Variation of gutta-percha content characteristics of leaves of Eucommia ulmoides Oliv. in different areas

To make clear the geographic variations of gutta-percha content in leaves of Eucommia ulmoides Oliv.and provide scientific guide for developing high-yield gutta-percha industry bases,studies were carried out in 16 areas which are the main producing areas and introduction areas.Two methods,typical sample-tree selection and random selection,were adopted.The results showed that there existed obvious diversities and complexities of variation characteristics of gutta-percha content rate among different producing areas.Gum content rate decreased gradually with the increase of latitude.The content rate of gutta-percha in leaves from southern areas was generally higher than that from northern areas.Higher latitude,longer sunlight and higher soil pH value resulted in lower gum content rate in leaves;while more precipitations,higher altitude and longer frost-free period leaded to higher gutta-percha content rate.