Abstract: The effects of different nitrogen application strategies (nitrogen rates and nitrogen application stage) on yield and forage nutritive quality of summer Zea mexicana were studied in an experiment of pool culture. When the natural plant height was 110 cm the plant should be clipped. In the whole growth period, it could be clipped 3 times (H1,H2 and H3 means the first, second and third harvest stage, respectively).To evaluate the forage nutritive value, six items including crude protein (CP), ether extract (EE), nitrogen free extract (NFE), acid detergent fiber (ADF), crude ash (CA), and gross energy (GE) were used. The results showed that the content of CP and EE increased and the content of CA and ADF dereased by two nitrogen rates (High-rate N, 600 kg·ha-1;Mid-rate N, 300 kg·ha-1),which also improved the fresh and dry harvest biomass of the whole plants at H1 and the leaves at H2. But the stalks at H2 and the whole plants at H3 were affected by additional application of nitrogen fertilizer. The yield of CP, EE, CA, NFE, and GE was affected by nitrogen rates, the ADF yield increased with the increase of fresh and dry harvest biomass. It is concluded that all nitrogen applied as base fertilizer can harvest the higher biomass and improve the forage nutritive quality of summer Zea mexicana.

Key words: Zea mexicana, Nitrogen, Application, Yield, Forage nutritive quality