Abstract: The seed germination rates, seeding fresh weights, daily taproot lengths, seed vigor indexes and germination value of Periploca sepium Bge. was investigated under iso-osmotic potential NaCl and PEG with different osmotic potential. The regression analyses were done between the seed germination and different osmotic potential. It was shown that (1) the total germination rates, seeding fresh weights, seed vigor indexes and seed germination value of P. sepium Bge. tended to decrease as the osmotic potential of NaCl and PEG become intensified; the seed germination was restrained more seriously by PEG than by NaCl under the high osmotic potential (≥-0.5 MPa),and low osmotic potential (≤-1.4 MPa) through meta-analysing seed vigor indexes and germination value, but it reversed under other ranges; (2)the daily germination rates and taproot lengths of P. sepium Bge. indicated that compared with NaCl, PEG delayed the seed germination and inhibited taproot lengths growth more seriously; (3)the regression equation between the seed germination and different osmotic potential under salt and water stress showed that the critical value of the seed of P. sepium Bge. was -0.9 MPa and the maximum value was -1.3 MPa under NaCl, while they were -1.0 MPa and -1.4 MPa under the PEG. When the osmotic stress was released, the germination recovery rates of the different osmotic potential has achieved 100%. It was resulted that P. sepium Bge. owns the characteristics of salinity tolerance and drought resistance.

Key words: iso-osmotic, seed germination, seed vigor indexes, germination value of seed