SEASONAL CHANGE IN NAGILACTONE CONTENTS IN LEAVES IN PODOCARPUS-NAGI FOREST

Nagilactones isolated from Podocarpus nagi (Thunb.) Zoll. et Moritz, a re known by their physiological activities as a plant growth inhibitor or antiherbivory substance. As the first step in clarifying the nagil actone dynamics in a forest canopy, the seasonal variations in nagilac tone contents in leaves and mass of nagilactones accumulated in the ca nopy were examined at Mt. Mikasa, Nara City, central Japan. Nagilacton e content in mature leaves dropped sharply in May, when new leaves flu shed. The nagilactone content of new leaves was far greater than that of mature leaves, implying a translocation of nagilactones from old le aves to new leaves. The total mass of nagilactones in the canopy was 3 .9 kg/ha.