Seasonal changes of endogenous ABA and cytokininsin environmental adaptation of differentecotypes of reed plants

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Genotypic Differences in Effects of Cadmium Exposure on Plant Growth and Contents of Cadmium and Elements in 14 Cultivars of Bai Cai

Abstract

Fourteen cultivars of bai cai (Brassica campestris L. ssp. chinensis var. communis) were grown in the nutrient solutions containing 0–0.5 μg mL^?1 of cadmium (Cd) to investigate genotypic differences in the effects of Cd exposure on the plant growth and uptake and distribution of Cd in bai cai plants. The Cd exposure significantly reduced the dry and fresh weights of roots and shoots, the dry weight ratio of shoot/root (S/R), total biomass, and chlorophyll content (SPAD value). Cd concentrations in bai cai ranged from 13.3 to 74.9 μg g^?1 DW in shoots and from 163.1 to 574.7 μg g^?1 DW in roots under Cd exposure, respectively. The considerable genotypic differences of Cd concentrations and accumulations in both shoots and roots were observed among 14 bai cai cultivars. Moreover, Cd mainly accumulated in the roots. Cd also caused the changes of uptake and distribution of nutrients in bai cai and under the influence of cadmium, the concentration of potassium (K) decreased in shoot and increased in root. However, the concentrations of magnesium (Mg), phosphorus (P), manganese (Mn), boron (B), and iron (Fe) increased in shoots and decreased in roots. In addition, Cd exposure resulted in an increase in calcium (Ca), sulphur (S), and zinc (Zn) concentrations in both shoots and roots but had no significant effects on the whole uptake of the examined mineral nutrients except for S.     

Effect of some heavy metals and soil humic substances on the phytochelatin production in wild plants from silver mine areas of Guanajuato, Mexico

Phytochelatins (PCs) were determined in the wild plants, focusing on their relationship with the levels of heavy metals and humic substances (HS) in soil. Ricinus communis and Tithonia diversifolia were collected from several sites in Guanajuato city (Mexico), which had long been the silver and gold mining center. The analysis of PCs in root extracts was carried out by liquid chromatography (derivatization with monobromobimane). Total Ag, Cd, Cu and Pb in plant roots and in soil samples, as well as soil HS were determined. The association of metals with HS in soils was evaluated by size exclusion chromatography (SEC) with UV and ICP-MS detection. The results obtained revealed the induction of PCs in R. communis but not in T. diversifolia. The levels of Cd and Pb in plant roots presented strong positive correlation with PC-2 (r = 0.9395, p = 0.005; r = 0.9573, p = 0.003, respectively), indicating that these two metals promote PCs induction in R. communis. On the other hand, the inverse correlation was found between soil HS and metal levels in roots of R. communis (Cu > Pb > Cd > Ag), in agreement with the decreasing affinity of these metals to HS. Importantly, the inverse correlation between soil HS and plant PC-2 was observed (r = −0.7825, p = 0.066). These results suggest that metals strongly bound to HS could be less bioavailable to plants, which in turn would limit their role in the induction of PCs. Indeed, the SEC elution profiles showed Pb but not Cd association with HS and the correlation between metal in soil and PC-2 in plant was statistically significant only for Cd (r = 0.7857, p = 0.064). Based on these results it is proposed that the role of heavy metals in PCs induction would depend on their uptake by R. communis, which apparently is controlled by the association of metals with soil HS. This work provides further evidence on the role of environmental conditions in the accumulation of heavy metals and phytochelatin production in plants.     

湖北铜绿山古铜矿冶炼渣植被与优势植物的重金属含量研究

对已废弃3000余年的湖北铜绿山古冶炼渣堆进行了植被和土壤调查。化学分析表明,冶炼渣的含Cu量极高,总量和有效态的Cu质量分数ω（Cu)分别为7789和538mg kg^-1。Cu的毒是影响铜绿山植物自然定居的限制因子。铜绿山现已形成了以草本植物为主体的良好植被,本次调查共记录有高等植物28种,隶属25属15科。优势种包括海洲香薷、蝇子草、鸭跖草、头花蓼、滨蒿、白茅和狗尾草等7种植物。植物分布与土壤中Cu含量有一定的相关性,鸭跖草分布区土壤中的Cu含量最高,白茅分布区土壤中的Cu含量最低,而其它5种植物的分布区含Cu范围较广,平均在7000mg kg^-1左右。除白茅、狗尾草和滨蒿外,其它4种优势植物都有一定的Cu指示作用,尤其以这些植物的单优群落或者是它们的集合具有更高的指示价值。本文首次报道鸭跖草是Cu的超富集植物,Cu^2 在地上部分（DW）和根部（DW）的质量分数（ω）分别为1034和1224mg kg^-1。而早期报道Cu超富集植物的海洲香薷则证明不是Cu超富集植物。综合植物分布区土壤中的Cu含量和植物体的Cu含量,认为铜绿山海洲香薷、鸭跖草、蝇子草、头花蓼、滨蒿种群都是Cu耐性植物,可用于富Cu土壤如矿业废弃地的植被重建,而超富集植物鸭跖草可用于Cu污染土壤的植物修复。表4参22     

蓖麻对重金属锌的耐性与吸收积累研究

采用60d温室盆栽试验研究蓖麻对土壤中重金属Zn污染的耐性和积累效应。通过不同Zn浓度下蓖麻植株生长状况和叶绿素变化及蓖麻根、茎、叶各部分对Zn的积累量的研究,发现蓖麻对土壤Zn污染有较高的耐性,分别在叶、茎、根中对Zn有不同程度的积累,随着土壤Zn浓度的增加积累量也增大。说明蓖麻适合较高程度Zn污染土壤的修复。     

铜、镉及其交互作用对泡泡草细胞超微结构的影响

为了解铜、镉对泡泡草根、茎、叶细胞亚显微结构的毒害及作用位点 ,以期为进一步研究鸭跖草属植物的耐重金属机理提供理论基础 ,本文通过透射电子显微技术研究了 75 μmol·L-1铜和 5 0 μmol·L-1镉及其交互污染对泡泡草根、茎、叶细胞超微结构的影响和铜、镉在细胞中的分布 .结果表明 :75 μmol·L-1铜和 5 0 μmol·L-1镉均对泡泡草根细胞造成明显损伤 .铜使根细胞产生质壁分离、细胞质浓缩、部分细胞空泡化 ,使线粒体脊突消失、结构模糊、外膜破坏 ;镉使根细胞空泡化 ,并在部分空泡化的细胞里产生大小不等的颗粒状物 ;铜、镉交互污染使根细胞受害程度加深 ,并兼有两者的受害症状特征 :线粒体结构彻底破坏、空泡化细胞里的颗粒物更大电子密度更高、质壁分离现象更普遍、质膜上的颗粒物沉淀更大 .铜、镉及其交互污染使泡泡草茎细胞产生质壁分离 ,对叶细胞无明显伤害 .所以铜、镉及其交互作用在试验浓度下 ,对泡泡草各器官的损伤程度为根 >茎 >叶 .     

鸭跖草(Commelina communis)对铜的耐性和积累研究

采用溶液培养法 ,研究了生长于铜矿山上的鸭跖草 (Commelinacommunis)和生长于正常土壤中的鸭跖草对Cu的耐性和吸收积累的差异 .实验显示 ,随着溶液中Cu浓度的增加 ,生长于矿山的鸭跖草的干重、生长速率均增加 ,而生长于非矿山的鸭跖草的干重、生长速率降低 ,2种鸭跖草体内含Cu总量和根、茎、叶Cu含量均随着培养液Cu浓度的增加而增加 ,两者呈明显正相关 .在相同Cu处理浓度下 ,矿山的鸭跖草体内Cu的含量高于非矿山的鸭跖草体内Cu含量 ;Cu在 2种鸭跖草体内各器官的分布一致 ,均为根 >茎 >叶 .在高Cu浓度处理下 ,矿山的鸭跖草地上部Cu含量 根Cu含量的比值不超过 1,但随着溶液中Cu浓度的增加而增加 ;而非矿山的鸭跖草除去对照处理 ( 0 2 5μmol L)外 ,地上部Cu 根Cu比值为 40— 2 40 μmol L ,随着溶液中Cu浓度的增加而增加 ,其比值超过了 1,但到了 3 2 0 μmol L时开始急剧下降 .结果表明矿山的鸭跖草已形成对Cu的耐性     

芦苇化感组分对斜生栅藻Scenedesmus obliquus生长特性的影响

水华或赤潮现象是备受关注的环境问题之一。利用植物化感作用抑制藻类生长作为一种新型的生物抑藻技术在近年来开始受到研究者的重视,并取得了一定的研究成果。文章研究了从芦苇PhragmitiscommunisTrin中分离得到的化感组分对斜生栅藻Scenedesmusobliquus生长特性的影响。在藻类的对数生长期向培养液中投加不同浓度的化感组分,分别测定并观察了培养期间受试藻种藻密度、藻细胞结构和群体形态的变化。结果表明,该化感组分在培养初期对斜生栅藻藻密度的增长具有明显的抑制作用,半效应质量浓度(EC50,4d)值为0.45mg·L-1,但在培养6d后,出现促进作用,且随投加浓度的增加而增强。斜生栅藻生长受到抑制期间,藻细胞形态变大,投加0.5mg·L-1化感组分时,藻细胞平均宽度是对照组的2倍。TEM观察观察结果表明藻细胞亚显微结构受到破坏。另外,EMA提高了斜生栅藻的沉降性和吸附性。     

Assessment of the allelopathic effect of leaf and seed extracts of Canavalia ensiformis as postemergent bioherbicides: A green alternative for sustainable agriculture

The herbicidal potential of aqueous extracts prepared from leaves and seeds of Canavalia ensiformis was tested by applying them postemergence to the crop weeds Ipomoea grandifolia and Commelina benghalensis. Considering the possible objective of using this bioherbicide on soybean fields, the extracts were also tested for deleterious effects on both transgenic and conventional soybean (Glycine max). In addition, the concentrations of four phenolic compounds and alkaloids with allelopathic properties in these extracts were estimated by high-performance liquid chromatography. The seed extract at concentrations of 25 g L^?1 and 50 g L^?1 was the most efficient postemergent bioherbicide. By applying these extracts, the development of the weed seed was progressively hindered until no recovery was observed. The application of 3.5 mL of crude extract on a plant that takes 30 days after germination of the seed to develop is sufficient for full control of the species within 5 days. Since both Ipomoea grandifolia and Commelina benghalensis are broadleaf dicotyledons, it is possible that other species with these characteristics can also be controlled or suffer the same effects under the action of the seed extract, if the same volume and mode of application are used. The selectivity of the treatments with 25 g L^?1 and 50 g L^?1 was assessed on transgenic and conventional cultivars. The treatments did not visibly affect the soybean cultivars, which developed normally during the observation period that continued up to 15 days after the death of the weeds.     

北固山芦苇湿地土壤对铜铬（Ⅵ）的吸附研究

北固山芦苇(Phragmites communis)湿地是长江中下游典型湿地类型之一,沿江工业化和城市化的快速发展使其面临严重的重金属污染威胁。然而,目前有关湿地重金属污染的吸附尤其竞争吸附的研究还少见报道。该文以北固山芦苇湿地为对象,采用平衡法对Cu2 、Cr(VI)在湿地土壤中的吸附行为进行了研究,旨在服务于湿地重金属污染的修复与生物学效应评价。研究结果表明:(1)湿地土壤吸附Cu2 、Cr(VI)的过程符合Langmuir等温模型;二者的表观最大吸附量(xm)分别为36.10g·kg-1和178.57g·kg-1(初始液质量浓度c0<500g·m-3),平均吸附率分别达到99.82%±0.35%和93.17%±1.14%。(2)无论单一吸附或竞争吸附体系,当c0(Cu2 )>250g·m-3时,平衡液Cu2 质量浓度快速升高。(3)c0相等的Cu2 、Cr(VI)竞争吸附体系中,平衡液中Cu2 质量浓度升高,Cr(VI)质量浓度下降;但xm的变化表现为Cu2 增加了2.7倍,Cr(VI)降低了2.4倍。(4)Cu2 、Cr(VI)的竞争吸附体系中,随Cr(VI)初始液质量浓度的变化(c0(Cu2 )恒定),Cr(VI)的xm下降至其单一吸附时的6%;而随Cu2 初始液质量浓度的变化(c0(Cr(VI))恒定),Cu2 的xm仅为其单一吸附时的1/3。