【作者】 甘尼格；

【导师】 夏宜平； 朱祝军；

【作者基本信息】 浙江大学 ， 观赏园艺学， 2009， 博士

【摘要】 非洲菊（Gerbera jamesonii L．）作为重要的商品切花，近年来栽培面积和消费量剧增，位居世界切花销售量的第五位。然而，由于可耕地面积的锐减和全球的灌溉水供应受限等问题，常导致保护地栽培中的盐害发生，对非洲菊的切花生产影响较大。可是，有关盐胁迫对非洲菊的影响以及有效的盐害防治措施却几乎未见报道。鉴于此，本论文主要针对长期NaCl胁迫对非洲菊品种‘Ameretto’的生理生化特性展开研究，同时，对外施水杨酸以提高非洲菊耐盐性的生理机制也进行了研究。主要研究内容和主要结果如下：1) NaCl长期胁迫试验，植株材料选择3个月苗龄的非洲菊，NaCl浓度梯度设置为：0，10，20，30和40mM，处理时间为10周，研究其不同生长发育阶段及不同盐浓度处理下的植株生长、生化特征、养分含量和亚显微结构变化。NaCl处理水平的提高，显著地降低了叶片和根的生物量。当NaCl浓度大于10mM时，生物量开始急剧减少，开花品质下降，植株死亡率也较高。各种浓度盐胁迫均明显增加了叶片、茎及根中的Na⁺含量，降低了K⁺含量，导致K⁺／Na⁺比值大幅下降。Mg²⁺含量在茎和根中也呈现下降趋势，而在叶中则不显著。脯氨酸对于渗透压的调节作用并不明显。当植株从营养生长阶段过渡到生殖生长阶段时，其阳离子浓度、叶绿素含量、根和叶的脯氨酸含量均呈明显变化。原生质体、叶绿体和其它亚显微结构都受到严重的盐害影响。这些数据表明，非洲菊的灌溉水中NaCl含量的极端上限宜在10mM左右，尤其是品种‘Ameretto’。叶绿素含量、叶鲜重、K⁺／Na⁺比值可认为是衡量非洲菊耐盐性的指标。2)通过对非洲菊在生殖生长期的光合抑制和抗氧化特性试验，研究了外源水杨酸（SA）处理对改善盐胁迫耐性的影响。分别用0、0.5和1.0mM SA对非洲菊植株进行预处理，预处理3天后用100mM NaCl进行灌溉，持续进行2周。对照植株未经任何NaCl和SA处理。盐胁迫处理明显降低了叶片细胞的气体交换特性和光合色素含量，并影响了细胞膜完整性和叶绿体超微结构。由于盐胁迫的影响，超氧化物歧化酶（SOD）和过氧化物酶（POD）的活性增加，而丙二醛（MDA）含量的增加则表明盐胁迫破坏了细胞膜的完整性，而脂质过氧化作用和电解质外渗加剧，以及叶绿素含量降低，则与叶片组织中盐浓度增加直接相关。水杨酸（SA）的施用明显增强了气体交换特性，即便是未经盐胁迫处理的植株也有一定的变化。明显增加的光合色素含量和叶绿体超微结构未被破坏，进一步证实了SA对盐胁迫下非洲菊叶片光合系统的改善功能。在外源SA的影响下，叶片脂质过氧化作用显著降低，而膜结构仍保持良好的完整性；SA预处理后，植株SOD和POD活性均高于未经处理的。这些结果表明，外源SA能够激发盐胁迫下非洲菊植株的抗氧化系统。一般而言，在本试验的两种浓度中，0.5mM SA的增强盐胁迫耐性效果更好，甚至某些指标与对照没有太大差异。SA预处理后的植株生长和相关生理指标呈显著相关，加之其低廉的成本，可以证明水杨酸将是一种提高非洲菊植株耐盐性的有效物质。更多还原

【Abstract】 Gerbera （Gerbera jamesonii L.; family Asteraceae） represents an important commercial cutflower crop, ranking the fifth most demanded cutflower in the international cutflower trade. The productivity and distribution of cut gerbera are threatened by ever shrinking cultivable land area and global constraints on fresh irrigation water supplies, due to salinity, especially under protected cultivation systems. However, the deleterious effects of long-term salt stress as well as effective alleviation of salt stress-damage in gerbera have rarely been studied. Hence, the present work briefed bellow, was carried out to investigate the effects of long-term NaCl salt stress on Gerbera jamesonii L. ’Amaretto’ and the role of exogenously applied salicylic acid in improving its salinity-tolerance.1) Three-month old micropropagated plants were subjected to five salt treatments as 0, 10, 20, 30 and 40 mM NaCl for 10 weeks to investigate the effects of prolonged salt stress as characterized by growth, physiological, biochemical and ultrastructural responses. Increasing salt stress significantly declined the growth, plant survival, yield and flower quality. Salt stress significantly increased Na⁺ but decreased K⁺ concentration in leaves, stems and roots leading to a marked decline in K⁺/Na⁺ ratios. Salt stress significantly affected Mg²⁺ concentrations in stems and roots, too. Cationic nutrient concentrations, chlorophyll content, root and leaf proline content critically changed when plants switched from vegetative to reproductive growth. Plasmolysis and severe destruction of chloroplast and other organelle ultrastructure were prominent under higher salt stress. NaCl threshold level in irrigation water for the normal vegetative growth of gerbera is around 10 mM for this cultivar in particular. However, even this level of NaCl significantly reduces the flower yield and quality. Chlorophyll content, leaf fresh weight and K⁺/Na⁺ ratio are promising indicators of salt-sensitivity of gerbera.2) Protective roles of exogenously applied salicylic acid （SA） against salt-induced photosynthetic inhibition and oxidative damage in gerbera at reproductive stage were investigated. At the onset of flower initiation, plants pretreated with 0, 0.5 and 1.0 mM SA, were irrigated with 100 mM NaCl （three days after the first SA application） and continued for two weeks. Control plants did not receive either NaCl or SA. Salt stress negatively affected the gas exchange attributes, photosynthetic pigments content, membrane integrity and chloroplast ultrastructure. SA application significantly enhanced all gas exchange attributes tested. Further, the photosynthetic pigments content was also enhanced while the chloroplast ultrastructure was effectively prevented from damage by exogenous SA. Membrane permeability and lipid peroxidation were markedly lowered while superoxide dismutase and peroxidase activities were significantly enhanced by SA pretreatment. Results suggest that photosynthetic capacity and antioxidative defense system in salt stressed plants are enhanced by SA pretreatment. Generally, of the two concentrations tested, 0.5 mM SA seemed to have greater effect throughout the experiment showing no significant variation from control in some attributes. Responses of plants pretreated with SA, significant correlation among them as well as the low cost, plausibly predict its future potential in practical application to alleviate adverse effects of salt stress in gerbera.更多还原