The asiatic plantain (Plantago asiatica L) growing in paddy field levee has distinctive seed germination characteristics

In paddy field levees, the Asiatic plantain is a necessary plant that supports prevention of soil run-off and maintenance of a green environment. At such places, grass mowing is done as farmland management. For the Asiatic plantain, which reproduces solely from seed, mowing could negatively affect generative growth and seed propagation. Despite this potential damage, thickly regrown seedlings can be observed soon after mowing operations. This rapid emergence response of the plant indicates that many seeds of this species exist in and on the soil. It is assumed that the seed dormancy is weak in the paddy field levee. Thus, the seed dormancy of the Asiatic plantain was investigated using seeds in many growing locations including paddy field levees. Furthermore, seasonal germination characteristics of the Asiatic plantain seed in a paddy field levee were compared with those in other areas (an open land), thereby clarifying the germination characteristics of this plant's seeds. Based on the results obtained, the adaptability for mowing of the Asiatic plantain seed in the paddy field levee was examined. Consequently, the seed collected from the paddy field levee showed a high germination percentage of greater than 90% without exception, and the ratio of dormant seeds was small. Regarding the seeds of plants grown in open land, the emergence varied among seasons: seed collected in mid-July showed a low emergence rate and that in autumn a delayed emergence. The seed collected in the open land during late fall to early winter was unable to emerge soon after sowing, but emerged in the following spring. These results show that, regardless of the seed production season, the mature seeds of the Asiatic plantain growing in paddy field levee can germinate immediately after sowing under environmental conditions suitable for germination. Therefore, it is considered that the seed grown in a certain place begins to germinate in response to full sunlight exposure on the moist soil after mowing, and thereby the Asiatic plantain can succeed its life cycle in the paddy field levee.