Comparison on the Activities and Isoenzymes of Polyphenol Oxidase and Indoleacetic Acid Oxidase of Difficult and Easy to root Eucalyptus Species Effects of phosphogypsum extracts on seed physiology and seedlings growth of pea Studies on Activities of Indoleacetic Acid Oxidase, Polyphenol Oxidase and Peroxidase in Cuttings of Broussonetia papyrifera during Rooting Process Study on the Relationship between the Changes of Activities and Isoenzymes of Oxidases and the Rooting of Eucalyptus Cuttings Treated with Indoleacetic Acid