刺毛碱蓬种子多型性及其对极端盐渍环境的适应

Seed Polymorphism of An Euhalophyte,Suaeda acuminata and Its Adaptation Strategy to Extremely Saline Soil

采用盆栽和生长箱培养方法,对真盐生植物刺毛碱蓬2种形态种子的发育形态特点和萌发过程中对盐度响应的特征进行研究,以了解其对极端盐渍环境的适应。结果表明:(1)在施加0.2%～0.6%NaCl条件下刺毛碱蓬种子产量对盐度增加存在正响应,且在不同生长时期产生形态特征完全不同的2种形态种子,其中一种体积较大、种皮较软且脱水子叶为深绿色(简称软皮种子),软皮种子成熟、干燥脱水后的子叶中有叶绿素存在;另一种体积较小、种皮坚硬且子叶为白色(简称硬皮种子)。(2)对2种形态成熟的脱水种子分别在去离子水和700 mmol.L-1NaCl溶液中浸泡0、12、24 h后测定其种子萌发率、子叶叶绿素含量及光合作用能力的变化,结果发现,无论是否有盐胁迫,软皮种子吸水后的总萌发率均显著高于硬皮种子;软皮种子吸水3 h后即能检测到光合放氧,但经盐处理的种子与去离子水处理的种子其光合放氧能力无显著差别。(3)刺毛碱蓬2种形态的种子在高盐度条件下具有分批次萌发的特征;软皮种子子叶含有叶绿素在吸水后不久进行光合作用并形成幼苗,而硬皮种子萌发迟,但传播扩散远,这些特征在种子萌发和种群建成过程中起到了分摊萌发风险的作用,使刺毛碱蓬具有对更大范围盐渍环境的适应特性。

Both pot and growth chamber cultivation methods were used to investigate the characteristics of seed development and germination for Suaeda acuminata,the results showed that：（1）the seed production had positive correlationship with the NaCl concentration from 0.2% to 0.6%.Two morphological types of seed were found in different stages,one had green embryo with soft and transparent seed coat,the other had white embryo with hard and black seed coat.（2）A seed germination experiment was conducted in a growth chamber in 0 and 700 mmol·L-1 NaCl for 0,12 h,24 h to test the seed germination,cotyledonal chlorophyll and photosynthesis for both seed types.The germination rate of the seed with soft-coat was significantly higher than that of the seed with hard-coat both in 0 and 700 mmol·L-1 NaCl.And the oxygen evolution was found in the soft seeds after 3 h of water absorption for both treatments.（3）The two morphological types of seed germinated in different time,the soft ones germinated into seedlings quickly with cotyledonal photosynthesis.Meanwhile the hard ones germinated slowly,but could be widely dispersed.All these characteristics shared the risk in germination and seedling establishment stage,which made S.acuminata more adaption to large area of saline environment.