Effects Of Simulated Salt-alkaline Mixed Conditions On The Seed-seedling Stage Of Chloris Virgata

Inland saline and sodic soil includes two kind of neutral salt NaCl and Na2SO4 generally, and two kind of alkaline salt NaHCO3 and Na2CO3. But the massive facts proved that the alkaline salt has the bigger ecology destructive power compared to the neutral salt. Salt-alkalized grassland in Northeast China also include neutral salt and alkaline salt,where plants are destroyed not only by salt-stress, but also by alkali-stress.According to the habitat feature of salt-alkalized soil in Northeast China, a native alkali-resistant halophyte, Chloris virgata, was chosen as experimental material. NaCl, Na2SO4, NaHCO3, and Na2CO3 were mixed to simulate 20 kinds of salt-alkaline mixed conditions with different pH and salinity, and applied to sand culture. Then the seeds of Chloris virgata were sowed on various salt-alkalized conditions. The seed germination and seeding establishment were monitored in order to investigate the effects of soil salt-alkalization on the seed-seedling stage of Chloris virgata.The results show that:(1) The optimum seedling emergence of C. virgata is at pH 8.65 and 80mmol/L salinity, which is much higher than control group. This showed that C. virgata is a high alkali resistant halophyte. Adequate salinity and alkalinity were more beneficial to the survival of C. virgata. (2) At the same salt concentration,with increasing pH,seedling emergence and survival seedling rate of C. virgata all showed a similar trend: go up first and then drop. The highest point was around pH 8.74,and seedling emergence and survival seedling rate of C. virgata decrease at higher or lower than 8.74. (3) With the increasing intensity of salt-stress, the time of emergence delayed significantly. However,the impact of alkali-stress (pH) on emergence time was insignificant. (4) The results of variance analysis showed that the effects of salinity and alkalinity on seedling emergence and survival seedling rate were all significant (P<0.01), and interactions between salinity and pH were significant (P<0.01) also.From the above we can come to the conclusion that the soil with adequate salinity and alkalinity is the optimal habitat for C. virgata. High salinity and high pH inhibit seedling emergence and reduce survival seedling rate.According to the adaptive character of C. virgata to salt-alkalized soil, artificial planting C. virgata in appropriate salt-alkalized areas may be one of the ideal way to improve salt-alkalized soil conditions by bio-treatment.