不同浓度海水对菊芋幼苗生长及生理生化特性的影响

种植抗盐耐海水植物是合理利用和开发海涂资源的有效措施之一。采用水培的方式,用1/2Hoagland营养液培养菊芋幼苗至6叶完全展开时进行处理,设0%(对照)、10%、25%和50%海水4个处理。随后分别在第4、8和12天采样进行分析,研究不同浓度海水对菊芋幼苗生长、体内渗透物质的积累、保护性酶活性、膜透性及离子吸收分布的影响情况。结果表明:(1)在不同浓度海水处理下,菊芋地上部、地下部总鲜重及干物质重从0%到25%海水浓度没有明显变化,在50%海水胁迫下显著下降,干物质百分比则为50%海水处理的最高。随着时间延长,10%海水处理下,菊芋幼苗茎叶和根鲜重均增加,但与对照没有显著差异,25%海水处理生长速率较对照低,而50%海水处理下根鲜重和干重都降低。(2)随着时间的延长、海水浓度的增加,菊芋幼苗叶片保护性酶系SOD、POD、CAT的活性呈上升趋势,在10%海水处理下膜脂过氧化物MDA含量甚至低于对照,而50%海水处理下的MDA含量较其他处理高,在10%和25%海水处理下膜透性较对照变化不显著,而50%海水处理下膜透性增加明显,且随时间延长更显著。(3)菊芋幼苗叶片脯氨酸和可溶性糖含量随海水浓度增高而显著增加,随着时间的延长,10%和25%海水处理下,脯氨酸含量先增加后降低,而50%海水处理下,脯氨酸含量一直在升高,而10%、25%和50%海水处理下,可溶性糖含量先增加后降低。随海水浓度增高,菊芋幼苗地上部单位干重积累的Na 和Cl-依次增大,且随着时间延长,10%、25%和50%海水处理下地上部Na 和Cl-含量均增大;而K 与Na 积累情况不同,K 在25%海水胁迫下地上部单位干重积累得最多,随着时间延长,25%和50%海水处理下地上部K 含量均降低,且50%海水处理下降低幅度更大;地下部单位干重积累的Na 、Cl-和K 情况与地上部单位干重积累的各离子趋势相似。由此可见,菊芋能够通过生理生化机制适应一定浓度海水的灌溉,即利用一定浓度海水灌溉菊芋是安全有效的。

Effects of seawater with different concentrations on growth and physiological and biochemical characteristics of Helianthus tuberosus seedlings

Growing plants that can tolerate seawater is one of the valid measures of reasonable use and exploitation of coastal beaches. Pot experiments were carried out to study effects of different concentrations seawater on growth,osmotica accumulation antioxidant enzyme, membrane leakage and ion distributions of Helianthus tuberosus seedlings. Four treatments with six replicates consisting of 0% (distilled water), 10%, 25% and 50% seawater were set up by a randomized complete block design. Plant aerial parts and roots were harvested 4, 8 and 12 days after treatment and assayed for fresh weight (FW), dry weight (DW), and contents of water, Na~ , K~ and Cl~-. Meanwhile, leaves were assayed for activities of antioxidant enzymes, malondialdehyde (MDA) contents, electrolytic leakage percentage (ELP), proline and soluble-sugar contents. Results were as follows: (1) Compared with the control, there were slight changes of FW and DW in roots and aerial parts of Helianthus tuberosus seedlings treated with 10% and 25% seawater, whereas a significant (p<0.05) decrease in both FW and DW occurred under 50% seawater. But the water content in aerial parts and roots were the lowest under 50% seawater. (2) The activities of SOD (superoxide dismutase), POD (peroxidase) and CAT (catalase) in leaves of seawater-stressed plants were stimulated significantly compared with controlled plants, and increased with increasing seawater concentrations. Compared with the control, there was slight change of ELP in leaves of Helianthus tuberosus seedlings treated with 10% and 25% seawater, whereas ELP increased significantly with the treatment of 50% seawater. With time lasting, ELP increased more under 50% seawater. (3) Contents of proline and soluble-sugar increased with increasing seawater concentrations. Contents of proline increased on Day 8 and decreased on Day 12 under 10% and 25% seawater, but increased significantly on Day 8 and onward under 50% seawater. Contents of soluble-sugar on Day 8 increased compared with those on Day 4 and decreased on Day 12 under 10%, 25% and 50% seawater. Contents of Na~ and Cl~- in the aerial parts increased with increasing seawater concentration. Compared with Na~ , K~ contents were highest under 25% seawater. And the tendencies of Na~ , Cl~- and K~ in roots were similar with those in the aerial parts. The results of the present study strongly suggest that Helianthus tuberosus could adapt appropriate concentration seawater irrigation through physiological and biochemical mechanisms, which was effective and secure.