Abstract: 【Objective】Ecological factors play an important role in maize yield. In order to clarify the relationship between light, temperature, water in the growing period and yield performance of maize, provide a reference to the high yield of maize in the North China Plain. 【Method】 Three types of cultivars (YN 103, XY335, ZD 958 and DH 661) were used as materials, and three sowing dates (May 3rd, May 28th, and June 22nd) and four density treatments (45 000, 60 000, 75 000 and 90 000 plants/hm2) were designed. The dynamic of leaf area index, grain yield were measured and the growing period and ecological factors were recorded. 【Result】 Yield showed an order of XY335>ZD958> DH661>YN103, early sowing date>medium sowing date >late sowing date. Ecological factors had a regulatory effect on yield and yield performance indexes, effective temperature after silking affected the average leaf area index and mean net assimilation rate, daily average temperature affected the growth days and harvest index, total rainfall and sunshine hours affected grains number per spike and grain weight. Effective temperature of whole growth period, especially after silking was the most important ecological factors affecting grain yield. The order of correlation coefficient was that ，the effective temperature of whole growth period(0.64**)，the effective temperature after silking(0.55**), the daily average temperature after silking (0.51**), the daily average temperature of whole growth period(-0.49*), the rainfall after silking(-0.47*), the sunshine and silking(0.42*). The effective temperature was the main effective factor on yield. 【Conclusion】 Two-crop a year system is practiced in Huanghuaihai area, so medium maturing cultivars, such as ZD 958, should be selected, optimum early sowing should be practiced to ensure adequate and effective accumulated temperature of grain sufficient filling time for further enhancing corn yield in this area.

Key words: planting dates, yield performance, ecological factors, summer maize