Effect of nano-TiO(2) on strength of naturally aged seeds and growth of spinach.
TL;DR: It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO2 improves the growth of spinach seeds still needs further study.
Abstract: The effects of nano-TiO2 (rutile) and non-nano-TiO2 on the germination and growth of naturally aged spinach seeds were studied by measuring the germination rate and the germination and vigor indexes of aged spinach seeds. An increase of these factors was observed at 0.25–4‰ nano-TiO2 treatment. During the growth stage, the plant dry weight was increased, as was the chlorophyll formation, the ribulosebisphosphate carboxylase/oxygenase activity, and the photosynthetic rate. The best results were found at 2.5‰ nano-TiO2. The effects of non-nano-TiO2 are not significant. It is shown that the physiological effects are related to the nanometer-size particles, but the mechanism by which nano-TiO2 improves the growth of spinach seeds still needs further study.
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TL;DR: This review critiques existing nanomaterial research in freshwater, marine, and soil environments and illustrates the paucity of existing research and demonstrates the need for additional research.
Abstract: The recent advances in nanotechnology and the corresponding increase in the use of nanomaterials in products in every sector of society have resulted in uncertainties regarding environmental impacts. The objectives of this review are to introduce the key aspects pertaining to nanomaterials in the environment and to discuss what is known concerning their fate, behavior, disposition, and toxicity, with a particular focus on those that make up manufactured nanomaterials. This review critiques existing nanomaterial research in freshwater, marine, and soil environments. It illustrates the paucity of existing research and demonstrates the need for additional research. Environmental scientists are encouraged to base this research on existing studies on colloidal behavior and toxicology. The need for standard reference and testing materials as well as methodology for suspension preparation and testing is also discussed.
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TL;DR: This review presents an overview of the classes of NP relevant to the environment and summarizes their formation, emission, occurrence and fate in the environment.
2,093 citations
TL;DR: The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi as mentioned in this paper.
Abstract: Developments in nanotechnology are leading to a rapid proliferation of new materials that are likely to become a source of engineered nanoparticles (ENPs) to the environment, where their possible ecotoxicological impacts remain unknown. The surface properties of ENPs are of essential importance for their aggregation behavior, and thus for their mobility in aquatic and terrestrial systems and for their interactions with algae, plants and, fungi. Interactions of ENPs with natural organic matter have to be considered as well, as those will alter the ENPs aggregation behavior in surface waters or in soils. Cells of plants, algae, and fungi possess cell walls that constitute a primary site for interaction and a barrier for the entrance of ENPs. Mechanisms allowing ENPs to pass through cell walls and membranes are as yet poorly understood. Inside cells, ENPs might directly provoke alterations of membranes and other cell structures and molecules, as well as protective mechanisms. Indirect effects of ENPs depend on their chemical and physical properties and may include physical restraints (clogging effects), solubilization of toxic ENP compounds, or production of reactive oxygen species. Many questions regarding the bioavailability of ENPs, their uptake by algae, plants, and fungi and the toxicity mechanisms remain to be elucidated.
1,548 citations
Cites background from "Effect of nano-TiO(2) on strength o..."
...TiO2 NPs have also been found to induce spinach seed germination and plant growth by regulating the germination of aged seeds and its vigor (Zheng et al. 2005)....
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TL;DR: Effects of five types of nanoparticles on seed germination and root growth of six higher plant species were investigated and inhibition on root growth varied greatly among nanoparticles and plants.
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TL;DR: The delivery of nanoparticulate materials to plants and their ultimate effects are reviewed to provide some insights for the safe use of this novel technology for the improvement of crops.
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References
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TL;DR: Evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis is presented.
Abstract: The chloroplast, as the seat of chlorophyll pigments in plants, occupies a unique position in the economy of the green cell. In recent years there has been a renewed interest in the reactions and properties of chloroplasts as a result of the work of Hill (11, 12) and Hill and Scarisbrick (13, 14) who demonstrated that the reaction characteristic of photosynthesis in green plants, the evolution of oxygen, occurs in appreciable quantities in isolated chloroplasts under the influence of light and in the presence of suitable oxidants (2, 7, 8, 26). In the course of an investigation of oxygen evolution by isolated chloroplasts it was deemed important to explore their enzymatic composition. Of special interest were considered enzymes capable of participating in oxidation-reduction reactions, and more particularly, those localized principally, if not entirely, in the chloroplasts. This paper presents evidence that a copper enzyme, polyphenoloxidase (otherwise known as tyrosinase or catecholase), is localized in the chloroplasts of spinach beet (chard), Beta vu?garis.
20,139 citations
"Effect of nano-TiO(2) on strength o..." refers methods in this paper
...The chlorophyll content was determined by Arnon’s method ( 11 )....
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TL;DR: Crabtree as mentioned in this paper discusses recent work in which entirely new kinds of hydrogen bonds have been discovered and discusses how to control these new types of bonding may enable researchers to harness a variety of important catalytic processes.
Abstract: Hydrogen bonding is responsible for a wide array of chemical properties, from the melting point of water to the behavior of enzymes. In his Perspective, Crabtree discusses recent work in which entirely new kinds of hydrogen bonds have been discovered. Understanding and controlling these new types of bonding may enable researchers to harness a variety of important catalytic processes.
220 citations
"Effect of nano-TiO(2) on strength o..." refers background in this paper
...Under light, nano-TiO2 is able to generate superoxide ion radical and hydroxide (8)....
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TL;DR: In this paper, the root cell walls are the main internal sites of aluminosilicate (AS) and/or HAS formation and of Al detoxification, and it is shown that Al and Si can ameliorate the toxic effects of Al in hydroponic culture.
Abstract: Aluminium (Al) toxicity is a very important factor limiting the growth of plants on acidic soils. Recently, a number of workers have shown that, under certain conditions, silicon (Si) can ameliorate the toxic effects of Al in hydroponic culture. The mechanism of the amelioration is unclear, but three suggestions have been put forward: Si-induced increase in solution pH during the preparation of hydroponic solutions: reduced availability of Al due to the formation of hydroxyaluminosilicate (HAS) species in those solutions during plant growth; or in planta detoxification. It is now known that it is possible to make up Al and Si solutions in an order in Which pH is lowered prior to Al addition: in these cases amelioration has still been observed. Amelioration has also been noted in experiments where HAS formation is minimal. These observations would suggest that, at least under some circumstances, there is an in planta component to the amelioration phenomenon. Several microanalytical investigations have noted codeposition of Al and Si in root cell walls. We propose a model in which root cell walls are the main internal sites of aluminosilicate (AS) and/or HAS formation and of Al detoxification. Factors promoting AS/HAS formation in this compartment include: high apoplastic pH; the presence of organic substances (e.g. malate); and the presence of suitable local concentrations of reactive forms of Al and Si, on or within the surfaces of the wall matrix. All these are likely to be important in the amelioration of Al toxicity.
175 citations
TL;DR: Macromolecular assemblages intimately associated with biogenic silica in plants are released on solubilization of the siliceous phase by treatment with buffered aqueous solutions of HF following treatment of plant material with concentrated oxidizing acids to remove cytoplasmic contents and the largely polysaccharidic cell wall.
127 citations
"Effect of nano-TiO(2) on strength o..." refers background in this paper
...NMs could increase the strength of roots and the activity of nitrate reductase, enhancing the root’s ability to absorb water and fertilizers and to increase the activities of the antioxidant enzymes like superoxide dismutase and catalase, resulting in an improvement of the soybean resistance to stress (7)....
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...Previous studies have shown that some NMs could enhance the plants’ ability to absorb water and nitrogenated fertilizers, promote the vigor of root system and the activities of the nitrate reductase, and accelerate the breakdown of organic substances, aiding the formation of essential amino acids (7)....
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TL;DR: In this paper, the response of seedlings of the monocotum vulgare L. cv. to 0,25 and 50 μM aluminium in factorial combination with 0, 1.4, 2.0 and 2.8 mM Si was tested in hydroponic culture at pH 4.5.
Abstract: The response of seedlings of the monocot Hordeum vulgare L. cv. Bronze to 0,25 and 50 μM aluminium in factorial combination with 0, 1.4, 2.0 and 2.8 mM Si was tested in hydroponic culture at pH 4.5. Nutrient solution (500 μM calcium nitrate) and Al/Si treatments were designed to avoid the precipitation of Al from solution. Silicon treatments gave significant amelioration of the toxic effects of Al on root and shoot growth and restored calcium levels in roots and shoots at harvest to levels approaching those of control plants. Aluminium uptake by roots was also significantly diminished in the presence of Si. Silicon alone gave a slight stimulation of growth, insufficient to explain its ameliorative effect on Al toxicity. The mechanism of the Si effect on Al toxicity in monocotyledons awaits further investigation.
122 citations