Prolongation of seed dormancy by dry storage in Brassica japonica SIEB

Abstract

The seeds of“Mizuna, ”Brassica japonica SIEB., usually have dormancy during two months after harvest, but, when they are stored in the desiccator, the dormancy continues for as long as more than three years. The dormancy of such desiccated seeds is partial or incomplete, and their percentage germination shows a considerable fluctuation during the period of prolonged dormancy. When desiccated, not only mature seeds but also immature ones show prolongation of dormancy, and the former seems to be less dormant than the latter. When dormant seeds are taken out from the desiccator, their dormancy is completely removed in four weeks, but non-dormant seeds do not enter dormant state even if they are put into the desiccator. In germination, desiccated seeds are more sensitive to temperature than air-dry seeds. Following methods are partially useful for breaking dormancy, i.e., low-temperature, slitting or removing of the seed coat, and soaking in running water.