Abstract: 【Objective】It is very important to study photosynthesis of super high-yielding maize hybrids, so a field trail was conducted to research the relation to photosynthetic traits and yield of over-15000 kg ha-1 summer maize hybrids during grain filling period. 【Method】Three summer maize hybrids (XY335, DH3632 and DH3806) were planted at 78000 plants ha-1 in National Corn Project Technology Research Center (Shandong) randomly. Above-ground biomass partitioning and photosynthetic characteristics of ear leaves were investigated to evaluate yield formation of three super high-yielding maize hybrids during grain filling period.【Result】Yields of three-type maize hybrids were over 15000 kg ha-1, and yield of XY335 was higher than that of DH3632 and DH3806 significantly (P＜0.05). Characteristic of grain filling analyzed by Richards equation showed XY335 had the higher grain-filling rate, the longer active growing period, and it reached the maximum grain-filling rate earlier than DH3632 and DH3806. The result indicated grain-filling traits like XY335 was favorable to high yield in the experiment. The leaves’ photosynthetic physiology quantity of XY335 was highest of the three-type hybrids. XY335 had high net photosynthetic rate (Pn), PEPCase activity, RuBPCase activity and chlorophyll a/b value after anthesis, and the leaf area index (LAI) and soluble protein content decreased slowly from 20d and 30d after flowering, respectively. 【Conclusion】To obtain 15000 kg ha-1 of super high-yielding breeding and cultivation in practice, we need to improve the leaves photosynthetic physiology quantity to maintain high grain-filling rate and long active growing period after anthesis, enhance the solar energy use efficiency.

Key words: Summer maize, Super high-yielding, Grain filling, Photosynthetic traits