【作者】 薄鹏飞；

【导师】 杜希华；

【作者基本信息】 山东师范大学 ， 植物学， 2008， 硕士

【摘要】 用NaCl浓度为0、50、100、150和200 mmol·L^-1的1/4 Hoagland营养液培养海滨木槿（Hibiscus hamabo Sieb.et Zucc.）的种子,逐日测定萌发率、吸胀率;5 d、10 d后测定种皮和种胚的Na⁺、K⁺含量;培养15 d后,将含有NaCl的营养液中未萌发的种子分别转入1/4 Hoagland营养液继续培养,测定解除盐胁迫后种子萌发的恢复率;以探索不同浓度的NaCl处理对海滨木槿种子萌发及其种皮和胚的Na⁺、K⁺含量的影响。结果发现,随着NaCl浓度的升高,海滨木槿种子的萌发率逐渐降低,在NaCl浓度为200 mmol·L^-1时种子的萌发率和吸胀率最低。150、200 mmol·L^-1NaCl中未萌发种子的恢复率与对照无显著差异,而比100 mmol·L^-1NaCl的显著升高。种皮和胚的Na⁺含量随着NaCl浓度升高和盐处理天数增多而增大;在相同的盐浓度下,胚的Na⁺含量明显低于种皮;随着NaCl浓度升高和盐处理天数增多,种皮的K⁺含量逐渐升高,胚的K⁺含量逐渐降低,但胚的K⁺含量仍明显高于种皮;此外,胚的Na⁺/K⁺随着盐处理浓度升高和盐处理天数增多而增大,但胚的Na⁺/K⁺明显低于种皮。上述结果表明:高浓度的盐可以诱导海滨木槿种子休眠并促进盐胁迫解除后种子的萌发,这种机制可以使之避开不良的萌发条件,等到降雨使土壤溶液浓度降低再萌发,这是盐生植物的种子适应盐渍生境的一种有效方式;海滨木槿的种皮有阻挡Na⁺进入胚的作用或胚具有某种拒Na⁺的机制,使胚保持较高含量的K⁺和较低的Na⁺/K⁺,这可能是海滨木槿种子耐盐的主要生理原因之一。另以不同浓度的NaCl处理海滨木槿一年生实生苗,研究NaCl胁迫对其根、下位叶、上位叶中Na⁺、K⁺含量、叶片中抗氧化酶活性、抗氧化物质和渗透调节物质含量的影响。结果显示,在不同浓度的NaCl胁迫下,随着NaCl浓度升高,根及叶片中Na⁺的含量逐渐升高; K⁺的含量先降后升,始终低于对照;Na⁺/K⁺逐渐升高。Na⁺的含量和Na⁺/K⁺过高对植物是有害的,海滨木槿通过增加有机渗透调节物质的含量增强植株的吸水能力并缓解Na⁺的危害,因而植株的生长受到不同程度的抑制。在相同浓度的NaCl处理下,叶片中Na⁺的含量显著低于根,K⁺的含量显著高于根,因而叶的Na⁺/K⁺显著低于根。这表明海滨木槿是一种喜K拒Na的盐生植物。在相同浓度的NaCl处理下,下位叶中Na⁺、K⁺的含量均高于上位叶,这可能是由于蒸腾强度不同导致的。在NaCl浓度为100和200 mmol·L^-1时,两者的Na⁺/K⁺并没有显著差异;在NaCl浓度为400 mmol·L^-1时,下位叶的Na⁺/K⁺显著低于上位叶,这能保证下位叶通过光合作用制造更多的有机渗透调节物质,并使植株的生长受到明显抑制。随着NaCl浓度的升高,海滨木槿叶片中超氧化物歧化酶（SOD）、抗坏血酸过氧化物酶（APX）、过氧化物酶（POD）、谷胱甘肽还原酶（GR）和谷胱甘肽转硫酶（GST）的活性先升高后降低,但达到最高活性时NaCl的浓度并不一致;过氧化氢酶（CAT）的活性呈下降趋势;丙二醛（MDA）的含量先下降后升高,但始终低于对照;抗坏血酸（AsA）和谷胱甘肽（GSH）等抗氧化物质的含量均高于对照,且在200 mmol·L^-1时达到最高;可溶性糖和脯氨酸（Pro）等渗透调节物质的含量均较对照上升,且升幅较大。这些结果均表明,海滨木槿在盐胁迫下具有较强的活性氧清除能力和渗透调节能力,从而表现出较强的耐盐性。更多还原

【Abstract】 In order to study the effects of salt treatment with different NaCl concentration on the seed germination and the content of Na⁺ and K⁺ in the seed coat and embryo of Hibiscus hamabo Sieb.et Zucc., the seeds were cultivated by 1/4 Hoagland nutrition solution with 0, 50, 100, 150 and 200 mmol·L^-1 NaCl, the germination rate and imbibition rate were measured every day, the content of Na⁺ and K⁺ in seed coat and embryo was determined when the seeds were treated for 5 and 10 days respectively; and after 15 days , the ungerminated seeds in 1/4 Hoagland nutrition solution with NaCl were cultivated by 1/4 Hoagland nutrition solution without NaCl. The results showed that the seed germination rate decreased gradually as the NaCl concentration increased .The seed germination rate and imbibition rate was lowest when the seeds were treated with 200 mmol·L^-1NaCl; the recovery rate of ungerminated seeds in 150 and 200 mmol·L^-1NaCl had no significant difference with the control and it was more higher than the seeds in100 mmol·L^-1NaCl. The Na⁺ content in seed coat and embryo increased gradually as the NaCl concentration increased and days progressed, and Na⁺ content in the embryo was significantly lower than which in the seed coat under the same NaCl concentration. As the NaCl concentration increased and days progressed, the K⁺ content in the seed coat increased gradually while it decreased gradually in the embryo, but the latter was significantly higher than the former. In addition, the ratio of Na⁺/K⁺ in seed coat and embryo increased gradually as the NaCl concentration increased and days progressed, but the ratio in embryo was significantly lower than in seed coat. These results suggested that higher concentration of NaCl could cause the seed dormancy and accelerate the germination of ungerminated seeds. Perhaps there was a mechanism that the seed coat or embryo could prevent Na⁺ from entering into the embryo so as to keep higher K⁺ and lower Na⁺/K⁺ in the embryo. And it might be one of the physical mechanisms that the seed of Hibiscus hamabo Sieb.et Zucc. could resist high salinity stress. In addition, the annual seedlings of Hibiscus hamabo Sieb.et Zucc. were respectively treated with different concentration of NaCl solution. The effects of NaCl stress on the Na⁺ and K⁺ content of roots, mature leaves and young leaves, antioxidative system and osmotic regulation in the leaves were studied in this part. The result showed that, with the increasing of NaCl concentrion, Na⁺ content and ratio of Na⁺ /K⁺ in roots and leaves increased; K⁺ content decreased firstly and then increased, but it was always lower than the control. Na⁺ and higher Na⁺ /K⁺ was harmful to the plant, the harm could be alleviated because of organic osmolyte content and absorbing capacity increasing, but this must be at the expense of sacrificing growth. At the same time, the content of Na⁺ in leaves was distinctly lower than roots and the content of K⁺ was the reverse under the same NaCl concentration treation.So, the ratio of Na⁺ /K⁺ in leaves was evidently lower than in roots. The results indicated that the seedlings of Hibiscus hamabo Sieb.et Zucc. could prevent Na⁺ from transporting to upground by withholding Na⁺ in roots. The Na⁺ and K⁺ content of mature leaves was higher than young leaves when Hibiscus hamabo Sieb.et Zucc. was treated by the same concentration of NaCl, this might be due to varying intensity caused by transpiration. Under the treatment of 400 mmol·L^-1NaCl , the ratio of Na⁺ /K⁺ in young leaves was remarkably higher than mature leaves , and the plant growth was inhibited significantly.The activities of superoxide dismutase （SOD）, peroxidase （POD）, ascorbic acid peroxidase （APX）, Glutathione reductase （GR） and Glutathione- S-transferase （GST） had similar trend, which were increasing firstly, then decreasing with NaCl concentrations from 0 up to 400 mmol·L^-1. However, the concentrations of NaCl in which the enzymes activity came to the highest level were different; The catalase （CAT） activity decreased with the increasing of NaCl concentrations; The MDA content and electrolyte leakage（%） decreased firstly and then increased with the increasing of NaCl concentrations, the fomer was always lower than the control level. The content of AsA and GSH was the highest when the NaCl concentration was 200 mmol·L^-1; The content of proline （Pro） and soluble sugar（SS） increased evidently with the increasing of NaCl concentration as well. It was thus suggested that the high-salinity resistance of Hibiscus hamabo Sieb.et Zucc. was related to its stronger antioxidance and osmotic regulation capacity.更多还原