【作者】 陈兴；

【导师】 林瑞余；

【作者基本信息】 福建农林大学 ， 生物化学与分子生物学， 2011， 硕士

【摘要】 水葫芦又名凤眼莲,属雨久花科、凤眼莲属,为直立多年生草本植物,原产南美,最初作为水生饲料被引进,后逐渐脱离人为控制,广泛分布于浙江、上海、福建、云南等东南部18个省市自治区,成为十大入侵害草之一,研究水葫芦生物入侵机理对其综合治理与利用具有重要意义。本研究以采自闽江水口电站的水葫芦为材料,通过室外调查和模拟实验,研究用不同营养水平及重金属镉胁迫对水葫芦生长和分蘖动态、形态特征、生理生化特性、内源激素及根际微生物群落功能多样性的影响,主要结果如下:（1）在富营养化内河放养水葫芦研究表明,水葫芦具有强大的无性繁殖力。在放养的210d内,水葫芦在5～7月份鲜重和分蘖数增加明显,鲜重相对生长高达9.42倍,分蘖数相对增加最高达到3.67倍,8月份后增重明显放慢,到10月份下旬至11月份下旬无明显增重,水葫芦在富营养内河中的最大密度约为55.7kg/m²,分蘖数量约为133个/m²。（2）以0.01、0.025、0.05、0.2、1、5、10倍Hoagland营养液室内模拟培养水葫芦,结果表明:在培养120d内,水葫芦在1倍Hoagland完全培养液生长最好,相对生长率高达22倍。缺N、缺P培养水葫芦结果表明,缺素条件下水葫芦株高变矮,侧根系变长,叶片变薄、变小,以缺N培养的最为明显,对水葫芦的生长影响最大,分蘖数仅为对照和缺磷培养的47.1%和50.0%,鲜重分别是38.7%和44.3%。氮素浓度为30.0mg/L、15.0mg/L、7.5mg/L和3.75mg/L的水培模拟试验表明,培养125d后,水葫芦鲜重分别增加到开始放养时的20.5、32.1、14.9和10.2倍,最佳营养液氮素浓度为15.0mg/L。（3）以含有0mg/L Cd²⁺、1mg/L Cd²⁺、5mg/L Cd²⁺和10mg/L Cd²⁺的Hoagland营养液室内模拟培养水葫芦试验表明,5mg/L Cd²⁺处理30d后,水葫芦的镉富集系数达到448,富集的镉主要分布在根系,镉富集量与处理浓度正相关;在10mg/L Cd²⁺下处理30d,根系中镉含量为2741.3mg/kg,是茎叶的20.7倍。生理生化分析表明,镉胁迫下水葫芦叶片和根系的可溶性蛋白和保护酶系活性均显著升高,叶片中可溶性蛋白含量约为根系的1.5～1.8倍;水葫芦叶片中MDA含量无明显变化,根系中MDA含量在10mg/L Cd²⁺条件下处理后显著的升高,镉对水葫芦根系的伤害比叶片伤害早且大。镉胁迫下,IAA、GA和ZR含量趋势均为先升高后降低,在5mg/L Cd²⁺内, IAA、ZR、GA含量均增加,在10mg/L Cd²⁺下,IAA、ZR、GA含量显著降低。植物内源激素ABA含量与镉浓度正相关,10mg/L Cd²⁺下ABA含量达到135.33ng/g·FW,是0mg/L Cd²⁺下的2倍,IAA、ZR、GA之间共同调控,提高了镉胁迫下水葫芦的抗逆性。（4）镉胁迫下,水葫芦根际微生物总量随镉处理浓度升高而减少,CK和1mg/L Cd²⁺条件下,种群数量无明显差异,但在10mg/L Cd²⁺条件下的微生物总量仅为是CK的67%。生理类群分析表明,自生固氮菌、硝化细菌和亚硝化细菌随镉浓度的增大种群密度在减小,以10mg/L Cd²⁺下最为显著,其中亚硝化细菌减少最多,是CK组的45%;反硝化细菌在低浓度镉胁迫下种群密度增大,高浓度下受到抑制,氨化细菌和好气性纤维素分解菌呈相似的变化趋势。生物群落功能多样性的BIOLOG分析表明,水葫芦根际微生物在0mg/L Cd²⁺和1mg/L Cd²⁺环境中对有机物利用率较高,在5mg/L Cd²⁺和10mg/L Cd²⁺下,有机物的利用率显著下降。综上所述,水葫芦具有强大的无性繁殖力,具有高的表型可塑性,以及保护酶和激素的调节增强了水葫芦的抗逆性,根际微生物多样性的改变也对维持养分循环、修复富营养化和镉污染水域具有重要作用。在氮素浓度为3.75～30mg/L、0～5mg/L Cd²⁺、0～10倍Hoagland营养液中均能正常生长,具有强大的生长适应性。更多还原

【Abstract】 Eichhornia crassipes （Mart.） Solms （Pontederiaceae）, also known as water hyacinth, is a perennial erect herb native to South America. It was introduced to China as aquatic feed originally and then naturalized in wild gradually. E. crassipes has become one of the top ten invasive plants widely distributing in 18 regions in southeast China （province, city and municipality） , including Zhejiang, Shanghai, Fujian, and Yunnan. Accordingly, it is very important to elucidate the mechanisms of biological invasion of E. crassipes for the integrated control and utilization of this species. In this study, we selected E. crassipes collected from Shuikou power station of Min River as experimental materials and studied the effects of nutrient level, and heavy metal stress of cadmium on growth dynamics, tillering dynamics, morphological characteristics, physiological and biochemical characteristics, endogenous hormones and rhizosphere microbial community functional diversity of the plant through field survey and indoor simulation experiments. The main results are as follows:（1） By cultivating E. crassipes in an eutrophic inner river for a interval of 210 days, the plant showed its strong asexual reproductive ability. The fresh weight and tiller number significantly increased from May to July, the relative growth rate of fresh weight was up to 9.42 times and the relative tiller number reached 3.67 times. The growth of the plant slowed down significantly from August and there was no significant fresh weight increase from late October to late November. The maximum density of E. crassipes in nutrient-rich river was about 55.7 kg/m² and the density of tiller number was about 133/m².（2） The results of indoor simulation experiments of culturing E. crassipes in the hydroponic solution, which the concentration of the nutrients was 0.01, 0.025, 0.05, 0.2, 1, 5, 10 times as higher as that of Hoagland hydroponic solution. The results showed that E. crassipes grew best in 1 time Hoagland nutrient solutions and the relative growth rate of it was up to 22 times, within 120 days. By culturing E. crassipes in nutrient solutions lack of N, P, E. crassipes performed with more shorter height, longer lateral roots, thinner and smaller leaves .There is significant impact on the growth of E. crassipes under the N deficit condition. The tiller number was only 47.1% as many as that of control and 50.0% of which lacking of P, and fresh weight is 38.7% and 44.3% respectively. In addition, when E. crassipes was cultured in the solutions containing nitrogen 30.0 mg/L, 15.0 mg/L, 7.5 mg/L and 3.75 mg/L for 125 days, respectively, the fresh weight of E. crassipes increased to 20.5, 32.1, 14.9 and 10.2 times as that of beginning. and the highest biomass was found in the 15.0 mg/L nitrogen condition（3） Laboratory experiments of culturing E. crassipes in Hoagland solutions containing 0 mg/L, 1 mg/L, 5 mg/L and 10 mg/L Cd2 + showed that the cadmium accumulation index of E. crassipes was up to 448 by treating the plant for 30 days in 5 mg/L Cd²⁺solution, and Cadmium mainly accumulated in roots,the accumulation of Cd was positive related to the concentration of Cd²⁺ treated. Under 10 mg/L Cd²⁺solution, the content of cadmium in roots was 2741.3 mg/kg, which was 20.7 times as higher of that in the stems and leaves. Furthermore, physiological and biochemical analysis indicated that the content of soluble protein and protection enzyme system activity significantly increased in leaves and roots of E. crassipes under cadmium stress, showing soluble protein content in leaves was about 1.5～1.8 times as higher as that in roots, MDA content in leaves of E. crassipes had no significant changes, MDA content in roots significantly increased after 20 days treatments by 10 mg/L Cd²⁺, so the earlier and severe damage of cadmium to roots than to leaves was recorded. Under the condition of cadmium stress, IAA, GA and ZR contents increased initially and decreased latter, all of them increased under 5 mg/L Cd²⁺ while significantly reduced under 10 mg/L Cd²⁺ conditions. Endogenous hormone ABA content was positive correlated with cadmium concentration, it was 135.33 ng/g·FW under 10 mg/L Cd²⁺, which was 2 times as higher as that of control. The co-regulation among IAA, ZR and GA respond for the higher resistance of E. crassipes to cadmium stress.（4） Under the condition of cadmium stress, the population density of microorganisms in the rhizosphere of E. crassipes reduced with the increasing of cadmium concentration. but no significant difference was found between CK and 1mg/L Cd²⁺ treatment. But the population density of microbet was only 67%of CK under 10 mg/L Cd2 +treatment. The analysis of components of the microbe in the rhizospheric soils showed that population density of Azotobacteria, Nitrobacteria and Ntrosobacteri reduced with the increasing of cadmium concentration. There was significantly change found under 10 mg/L Cd²⁺ , nitrification bacteria population density reduced to 45% of that in CK. The population density of denitrifying bacteria increased under low cadmium stress, while decreased under high cadmium concentration. Similar trend was found in ammonification and aerobic cellulose decomposing bacteria. Biological community functional diversity of rhizospheric microbe, which was analysed by BIOLOG method, showed higher utilization ability of organic compounds under 0 mg/L and 1mg/L Cd²⁺ environments than under 5 mg/L or 10 mg/L Cd²⁺ conditions, by rhizospheric microorganisms of E. crassipesIn summary, E. crassipes has stronger asexual reproductive ability, higher plasticity, together with the changing of protection enzymes system and hormones, which resulting in higher resistance to stressful environment. The changing diversity of rhizospheric microbe also played an important role in maintaining the cycling of nutrient, restoring eutrophication and cadmium-containing water area, indicating a strong growth adaptability of E. crassipes as well.更多还原