Abstract: This paper studied the source-sink characters and grain-filling traits of six genotype summer maize varieties under 2 years (from 2007 to 2008) application of low dosage (105 kg·hm^-2) and normal dosage (337.5 kg·hm^-2) fertilizer nitrogen. Under low nitrogen stress, the population yield, leaf area index (LAI), sourcesink characters, and grain-filling traits of test varieties differed significantly. The varieties tolerant to low nitrogen, e.g., Xianyu 335 and Zhengdan 958, had longer active grain-filling stage, higher maximum filling rate, longer duration of maximum LAI, and more harmonious sink-source relation; while less tolerant species,e.g., Shaandan 902 and Yuyu 22, had shorter active grain-filling hours, lower maximum filling rate, lower mass increment and LAI under maximum grain-filling rate after silking, and significantly decreased source supply capacity. Low nitrogen stress increased the yield difference among the test varieties significantly.

Key words: maize, nitrogen, genotype, grain-filling trait, source-sink characters, leguminous green manure, rotation, summer fallow, winter wheat, soil water, soil fertility.