Abstract: A field experiment was conducted in the south part of Loess Plateau with 632 mm precipitation each year.Three genotypes winter wheat 9430,Xiaoyan No.6 and Shang188 were used as test materials to study their grainfilling characters under two nitrogen application levels (0 and 90 kg·hm^-2).The results showed that genetic difference was the main factor affecting grainfilling characteristics,while nitrogen fertilization had a less effect.There were significant differences among genotypes in the duration of maximum grain filling rate (GFRmaxD),active grain-filling period (D),and the days reaching to the maximum grain-filling rate (GFRmaxGD).For Shang188,Xiaoyan No.6 and 9430,the GFRmaxD was 17.20,14.15 and 14.13 d,D was 29.00,26.40 and 2688 d,and GFRmaxGD was 28.14,23.90 and 23.89 d,respectively.All the parameters of Shang188 were significantly bigger than those of 9430 and Xiaoyan No.6,while those of the latter two had no significant difference.There was an interaction between nitrogen fertilization and genotype,but the effect of nitrogen fertilization on the three parameters was relatively small.1000 kernel weight had a significant positive correlation with GFRmaxD,GFRmaxGD and D,suggesting that the three parameters were the main factors affecting grain weight.

Key words: Biological indicator, Bryophytes, Environmental pollution, Environmental factor