Abstract: Flower bud abortion of Paeonia lactiflora can occur at any developmental stage in the shoot growth cycle and reduce the proportion of flowering shoots. The flower development of P. lactiflora‘Qiaoling’cultivated in open field，outdoor potted and forcing potted conditions were investigated to elucidate the reasons for flower abortion. At each developmental stage，the flower abortion rate was related to bud diameters and varied significantly under different cultivation methods. The rate of aborted flower buds with a diameter 2–4 mm were 67.9%–86.6% in forcing potted plants，44.9% in outdoor potted plants and 16.3% in field plants respectively. Such aborted flower buds grew from the stunt mixed buds whose differentiations were slower than that of normal buds and had completed differentiation of pistil and stamen primordium when their diameters reached 2 mm；The rate of aborted buds with a diameter 4–8 mm were 29.6% in outdoor potted plants，9.2%–25.6% in forcing potted plants and 11.8% in field plants respectively，and aborted buds with a diameter 5 mm were in the phase of differentiation of ovule primordium；Aborted buds with a diameter 8–17 mm only occurred in forcing potted plants with abortion rate of 0–4.8%，and the nucellus and funiculus had been formed when flower bud diameter reached 10 mm. The rate of aborted buds with a diameter 17–27 mm were 0–1.4%，19.9% and 9.2% respectively in forcing potted plants，outdoor potted plants and open field plants，and nucellus，integument and micropyle had appeared in aborted buds with a diameter 18 mm. The results suggested that the highest abortion rate occurred at shoot elongation stage when diameters of flower buds reached 2–4 mm，so this stage is the key stage to reduce flower abortion in greenhouse forcing by providing enough fertilizer，extending chilling duration and keeping stable temperature from buds emerge to flowering.

Key words: Paeonia lactiflora, flower bud abortion, anatomical structure, forcing culture