Abstract: With the strategic thinking of developing great agriculture as a basis, this paper discussed the necessity of developing forestry in Yangzhou region and the land resource characteristics in developing such affair in flatlands,collected some data and materials about the forest nets in crop lands and the planting of trees in"four sites" in nine brigades of Yangzhou region and put forward the index of rational covering rate of forest and the conditions and budgets for realizing this index in such region.

Key words: Mycorrhizal fungi, Tobacco, Physiological metabolism