Abstract
To make clear the relation between the respiration rate and the flood injury in rice seedlings grown under different nitrogen conditions, this study was carried out under the guidance of Dr. N. ENOMOTO in 1954 and 1955 at the Crop Science Laboratory, Faculty of Agriculture, Kyoto University. Pot cultures of rice Senbon-Asahi were divided into two groups which received different amounts of nitrogen fertilizer, i. e. were grown with high and low N-levels, respectively. The respiration rate was measured by WARBURG manometer. Respiration rate as expressed by dry-weight basis was higher at the early stage of seedling growth, and decreased gradually as the plant grew. The seedlings grown on a high N-level showed higher respiration rate than that grown on a low N-level, and the former suffered flood injury strikingly after three days of flooding, while the latter showed remarkable resistance to submersion. When the seedling was submerged under water, the plant-length increased rapidly, but the dry-weight decreased. These results suggest that since the respiration is promoted on a higher N-level of nutrition, the respiration-substrate in the plant tissue under flooding is consumed more rapidly, the plant being thus brought to death within a short period.
