盐生植物海马齿耐盐的生理特性

The physiological characteristics of salt-tolerance in Sesuvium portulacastrum L.

以盐生植物海马齿为研究材料,分别用淡水、1/4海水、1/2海水、全海水浇灌15 d和30 d,研究盐生植物耐盐的生理特性和机理。海马齿植物在低于1/2的海水浇灌时,植物生长旺盛,主要表现为叶片增大和变厚,地上部分生物量增加;而全海水抑制了植物的生长。在盐胁迫下,海马齿植物中Na+的含量叶中最高,茎中含量次之,根中含量最低。长时间盐胁迫时,海马齿植物根、茎、叶中的相对含水量与淡水浇灌相比,变化不大,叶中略有增加;而脯氨酸含量显著增加,且可溶性糖的含量也比淡水浇灌的高。由此推测:海马齿植物主要以有机小分子作为渗透调节物质来维持细胞渗透压,在其耐盐中起着重要的作用。土壤中Na+的毒害,并没有减少土壤中可被植物利用的可交换K+,反而使其增加,说明海马齿植物根部对Na+的吸收能力和Na+/K+交换能力非常强。海马齿植物耐盐性强,还表现为能阻止盐胁迫对植物细胞原生质膜的氧化损伤,不破坏植物叶片内叶绿素的合成,能基本维持植物茎、叶中K+和根、茎中Mg2+的相对稳定。

In this paper,the physiological characteristics of salt-tolerance in S.portulacastrum have been researched by watering the plants with tap-water;1/2 sea-water;1/4 sea-water;sea-water for 15 d and 30 d.The results showed that the plant vigorously grew with larger and thicker leaves,and an increased shoot weight when they were watered with 1/2 and 1/4 sea-water.However,when plants were watered with high NaCl（sea-water）,their growth was inhibited,which mainly reflected in lower FW weights as well as fewer and shorter stem nodes than the controls（watered with tap-water）,but,they also had larger and thicker leaves.Under salt-stress,Na＋ concentration in plant leaves was higher than that in stems and roots,which was the lowest in roots.It was showed that under sea-water for 30 d,the Na＋ content in leaves,stems and roots was 31.78 mg/g（dry weight,DW）,14.04 mg/g DW,and 7.53 mg/g DW respectively,but that was 12.92 mg/g DW,5.89 mg/g DW and 1.25 mg/g DW in leaves,stems and roots of controls.When the plants were under longer time salt-stress,the relative water content in plants was similar as they were watered with tap-water,except slightly higher in leaves,which was in roots as 64.9%（tap-water）,68.5%（1/4 sea-water）,66.9%（1/2 sea-water）,63.6%（sea-water）;in stems as 84.4%（tap-water）,84.07%（1/4 sea-water）,84.10%（1/2 sea-water）,83.80%（sea-water）;in leaves as 68.83%（tap-water）,78.43%（1/4 sea-water）,79.9%（1/2 sea-water）,80.93%（sea-water）.Under longer time salt-stress,the content of praline in salt-stressed plants was obvirously higher than that in controls.Also the concentration of soluble carbohydratein in salt-stressed plants was higher than that in the controls.It is deduced that the small organic molecules working as osmotic potentials in cells play a key role in salt tolerance of S.portulacastrum.The rich Na＋ in soil could increase the exchanging K＋ between plants and soil.It was showed that after the plants were watered sea-water for 30 d,the exchanging K＋ in soil was 41.63μg/g（tap-water）,119.43 μg/g（1/4 sea-water）,167.87 μg/g（1/2 sea-water）,228.73 μg/g（sea-water）;the rate of the exchanging Na＋/K＋ in roots（ASK,Na） was 1.49（tap-water）,5.21（1/4 sea-water）,9.71（1/2 sea-water）,7.67（sea-water）;in tems（TSK,Na） was 0.43（tap-water）,0.62（1/4 sea-water）,0.58（1/2 sea-water）,0.71（sea-water）;in leaves（TSK,Na） was 0.12（tap-water）,0.29（1/4 sea-water）,0.21（1/2 sea-water）,0.26（sea-water）.It indicates that the root membrane of S.portulacastrum functionally exchange Na＋ and K＋/Na＋ between plant and soil.Under longer time salt-stress,the content of the chlorophylls was not decreased in plants of S.Portulacastrum;and the plants could inhibit the cell membrane to be oxidative damaged as the content of the malondialdelyde（MDA） was increased,which is one of the compounds produced from damaged cell membrane oxidation,and the main index reflecting the degree of cell destruction by stress.Under longer time salt stress,the K＋ content was approximately constant in leaves and stems of salt-treated plants at all concentrations of salt stress,and the Mg2＋ was approximately constant in stems and roots as well.