Abstract: In order to make clear the effect of photo-temperature on ear differentiation of wheat and the relationship between ear differentiation and leaf number on the main stem,field experiments were carried out in Beijing in 1982-1985 with 3 varieties of wheat(Triticum A aeslivnm L.). The results showed that the corresponding reationship between the stage of ear differentiation and the leaf number on the main stem is changeable in accordance with the difference of wheat varieties or ecological conditions. The variety of strong springness enters elongating stage when having three leaves. There are more leaves when the variety of stronger winterness enters elongating stage, and it spends more days from sowing to ear elongating. The need of strong springness variety for photo-temperature is not strict, so ear differentiation of this kind of variety could be promoted by higher temperature.Low temperature with short daylength in the earlier stage followed by higher temperature with longer daylength is fav ourable to ear differentiation of winter variety. Vernalization completes when the elongating stage or the later phase of the double ridge appears in the winterness variety and transitional type of the wheat variety ecotype.

Key words: Wheat, Ear differentiation, Response to photo-temperature