Dynamics of Growth and Development, and Nutrient Accumulation in Herbaceous Peony Cultivar ‘Red Charm’

Herbaceous peony (Paeonia lactiflora Pall.), as an important cut-flower variety, suffers from a lack of systematic fertilization protocols, leading to unstable cut-flower quality and yield, which consequently impacts economic returns. To establish precise fertilization strategies, this study investigated the above-ground morphological traits and the dynamics of nitrogen (N), phosphorus (P), and potassium (K) accumulation in the dominant cultivar ‘Red Charm’ during key growth stages. Before the full bloom stage, the above-ground morphological indices exhibited a progressive trend. After this stage, stem diameter and the number of compound leaves slightly decreased, while the accumulation of N, P, and K in the above-ground parts turned negative, indicating nutrient translocation to below-ground organs. Dry matter accumulation in both stems and leaves followed a typical sigmoidal growth curve. Peak nitrogen accumulation occurred during the stem elongation stage, accounting for 36.0% of the total accumulation. The peaks of phosphorus and potassium accumulation were concentrated during the bud differentiation stage, contributing 45.0 and 44.0%, respectively. Throughout the growth cycle, nutrient accumulation followed the order N > K > P, with an approximate ratio of 12 : 2 : 8. These findings indicate that the ‘Red Charm’ cultivar exhibits distinct stage-specific nutrient demand characteristics: nitrogen supply should be emphasized during the stem elongation stage, phosphorus and potassium application should be strengthened during the bud differentiation stage, and fertilization should be reduced after flowering to promote nutrient reflux to storage organs. This study clarifies the growth, development, and nutrient demand patterns of herbaceous peony, providing a scientific basis for precision fertilization and high-quality cultivation.