【作者】 周大寨；

【导师】 陈少良； 郑小江；

【作者基本信息】 湖北民族学院 ， 野生动植物保护与利用， 2010， 硕士

【摘要】 本文采用盆栽试验的方法,系统研究了干旱、盐及干旱+盐三种胁迫条件下,颗粒吸水剂和粉末吸水剂处理的2年生水杉实生苗生长、渗透调节作用、活性氧产生、膜脂过氧化及抗氧化系统等生理生化变化机制,旨在阐明吸水剂提高水杉抗旱耐盐的作用机理,同时为吸水剂在我国干旱盐碱地区的推广应用提供相关理论基础。主要研究结果如下:⑴在干旱、盐及干旱+盐三种胁迫条件下,水杉苗生长速率、营养器官生物量及整株生物量均显著下降。吸水剂处理能延缓水杉萎蔫症状出现的时间,维持水杉正常日蒸腾耗水量,增加水杉生长速率和营养器官及整株生物量。其中,颗粒吸水剂处理与无吸水剂处理相比,水杉生长速率分别增加170%、90%和390%,整株生物量分别增加30%、19%、45%;粉末吸水剂处理与无吸水剂处理相比,水杉生长速率分别增加170%、100%和390%,整株生物量分别增加30%、21%、40%,两种吸水剂处理间无显著差异。⑵在干旱、盐及干旱+盐三种胁迫条件下,水杉叶片中丙二醛（MDA）含量、O₂^-·产生速率和电解质外渗率均显著增加,吸水剂处理后,水杉叶片中MDA含量、O2·-产生速率和电解质外渗率均显著降低。其中,颗粒吸水剂处理与无吸水剂处理相比,水杉叶片电解外渗率分别降低21%、18%和17%,MDA含量分别降低19%、15%和17%,O₂^-·产生速率分别降低27%、22%和22%;粉末吸水剂处理与无吸水剂处理相比,水杉叶片电解外渗率分别降低8%、35%和41%,MDA含量分别降低6%、18%和34%,O₂^-·产生速率分别降低1%、16%和18%。⑶在干旱、盐及干旱+盐三种胁迫条件下,水杉叶片中脯氨酸、可溶性糖及可溶性蛋白质均增加,而且在同一种胁迫条件下,脯氨酸变化幅度最大。吸水剂处理均降低了三种胁迫条件下水杉叶片中渗透调节物质——脯氨酸、可溶性糖及可溶性蛋白质的含量。颗粒吸水剂处理与无吸水剂处理相比,三种胁迫处理的水杉叶片中脯氨酸含量分别降低了27%、67%和51%,而粉末吸水剂处理与无吸水剂处理相比只显著降低了干旱+盐胁迫下脯氨酸含量。⑷在干旱、盐及干旱+盐三种胁迫条件下,伴随水杉叶片内O₂^-·产生速率的增加,SOD活性也增加,进而引起POD、CAT和APX活性增加。吸水剂处理后,SOD、POD、CAT和APX四种酶活性均不同程度降低。颗粒吸水剂处理的干旱胁迫下,APX活性降低了25%;盐胁迫下,CAT活性降低了37%,APX活性降低29%;干旱+盐胁迫下,SOD活性降低了14%,CAT活性降低了45%,POD活性降低了58%。粉末吸水剂处理的干旱胁迫下,APX活性降低了16%;盐胁迫下,APX活性降低了20%;干旱+盐胁迫下,CAT活性降低了51%,POD活性降低了33%,APX活性降低了16%。⑸在干旱、盐及干旱+盐三种胁迫条件下,水杉根、茎、叶中的Cl^-、Na⁺、K⁺浓度显著增加,且Cl^-、Na⁺浓度分布为根>茎>叶。在干旱及干旱+盐两种胁迫条件下,土壤中Cl^-、Na⁺浓度显著增加,K⁺、Ca²⁺、Mg²⁺浓度无显著变化。吸水剂处理降低了三种胁迫下水杉根、茎、叶中Cl^-、Na⁺浓度,增加了K⁺浓度,使K/Na增大,且粉末吸水剂处理的水杉根、茎、叶的K/Na高于颗粒吸水剂处理。三种胁迫下,吸水剂自身中Cl^-、Na⁺浓度显著低于土壤中Cl^-、Na⁺浓度,而K⁺、Ca²⁺、Mg²⁺浓度显著高于土壤中K⁺、Ca²⁺、Mg²⁺浓度。更多还原

【Abstract】 The changes of physiological and biochemical mechanisms in growth, osmotic regulation, the production and elimination of reactive oxygen species, lipid peroxidation and antioxidant system in leaves of two-year-old Metasequoia glytostroboides Hu et Cheng were tested systematically under the stress of drought, salinity and drought plus salinity, taken by the method of plant-potted. The object of this study is to elucidate the the mechanism of salt and drought tolerance of hydrogel-treated plants. This study provides theoretical basis for the application of hydrogel polymers in arid and saline-alkali areas. The main results were as follows:1. The two polymers both postponed the occurrence of plant wilting and improved growth rate, root and shoot dry weight of stressed Metasequoia glytostroboides, although drought and salt stress significantly suppressed plant growth and biomass. Polymer-treated plants showed a stable transpiration during the period of drought and salinity treatments. Furthermore, hydrogel treatment significantly increased the biomass of stressed plants at the end of experiment. Compared to non-hydrogel treatment, granual polymer increased the growth rate by 170% （drought）, 90% （salinity） and 390% （drought+salinity）. Biomass of thess plants was 30% （drought）, 19% （salinity） and 45% （drought+salinity） higher than non-hydrogel-treated ones. Powder polymer exhibited an effect similar to that of granual polymer, which increased growth rate by 170% （drought）, 100% （salinity） and 390% （drought+salinity） and biomass by 30% （drought）, 21% （salinity） and 40% （drought+salinity）. There were no marked differences between the two type polymers. The enhancements of salt and drought tolerance of plants are mainly due to the water-retaining capacity of polymers, which increased the water available to plants and meanwhile decreased the salt concentrations in the soil solution.2. Drought, salinity and drought plus salinity markedly increased production rate of O₂^-·, MDA content and electrolyte leakage （EL） in leaves. However, polymer application reduced the production rate of O₂^-·, MDA content and EL in stressed plants. Granual and powder polymers lowered the level of O₂^-·by 1-17% （drought）, 16-22% （salinity） and 18-22% （drought+salinity）. MDA content was decreased by 6-19% （drought）, 15-18% （salinity） and 17-34% （drought+salinity） in polymer-treated plants. Correspondingly, hydrogel application reduced EL by 8-21%, 15-38% and 17-41% in drought-, salt- and drought+salinity-treated plants. Collectively, results show that hydrogel application, on the one hand, down-regulated the production of active oxygen species （ROS）, and on the other hand, accelerated the capacity to remove the ROS in stressed palnts.3. Under conditions of drought, salinity and drought+salinity, the levels of proline, soluble sugar, soluble protein in leaves were found to increase, although drought and salt treatment had a more pronounced effect on leaf proline. However, the stress-induced increase of proline, soluble sugar, soluble protein was reduced by the two polymers. Compared to non-hydrogel amendment, granual polymer lowered the proline level by 27% （drought）, 67% （salinity） and 51% （drought+salinity）, while powder polymer only reduced the proline content in drought stressed plants. Our results show that hydrogel alleviated the stress effects of drought and salinity, thus down-regulating the osmolyte solutes that enhanced by water and salt stress.4. Drought, salinity and drought+salinity up-regulated the production rate of O₂^-·in leaves, as well as the activity SOD, CAT, POD and APX during the period of treatment. The enhanced antioxidant system is thought to be helpful to control ROS homeostasis in stressed plants. However, the stress-induced increase of antioxidant enzyme was reduced by the two polymers, indicating that hydrogel alleviated the stress effects of drought and salinity. Hydrogel lowered the APX by 25% （granual polymer） and 16% （powder polymer） in drought-stressed plants. Under saline conditions, APX activity was reduced by 29% （granual polymer） and 20% （powder polymer） and CAT declined by 45% in granual polymer-treated plants. Under conditions of drought and salinity, the reductions of antioxidant enzymes in hydrogel-treated plants were: 45-51% （CAT）, 33-58% （POD） and 14% （SOD, granual polymer）.5. Cl^-, Na⁺ and K⁺ significantly increased in shoot and root tissues in drought and salinised plants. Noteworthy is that more Cl^- and Na+ accumulated in roots than in stem and leaves. Under conditions of water stress, concentrations of K⁺, Cl^- and Na⁺ in soil solutions markedly increased, while K⁺, Ca²⁺ and Mg²⁺ were remained unchanged over the observation period. Hydrogels reduced the concentration of toxic Cl^- and Na⁺ in root, stem and leaves, but increased K+ in drought and salt stressed plants. As a result, K⁺/Na⁺ in root and shoot tissues was improved, especially in powder polymer-treated plants. A much lower concentration of Cl^- and Na⁺ was found in gel matrix compared to soil solutions, but the level of K⁺, Ca²⁺ and Mg²⁺ showed an opposite trend. In conclusion, the two type hydrogels have a salt buffering capacity, which diluted the salt concentrations in the soil, thus restricting the salt uptake by roots. Moreover, the improved K/Na ratio indicates that the nutrient selectivity was enhanced by polymer treatment.更多还原