| Cleistogenes songorica and Plantago lessingii are important native plant species in North-west desert grassland of China. The two plants are high quality food-stuff, and they play an significant role in pasture production and vegetation restoration. Also, the specis of Cleistogenes songorica has some value in turf grass breeding. The seeds of C. songorica and P. lessingii were collected from Alashan desert, Inner Mongolia, and a serious laboratory test were, therefore, conducted to study germination response of the two species to temperature, osmotic potential, light conditions,NaCl solution, and sowing depth. Because some seeds of the two species were in dormancy, so a number of treatments were used to remove dormancy.Results showed that almost all seeds enclosed in the leaf sheath of C. songorica were viable. Germination temperature range of C. songorica was very wide ranged from 10℃　to 50/20℃, and higher temperature promoted germination. On the opposite, P. lessingii seed had a narrow range of germination temperature being from 10℃ to 30℃, and lower temperature promoted the germination. The optimal germination temperature reached 35/20℃ for C. songorica and 20℃ for P. lessingii, in which germination percentage was 94% and 61%, respectively. The germination percentage of C. songorica and P. lessingii seed incubated in 20℃ was 74% and 61%, respectively, so some seeds were in dormancy. According to the principles of seed dormancy classification, dormancy of the two plant seeds were embryo-type. Dormancy of C. songorica seed can be removed effectively by using alternative temperature of 35/20℃. For P. lessingii seed, its dormancy can be removed completely by moistening germination paper with 0.02%~0.1% GA3 solution. Theа-amylase activity in P. lessingii seeds treated with 0.02% GA3 was higher than that of CK seeds during 12~72h germiantion, in which, the most difference appeared at 24th h, and а-amylase activity induced by 0.02% GA3 solution was 11.3 times as many as that of CK. The germination declined as osmotic potential decreased from 0 to –1.6 MPa, and the declining tendency in C. songorica was faster than that in P. lessingii. Regression analysis indicated that germination percentage (y) of both species were highly related to osmotic potential (x) which can be expressed by: y1 = -10.976x1 + 98.4 (r2 = 0.954) for C. Songorica, and y2 = -5.909x2 + 60.2(r2 = 0.964) for P. lessingii. The plumule growth was prohibited as the osmotic potential decreased, however the radical growth was promoted from 0MPa to -0.6MPa in C. songorica and to -0.4MPa in P. lessingii, thereafter was decreased.The higher germination percentage was obtained from C. songorica and P. lessingii seeds fostered in the light than under the dark. Athough light is requisite for C. songorica and P. lessingii seeds to germinate, natural light in culturing chamber does satisfy both seeds for germination.The germination declined as concentration of NaCl solution increased from 0 to 0.3 mol/L, and the declining tendency in C. songorica was faster than that in P. lessingii. Regression analysis indicated that germination percentage (y) of both species were significantly nagtively related to concentration of NaCl solution (x) which can be expressed by: y1 = -260.84x1 + 95.8(r2= 0.9618)for C. songorica, and y2 = -143.03x2 + 56.7(r2= 0.9769)for P. lessingii. The plumule growth was prohibited as the concentration of NaCl solution increased, however the radical growth was promoted from 0 to 0.05mol/L, thereafter was decreased.The germination declined as sowing depth increased. The germination percentage of C. songorica and P. lessingii seeds was 59% and 31%, respectively, when sowing depth was 0.5 cm, while both were 15% when sowing depth was 1 cm, and no seed was germinated when sowing depth increased to 2cm.
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