K. longiflora delayed the appearance of wilted flowers. Plant height increased in plants that received GA3, but the number of nodes did not differ from the control plants. Thus, we conclude that the application of GA3 improves flowering of Kalanchoë species and can be a useful tool for the production of cut flower cultivars.