Abstract: Upland maize is a main cereal crop in Shouyang County, a representative area of high elevation region in Jinyhong Dstrict of Shanxi Province.The key to successful planting of maize is the use of varieties with appropriate mature periods.The hybrid varieties of maize used in this area are medium-early maturing to medium-late maturing varieties because of the difference between growing areas.The early-maturing varieties also can be used in some areas.The classification indes of mature period types must be well-selected for the correct use of mature period types of varieties.Experimental researches carried out for many years show that the number of leaves, the number of days from sowing to maturity, and the accumulated temperature above or than or equals to 0℃ during the growing period from sowing to maturity, constitute the morphological index, growth index, and ecological index for classification of mature periods. The number of leaves is the easiect index to be identified and used.

Key words: Maize, High altitude upland, Mature period, Number of leaves