NaCl胁迫对2种表型盐地碱蓬种子萌发的渗透效应和离子效应研究

采用高低2个浓度的NaCl、LiCl及等渗甘露醇溶液处理紫红色表型(紫色型)和绿色表型(绿色型)盐地碱蓬种子,通过测定它们的种子萌发率、吸胀速率和胚内离子含量,研究NaCl胁迫对2种表型种子萌发的离子效应和渗透效应.结果表明:(1)2种表型盐地碱蓬种子萌发率在高浓度(300 mmol/L)和低浓度(100 mmol/L)NaCl处理下均显著降低,紫色型种子萌发率在低浓度下显著低于绿色型,而在高浓度下却显著高于绿色型;绿色型种子萌发率在高浓度(30 mmol/L)和低浓度(10 mmol/L)LiCl处理下均未受到显著影响,但紫色型种子萌发率却均极显著降低;2种表型盐地碱蓬种子萌发率在低浓度等渗甘露醇处理下均极显著低于低浓度NaCl处理,而高浓度等渗甘露醇处理却均与高浓度NaCl处理无显著差异.(2)2表型种盐地碱蓬种子的吸胀速率在低浓度NaCl处理下没有受到显著影响,但高浓度NaCl处理及与之等渗的高浓度甘露醇处理下都显著降低,而且紫色型种子的吸胀速率在等渗甘露醇处理时显著高于绿色型.(3)2种表型盐地碱蓬种子胚中的Na 含量和Na /K 在对照和低浓度NaCl处理下无显著差异,但紫色型种子胚中的Na 、K 含量在高浓度NaCl处理时都显著高于对照,且K 含量增加的幅度远大于Na 含量,导致紫色型种子胚中的Na /K 显著低于绿色型.研究发现,盐地碱蓬种子萌发在低浓度NaCl胁迫下主要受离子效应抑制,而高浓度NaCl胁迫下则主要受渗透效应抑制,紫色型种子萌发率在高浓度NaCl胁迫下高于绿色型的原因之一是前者能维持更低的Na /K 比.

Osmotic and Ionic Effect on the Seed Germination of Two Phenotypes of Suaeda salsa L. under NaCl Stress

In the present study,ionic and osmotic effects of NaCl stress on the seed germination of two phenotypes of Suaeda salsa(green phenotype:G-S.salsa;red-violet phenotype:R-S.salsa) were examined by measuring the seed germination rate,imbibition rate and the ionic contents of embryo using two concentrations of NaCl,LiCl and iso-osmotic mannitol treatments.The results indicated that(1) the seed germination rate of two phenotypes of S.salsa significantly decreased under the high(300 mmol/L) and low(100 mmol/L) concentrations of NaCl treatments.Seed germination rate of red-violet phenotype of S.salsa was significantly lower than that of green ones under the condition of low concentration of NaCl.In contrast,when treated with high concentration of NaCl,seed germination rate of the red-violet phenotype was markedly higher than that of the green one.Both the high(30 mmol/L) and low(10 mmol/L) concentrations of LiCl treatment had no significant effect on the seed germination rate of green phenotype of S.salsa,but significantly reduced seed germination rate of red-violet ones.Under the iso-osmotic manntiol treatment,the seed germination rate of the two phenotypes of S.salsa was significantly lower than that under condition of low concentration of NaCl.However,there is no different effect on the seed germination rate of the two phenotypes of S.salsa between high concentration of NaCl and its iso-osmotic manntiol treatments.(2) Low concentration NaCl had little effect on the seed imbibition rate of two phenotypes of S.salsa.Nevertheless,both high concentration of NaCl and its iso-osmotic manntiol treatments significantly decreased the imbibition rate of the two phenotypes of S.salsa,and the imbibition rate of red-violet ones was markedly higher than that of green ones under iso-osmotic manntiol treatment.(3) Under the conditions of control and low concentration of NaCl,both of the Na content and Na /K ratio in the seed embryo of two phenotypes were not affected.But under the condition of high concentration of NaCl,Na and K contents of red-violet phenotype of S.salsa were markedly higher than those of red-violet ones treated with control,and the increase degree of K content was much higher than that of Na content leading to the lower Na /K ratio than that of green ones.These results suggest that ionic effect is the main reason for the inhibition of seed germination caused at low concentration of NaCl,while osmotic effect is the main reason for the inhibition at high concentration of NaCl,and one of the reasons for higher seed germination rate of red-violet phenotype than that of green ones is that the former has lower Na /K ratio than the latter at high concentration of NaCl.