3.1.1 Protein and fat
The crude protein content of L. chinensis increased significantly from 2.73% to 4.94% with N addition increasing (P <0.05). In particular, when N addition rate was from 0 kg ha-1 to 90 kg ha-1, the crude protein content ofL.chinensis increased in a straight line (Fig. 1A). Compared with the control, the protein content increased 20.5%, 38.5% and 66.3%, respectively. However, the protein content increasing was no significance when N addition was more than 90 kg ha-1(P ≥0.05). In all treatments, the crude protein content of L.chinensis was the highest when N addition rate reached 150 kg ha-1, and increased by 80.9% more than that of the control.
Similarly, the fat content of L. chinensis also increased markedly with increasing of N addition rates (Fig.1B). The fat contents of N addition treatments increased 6.9%-69.3% compared with that of the control, and the difference was very significant (P <0.05). While N addition rate reached 90-210 kg ha-1, there was no significant differences between the fat contents of each treatment (P >0.05).