Abstract: The injury responses of several woody plants to exposure of SO₂ and HFalone and in combination under artificial fumigation were studied, from which several results emerged; The electro-conductance increased in foliage exposed, and generally this change coincided with the appearance of perceptable damage of leaves. The production of injurious ethylene in foliage of Camphortree, Chinese Redbud and Glossy Privet increased, and in combined exposure with high HF concentration, it increased markedly. S accumulation in foliage of Camphortree, Japanese viburnum and Chinese Redbud increased, but in combined exposure of Glossy Privet and Sweet Osmanthus leaves, it remained unchanged or decreased. Fcontent of exposed leaves was generally higher than the control. The presence of SO₂ reduced Faccumulation in foliage, but the 3 times rise of HF concentration brought about its sharp increase.

Key words: Induced insect-resistance, Plumular axis cutting, Cotton, Heliothis armigera