TRANSITION OF GERMINATION CAPACITY OF THE SEEDS FROM WILD GRASSES WHILE STORED IN NATURAL DRY ATMOSPHERE

Abstract

The transition of germination capacity of seeds from 37 species of mature grasses gathered late in autumn was investigated during storage in the natural dry atmosphere at room temperature for a year. 1) The seeds of the following seven species did not germinate. Paederia scandens, Trichosanthes cucumeroides, Clematis apiifolia, Villebrunea frutescens, Phryma leptostachya, Dioscorea japonica, Cardiocrinum cordatum It may be considered that these seeds did not germinate because of the storage in the dry condition, but this needs confirmation by more experiments. 2) The seeds of 30 species germinated, and they were classified into the following six groups : A. Adenocaulon himalaicum-type ; The seeds of this type germinate soon after harvesting, but they lose the ability to germinate as time goes and finally they can scarcely germinate. ……Adenocaulon himalaicum. B. Epilobium pyrricholophum-type ; The seeds of this type germinate soon after harvesting, but their germination capacity lowers as the air temperature lowers. They regain their ability with the warm season spring. Their germination capacity reaches a peak towards May ; it again lowers in and after August. ……Picris hieracioides var. japonica, Adenostemma lavenia, Hosta minor, Plantago asiatica, Epilobium pyrricholophum. C. Sonchus oleraceus-type ; These seeds germinate soon after harvesting, and they continue germinating even after the climate becomes cold, until they gradually lose such ability in and after August. ……Aster hispidus, Lactuca denticulata, Erigeron canadensis, Sonchus oleraceus. D_1. Polygonum cuspidatum-type ; These seeds do not germinate immediately after harvesting, and follow the same course as the Epilobium pyrricholophum-type, beginning to germinate with the warm season of the next spring. ……Stellaria aquatica, Melilotus suaveolens, Perilla frutescens, Crassocephalum rubens, Polygonum filiforme, Isodon japonicus, Polygonum cuspidatum, Setaria chondorachne, Eclipta alba, Isodon inflexus, Ligularia tussilaginea, Solanum lyratum. D_2. Cyperus Iria-type ; These seeds begin to germinate towards the next warm season just as the Polygonum cuspidatum-type, however, their germinability changes with the air temperature and reaches a peak in the hottest season. The seeds of this type germinate fairly well towards the end of autumn. ……Corchoropsis tomentosa, Justicia procumbens, Phyllanthus Urinaria, Cyperus Iria, Carpesium cernuum. E. Digitaria adscendens-type ; Though the seeds of this type begin to germinate towards the next warm season as the last two types mentioned above. These seeds nearly retain the power to germinate up to the end of autumn from about May. ……Cosmos bipinuatus, Kummerowia striata, Digitaria adscendens. Although we can predict several factors that would bring into existence the above types in relation to the dormancy, such the temperature during the preservation and experiments on the seeds, and the length of time preserved, these factors should be ascertained by experiments. 3) As a rule, the groups that do not need dormancy and the groups that need only short dormancy reduce the germinability in and after the next August, and there are many species that show a high ratio of germination in and after August in the groups that seem to have long dormancy. Few annual plants, as a rule, belong to the Adenocaulon himalaicum-type, Epilobium pyrricholophum-type, Sonchus oleraceus-type, and the Polygonum cuspidatum-type, which lose germinability, and most of them belong to the Cyperus Iria-type and the Digitaria adscendens-type, which keep up germinability in and after August.