Abstract: The rice seedlings for experimental use were raised by water culture. When the seedlings were grown in sulfur deficient solutin for 13–15 days, the ethylene production from the roots and the leaves was decreased. If seedlings were continuously grown in sulfur deficient solution, the ethylene production was decreased in roots, lint increased in leaves. When the S-deficient seedlings were supplied with SO42- or 0.1 mmol/l cysteine, the ethylene production was increased approximately up to that in control after 36 and 12 hours respectively. The S-deficient seedlings supplied with 0.1 mmol/l methionine for 6 hours will produce much more ethylene than that in control. The contents of cystine and methionine were decreased in leaves of S-deficient seedlings grown for 13 days.

Key words: Sulfur, Cysteine, Methionine, Ethylene production, Rice seedlings