Abstract: The effects of different salt stress and exogenous Ca²⁺ and their interactions on the seed germination characteristics of Phragmites australis which is widespread in the Yellow River Delta wetland were studied here. Salt stress and exogenous Ca²⁺ were respectively simulated using different concentrations of NaCl(0,50,100,150,200,300 mmol/L) and CaCl₂(0,5,10,20,40 mmol/L). The results showed that the seed germination rate,germination potential,germination index and vigor index among treatments significantly decreased and the relative salt harm rate increased compared to the control with the increased of NaCl stress. Under exogenous CaCl₂ treatments,the medium or low concentrations of exogenous Ca²⁺(<20 mmol/L) had lesser effects on the seed germination parameters in Phragmites australis,whereas the higher concentrations of exogenous Ca²⁺(40 mmol/L) had inhibition effect on the seed germination. The four germination indexes in Phragmites australis under NaCl stress increased at first and then decreased with the increased of exogenous Ca²⁺,but the relative salt harm rate showed the opposite tendency and 10 mmol/L Ca²⁺was the most effective concentrations in alleviating NaCl stress. The four germination indexes decreased when the concentrations of exogenous Ca²⁺ was 20 mmol/L,and it decreased to the minimum when the concentrations of exogenous Ca²⁺ was 40 mmol/L,while the relative salt harm rate achieved the maximum at the same time,and then the trend of the decrease was obvious with the increase of NaCl stress. In summary,in the restoration of salt-alkalization wetland in the supratidal zone,the seed of Phragmites australis could be presoaked in the CaCl₂ solution at concentration of 10 mmol/L in order to improve the rate of seedling.

Key words: NaCl stress, Exogenous calcium, Phragmites australis, Seed germination

CLC Number: 

• S143.7