旱柳无性系在富营养化水体中的生长及去除氮磷能力

【目的】比较旱柳无性系的生长以及对水体中氮、磷去除效果,以筛选出处理富营养化水体效果较好的无性系。【方法】利用8个旱柳无性系在富营养化水体中进行静态培养试验,研究各无性系的形态特征、叶绿素相对含量指数、对营养元素的吸收以及对废水中氮、磷的去除效率。【结果】旱柳无性系在整个试验期间生长良好,无死亡现象。各无性系最终生物量、苗高和相对生长率有显著差异,其中,旱59和旱97整体表现最好。旱柳无性系对富营养化水体中氮、磷吸收较好,地上部分营养元素浓度较高。旱柳各无性系对总氮、氨氮和硝态氮的去除效率分别为87.17%96.94%、90.35%99.33%和66.66%88.19%,对总磷的去除效率为76.59%83.15%,无性系旱13总的去除效率最高。【结论】参试8个旱柳无性系均能在富营养化水体中正常生长,但各无性系在富营养化水体中的生长响应有较大差异。综合多个指标并结合长期野外试验观察,旱13、旱59、旱97是适合修复富营养化水体的较好材料。     

Genetic improvement for root growth angle to enhance crop production

The root system is an essential organ for taking up water and nutrients and anchoring shoots to the ground. On the other hand, the root system has rarely been regarded as breeding target, possibly because it is more laborious and time-consuming to evaluate roots (which require excavation) in a large number of plants than aboveground tissues. The root growth angle (RGA), which determines the direction of root elongation in the soil, affects the area in which roots capture water and nutrients. In this review, we describe the significance of RGA as a potential trait to improve crop production, and the physiological and molecular mechanisms that regulate RGA. We discuss the prospects for breeding to improve RGA based on current knowledge of quantitative trait loci for RGA in rice.     

丛枝菌根真菌对万寿菊生长、吸镉及生理特性的影响

A pot experiment was carried out to study the effects of three arbuscular mycorrhizal fungi (AMF), including Glomus intraradices, Glomus constrictum and Glomus mosseae, on the growth, root colonization and Cd accumulation of marigold (Tagetes erecta L.) at Cd addition levels of 0, 5 and 50 mg kg-1 in soil. The physiological characteristics, such as chlorophyll content, soluble sugar content, soluble protein content and antioxidant enzyme activity, of Tagetes erecta L. were also investigated. The symbiotic relationship between the marigold plant and arbuscular mycorrhizal fungi was well established under Cd stress. The symbiotic relationship was reffected by the better physiobiochemical parameters of the marigold plants inoculated with the three AMF isolates where the colonization rates in the roots were between 34.3% and 88.8%. Compared with the non-inoculated marigold plants, the shoot and root biomass of the inoculated marigold plants increased by 15.2%- 47.5% and 47.8%-130.1%, respectively, and the Cd concentration and accumulation decreased. The chlorophyll and soluble sugar contents in the mycorrhizal marigold plants increased with Cd addition, indicating that AMF inoculation helped the marigold plants to grow by resisting Cd stress. The antioxidant enzymes reacted differently with the three AMF under Cd stress. For plants inoculated with G. constrictum and G. mosseae, the activities of superoxide dismutase (SOD) and catalase (CAT) increased with increasing Cd addition, but peroxidase (POD) activity decreased with increasing Cd addition. For plants inoculated with G. intraradices, three of the antioxidant enzyme activities were significantly decreased at high levels of Cd addition. Overall, the activities of the three antioxidant enzymes in the plants inoculated with AMF were higher than those of the plants without AMF inoculation under Cd stress. Our results support the view that antioxidant enzymes have a great influence on the biomass of plants, and AMF can improve the capability of reactive oxygen species (ROS) scavenging and reduce Cd concentration in plants to alleviate Tagetes erecta L. from Cd stress.     

氮肥形态对日本毛连菜生长及Pb累积特性的影响

通过盆栽试验研究Pb胁迫浓度为2 000 mg/kg时,不同形态氮肥对日本毛连菜生长及Pb累积特性的影响。结果表明：在Pb胁迫下,施用适量的氮肥可促进日本毛连菜的生长和累积Pb的能力,而施用过量氮肥则对日本毛连菜的生长和Pb累积均有一定抑制作用。铵态氮处理下Pb在日本毛连菜各器官的分配顺序为：根〉叶〉茎;与硝态氮肥处理相比,铵态氮肥更有利于Pb向日本毛连菜叶部转移。因此,在Pb污染土壤中施加适量铵态氮肥（≤100 mg/kg）,既能提高日本毛连菜生物量,又能提高日本毛连菜对Pb的累积量,这对Pb污染土壤的植物修复具有一定价值。     

An effective planting model to decrease cadmium accumulation in rice grains and plants: Intercropping rice with wetland plants

Cadmium (Cd) pollution affects plant growth and poses a serious threat to food safety and human health.Cadmium-contaminated rice is assumed to be the main source of Cd exposure to humans,with grave health risks.Phytoremediation is an efficient,cost-effective,and eco-friendly approach to minimize Cd accumulation in rice.However,research on the effect of rice intercropping with wetland plants that exhibit great capacity for phytoremediation in decreasing Cd concentrations in paddies is limited.A p...     

Heavy-Metal Phytoextraction Potential of Spinach and Mustard Grown in Contaminated Calcareous Soils

Laboratory batch and greenhouse pot experiments were conducted to determine the extraction efficiency of ethylenediaminetetraacetic acid (EDTA) for solubilizing lead (Pb) and cadmium (Cd) and to explore the natural and chemically induced Pb and Cd phytoextraction efficiencies of spinach and mustard after EDTA application. The EDTA was applied at 0, 1.25, 2.5, and 5.0 mM kg^?1 soil in three replicates. Addition of EDTA increased significantly the soluble fraction Pb and Cd over the control and maximum increases for Pb (1.42- and 1.96-fold) and Cd (1.45- and 1.38-fold) were observed with the addition of 5.0 mM EDTA kg^?1 in Gujranwala and Pacca soils, respectively. Similarly, addition of EDTA increased significantly the Pb and Cd concentrations in the plant shoots, soil solution, bioconcentration factor, and phytoextraction rate. Mustard exhibited better results than spinach when extracting Pb and Cd from both contaminated soils.     

Influence of Organic and Synthetic Fertility on Nitrate Runoff and Leaching,Soil Fertility,and Sweet Corn Yield and Quality

Abstract

Organic farming practices have been reported to reduce agricultural pollution and improve yield and quality compared to conventional practices. Frequently, research has involved comparing completely conventional and organic farming systems over many years. This study was conducted to test whether the use of organic fertilizers versus synthetic fertilizers improved soil fertility and sweet corn (Zea mays L. var rugosa Bonaf.) vigor, yield, size, and nutrient content and minimized nitrate (NO₃) leaching and runoff after a single growing season. Sweet corn vigor, yield, and nutrient content were superior for synthetically fertilized sweet corn compared to organically fertilized corn. Runoff NO₃ levels were similar regardless of fertilizer type. The use of organic fertilizers neither improved crop yield and quality nor reduced NO₃ loss after a single season. These findings are consistent with previous research that reports that more than a single season of organic management is needed to improve soil properties and increase yields.     

Polyaromatic Hydrocarbons in Rhizosphere Soil of Different Plants: Effect of Soil Properties,Plant Species,and Intensity of Anthropogenic Pressure

Abstract

The objective of the present study was to determine the content of polycyclic aromatic hydrocarbons (PAH) in the rhizospheres of some selected plant species (Cucumis dativus, Daucus carota, Allium cepa, Cueurbita, Petroselinum sativum, Cucurbitaceae, Phaseolus vulgaris, Beta vulgaris, Apium graveolens, Allium porrum, Vicia faba). Various anthropogenic influences on the PAH content in the rhizospheres of the three species selected were also studied. The PAH content was determined using the high performance liquid chromatography (HPLC) method with ultraviolet (UV) detection after a preliminary sample treatment with ultrasonic techniques. On the basis of the PAH content, the organic carbon content and the value of log K_oc, a potentially bioavailable PAH fraction present in the rhizospheres of the plants studied, were calculated.

The lowest content of the PAH sum (<1100 µg/kg) was found in the Petroselinum sativum, Cucurbitaceae, and Allium porrum rhizospheres. The content of the compounds studied was more than 67% lower than in the control soil (3307 µg/kg). Moreover, in the rhizosphere of the Allium porrum, the lowest content of all the five‐ and six‐ring PAH samples studied was found. The contribution of the 16 PAHs' sum, determined on the basis of an equilibrium partition in all rhizospheres studied, was higher than in the control soil. The evaluation of the PAH content in the rhizospheres of the three plants as related to the influence of anthropogenic sources showed a higher PAH content in them than in the control soil. The evaluation of the relation between the PAH content and the soil properties studied showed only sporadically statistically significant correlations.     

Accumulation of Copper,Lead, and Zinc by In Situ Plants Inoculated with AM Fungi in Multicontaminated Soil

Pot and field experiments were conducted to (1) evaluate bioavailability of copper (Cu), lead (Pb), and zinc (Zn) in contaminated soil and phytoremediation potential by in situ plants, B. pilosa var. radiate and Passiflora foetida var. hispida, as inoculated with arbuscular mycorrhizal (AM) fungi, and (2) compare the results of pot and field experiments. The B. pilosa var. radiate plant inoculated with AM fungi had significantly greater Cu concentrations in the shoots and roots than noninoculated plants. Passiflora foetida var. hispida plant inoculated with AM fungi also had significantly greater Cu and Pb concentrations in the roots than noninoculated plants. As the root dry weight of Passiflora foetida var. hispida inoculated with AM fungi dramatically increased, the root Cu, Pb, and Zn content of Passiflora foetida var. hispida inoculated with AM fungi increased by 9–14 times, as compared with the noninoculated plants. The AM fungi have potential to either promote plant growth or increase heavy‐metal accumulation. The values of element translocation proportion from root to shoot were Zn > Cu > Pb for both plant species in pot and field experiments. For both plant species, the results of the pot and field experiments were significantly different. The concentration values of the pot experiment were greater in comparison to the field experiment, and some values were significantly greater than those in the field experiment.     

镉在土壤-金丝垂柳系统中的迁移特征

以金丝垂柳为试验对象,采用盆栽试验方式,设置无植物和金丝垂柳两组试验,分别对两组试验的土壤做梯度浓度Cd处理:0(无镉处理)、2(低浓度处理)、20(中浓度处理)、80(高浓度处理) mg/kg 土壤干重,无植物组各处理分别定义为CK(无镉处理)、L(低浓度处理)、M(中浓度处理)、H(高浓度处理),金丝垂柳组各处理分别定义为CKP(无镉处理)、LP(低浓度处理)、MP(中浓度处理)、HP(高浓度处理)。通过对土壤中各形态Cd含量及金丝垂柳叶、韧皮部、木质部、根部的Cd含量测定,分析了金丝垂柳及不同浓度Cd处理对土壤中中性交换态、螯合态和残渣态Cd含量的影响,并评价了富集指数(BCF)、转移系数(TF)和生物有效性(BF),明确了Cd在土壤-金丝垂柳系统中的转移特征及金丝垂柳对土壤中Cd的清除效果。结果表明:(1)金丝垂柳对土壤中中性交换态、有效态Cd含量及总Cd量的降低具有极显著影响,HP组与无植物H组相比,中性交换态及有效态Cd含量分别降低了52.73%、25.34%,MP、HP组与对应的无植物处理组的总Cd量相比分别降低了11.33%、13.89%;(2)金丝垂柳各处理组的Cd积累量随Cd处理浓度的增加和处理时间的延长而增加,处理90 d后,HP处理中木质部和根部的Cd含量可达170.64 mg/kg、212.49 mg/kg;(3)各浓度Cd处理下,金丝垂柳各部位生物富集系数呈根>木质部>韧皮部、叶,且随着Cd处理浓度的增加而显著降低,随处理时间的延长而升高;与40 d相比,90 d时LP组叶的生物富集系数增加了6.90倍,增幅最大。(4)各部分转移系数均随处理时间的延长而降低,90 d时LP、MP的转移系数分别比40 d时的结果低47.94%、41.34%。(5)金丝垂柳LP、HP组土壤Cd的生物有效性显著低于相应的无植物处理L、H组,分别低70.73%、88.46%,MP组与M组无显著差异。研究结果表明,金丝垂柳能有效地吸收土壤中的有效态Cd,降低土壤中Cd的生物有效性及总Cd量,提高土壤的安全性,并能将吸收的Cd有效地转移至地上部分,尤其是木质部储存。随着植株不断生长,生物量的增加,金丝垂柳可有效地清除土壤中的Cd,适用于对Cd污染地区进行长期植物修复。