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.     

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.     

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.     

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.     

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.     

土壤重金属污染植物修复及基因技术的应用

叙述了植物修复基本内容,重点介绍了基因技术在植物修复中的应用。文章认为,与传统的修复技术相比,污染土壤植物修复技术由于具有成本低、不破坏环境、保护人类健康和易为大众接受等优点而引起了人们极大的关注,但是,应用于修复的植物往往植株矮小、生长速度慢,近年来,国外出现了将基因技术应用到植物修复中的研究,能有效地克服上述缺点。将基因技术应用于植物修复将是今后该领域研究的一个重要方向。     

接种耐铬细菌菌株对二月兰中铬积累及其生长状况的影响

Beneficial interactions between microorganisms and plants, particularly in the rhizosphere, are a research area of global interest. Four cadmium （Cd）-tolerant bacterial strains were isolated from heavy metal-contaminated sludge and their effects on Cd mobility in soil and the root elongation and Cd accumulation of Orychophragmus violaceus were explored to identify the capability of metal- resistant rhizobacteria for promoting the growth of O. violaceus roots on Cd-contaminated soils. The isolated strains, namely, Bacillus subtilis, B. cereus, B. megaterium, and Pseudomonas aeruginosa, significantly enhanced the plant Cd accumulation. The Cd concentrations in the roots and shoots were increased by up to 2.29- and 2.86-fold, respectively, by inoculation of B. megaterium, as compared with the uninoculated control. The bacterial strains displayed different effects on the shoot biomass. Compared with the uninoculated plants, the shoot biomass of the inoculated plants was slightly increased by B. megaterium and significantly decreased by the other strains. B. megaterium was identified as the best candidate for enhancing Cd accumulation in O. violaceus. Thus, this study provides novel insight into the development of plant-microbe systems for phytoremediation.     

植物对环境重金属污染的修复技术研究进展

植物修复技术(Phytoremediation)是近年来发展起来的一种主要用于清除土壤重金属污染的生态技术。重金属超积累植物(Hyperaccumulator)及植物修复技术是当前国内外学术界研究的热点领域之一。植物修复重金属污染的机制主要是植物对污染物的吸收积累和降解转化,具有成本低、不破坏土壤和河流生态环境、不引起二次污染等优点,就近十年来国内外植物修复重金属污染的机理、对象及超积累植物的研究作一综述。     

修复镉污染土壤的油菜品种的筛选及吸收累积特征研究--高积累镉油菜品种的筛选(Ⅰ)

研究从具有积累镉遗传背景的油菜种质资源中筛选高积累镉的油菜品种．以富集镉植物印度芥菜为参比，通过水培试验对22个油菜品种植株地上部相对生物量、地上部镉含量和植株吸镉量进行比较，筛选出高吸收累积镉油菜品种川油Ⅱ-10、白芥和绵阳蛮油菜。     

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...