Title: Studies on the Emergence of Rice Seedlings Seeded in Autumn and Winter : IV. The effect of low temperature treatment to soaking seeds on the growth of young seedlings
Abstract: The present experiments were made to clarify the characteristics of the growth of young seedling from seeds soaked and kept under 5°C over a long term (45-135 days). Young seedlings were grown under un-fertilized condition until the foods-exhausted period of seeds. Resu lts are as follows. (1) In comparison of the treated plots with the control one, the growth rate of young seedlings was slow in the early stage, which was caused by the decreased activity of the foods-decomposing enzyme (as Amylase) in seeds. On the contrary, the leaf-number was increased and this fact shows the promotion in the development of seedlings. (2) The plant hight, the length of the second and the third leaf blade were shortened. The elongation of selninal roots was also suppressed, resulting in the lowered ratio of seminal roots to crown roots in weight. Coefficients of variation in these characters were increased, as the individual difference was enlarged with the growth of young seedlings. However the increased number of roots was observed, being assumably brought about by the increase of rooting nodes accompanied with that of leaf-number. (3) The physiological activity of roots was decreased and this may be related to the growth suppression of young seedlings observed at the foods - exhausted period of seeds in case of autumn and winter sowing.