Abstract
To determine the promotive effect of isoprothiolane (diisopropyl-1, 3-dithiolan-2-ylidenemalonate, IPT) on ripening in rice plant (Oryza sativa L., cv. Nipponbare), 14C-tracer studies after 14CO2 assimilation were conducted with pot-cultivated rice plants grown in a greenhouse. IPT (FUJI-ONE (R), 12% granule) at 80mg/l/5, 000a plastic pot (400g/a as a formulation) was applied under flooded condition at 11 days before the heading time. Rice plants were fed with 14CO2 to make them carry out 14CO2 assimilation and then kept under an artificial day-light at 25°C in a growth chamber. The plants treated with 14CO2 were time-dependently sampled and both the distribution and radioactivity of 14C in each plant organ were determined by autoradiography and by liquid scintillation spectrometer, respectively. The effect of IPT on translocation rate of 14C into panicles was obvious in the lower halves of panicles, especially at 4 day after 14CO2- feeding. These observations suggest that IPT enhances ripening under the present experimental conditions of pot-cultivated rice plants. This promotive effect may be attributed to promotion of translocation of photosynthetic products in rice plants.
