A newly devised apparatus for measuring the resisting power of rice seedlings during the uprooting operation in the seed bed are described. According to the results of measurements by means of the device, following facts were elucidated: The thinner the seeds were sown, the larger was the resistance of seedlings. On the other hand, the thinner the seeds were sown, the smaller was the resistance per unit area of seed bed. Thinner sowing, however, requires larger areas of seed bed per unit area of the main field, and so a larger energy for pulling up the seedlings are required finally. The higher the specific gravity of seed grains, the larger was the resistance. The following equations were obtained from the experimental data (X, representing specific gravity) y=1313.3+23.1x for 40 days seedling y=1593.3+41.6x for 45 days seedling Amount of fertilizer used had a great influence on the resistance power, remarkahle differences due to the amount of fertilizer applied being already recognized on the 15th day after sowing. And, the differences became progressively large according to the number of days elapsing. But, no difference was found between the plots 1.5 times and those 2.0 times the ordinary quantity of fertizer applied. Consequently, resistance ofseedling for pulling up is considered to show the degree of health of seedling when they are grown under same environmental conditions. And, remarkable differences in the resisting power in accordance with the quantities of fertilizer applied could be oserved just after 15 days of sowing. These differences increased according to the number of days. But no great differences were found between the plot fertilized with 1.5 times the amount of the standard and that with 2.0 times the amount. So it should be understood that the resistane power of seedlings against uprooting is more closely connected with the degree of growth of the plant, grown under the similar environmental conditions.
