Abstract: In order to clarify the growth characteristics of the new polyploid germplasm in Lilium，variation of plant regeneration ability，drought resistance and saline-alkali resistant ability were compared between the diploid seedlings and its homologous polyploid seedlings in vitro in Lilium davidii var. unicolor and Lilium pumilum DC. Fisch. The results showed that the duration for the formation of adventitious buds and somatic embryos in the tetraploid plants scales were significantly shortened and the regeneration seedlings were larger with the stable ploidy compared with the diploid plant scales. The regeneration ability of the aneuploid scales was reduced significantly，and the callus without embryo ability was produced. The regenerated plants produced by the mixoploid scales have different morphology and unstable traits，and the induced somatic embryos gradually brown during culture. PEG-6000 and NaHCO3 were used to simulate drought stress and saline-alkali stress，respectively. Under low concentration stress，the tetraploid seedlings kept good adaptability，while the diploid seedlings were more sensitive. The tetraploid plants of both lily species maintain their stability under stress by extending roots length and keeping a good water balance in leaves.

Key words: Lilium davidii var. unicolor, Lilium pumilum, polyploid, drought stress, saline-alkali stress