Abstract: Single-peaked ESRsignals with g factor 2.0044 and 2.0037 were clearely shown respecti vely from overwintered korean pine needles and their lyophylized chloroplasts. The more serious the injury of the needles, the stronger the signal. The signals were diminished by adding Vc or fruit juice of Elaeagnus angustifolia containing rich SODand other free-radical scavengers.The more serious the injury, the more effective of the fruit juice, but Jess of Vc in inhibiting the ESRsignals. The results indicate that the winter injury of korean pine seedlings is related to the formation of organic free radicals. The major kinds of the radicals are differ in advancing stages of the injury development.

Key words: Organic free radicals, ESR, Pinus koraiensis, Chloroplast, Thylakoid, Photooxi dation