Abstract
We examined endogenous ethylene levels in leaf sheath and the panicle of growing rice plants. 1)Endogenous ethylene within the leaf sheaths could be sampled by mechanical squeezing. Ethylene levels reached a maximum in one hour after a lag time of thirty minutes after the harvesting. 2) Levels of endogenous ethylene in leaf sheaths showed diurnal variation with high levels in the day and low in the night. 3) The ethylene levels within leaf sheaths were similar among upper four leaves when measurement was made twenty three days before heading (The flag leaf was not emerged yet). But at the time of anthesis, ethylene level in the leaf sheath of the flag leaf on the main stem showed the highest value among the upper four leaves, decreasing in the order of leaf position from the top. The ethylene level in the panicle after heading was found to be higher than that in the flag leaf.
