Effects of Simulated Acid Rain on Seed Germination and Seedling Growth of Cunninghamia lanceolata

Observation and analysis were made on changes in physiology and growth of seeds and seedlings of Cunninghamia lanceolata which were subjected to a simulated acid rain adjusted to different pH levels.The results showed that pH2.0 and pH3.5 acid treatments were found to significantly inhibit seed germination and subsequently the survival rate of the seedlings.Under the exposure to pH2.0 treatment,seedling growth was severely retarded,due to the visible damage to foliage,decreased chlorophyll contents,elevated leaf cell permeability,and acidified leaf sap.The pH3.5 treatment also caused foliar damage and decline in pH of the leaf sap,leading to growth inhibition of the seedlings.Growth was stimulated by pH5.0 acid treatment,but no significant treatment effects were observed at pH6.0.