赤泥颗粒对韭菜吸收污染土壤中铅锌的抑制效应研究

采用盆栽试验方法,通过添加赤泥颗粒修复铅锌污染土壤,按照火焰原子吸收分光光度法测定不同时期种植韭菜的土壤中重金属的含量,分析赤泥颗粒对土壤中重金属的钝化行为与机理,确定赤泥颗粒对土壤修复和对韭菜生长促进最佳的添加量。结果表明,赤泥颗粒能缓释OH-,促进重金属铅、锌化学形态转化和抑制生物吸收。铅、锌污染土壤修复的最佳赤泥颗粒添加量为5%,此时,土壤中铅、锌的生物有效态含量在修复期内分别降低了41.03%、26.55%;结合铅锌污染土壤修复与韭菜生长影响,初步确定赤泥颗粒的最佳施用量为1%,此时,土壤中铅、锌的生物有效态含量在修复期内分别降低了24.81%、15.9%;赤泥颗粒对铅锌污染土壤的修复能力大小为铅〉锌。     

铀尾矿库中重金属元素的生态迁移风险研究

用ICP-AES方法检测了铀尾矿库内人工修复植被生境与自然修复植被生境覆土中重金属元素镉、铅、铜、锌、锰、铬、镍的含量,同时检测了自然修复植被生境中先锋植物加拿大蓬与鸡眼草茎叶、植食性昆虫蝗虫、蝽与捕食性节肢动物螳螂、蜘蛛体内的镉、铅、铜、锌、锰、铬、镍的含量.结果显示,人工栽植蜈蚣草覆土中镉、铜、锌、锰、铬的含量均显著高于对照土壤、人工栽植苍耳、商陆与自然修复植被覆土中的含量,其中锰、镉、锌与铬的含量分别是对照土壤中的7.6,2.8,1.4,1.8倍.自然修复植被生境覆土中铅的含量显著高于人工栽植苍耳、商陆生境、人工栽植蜈蚣草生境覆土与对照土壤,其锰含量约为对照土壤的2倍.人工栽植苍耳、商陆生境中覆土中锰,铬含量显著高于对照.加拿大蓬与鸡眼草茎、叶中均含有被检测的7种重金属,加拿大蓬茎与鸡眼草茎叶对Zn、鸡眼草叶对Mn具有明显富集作用.蝗虫对铜与铬有一定的富集作用,对镉、铅、锌、锰与镍未表现富集作用.蝽对镉、铅、铜、锌、锰、铬与镍均具有较强的生物放大作用,其中蝽体内Cr的含量是土壤含量的191.26倍.蜘蛛与螳螂体内的重金属含量很高,对7种被检测重金属均具有非常明显的生物放大作用.蜘蛛体内各种重金属的含量显著高于螳螂体内的含量,蜘蛛体内Cd含量是其环境土壤中含量的693.13倍.研究表明,被检测的7种重金属均能从尾矿沙向上层覆土中迁移.且均能沿着"土壤-生产者-初级消费者一次级消费者"生态链迁移.     

Pb(铅)富集植物品种的筛选

为选择和筛选富集重金属或对重金属具有耐性的植物，为利用植物修复重金属污染土壤提供参考，该研究通过温室砂培和土培的方法，对生长于铅锌尾矿区的36种植物进行了筛选，以叶片叶绿素含量、株高、植株含Pb量为Pb富集植物的筛选指标。同时满足下列条件，即：植物叶片中叶绿素含量：处理/对照＞0.90；株高：处理/对照≥1.00和含Pb量＞500 mg/kg的植物可以用做进一步的耐性试验。按以上标准筛选出6个富集Pb的植物品种，分别是香根草、绿叶苋菜、裂叶荆芥、羽叶鬼针草、紫穗槐和苍耳。     

铜矿区重金属污染分异规律初步研究

针对江西德兴铜矿、安徽铜陵铜矿和江苏九华铜矿的矿区典型污染土壤现状进行了初步研究，分析了铜矿区环境现状，提出了一些可能对策的建议。研究发现，3个矿区典型污染土壤各自表现出不同的污染状况。三个铜矿尾矿砂中铜含量超标，其高低次序为德兴铜矿＞铜陵铜矿＞九华铜矿，而锌含量顺序依次为铜陵铜矿＞九华铜矿＞德兴铜矿。矿区周围土壤以铜污染为主，锌有部分超标情况发生。同时，在矿区典型土壤生长的作物中，铜、铅、锌、镉都有超标的情况，部分作物重金属含量超过食品卫生标准达10－20倍之多。被调查的多种植物中也存在重金属含量过高的结果。     

5个蓖麻品种对土壤中镉富集的差异

为了评价能源作物蓖麻对污染农田中重金属镉(Cd)的富集修复能力,本研究以5个蓖麻品种为试验材料,通过大田试验对比了不同蓖麻品种在Cd污染农田中的生长情况、对Cd的富集和转运能力以及对Cd污染土壤的修复能力。结果表明,5个蓖麻品种在Cd污染农田中生长良好,其中滇蓖2号的株高、茎粗及单株产量显著高于其他品种,分别为440.78 cm、5.04 cm以及338.85 g。5个蓖麻品种根、茎、叶及果实的Cd含量、Cd积累量和富集系数均存在显著差异,其中经作蓖麻1号根、茎和果实的Cd含量最高,分别为1.40、1.14和0.33 mg·kg^-1。污染修复能力方面,滇蓖2号Cd的积累量达3.38 mg/株,提取率为5.34%,显著高于其他品种。经作蓖麻1号尽管富集能力最强,但由于其生物量最小,其Cd积累量及年提取效率均最低。综上可知,蓖麻对土壤中重金属Cd的富集能力较强,可用于修复云南个旧地区的Cd污染土壤,且种植滇蓖2号可以获得较好的修复效果。本研究结果为云南Cd污染土壤治理提供了理论基础和参考依据。     

南京栖霞重金属污染区植物富集重金属效应及其根际微生物特性分析

以南京栖霞重金属污染区5种植物及其根际土壤为研究对象,对植物富集重金属特征以及重金属含量与根际土壤细菌数量、土壤酶活性等的相关性进行了调查分析。结果发现,植物根际重金属污染物以Zn和Cd为主;重金属污染地区的植物有较强的吸收重金属能力,龙葵和茼草具备了超积累植物的基本特征;植物根际细菌和Pb抗性细菌的数量达到了107CFU g-1土;根际土壤酶活性未受到重金属的毒害或受到的毒害很小;植物体中重金属含量与土壤重金属含量及其存在状态、土壤酶、土壤重金属抗性细菌有显著的正相关性。根际土壤细菌尤其是具有重金属抗性的活性细菌可能会促进土壤重金属的活化,由此促进植物体对重金属的吸收和转运。     

油葵和苦荬菜根际土壤中镉和锌的活化机制及修复潜力比较

  目的  研究油葵和苦荬菜根际土壤固、液相对镉（Cd）和锌（Zn）的活化机制,比较两种植物在轻、中度复合污染农田的修复潜力。  方法  通过大田试验种油葵和苦荬菜,测定成熟期土壤的pH值、有机酸、重金属总量及其生物有效性;测定土壤溶液中的溶解性有机质（DOM）、主要离子、水溶态重金属及其形态分布;测定植物各部位中重金属的浓度及形态,通过计算重金属在植物中的富集系数（BCF）和转运系数（TF）,比较两种植物对土壤重金属污染的修复潜力。  结果  油葵和苦荬菜根系分泌的低分子有机酸均使根际土壤pH值下降明显,显著低于非根际土壤（P < 0.05）;苦荬菜根际土中低分子有机酸及DOM的浓度显著高于油葵根际土（P < 0.05）。两种植物根际土壤溶液中的Cd以离子态和DOM结合态为主,Zn以离子态为主;两种植物根际土壤中有效态的Cd差异不显著,油葵根际有效态Zn显著高于苦荬菜;两种植物根际土壤的Zn和Cd有效态与土壤溶液中Cd-DOM和Zn-DOM呈显著相关。苦荬菜根对重金属的富集能力较强,但油葵地上部分能吸收转运更多的Cd和Zn,并在叶中以毒性较低的不溶性磷酸盐结合态和草酸结合态富集。  结论  两种植物根际分泌的有机酸可以增加根际土壤中的Cd-DOM和Zn-DOM的浓度,提高土壤中的Cd和Zn的有效性,苦荬菜根际对重金属有较强的活化能力,但油葵地上部分对Cd和Zn的吸收转运能力更强。两种植物都具有较强的土壤重金属修复潜力,但从经济角度出发,油葵更适合现阶段我国农田重金属污染的修复。     

吊兰生长对锌污染土壤微生物数量及土壤酶活性的影响

选用观赏植物吊兰进行盆栽试验,通过测定吊兰根际、非根际以及未栽培吊兰的空白组土壤微生物数量、土壤酶活性及化学性质,研究吊兰对重金属锌污染土壤的修复作用.结果表明:土壤微生物数量、土壤酶活性、有机质含量及土壤呼吸作用强度均表现为吊兰根际组＞吊兰非根际组＞未栽培吊兰的空白组.而土壤锌总量、pH、电导率及氧化还原电位均表现为未栽培吊兰的空白组＞吊兰非根际组＞吊兰根际组.土壤锌浓度为200mg/kg时,细菌、真菌的数量最多,土壤呼吸作用强度、脲酶及磷酸酶的活性也达到最高值;土壤锌浓度为500 mg/kg时,放线菌数量最多,且蔗糖酶活性达到顶峰.三类微生物对锌的敏感性顺序为真菌＞放线菌＞细菌.土壤酶对重金属锌的敏感性顺序为蔗糖酶＞脲酶＞磷酸酶＞过氧化氢酶.通过微生物数量与土壤酶活性的双变量相关性分析可知,放线菌的变化对土壤酶的影响最大,其次是真菌,细菌影响最小.吊兰生长能够有效改善土壤环境,在重金属锌污染修复方面有广阔的应用前景.     

长期施肥对作物铜、铅、铬、镉含量的影响

为了弄清长期施肥对作物重金属含量的影响,利用长期定位试验,研究了不同施肥措施对小麦、水稻铜、铅、铬、镉含量的影响,并对其籽粒中重金属的含量进行了安全性评价,结果表明,长期施肥影响了小麦和水稻中铜、铅、铬、镉的含量,小麦、水稻籽粒中铅、铬、镉含量长期施肥处理均明显增加,其中铅、铬含量都超过了国家食品卫生标准,施磷处理水稻籽粒中镉含量也严重超标.小麦、水稻对土壤铜和铬的富集能力较强,对铅、镉的富集能力较小;小麦对铬和铜的富集能力大于水稻,其富集系数分别是水稻的2.5倍和2.8倍.而水稻对镉的富集能力大于小麦,富集系数是小麦的2.1倍.     

林芝河谷地区典型农田土壤主要性质及重金属状况初探

选择西藏林芝河谷地区代表性麦田及蔬菜大棚土壤,对其主要土壤肥力指标、重金属浓度及相应小麦及蔬菜样的重金属浓度进行了测定。结果发现:该区耕地土壤有机质、全氮、碱解氮处于中等及较缺乏水平,全磷、全钾、有效锌处于缺乏水平,速效磷、钾及有效铜处于较丰富水平;研究区土壤及作物铜、锌、镉浓度均未超出我国土壤环境质量标准,但农业生产活动造成了表层土壤铜、锌、镉的富集。研究区耕地应注重有机肥、化肥及微量元素的合理施用,同时注意农业生产活动造成的土壤酸化、重金属富集问题并加以监控,以促进该区农业的可持续发展。     

Bragg soybeans grown on a southern coastal plains soil i. dry matter distribution,nodal growth analysis,and sample variability

Yields of soybean [Glycine max (L.) Merr.] are affected by the manner in which available resources are partitioned into component plant parts. Little is known about these partitioning processes and much of what has been reported describes indeterminate cultivars or comes from other than field studies. A field investigation was conducted, therefore, on a Goldsboro loamy sand (Aquic Paleudult) to characterize in detail the growth and development of a determinate soybean cultivar ‘Bragg’. Soybean were grown in well watered field plots in four replications from each of which 4 nested samples of 0.3 m² each were combined at each sampling. Leaf area, dry matter production, internode length, and sample variability were determined nodally at 10‐ to 14‐day intervals from 7 July to 17 October. Plant components at each node were separated into stems, leaf blades, pods, and petioles. Primary and secondary branches were combined in the petiole fraction.

Maximum above ground plant dry weight achieved was 1027 g/m² and maximum combined nodal dry weight was 92 g/m² (at node 8), both occurring at the R7 growth stage. Canopy dry weight distribution over time was unique for each plant part. Growth analyses showed that RGR, NAR, LAR, and LWR declined with plant age at a rate that could be described with either linear or exponential models. A maximum CGR of 16.24 g/m²/day occurred at mid‐podfill and declined thereafter due to maturity. Leaf area per node peaked between nodes 7 and 12, decreasing uniformly toward the top of the canopy. Maximum nodal LAI was 0.79 at node 7 on 31 August.

Distribution of dry weight among parts varied with plant age and node position. Maximum dry weights of stems (276 g/m²), petioles (253 g/m²), and leaves (263 g/m²) were found during mid‐podfill. During mid‐August, the dry weights of the stems, petioles, and leaves were similar and approximately 250 g/m². Stem dry weights had the lowest coefficients of variation of all plant fractions once maximum dry weight was achieved. Internode length varied along the stem with the maximum at node 12. By bloom, expansion of the internodes lower than 12 had ceased; expansion of the eight higher internodes ceased three weeks later. During vegetative growth, the ratio of stem internodal dry weight to internodal length had peak values at the lowest and highest internodes. During reproductive growth, the ratio decreased linearly with internode number. Coefficients of variation (CV) for the combined weight of plant parts, and for stems, petioles, leaves, and pods were relatively constant during the season and were 24.8, 23.4, 38.2, 25.5, and 26.8%, respectively. The CV's for the combined weight of plant parts were somewhat higher at the lowest and uppermost nodes. This variability resulted from the abscission of petioles and leaves in the lower nodes and the initiation of leaves, petioles, and pods in the upper nodes where rapid growth and development was occurring. Time from node initiation to achievement of lowest stable CV was determined for each node and plant part. Plant node position and morphological part with the lowest CV was identified for each sampling date (and growth stage).     

Rice (Oryza sativa L.) plant protection using dual biological control and plant growth-promoting agents: Current scenarios and future prospects

Various microorganisms live in association with different parts of plants and can be harmful, neutral, or beneficial to plant health. Some microbial inhabitants of plants can control plant diseases by contesting with, predating on, or antagonizing plant pathogens and by inducing systems for plant defense. A range of methods, including plant growth-promoting microorganisms(PGPMs) as biological control agents(BCAs)(BCA-PGPMs) are used for the biological management and control of plant pathogens. S...     

The influence of carbon dioxide on the growth,pigment, protein,carbohydrate, and mineral status of lettuce

Lettuce plants (Lactuca sativa L. cv. Grand Rapids) were grown in nutrient solution in controlled environment plant growth chambers to characterize certain qualitative responses to above ambient levels of CO₂. Increased plant material produced under high CO₂ levels did not differ nutritionally from plants grown under ambient levels. No differences were found in chloroplast pigment content, protein content, or in carbohydrate content on a weight basis. Sequential harvests did reveal, however, that there is a greater accumulation of carbohydrate, under high CO₂ conditions, prior to an increased growth rate as the plants reach maturity.     

Optimum N and P rates for greenhouse production of vegetative coleus using constant liquid feed

Many new coleus (C. hybridus cv.) cultivars are vegetatively propagated and require different fertilization practices from seed propagated cultivars. Two experiments were conducted to evaluate growth responses of Henna, Indian Summer, Mint Mocha, New Orleans Red, Red Head, and Trusty Rusty to 0, 70, 140, 280 and 420 mg·L^?1 nitrogen (N), and Henna, Mint Mocha, Red Head, and Trusty Rusty to 0, 6.2, 12.4, 24.8, or 49.6 mg·L^?1 phosphorus (P) to determine optimum constant liquid feed rates to produce marketable size plants from rooted cuttings. Positive growth responses in terms of biomass were found with increasing N rates but not P rates. For medium-sized cultivars such as Henna, Indian Summer, and New Orleans Red, quadratic responses were found in aboveground biomass, and N at 280 mg·L^?1 resulted in similar plant size and dry weight as those fertilized at 140 and 420 mg·L^?1 N. For large-sized cultivars such as Mint Mocha, Red Head and Trusty Rusty, plant dry weight responded linearly within the N range tested and were greatest at 420 mg·L^?1. However, plant visual quality was negatively affected by N rates at 280 and 420 mg·L^?1 in that, leaf color became less intense at these high N rates. Plants fertilized at 70 mg·L^?1 were smaller than those fertilized at 140 mg·L^?1, however, they received similar visual quality ratings because of more intense leaf color. Therefore, N at 70 to 140 mg·L^?1 can be used to grow most vegetative coleus for similar marketable quality. Mint Mocha and Henna were the only cultivars responded to P treatments that, 12.4 mg·L^?1 P rate resulted in greater biomass than the no-P control. All other cultivars had no response to supplemental P except a linear response in tissue P%. Therefore, supplemental P is not required during the 8 week production period when there is an initial P charge in the substrate. We found that substrate pH decreases with higher P rates, therefore supplemental P fertilizer can be used for adjusting pH. Both N and P rates found optimum in this study are lower than current industry practices (N at 150 to 250 mg·L^?1 and P at 24 mg·L^?1) and can significantly lower production cost and potential leaching of excessive nutrient into waterway. Nutrient treatments in further study on postharvest performance of vegetative coleus will be selected based on this study.     

The diagnosis of nitrogen deficiency in wheat by means of a critical nitrate concentration in stem bases

Abstract

Stem bases from wheat plants in a glasshouse pot experiment conducted under varying nitrogen and two water regimes, were analysed for nitrate (NO₃) concentration. The concentration of NO₃ at three stages of growth i.e. tillering, jointing and anthesis were related both to rates of applied nitrogen and to shoot dry matter yield at time of sampling. Plotted against rate of increasing nitrogen application, the response curve of NO₃ concentration in wheat stem bases was sigmoidal. The level of nitrogen application at which NO₃ began to accumulate in the plants was the supply at which plants reached maximum dry matter yield. The concentration of NO₃ at which plant yield was 90% of maximum dry matter was taken as the critical level. This concentration was around 1000 ppm NO₃‐N at all stages. Compared with plants supplied with unlimited water, plants under moderate water stress accumulated relatively more NO₃ but had a similar critical NO₃ concentration.

Maximum grain yield was obtained from plants which stayed above the critical level throughout the growing season.     

Fruit Quality and Nitrogen,Potassium, and Calcium Content of Apple as Influenced by Nitrate: Ammonium Ratios in Tree Nutrition

Evaluations of fruit quality and nitrogen, potassium, and calcium concentration of apple (Malus domestica Borkh. cvs. Gala and Golab) grown with five treatments of NO₃^?:NH₄⁺ ratios were made in pot culture. The concentrations of NO₃^?:NH₄⁺ ratios were 2.5:0.1, 6:1, 6:0.7, 6:0.5, 6:0.3 meq L^?1. Fruit size, percent dry matter, total dissolved solids, total acidity, or juice pH was not affected by increased ammonium in the ratio. Firmness decreased as the proportion of NH₄⁺ increased. Gala and Golab differed in some of these parameters. Concentrations of N and K increased as NH₄⁺ increased, whereas Ca had no trend or decreased. Generally, the treatment of 2.5:0.1 produced fruits with lower N but higher K and Ca concentrations than the other treatments. This research showed that some parameters such as fruit weight, length, and diameter, juice pH, and dry matter were not affected significantly by NH₄⁺ concentration whereas composition was affected.     

Nutrient deficiencies and toxicities in plants: Nitrogen

Current literature review and discussion of the N status of plants as related to their growth and yield and quality of produced product.     

Rapid and simple leaf tissue test for nitrate

Abstract

A simple and rapid procedure for the determination of nitrate in fresh leaf tissue, suitable for use by relatively untrained operators is presented. The method requires only 4 reagents and can be carried out in less than 20 min from start to finish. A 400 mg sample of fresh leaf tissue is macerated briefly with 5 drops of 10 N sulphuric acid, diluted with 10.0 ml of water and filtered. Nitrate‐N is estimated on an aliquot of the filtered extract by reducing the nitrate to nitrite by shaking with powdered zinc in ammonium hydroxide solution for 3 min. The reduced mixture is allowed to settle (5 min) and an aliquot is withdrawn through a cotton‐wool plug thus removing any particles of the zinc. The filtered aliquot is then reacted with a single colour reagent to yield a pink azo‐dye, the intensity of which is directly proportional to the amount of nitrate.

The method was found to have a coefficient of variation of about 4%. When compared with the phenoldisulphonic acid method for nitrate, on aliquots of the some plant extract, it yielded values which were on average 94.6% of those obtained with the former method. The coefficient of variation between the methods was 7%.     

植物营养生物学研究方向探讨

植物营养生物学是重点研究植物活化、吸收、转运与利用养分的生理、分子及遗传机制的科学。在过去的30年,我国植物营养生物学研究取得了长足的发展,但从国家自然科学基金资助情况分析,与相关学科相比,近10多年来植物营养生物学总体研究力量相对薄弱,缺乏新一代领军人才。一些研究更接近于“纯”植物生物学,与植物营养应用研究出现脱节,对农业绿色发展及化肥产业升级的支撑不够。植物营养生物学研究者应该重视与作物育种、耕作栽培、生态环境、植物保护及化肥产业的合作,跟踪这些领域的研究现状及生产中面临的技术需求,围绕这些领域的技术“瓶颈”开展植物营养基础研究,在提供解决途径的同时创新植物营养生物学机理,从而丰富植物营养学理论。在研究内容上,建议重视控制养分响应度的生理与遗传机制,养分信号与环境信号互作,养分×土壤×管理互作及其对根系生长的影响,养分供应与抗生物胁迫,高产高效的植物营养生理学基础,特种作物的营养机理,化肥产品升级的生物学途径等方向的研究。     

A simplified method for determining acetic acid soluble phosphorus in plant tissue

Abstract

The proposed procedure greatly simplifies the determination of 2% HOAc soluble P in plant tissue. Extraction with Darco G 60 eliminates the need for the H₂O₂ oxidation of the extract. The use of vanadomolybdic acid as the chromogen results in a high degree of color stability eliminating the need for careful timing of the period between color development and transmission readings.