Effects of Mowing Frequency on Biomass Allocation and Yield of Leymus chinensis

The effect of mowing frequency on cumulative dry matter yield (cDMY) in Leymus chinensis has been well studied. However, how biomass and nitrogen or phosphorus allocation among leaf, stem, and sheath of L. chinensis contribute to its cDMY under different mowing frequencies remains unclear. A 2-yr field experiment with five mowing frequencies was conducted to study effects of mowing frequency on biomass allocation and yield of L. chinensis. The mowing frequency treatments were extremely heavy mowing, heavy mowing, moderate mowing (MM), and light mowing (LM) in contrast with single mowing as the control (CK). In general, as mowing frequency increased, the cDMY of L. chinensis decreased (P < 0.05). The cDMY on the MM and LM treatments was equal or greater than that on the CK treatment in both years. Leaf biomass and leaf-to–individual tiller ratio of L. chinensis decreased as mowing frequency increased due to shorter recovery time, although the N and P concentrations of leaves were higher. The leaf-to–individual tiller ratio increased exponentially (P < 0.001), while the cDMY increased linearly (P < 0.001) with increased leaf biomass. Furthermore, stem and sheath biomass of L. chinensis were significantly lower in all mowing frequency treatments (P < 0.05) compared with the CK treatment, but no changes were observed in stem and sheath between mowing frequency treatments in both years. Our results reveal that leaf biomass primarily contributed the most to cDMY, and increased mowing frequency profoundly altered the biomass allocation among leaf, stem, and sheath. It is recommended that MM or LM be optimal to efficiently promote dry matter yield and maintain root biomass of L. chinensis.