The accelerated germination of Carrichtera annua seeds and the stimulating and inhibiting effects produced by the mucilage at supra-optimal temperatures

The beds on which the mucilagenous seeds of the desert annual Carrichtera annua (Cruciferae) had been germinated and removed, had an insoluble stimulatory activity on other C. annua but not on pepper seeds, which were sown in the same beds. It is suggested that this activity belongs to the large mucilagenous envelope of the C. annua seeds which may ‘sense’ water and regulate germination. Two principles from the seeds were found in the bed at supra-optimal temperatures — a stimulatory one (water soluble and leachable, at 35 °C) and an inhibitory one (dominant at 40 °C and 45 °C). These are novel phenomena. Such activities probably exist in nature on the surface of the seeds.