Abstract
Rice nurseling seedlings were raised under temperature-controlled condition (32°C) in darkness or with illumination of 500lux (Exp.1) and 170lux (Exp.2) by fluorescent lamp for 1, 2 and 4 days before the end of experiment to clarify the effects of light conditions during the nursery period (4 days) on the seedling characters; taking root and early growth after transplanting. Exp.2 included an additional plot in which the seedlings were raised under. 32°C with natural indoor light (Maximum: 70∼80lux during daytime) through plastic panel of the incubator. 1) Rice nurseling seedlings with 2.1∼2.3 plant age in leaf number, 7∼8cm in plant length and remained ca. 40% endosperm could be raised under 32°C, irrespective of light conditions tested in this study. Plant age in leaf number of the seedlings was a little promoted by illumination during raising period. 2) Although the chlorophyll content of the seedlings increased with increasing light intensity, the effect of the illumination period (1∼4 days) on that was scarcely detected. 3) The day of first tiller apperance, as an indicator of taking root, was faster in the seedlings raised under illumination, irrespective of the illumination intensity or period, than those under dark condition, and this result led to better early growth in those seedlings, especially in the case of removal of endosperm. 4) The results mentioned above showed that weak illumination, ranging from 1.00 to 500 lux, during thc nursery period hardly inhibited elongation growth of the seedlings, and the suitable rice nurseling seedlings with a length of 7∼8cm for trasnsplanter and ca. 40% of the endosperm remaining could be raised under 32°C with weak illumination for 4 days. Moreover, weak illumination promoted taking root and early growth of the seedlings due to the production of chlorophyll.
