Abstract:

The aim of this work was to determine the effects of different nitrogen-phosphorus and water couplings on soil nutrient contents and the photosynthetic characteristics and forage production performance of Bromus inermis. To this end， a field experiment was conducted using the B. inermis cultivar‘Wusu No. 1’ with a two-factor randomized block design. Irrigation was applied at three levels： W₁ （3800 m³·ha^-1）， W₂ （5300 m³·ha^-1）， and W₃ （6800 m³·ha^-1）； and there were three fertilization treatments： F₀ （no fertilizer）， F₁ （N 120 kg·ha^-1+P₂O₅ 100 kg·ha^-1）， and F₂ （N 180 kg·ha^-1+P₂O₅ 150 kg·ha^-1）. The results show that， compared with the W₁F₀ treatment， the net photosynthetic rate in the W₃F₁ treatment was increased by 21.22%， the leaf instantaneous water use efficiency was increased by 31.18%， and the light use efficiency was improved by 19.85%. The hay yield of B. inermis in the W₃F₁ treatment was increased by 28.31% compared with that in the W₁F₀ treatment. The crude protein content was increased by 24.32% in W₃F₁ and by 29.50% in W₂F₂ compared with that in W₁F₀ （P<0.05）. Furthermore， the soil available phosphorus and alkali-hydrolyzable nitrogen contents in the W₃F₁ treatment were increased by 13.79% and 131.27%， respectively， compared with those in W₁F₀. Thus， the regulation of irrigation and fertilization significantly improved the photosynthetic characteristics and forage production performance of B. inermis， and increased the amounts of soil nutrients. The W₃F₁ treatment demonstrated the best overall performance， indicating that an irrigation amount of 6800 m³·ha^-1 combined with fertilization with N at 120 kg·ha^-1 and P₂O₅ at 100 kg·ha^-1 resulted in superior photosynthetic characteristics and production performance of B. inermis.

Key words: Bromus inermis, water and fertilizer integration, productivity performance, photosynthetic characteristics, soil nutrients