Effects Of Nitrogen Application On The Yield,Quality And Bud Bank Of Mixed Planting Of Leymus.chinensis And Lespedeza.daurica

Compared with uni-sown grassland,the mixed-sown grassland improved the utilization rate of light,water and other resources,and finally increased productivity in grassland.Nitrogen application can increase the yield of grasses of mixed-sown grassland.Whereas,the interaction of nitrogen application and mixed sowing treatment on crude protein content,acid and neutral detergent fiber content and underground bud number of forage is not clear.In this paper,the effects of nitrogen application on the yield,quality and bud bank of mixed planting of Leymus chinensis and Lespedeza daurica were studied.At the same time,the nitrogen utilization of Leymus chinensis and Lespedeza daurica under different sowing patterns was comparatively studied by using stable isotope labeling technology,in order to obtain the relationship between different sowing patterns and grassland nitrogen utilization.This study concluded that :(1)In uni-sown grassland,the above-ground biomass of Leymus chinensis and Lespedeza daurica increased by 54.94% and 25.36% under nitrogen application compared with that without nitrogen application.In mixed-sown grassland,the above-ground biomass of nitrogen application increased by 16.57% compared with that of without nitrogen application treatment.Nitrogen application obviously increased the above-ground biomass of uni-sown grassland and mixed-sown grassland.The above-ground biomass of mixed-sown grassland was 74.99% higher than that of Leymus chinensis uni-sown grassland under nitrogen application,and 88.85% higher than that of the latter without nitrogen application.(2)Nitrogen application obviously increased the crude protein content of uni-sown grassland and mixed-sown grassland.Meanwhile,the crude protein content of mixed-sown grassland was obviously higher than that of uni-sown grassland.Nitrogen application obviously reduced the contents of acid and neutral detergent fibers in uni-sown grassland and mixed-sown grassland.The contents of acid detergent fiber and neutral detergent fiber in Lespedeza daurica,acid detergent fiber and neutral detergent fiber in Leymus chinensis and hemicellulose in mixed grassland were higher than those in uni-sown grassland,but the difference was not significant.(3)In uni-sown grassland and mixed-sown grassland,the total number of buds of Leymus chinensis treated with nitrogen increased by 284.22% and 270.53% compared with that without nitrogen application.In uni-sown grassland,the total number of buds of Lespedeza daurica increased by 57.55% under nitrogen application compared with that of without nitrogen application.In mixed-sown grassland,the total number of buds of Lespedeza daurica tended to increase with nitrogen application,but the difference was not obvious.Under nitrogen application,the total number of buds of Leymus chinensis in mixed-sown grassland increased 52.68% compared with that in uni-sown grassland.The total buds number of Leymus chinensis in mixed-sown grassland increased compared with that in uni-sown grassland without nitrogen application,but the difference was not obvious.The total number of buds of Lespedeza daurica.increased by 310.57% and 238.20% respectively in uni-sown grassland compared with mixed-sown grassland.(4)Nitrogen application obviously increased the total nitrogen content of Leymus chinensis and Lespedeza daurica in uni-sown grassland and mixed-sown grassland.The total nitrogen content of Leymus chinensis and Lespedeza daurica in mixed-sown grassland was obviously higher than that in uni-sown grassland.And the nitrogen content,the recovery and distribution rate of leaves was higher than that of stems.In summary,under the conditions of nitrogen application and mixed sowing,more nitrogen was allocated to the leaves,which promoted the growth of the leaves and increased the above-ground biomass and crude protein content of the mixed-sown grassland.Nitrogen application increased the number of underground buds of Leymus chinensis and Lespedeza daurica,and mixed-sown increased the number of underground buds of Leymus chinensis.