香根草对重金属铅离子的胁迫反应研究

研究了Pb²⁺对香根草生理生态指标的影响.结果表明, 随水培液中Pb²⁺浓度的增加(0～8 mmol·L^-1),香根草苗的生长受到严重影响;叶片电导率增大;SOD活性先上升后下降,但均高于对照,其活性与Pb ²⁺浓度呈正相关;POD和CAT活性虽也是先上升后下降,但在高浓度(＞4 mmol·L^-1)的Pb²⁺处理下,酶活性均低于对照,其酶活性与Pb²⁺浓度呈显著负相关.可以认为,酶活性升高是由于香根草苗对Pb2+胁迫做出的应激反应,而高浓度Pb²⁺却对香根草苗的保护酶活性有抑制作用.     

风车草和香根草在人工湿地中迁移养分能力的比较研究

为研究风车草(Cyperus alternifolius)和香根草(Vetiveria zizanioides)迁移养分的能力,建立17.0m²风车草潜流式人工湿地和13.3 m²香根草潜流式人工湿地处理猪场废水,在四个季节末测定植物生物量和组织氮、磷、铜、锌含量.结果表明,香根草地下部生物量大于风车草,地上部生物量则是风车草大于香根草.风车草年地上部收获量为3406.47 g·m^-2,比香根草的1483.88 g·m^-2高2.3倍;风车草的氮含量为22.69 mg·g^-1,比香根草的15.44 mg·g^-1高7.25 mg·g^-1;风车草的磷含量为6.09 mg·g^-1,比香根草的5.47 mg·g^-1高0.62 mg·g^-1.植株含铜、锌量风车草略比香根草高.风车草每年迁移N 68.72 g·m^-2和P18.49 g·m^-2,香根草迁移N 8.93 g·m^-2和P 3.69 g·m^-2.风车草人工湿地每年由植物迁移的氮、磷、铜、锌比香根草高4～7倍.     

香根草和百喜草对铅锌尾矿重金属的抗性与吸收差异研究

铅锌尾矿是一类重金属含量极高,对植物生长产生毒害的生境.盆栽实验的结果显示,香根草和百喜草在纯尾矿或由尾矿和垃圾组成的混合基质上都能生长,但植物的长势随基质中重金属含量的增加而减弱,其中香根草的生物量所受的影响比百喜草的更大,即百喜草有比香根草更强的重金属抗性.2种植物体内的重金属含量高低均为Zn＞Pb＞Cu,但二者对它们的富集能力大小分别是,香根草为Zn＞Cu＞Pb,百喜草则为Cu＞Zn＞Pb.香根草和百喜草的根系对3种重金属都有较强的滞留效应,滞留率均在50%以上;其中香根草对重金属的滞留率又明显高于百喜草;而且,同一植物对不同的重金属的滞留率也明显不同,香根草对Pb的滞留率最高,而百喜草对Cu的滞留率显著高过对Zn和Pb.由于香根草的生物量明显大于百喜草,结果香根草对Pb、Zn的吸收量比百喜草高.当用25%的垃圾改良金属尾矿时,百喜草对重金属的吸收量即达最大;而香根草则在尾矿和垃圾各占50%的基质中吸收最多的重金属;因此,添加一定量的垃圾(25%～50%左右)用于尾矿改良时,不仅能使尾矿得到更快的植被恢复与更高的植物修复效果,而且能使垃圾资源得到充分合理的利用.总之,当开展对金属尾矿的植被恢复时,可选择种植抗性强、覆盖快的百喜草,但如果要对尾矿中的重金属进行生物净化,则应选择种植生物量大的香根草,种植香根草还可较好地防止重金属的二次污染或生物富集.     

N、P、K肥对香根草修复土壤镉、锌污染效率的影响

通过盆栽试验研究在30 mg/kg镉(Cd)污染土壤条件下N[CO(NH2)2:100、200、300 mg/kg土]、P(P2O5:50、100、200 mg/kg土)和K(KCl:100、200、300 mg/kg土)处理对香根草修复土壤Cd和锌(Zn)污染效率的影响。结果表明:3种N处理能促进香根草地上部生长,而且显著提高地上部特别是叶的Cd和Zn含量,导致其修复效率成倍显著增加;200 mg/kg K处理显著提高Zn修复效率,但300 mg/kg K和50、200 mg/kg P处理却显著降低Cd、Zn修复效率。因此,为改善香根草对较贫瘠土壤中Cd、Zn污染的修复效率,应对香根草适施N肥,并控制或者不施P、K肥为佳。     

镉在土壤-香根草系统中的迁移及转化特征

以无植物组处理为对照,采用盆栽试验方式探讨不同Cd浓度胁迫条件下香根草根际土壤中重金属Cd的积累、迁移及转化特征。土壤Cd处理设4个浓度梯度,分别为0、2、20、80 mg/kg土壤干重。结果表明:(1)香根草可以显著降低土壤中生物有效态Cd和总Cd含量。(2)香根草各部分Cd积累量随处理浓度的增加和处理时间的延长而增加,90 d时80 mg/kg处理组地上部分和根的Cd积累量分别高达180.42 mg/kg和241.54 mg/kg。(3)各浓度Cd处理下,富集系数随着Cd处理浓度的增加而显著降低,随处理时间的延长而升高。(4)香根草地上部分Cd含量小于根部,各处理转移系数均小于1。随着处理时间的延长,中低浓度处理组的转移系数稍有降低,高浓度处理组的转移系数则显著上升。(5)种植香根草使其根际土中残渣态的Cd转化为生物有效态Cd,提高Cd清除效率。研究结果表明,香根草能够有效地吸收土壤中的Cd,降低土壤中总Cd含量,提高土壤安全性,可作为Cd污染地区植物修复的备选物种。     

根域限制对葡萄根中IAA含量及其代谢相关基因表达的影响

以1年生“玫瑰香”葡萄为试验材料,进行根域限制栽培处理,以传统地栽为对照,研究根域限制对葡萄根系构型、细胞结构、IAA含量及其代谢和根系生长发育相关基因表达丰度的影响,以探讨根域限制栽培影响葡萄根系构型变化的内在机制。结果表明:(1)根域限制处理后,葡萄根系构型发生显著变化,主要表现在根尖处出现大量集群根、不定根持续发生、根系出现螺旋卷曲;根系细胞排列更加疏松,幼根根尖的根冠区更厚,细胞更大、更长;毛细根的内皮层细胞加厚,中柱鞘和皮层细胞更大。(2)根域限制处理显著降低了葡萄根中IAA的含量;在葡萄定植后40、100和205 d时,根系IAA合成关键基因VvYUC6和VvYUC8的表达量变化趋势与IAA含量变化趋势一致,同时根域限制处理诱导IAA合成相关基因VvTAR2、VvYUC2和VvYUC4的表达水平在大部分采样时期显著上调;在定植后70、85、130和205 d时,根域限制导致VvAUX1、VvLAX1等8个IAA运输相关基因的表达水平显著上调,这与根域限制下根系大量发生的时期相吻合。(3)根域限制条件下,葡萄细胞周期调控相关基因VvcycA1、VvcycB1、VvcycD3和Vvcdc2在8月中旬到11月初呈上调表达趋势。研究表明,根域限制下葡萄根系构型、细胞结构以及内源IAA均发生显著变化;根域限制可能通过改变根系中生长素合成和极性运输相关基因的表达丰度,从而影响根系中生长素的合成和运输,进而改变葡萄的根系构型以适应根域限制的栽培环境。     

四种湿地植物在人工湿地的生长特性研究

研究了表面流人工湿地中香根草(Vetiveria zizanioides)、风车草(Cyperus flabelliformis)、芦苇(Phrogmites australis)和水鬼蕉(Hymenocallis littoralis)4种植物的根生物量和生长量、根系分布、地上部分的生长情况.风车草、香根草和水鬼蕉根系及地上部分的生长节律相似,9月或10月前生长较快,以后生长减慢甚至停止;芦苇则不同,7月以前生长缓慢,以后生长加速,冬季也保持较快的生长.全年根生长量和根生物量以水鬼蕉最大,显著高于其它植物(P<0.01),香根草最小,显著低于其它3种植物(P<0.01).香根草的根系垂直向下生长,分布较深,而其它3种植物的根系主要分布在浅层土壤中.风车草分株最多,叶面积指数最大.香根草叶面积指数最小.结果表明,在构建多种植物人工湿地群落时,可以考虑将芦苇与大多数湿地植物搭配以保证湿地全年保持较好的净化效果;水鬼蕉可以作为底层植物,和风车草等生长早、植株较高的植物构建多种湿地群落.     

香根草对土壤中几种重金属离子富集能力的比较研究

用组织培养的香根草无菌苗作为试验材料,进行香根草对Cd、Cr、Pb和Ni四种重金属离子的富集能力比较试验,分别测定了香根草体内的重金属含量、香根草与重金属元素的相关性、香根草对重金属的富集系数和根系滞留率.结果表明：香根草对四种重金属离子都具有较高的富集能力.其中,香根草植物体中元素总含量表现为Ni＞Cr＞Pb＞Cd,在茎叶和根中的分含量,均表现为根＞茎叶;香根草与重金属元素的关系中,Cd的相关性最显著;富集系数与重金属浓度呈负相关,以Ni最为明显;从滞留率的角度来看,以Cr在香根草根系的滞留率最大,但对同一种重金属来说,随浓度的变化,香根草根系对它的滞留率却几乎是恒定的.     

香根草对镉毒害的生理响应——采用傅里叶变换红外光谱法(FTIR)

为阐明香根草(Vetiveria zizanioides)对镉(Cd~(2+))胁迫的耐性机理及其对重金属Cd~(2+)的积累特征,通过水培试验,采用傅里叶变换红外光谱法(FTIR)研究在不同Cd~(2+)浓度处理时香根草根、茎、叶化学组分的变化,同时测定香根草叶Cd~(2+)的亚细胞分布和其重金属Cd~(2+)含量。结果表明,其根组织在2927 cm~(-1)处峰高先下降后上升,表明在低Cd~(2+)(Cd~(2+)3 mg/L)处理条件下香根草分泌的有机酸不断螯合Cd~(2+),造成羧酸O—H的减少,但随着Cd~(2+)含量的升高,其羧酸螯合力变弱,有机酸含量渐渐升高;茎组织在1631 cm~(-1)峰高处先上升后下降,表明在低Cd~(2+)(Cd~(2+)3 mg/L)处理条件下香根草产生氨基酸、多肽和蛋白质等物质,通过渗透调节来增强抗逆性,但随着Cd~(2+)含量的升高,蛋白质二级结构中肽键间氢键的结合力受影响较大。当Cd~(2+)处理浓度为7 mg/L时,香根草生长10 d后,地上部分及根组织富集Cd~(2+)量分别高达212.49 mg/kg和290.59 mg/kg。香根草地上部分的Cd~(2+)含量随Cd~(2+)处理浓度的增加而增加。香根草叶片富集的Cd~(2+)主要分布于细胞质中,其次为细胞壁,而在线粒体和叶绿体中含量最低。     

潜在木质纤维素能源植物香根草的初步研究

对南京试验地种植的香根草[ Vetiveria zizanioides (L.) Nash]叶片的光合特性和主要矿质元素含量以及株高生长速率进行了测定,并对来源于南京试验地和东台滩涂地的香根草叶片中与纤维特性有关的化学组分的含量及水解产物的含量进行了分析和比较.结果显示:香根草叶片的净光合速率(Pn)对光量子通量密度的响应曲线呈单峰型,Pn最高可达15.3 μmol·m-2·s-1,光饱和点为1 528.6 μmol·m-2·s-1;Pn日变化曲线呈明显的双峰型,峰值分别出现在10:00和15:00.叶片中K、N、Ca、P、Mg和S的含量分别为11.2、7.6、4.3、2.7、2.8和1.5mg·g-1.5月份至10月份是香根草的快速生长期,7月份的株高生长速率最高,达42.1 cm.种植于试验地和滩涂地的香根草叶片中纤维素、半纤维素和木质素的含量分别为326.1和321.7 mg·g-1、380.2和369.5 mg·g-1、147.8和154.0 mg·g-1,产地间差异不显著(P＞0.05);苯-乙醇抽提物和灰分的含量分别为59.5和54.1 mg.g-1、81.7和71.7 mg·g-1,产地间差异显著(P＜0.05).种植于试验地和滩涂地的香根草叶片水解产物中葡萄糖和木糖含量均较高,分别为368.3和359.9 mg·g-1、245.7和204.3 mg·g-1;阿拉伯糖、半乳糖和甘露糖含量较低,三者的总含量仅为58.6和55.8 mg·g-1;其中,仅木糖含量产地间具有显著差异(P＜0.05).研究结果表明:香根草具有很强的光合能力及较快的生长速率,叶片中纤维素和半纤维素含量均较高,能够适应边际性土地种植,是一种潜在的优良木质纤维素能源植物.     

香根草油香气成分分析

以广东清远种植的香根草为原料,用浸提法提取香根油,采用色谱-质谱联用仪对香根油化学成分进行检测,从分离的94个化学组分中,鉴定出21个化学成分,主要成分含量53.9%,岩兰草醇等萜烯类化合物质占11.4%.在国内首次发现异丁香酚、香兰素2个香气成分在香根草中的天然存在,对香料的应用与合成具有重要意义.     

Growth and Contaminant Removal Effect of Several Plants in Constructed Wetlands

The aim of the present study is to probe the relation between plant growth and its decontamination effect in constructed wetlands.Four species were studied in the small-scale mono-cuitured constructed wetlands, which were fed with domestic wastewater. Plant growth indexes were correlated with contaminant removal performance of the constructed wetlands. Wetlands planted with Cyperus flabelliformis Rottb. showed the highest growth indexes such as shoot growth, biomass, root activity, root biomass increment, and the highest contaminant removal rates, whereas wetlands planted with Vetiveria zizanioides L. Nash had the lowest growth indexes and the lowest removal rates. Above-ground biomass and total biomass were significantly correlated with ammonia nitrogen removal, and below-ground biomass with soluble reactive phosphorus removal. Photosynthetic rate had higher correlation with nitrogen removal in these species. Root activity and root biomass increment was more correlated with 5 d biochemical oxygen demand removal.Chemical oxygen demand removal had lower correlations with plant growth indexes. All four species had higher removal rates in summer and autumn. The results suggest that the effect of plant growth on contaminant removal in constructed wetlands were different specifically in plants and contaminants.     

香附子块茎试管苗繁殖

以香附子块茎为材料,用组织培养的方法,进行试管苗繁殖研究。结果表明,1/3MS+炉灰渣培养基是块茎生长芽培养的适宜培养基;1/2MS+ZT 0.6 mg/L+NAA 0.1 mg/L是生长芽分化和继代分化繁殖培养的适宜培养基;1/2MS+ABT 2号6 mg/L+IAA 0.4 mg/L是生根和试管苗微型块茎培养的适宜培养基。培养30 d试管苗移栽成活率96%;培养60 d试管苗移栽成活率89.7%;种植的块茎发芽率99.8%;试管苗和微型块茎定植的成活率在99%以上;定植试管苗保持了香附子的植物学特征。     

DNA fingerprinting reveals clonal nature of Vetiveria zizanioides (L.) Nash, Gramineae and sources of potential new germplasm

Random amplified polymorphic DNAs (RAPDs) were used to examine accessions of vetiver ( Vetiveria zizanioides (L.) Nash, Gramineae) from around the world. It appears that only one genotype, 'Sunshine', accounts for almost all the germplasm utilized. Screening of numerous accessions of vetiver revealed only a few nonfertile germlines. Analysis of V . zizanioides and other Vetiveria species, Chrysopogon fulvus (Spreng.) Chiov., C . gryllus (L.) Trin., Sorghum bicolour (L.) Moench., and S . halepense (L.) Pers., revealed that Vetiveria and Chrysopogon are not separable by their RAPDs. This lends support to merging the genus Vetiveria with Chrysopogon . The lack of genetic diversity in this important cultivated plant is a critical factor and additional, suitable germplasm must be collected and introduced into erosion control projects around the world.     

The effect of light on IAA metabolism in different parts of maize seedlings in correlation with their growth

The inhibitory effect of light on the growth of plantscorrelates with a decrease of free IAA content in their tissues andmight be mediated through changes of IAA metabolism. In different partsof Zea mays L. seedlings (roots, mesocotyls and coleoptiles)that respond to light with a different growth rate, the effect of lighton the formation of IAA metabolites was examined in feeding experimentswith ¹⁴C-IAA. In all tissues, IAA was taken up andmetabolised mainly into six compounds, four of them were tentativelyidentified as IAA-1-O-glucose (IAGlc), IAA-myo-inositol, indoleacetamide and IAA-aspartate (IAAsp). IAA was metabolised most slowly inthe roots. In coleoptiles and mesocotyls, IAGlc was the most abundantmetabolite, except for mesocotyls in the light. In roots, a relativelylarge amount of IAA was also metabolised into IAAsp. Light stimulatedthe rate of IAA metabolism in all tissues, but its effect on theconversion of IAA was exceptionally high in mesocotyls. In mesocotyltissue the conversion into IAAsp was greatly stimulated by light.Conversely, the content of IAGlc in mesocotyls was decreased by light.Since light inhibited mesocotyl growth significantly and specifically,it is possible that the high capacity of mesocotyls to synthesise IAAspin the light may have caused a depletion of free IAA, which then led toan inhibition of growth. In mesocotyls from the light-grown plants IAAconjugated into IAGlc was probably used for IAAspbiosynthesis.     

香根草及其伴生种圆果雀稗光合特性比较研究

在人工控制有效光合辐射增强的条件下,测量了香根草与其伴生种圆果雀稗的光合特性,对比分析两者的光合速率、蒸腾速率、水分利用率和气孔导度对有效光合辐射增强的响应。结果表明,伴生种圆果雀稗的光合能力、蒸腾能力等光合特性都比香根草的强,两者的光合速率、蒸腾速率和气孔导度差异极显著(P<0.01),而圆果雀稗的水分利用率却低于香根草,表明香根草可能因在水分利用中占据优势而成为优势种,圆果雀稗仅为伴生种。     

Ontogenetic Changes in the Transport of Indol-3yl-acetic Acid into Maize Roots from the Shoot and Caryopsis

The quantities of endogenous indol-3yl-acetic acid (IAA) in endosperms and scutella of 6-day-old maize seedlings (Zea mays L. cv Giant White Horsetooth) were determined by a fluorimetric method. Endosperms were found to contain 33.4 nanograms IAA per plant, and scutella 7.5 nanograms IAA per plant. [5-³H]IAA applied to endosperms of 6-day-old seedlings moved into the roots and radioactivity accumulated at the apex of the primary root within 8 hours. Two to 7-day-old seedlings were treated simultaneously with [5-³H]IAA in the endosperm and [2-¹⁴C] IAA on the shoot apex. The patterns of transport into the root were found to change during ontogeny: in successively older plants, transport from the shoot into the roots increased relative to transport from the endosperm into the roots. The auxin required for the growth of maize roots could, therefore, partially be contributed by the shoot and endosperm. Ontogenetic changes in the relative importance of these two supplies could be of significance for the integration of growth and development between shoot and root.     

Abscisic Acid induces anaerobiosis tolerance in corn

Flooding is a frequently occurring environmental stress that can severely affect plant growth. This study shows that treatment of corn (Zea mays L.) seedlings with abscisic acid (ABA) increases their tolerance to anoxia 10-fold over untreated seedlings and twofold over seedlings treated with water. Corn seedlings stressed anoxically for 1 day showed only 8% survival when planted in vermiculite. Pretreatment of root tips with 100 micromolar ABA or water for 24 hours before the 1 day anoxic stress increased the anoxic survivability of seedlings to 87% and 47%, respectively. Cycloheximide (5 milligrams per liter), added together with ABA, reduced the seedling survival rate, indicating that the induction of anoxic tolerance in corn by ABA was partly a result of the synthesis of new proteins. ABA treatment induced a threefold increase in alcohol dehydrogenase enzyme activity in corn roots. However, after 24 h of anoxia, alcohol dehydrogenase enzyme activity between the ABA-pretreated and non-pretreated corn roots was not significantly different. The results indicated that ABA played an important role in inducing anoxic tolerance in corn and that the induced tolerance was probably mediated by an increase in alcohol dehydrogenase enzyme activity before the anoxic stress.     

Exogenously applied melatonin stimulates root growth and raises endogenous indoleacetic acid in roots of etiolated seedlings of Brassica juncea

Exogenous melatonin was applied to etiolated seedlings of wild leaf mustard (Brassica juncea) and the effect on root growth and endogenous indole-3-acetic acid (IAA) levels determined. The results show that 0.1microM melatonin has a stimulatory effect on root growth, while 100microM is inhibitory. Furthermore, the stimulatory effect was only detectable in young seedlings (2-d old). Older seedlings (4-d old) appear to be less susceptible to both the stimulatory and the inhibitory effect of melatonin. Exogenous application of 0.1microM melatonin also raised the endogenous levels of free IAA in roots, while higher concentrations had no significant effect. The specific mechanism that causes exogenous melatonin to increase the amount of free IAA in roots, paired with a stimulation of root growth, remains to be uncovered.