Germination is enhanced by removal of the funiculus in the halophyte glasswort (Salicornia herbacea)

This study was conducted to investigate a seed treatment aimed at enhancing germination to improve seedling establishment of glasswort ( Salicornia herbacea ), a halophyte, for agricultural use. Additionally, we examined whether the germination characteristics of processed seeds were affected by changes in salt concentration, light, and temperature. Glasswort has an ovate, non-endospermic dicot seed that is light brown and surrounded by a perianth. The seeds are very small, with a measured 1,000-seed weight of 321 mg. The germination efficiency of raw seeds in our experiments was very low (28%), despite the use of optimum environmental conditions for germination. However, the germination efficiency was dramatically increased to 95% when the funiculus was removed. To efficiently remove the funiculus from the seeds, we developed a mechanical seed treatment using a 500-μm sieve and a pestle. Processed seeds whose funiculus was removed with this mechanical treatment germinated with an efficiency of 74% under the same optimal conditions for germination. The germination enhancement associated with removal of the funiculus was apparent in all of the conditions we tested, including under various temperatures and NaCl concentrations, and in the presence or absence of light. The optimum conditions for germination of processed seeds were the same as those of the raw seeds. In conclusion, to enhance the germination efficiency of glasswort seeds, the funiculus should be removed and seeds should be germinated in fresh water (0 mM NaCl) at 30°C with light.