Abstract:

To investigate the effects of different replacement ratios of organic fertilizer for chemical fertilizer on post-anthesis nitrogen metabolism and yield of wheat，six treatments were established ：N0（no nitrogen fertilizer），CK（conventional fertilization， chemical fertilizer only），LO（organic fertilizer replacing 1/3 of chemical nitrogen fertilizer），MO（organic fertilizer replacing 1/2 of chemical nitrogen fertilizer），HO（organic fertilizer replacing 2/3 of chemical nitrogen fertilizer，respectively），and FO（full organic fertilizer）. Except N0， the nitrogen application rate in the other treatments were the same. The SPAD value，ammonium and nitrate nitrogen contents，nitrogen metabolism enzyme activities，free amino acids and soluble protein contents in flag leaves after anthesis，as well as nitrogen use efficiency and yield of wheat were analyzed. The results showed that compared with CK，the SPAD value，nitrate and ammonium nitrogen contents，nitrogen metabolism enzyme activities in flag leaves after anthesis gradually decreased with the increase of organic fertilizer replacement ratio in general. The yield of CK was the highest，followed by LO（1/3 replacement），with no significant difference between them. For other nitrogen treatments，yield significantly （p<0.05） decreased with the increase of organic fertilizer replacement rate，with a reduction range of 14.61%-29.21%. In terms of nitrogen use efficiency，except LO，both agronomic efficiency and partial factor productivity of nitrogen in organic fertilizer replacement treatments were significantly lower than those in CK to varying degrees. In conclusion，under this experiment condition，replacement of 1/3 of chemical nitrogen by organic fertilizer can maintain wheat yield while reducing chemical fertilizer input，and can be recommended as a green cultivation fertilization measure for wheat in this region.

Key words: wheat, organic fertilizer replacement, nitrogen metabolism, yield