CHANGES IN ENERGY-DEPENDENCE AND MORPHOLOGICAL-CHARACTERISTICS WITH THE DEVELOPMENT OF RICE NURSLING SEEDLINGS RAISED UNDER DIFFERENT LIGHTAND TEMPERATURE CONDITIONS

The developmental changes of energy dependence, from a reliance on end osperm to reliance on photosynthetic tissue, and the morphological cha racteristics of rice nursling seedlings were examined. The seedlings w ere raised in temperature-controlled greenhouses set at 30/25 degrees C, 24/19 degrees C and 17/12 degrees C with a day/night cycle after em ergence. The growth of the seedlings was compared to the growth of see dlings raised under dark conditions in the same greenhouses. The relat ionship between the consumption of endosperm nutrients and the shoot d ry weight is represented by two regression lines for the seedlings rai sed in light, but is represented by one regression line for those rais ed in the dark. The slope of the regression lines in light were signif icantly different from that in the dark after 74% of the endosperm res erves were consumed and plant age reached 2.4. As the consumption of e ndosperm nutrients increased, the ratio of the shoot dry weight to the consumption of endosperm nutrients in light increased about threefold (i.e., from 0.476 to 1.433). It is thought that this change is due to an increase in the energy received from photosynthesis as a result of emergence and expansion of the third leaf. Seedlings with a plant age of 2.4 in light attained enough plant length (7cm) for the normal tra nsplanting techniques under the three temperature conditions.