Effects of phosphorous application on the morphological characteristics and biomass yield of Poa pratensis var. anceps ‘Qinghai’

Phosphorus application may affect the morphological characteristics of plants, promote their growth, and increase productivity. This has great importance for natural degraded grassland restoration using rhizomatous plants. Poa pratensis var. anceps ‘Qinghai’ is one of the best rhizomatous grass species for degraded grassland restoration in alpine regions. However, it remains to be determined whether the effects of phosphorus addition on the morphological characteristics and growth of P. pratensis var. anceps ‘Qinghai’ are beneficial to the management of degraded grassland. The primary goal of this study was to explore biomass yield and morphological characteristics after applying six different concentrations (3.6, 7.2, 10.8, 14.4, 18.0, and 21.6 kg·ha⁻¹) of phosphorus fertilizer. We found that phosphorus addition had a significant effect on the morphological characteristics of P. pratensis var. anceps ‘Qinghai’. Plant biomass first increased and then decreased with increasing amounts of phosphorus addition, while morphological indices and biomass were best at 10.8 kg·ha⁻¹. Plant height, leaf width, leaf length, leaf area, and root bifurcation were the main factors affecting the biomass of individual P. pratensis var. anceps ‘Qinghai’ plants, and these factors contributed to 59% of individual biomass variation. Above-ground organs were sensitive to phosphorus addition and had stronger plasticity. Therefore, P. pratensis var. anceps ‘Qinghai’ showed the greatest plant height, leaf and root growth, and total biomass at a phosphorus fertilizer concentration of 10.8 kg·ha^−1. Thus, the plant had strong resistance to stress at this phosphorous level. This has great significance for the restoration and management of degraded grassland with this grass species.