Studies on the Emergence of Rice Seedlings Seeded in Autumn and Winter : II. Some physiological properties of soaking seeds under low temperature

Abstract

The present investigation was undertaken to clarify the physiological process of the survival of seed kept in wet soil, being tested mainly in laboratory. 1. The rot of seeds was observed when they were kept in wet soil under the temperature of 10°C or 5°C for 40 to 80 days and it was more remarkable in changes of the temperature from 13°C to 5°C or 40 days than in those from 5°C to 13°C or in case of the constant temperature of 5°C or 10°C. These facts corresponded to the previous results obtained in the field tests. 2. Being soaked in pathogen-free condition, however, seeds showed much higher germination rate than in wet soil under low temperature. 3. When seeds were kept in wet soil under low temperature, the elongation of seminal root was suppressed, while that of plumule showed no obvious change, according as the period of low temperature became long. This may mean that the vitality of sprouting is decreased. 4. In view of the above facts, assumably, soaking seeds hold the germination capacity in a long term of low temperature, while the power of resistance to the infection of micro-organism is decreased. Thus the death of seeds is primarily caused by the multiplication of micro-organism in fields, moreover the low rate of sprouting seeds is owing to the decreased vitality of sprouting of survival seeds.