5HANSON A A, Barnes D K, Hill R R. Alfalfa and alfalfa agronomy No.29[M]. USA, Wisconsin: ASA, CSSA, SSSA, Publisher Madison.
6MOLL R H, Jackson W A, Mikkelsen R L. Recurrent selection for maize grain yield: dry matter and nitrogen aeeurnulation and partitioning changes[J]. Crop Sci, 1994, 34: 874-881.
7PAU W L, Canberato J J, Mall R H, et al. Altering source-sink relationships in prolific maize hybrids:Consequences for nitrogen uptake and remobilization[J]. Crop Sci, 1995, 35: 836- 845.
8UHART S A, Andrade F H. Nitrogen and carbon accumulation and remobilization during grain filling in maize under different source sink ratios[J]. Crop Sci, 1995, 35: 183-190.