水盐胁迫对花花柴种子萌发的影响

Effects of Salt and Water Stresses on Seed Germination of Karilinia caspica

水盐胁迫直接影响盐生植物的种子萌发,本研究通过对盐生植物花花柴种子带冠毛与否及不同胁迫处理下种子萌发率的比较分析,探讨花花柴种子萌发期的耐盐特性。对花花柴带冠毛和不带冠毛种子在蒸馏水中的对比萌发结果表明,冠毛对花花柴种子的最终萌发率无影响,但明显延长种子的萌发时间,可能与阻碍种子吸水有关。花花柴种子经过冷处理,成熟的种子没有出现生理休眠现象,有利于种子在条件适宜时迅速起始萌发。采用不同浓度NaCl和等渗的PEG6000(聚乙二醇)处理花花柴种子,结果表明:①NaCl和PEG胁迫对花花柴种子的萌发具有非常明显的抑制作用,主要表现为降低种子的萌发率,延长种子的萌发时间,抑制胚根和胚芽的生长;②NaCl对花花柴种子萌发的抑制作用明显地大于等渗的PEG,说明离子胁迫是影响花花柴种子萌发的主要因素;③花花柴种子萌发的耐盐临界值为213mM,极限值为340mM;④低浓度的NaCl溶液(50mM)不影响花花柴种子的萌发和胚芽的生长,表明花花柴种子适宜在低盐条件下萌发;⑤盐胁迫下未萌发种子的复水实验结果表明,高盐处理后未萌发的种子具有较高的复萌率,但各处理下种子最终萌发率没有显著差异,表明高盐能使种子休眠,但种子的活力仍能保持,有利于种群的维持。

Salt and water stresses have direct influences on seed germination. The present study explored the salt-tolerance characteristics of Karilinia caspica seeds with or without pappus after treated with NaC1 of different concentrations. Seeds with or without pappus showed no significant difference in the final germi- nation percentage, but the germination time of seed with pappus was prolonged due to pappus＇s hindrance to seed water absorption. No distinct seed dormancy was observed when seeds were treated by cold stratifica- tion, which suggested K. easpica seeds could germinate quickly once environmental conditions were favora- ble. The effects of NaC1 stress and iso-osmotic PEG6000 （polyethylene glycol） stress on K. caspica seed germination were checked. Results showed that： （1） both NaC1 and iso-osmotic PEG greatly inhibited the seeds germination by reducing germination rate, prolonging germination time, and shortening germ and radicle; （2） the influence of NaC1 on K. caspica seed germination was obviously greater than that of iso-os- motic PEG, which suggested that ion stress was the main factor that inhibits seeds germination of K. caspi- ca ; （3） the critical and the extreme concentrations of NaC1 for K. caspica seeds germination were 213 mM and 34O mM respectively; （4） low concentration of NaCI （50 raM） had little influence on K. caspica seeds germination as well as the growth of germ, indicating that K. caspica seeds can germinate normally under low salt condition; （5） high concentration salt stressed ungerminated K. caspica seeds showed high reger- mination rate under rewatering treatment, though the final germination rates of the seeds treated with dif- ferent NaC1 concentrations were not significantly different, indicating that high NaC1 stress drove the seeds into dormancy but no damage to seed viability.