Promoting seed germination of Bunias erucago, a Mediterranean leafy vegetable

Knowledge of germination and propagation requirements are crucial for the use of plant genetic resources. Here, we compare different treatments to improve the germination of Bunias erucago (Cruciferae), a Mediterranean vegetable herb of growing commercial interest. Its cultivation is limited by the poor germination shown by the seeds which are enclosed in indehiscent silicles. To improve the germination, we investigated four treatments: (1) presoaking silicles in water for 48 hours; (2) scarification of silicles with sandpaper; (3) seed extraction; and (4) seed exposure to gibberellic acid (GA(3)). The same treatments (except the GA(3) treatment) were also used to investigate seedling emergence under glasshouse conditions. In the absence of treatments and/or soaking in water, there was very low final germination (< 10%), while scarification and seed extraction increased the germination to similar to 40% and > 90%, respectively. Scarification was the most effective treatment in a horticultural context, since the brittleness of seeds makes their extraction too delicate and time-consuming. The seedling emergence results confirmed those of seed germination in the laboratory, underlining the effectiveness of the treatments for plant cultivation. Seed germination performance varied among wild populations, underlining the importance of provenance when using wild plants as new crops.