Salicylic acid and Tocopherol improve wheat (Triticum aestivum L.) Physio-biochemical and agronomic features grown in deep sowing stress: a way forward towards sustainable production.

BACKGROUND: The rate of germination and other physiological characteristics of seeds that are germinating are impacted by deep sowing. Based on the results of earlier studies, conclusions were drawn that deep sowing altered the physio-biochemical and agronomic characteristics of wheat (Triticum aestivum L.). RESULTS: In this study, seeds of wheat were sown at 2 (control) and 6 cm depth and the impact of exogenously applied salicylic acid and tocopherol (Vitamin-E) on its physio-biochemical and agronomic features was assessed. As a result, seeds grown at 2 cm depth witnessed an increase in mean germination time, germination percentage, germination rate index, germination energy, and seed vigor index. In contrast, 6 cm deep sowing resulted in negatively affecting all the aforementioned agronomic characteristics. In addition, deep planting led to a rise in MDA, glutathione reductase, and antioxidants enzymes including APX, POD, and SOD concentration. Moreover, the concentration of chlorophyll a, b, carotenoids, proline, protein, sugar, hydrogen peroxide, and agronomic attributes was boosted significantly with exogenously applied salicylic acid and tocopherol under deep sowing stress. CONCLUSIONS: The results of the study showed that the depth of seed sowing has an impact on agronomic and physio-biochemical characteristics and that the negative effects of deep sowing stress can be reduced by applying salicylic acid and tocopherol to the leaves.

Effect of the seed coating with biomass of Dunaliella salina on early plant growth and in the secondary metabolites content of Coriandrum sativum.

The environmental and health risks associated with the application of synthetic chemical inputs in agriculture increased the demand for technologies that allow higher performance and quality of vegetable crops by implementing synergistic materials with the principles of sustainability. In this work, the seed coating with the biomass of Dunaliella salina incorporated in a bioplastic film of Manihot esculenta (cassava) was evaluated as an initial growth and secondary compounds stimulator of Coriandrum sativum (coriander) plants. The obtained results demonstrated that the coating stimulated an increase in the germination percentage (28.75%) and also in concentration of bioactive compounds, such as the six-fold increment of caffeic acid (13.33 mg 100 g-1). The carbohydrates, lipids, and proteins present in the microalgae biomass seem to be responsible for these increments once they are known for providing energy to the seedling development and coordinating the secondary metabolites synthesis. As conclusion, we consider the coating with biomass of D. salina an alternative for crop improvement that contributes to the development of sustainable agricultural practices.

Implementation of a Non-Thermal Atmospheric Pressure Plasma for Eradication of Plant Pathogens from a Surface of Economically Important Seeds.

Plant pathogenic bacteria cause significant economic losses in the global food production sector. To secure an adequate amount of high-quality nutrition for the growing human population, novel approaches need to be undertaken to combat plant disease-causing agents. As the currently available methods to eliminate bacterial phytopathogens are scarce, we evaluated the effectiveness and mechanism of action of a non-thermal atmospheric pressure plasma (NTAPP). It was ignited from a dielectric barrier discharge (DBD) operation in a plasma pencil, and applied for the first time for eradication of Dickeya and Pectobacterium spp., inoculated either on glass spheres or mung bean seeds. Furthermore, the impact of the DBD exposure on mung bean seeds germination and seedlings growth was estimated. The observed bacterial inactivation rates exceeded 3.07 logs. The two-minute DBD exposure stimulated by 3-4% the germination rate of mung bean seeds and by 13.4% subsequent early growth of the seedlings. On the contrary, a detrimental action of the four-minute DBD subjection on seed germination and early growth of the sprouts was noted shortly after the treatment. However, this effect was no longer observed or reduced to 9.7% after the 96 h incubation period. Due to the application of optical emission spectrometry (OES), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM), we found that the generated reactive oxygen and nitrogen species (RONS), i.e., N2, N2+, NO, OH, NH, and O, probably led to the denaturation and aggregation of DNA, proteins, and ribosomes. Furthermore, the cellular membrane disrupted, leading to an outflow of the cytoplasm from the DBD-exposed cells. This study suggests the potential applicability of NTAPPs as eco-friendly and innovative plant protection methods.

In vitro toxicity assessment of fungal-synthesized cadmium sulfide quantum dots using bacteria and seed germination models.

There is currently controversy over the use of quantum dots (QDs) in biological applications due to their toxic effects. Therefore, the purpose of the present study was to evaluate the toxic effect of chemical and biogenic (synthesized by Fusarium oxysporum f. sp. lycopersici) cadmium sulfide quantum dots (CdSQDs) using a bacterial model of Escherichia coli and sprouts of Lactuca sativa L. with the aim to foresee its use in the near future in biological systems. Physicochemical properties of both types of CdSQDs were determined by TEM, XRD, zeta potential and fluorescence spectroscopy. Both biogenic and chemical CdSQDs showed agglomerates of spherical CdSQDs with diameters of 4.14 nm and 3.2 nm, respectively. The fluorescence analysis showed a band around 361 nm in both CdSQDs, the zeta potential was -1.81 mV for the biogenic CdSQDs and -5.85 mv for the chemical CdSQDs. Results showed that chemical CdSQDs, presented inhibition in the proliferation of E. coli cell in a dose-dependent manner, unlike biogenic CdSQDs, that only at its highest concentration showed an antibacterial activity. Also, it was observed that after incubation with chemical and biogenic CdSQDs of L. sativa L. seeds, only the biogenic CdSQDs showed no inhibition on seed germination. In summary, our results suggest that the production route has a significant effect on the toxicity of QDs; in addition, it seems that the biological coating of the CdSQDs from F. oxysporum f. sp. lycopersici inhibit their toxic effect on bacterial strains and plant seeds.

Insights on Molecular Characteristics of Hydrochars by 13C-NMR and Off-Line TMAH-GC/MS and Assessment of Their Potential Use as Plant Growth Promoters.

Hydrochar is a carbon-based material that can be used as soil amendment. Since the physical-chemical properties of hydrochar are mainly assigned to process parameters, we aimed at evaluating the organic fraction of different hydrochars through 13C-NMR and off-line TMAH-GC/MS. Four hydrochars produced with sugarcane bagasse, vinasse and sulfuric or phosphoric acids were analyzed to elucidate the main molecular features. Germination and initial growth of maize seedlings were assessed using hydrochar water-soluble fraction to evaluate their potential use as growth promoters. The hydrochars prepared with phosphoric acid showed larger amounts of bioavailable lignin-derived structures. Although no differences were shown about the percentage of maize seeds germination, the hydrochar produced with phosphoric acid promoted a better seedling growth. For this sample, the greatest relative percentage of benzene derivatives and phenolic compounds were associated to hormone-like effects, responsible for stimulating shoot and root elongation. The reactions parameters proved to be determinant for the organic composition of hydrochar, exerting a strict influence on molecular features and plant growth response.

No fitness cost associated with Asn-2041-Ile mutation in winter wild oat (Avena ludoviciana) seed germination under various environmental conditions.

Knowledge about the fitness cost imposed by herbicide resistance in weeds is instrumental in devising integrated management methods. The present study investigated the germination response of ACCase-resistant (R) and susceptible (S) winter wild oat under different environmental conditions. The DNA of the plants was sequenced after being extracted and purified. The segregated F2 seeds were subjected to various temperatures, water potentials, NaCl concentrations, different pHs, darkness conditions, and burial depths. The results of the sequencing indicated that Ile-2041-Asn mutation is responsible for the evolution of resistance in the studied winter wild oat plants. The seeds were able to germinate over a wide range of temperatures, osmotic potentials, NaCl concentrations, and pHs. Germination percentage of R and S seeds under dark and light conditions was similar and ranged from 86.3 to 88.3%. The highest emergence percentage for both R and S plants was obtained in 0, 1, and 2 cm depths and ranged from 66.6 to 70.3%. In overall, no differences were observed in the germination response between the R and S winter wild oat plants under all studied conditions. No fitness cost at seed level indicates that control of R winter wild oats is more difficult, and it is essential to adopt crop and herbicide rotation to delay the further evolution of resistance.

Assessment of nanoencapsulated Cananga odorata essential oil in chitosan nanopolymer as a green approach to boost the antifungal, antioxidant and in situ efficacy.

In this study, a comparative efficacy of Cananga odorata EO (CoEO) and its nanoencapsulated formulation into chitosan nanoemulsion (CoEO-CsNe) against a toxigenic strain of Aspergillus flavus (AF-M-K5) were investigated for the first time in order to determine its efficacy in preservation of stored food from fungal, aflatoxin B1 (AFB1) contamination and lipid peroxidation. GC and GC-MS analysis of CoEO revealed the presence of linalool (24.56%) and benzyl acetate (22.43%) as the major components. CoEO was encapsulated into chitosan nanoemulsion (CsNe) through ionic-gelation technique and characterized by High Resolution-Scanning Electron Microscopy (HR-SEM), Fourier Transform Infrared spectroscopy (FTIR), and X-Ray Diffraction (XRD) analysis. The CoEO-CsNe during in vitro investigation against A. flavus completely inhibited the growth and AFB1 production at 1.0 µL/mL and 0.75 µL/mL, respectively. Additionally, CoEO-CsNe showed improved antioxidant activity against DPPH• and ABTS•+ with IC50 value 0.93 and 0.72 µL/mL, respectively. Further, CoEO-CsNe suppressed fungal growth, AFB1 secretion and lipid peroxidation in Arachis hypogea L. during in situ investigation without causing any adverse effect on seed germination. Overall results demonstrated that the CoEO-CsNe has potential of being utilized as a suitable plant based antifungal agent to improve the shelf-life of stored food against AFB1 and lipid peroxidation mediated biodeterioration.

Assessment of the potential risk of 1,2-hexanediol using phytotoxicity and cytotoxicity testing.

1,2-Hexanediol is commonly used in the cosmetic industry as a preservative, an emollient, and a moisturizing agent. However, studies on the scientific toxicity of 1,2-hexanediol are limited. In this study, we evaluated the potential toxic effects of 1,2-hexanediol using phytotoxicity and cytotoxicity testing methods. Phytotoxicity tests using Brassica campestris subsp. napus and Latuca sativa L. showed that 1,2-hexanediol significantly inhibited seed germination and root elongation at the lowest concentration (0.1%). Additionally, plants treated with 1,2-hexanediol failed to survive. In cytotoxicity tests, RAW 264.7 and HK-2 cells treated with 1.0% 1,2-Hexanediol showed a significant decline in viability, followed by death. Since most personal care products contain >2% 1,2-hexanediol, it is highly likely that 1,2-hexanediol is toxic to humans. Moreover, if 1,2-hexanediol enters the human body either via oral intake or through an open wound, it could have critical effects. Furthermore, upon release into the environment, 1,2-hexanediol could cause considerable damage to plants and other organisms. Therefore, further investigation of 1,2-hexanediol is required to prevent toxicity to humans and other living organisms.

Assessment of allelopathic, cytotoxic, genotoxic and antigenotoxic potential of Smilax brasiliensis Sprengel leaves.

Smilax brasiliensis (Smilacaceae) is a native Brazilian plant found in the Cerrado biome and commonly used in folk medicine. The aim of this study was to evaluate the allelopathic, cytotoxic, genotoxic, and antigenotoxic potential of extract and fractions of Smilax brasiliensis leaves. Quercetin and rutin isomers were observed in the subfractions. The dichloromethane fraction (1000 µg/mL) decreased lettuce (Lactuca sativa) seed vigor, while and ethyl acetate and hydromethanol fractions (1000 µg/mL) affected the germination, and quercetin and rutin affected the vigor and germination of onion seeds. The extract, fractions, quercetin, and rutin inhibited or promoted lettuce hypocotyl and radicle growth. The extract and fractions inhibited onion hypocotyl growth at all concentrations. With regards to radicle growth, the results were diversified: growth was either inhibited or promoted. Rutin and quercetin inhibited onion hypocotyl and radicle growth at all concentrations. The extract and fractions of Smilax brasiliensis, rutin, and quercetin did not cause cytotoxic effect evaluated by mitotic index. The extract and fractions showed genotoxic effects. Quercetin and rutin did not cause genotoxic effects. On the other hand, the extract and fractions showed antigenotoxic effects at all tested concentrations, where they were able to revert chromosomal abnormalities caused by glyphosate. However, additional studies are required to evaluate the possible use of the S. brasiliensis leaf methanol extract and fractions as natural sources of bioherbicides.

Assessment of Phenotypic Variations and Correlation among Seed Composition Traits in Mutagenized Soybean Populations.

Soybean [Glycine max (L.) Merr.] seed is a valuable source of protein and oil worldwide. Traditionally, the natural variations were heavily used in conventional soybean breeding programs to select desired traits. However, traditional plant breeding is encumbered with low frequencies of spontaneous mutations. In mutation breeding, genetic variations from induced mutations provide abundant sources of alterations in important soybean traits; this facilitated the development of soybean germplasm with modified seed composition traits to meet the different needs of end users. In this study, a total of 2366 'Forrest'-derived M2 families were developed for both forward and reverse genetic studies. A subset of 881 M3 families was forward genetically screened to measure the contents of protein, oil, carbohydrates, and fatty acids. A total of 14 mutants were identified to have stable seed composition phenotypes observed in both M3 and M4 generations. Correlation analyses have been conducted among ten seed composition traits and compared to a collection of 103 soybean germplasms. Mainly, ethyl methanesulfonate (EMS) mutagenesis had a strong impact on the seed-composition correlation that was observed among the 103 soybean germplasms, which offers multiple benefits for the soybean farmers and industry to breed for desired multiple seed phenotypes.

Assessment of toxic interaction of nano zinc oxide and nano copper oxide on germination of Raphanus sativus seeds.

Multiple applications of nanoparticles (NPs) could result in their potential release into agricultural systems and raised concerns about food safety. The NPs once released in the environment may interact with numerous pollutants, including other NPs. Present study assessed the impact of a single (CuO and ZnO NPs) and binary mixture (CuO+ZnO NPs) on the germination of Raphanus sativus seeds with a wide range of exposure concentration (0-1000 mg/L). Both the NPs have shown a deleterious effect on seeds at exposure concentration greater than 10 mg/L. Antagonistic interaction between effects of CuO and ZnO NPs on seeds was noticed for all the exposed concentrations. CuO NPs showed higher absorption capacity on the seedling surface than ZnO NPs. Internal uptake of Zn in ZnO NP-exposed seedlings was found to be greater than that due to CuO NP-exposed seedlings. Three different types of exposure adversely affected seed germination (reduction in root length, shoot length, and fresh weight). Reduction in growth parameters (length and weight) with concentration was compared using log-logistic dose-response model of "DRC" package of the "R" software, and EC50 was determined. As per EC50 values, the toxicity of CuO NPs was found to be maximum followed by CuO+ZnO NPs and then minimum for ZnO NPs. Seedlings accumulated Cu and Zn metals, and higher uptake was recorded for Zn (reported as mg/g seedling dry weight). The order of toxicity was found as CuO NPs > binary mixture (CuO+ZnO) NPs > ZnO NPs. Exposure concentration greater than 10 mg/L resulted in significant toxicity and uptake in germinated seedlings. These findings indicated that exposure of the mixture of NPs during germination might give different effects and thus, further attempts could prove quite beneficial to the literature.

Neonicotinoid seed treatments of soybean provide negligible benefits to US farmers.

Neonicotinoids are the most widely used insecticides worldwide and are typically deployed as seed treatments (hereafter NST) in many grain and oilseed crops, including soybeans. However, there is a surprising dearth of information regarding NST effectiveness in increasing soybean seed yield, and most published data suggest weak, or inconsistent yield benefit. The US is the key soybean-producing nation worldwide and this work includes soybean yield data from 194 randomized and replicated field studies conducted specifically to evaluate the effect of NSTs on soybean seed yield at sites within 14 states from 2006 through 2017. Here we show that across the principal soybean-growing region of the country, there are negligible and management-specific yield benefits attributed to NSTs. Across the entire region, the maximum observed yield benefits due to fungicide (FST = fungicide seed treatment) + neonicotinoid use (FST + NST) reached 0.13 Mg/ha. Across the entire region, combinations of management practices affected the effectiveness of FST + NST to increase yield but benefits were minimal ranging between 0.01 to 0.22 Mg/ha. Despite widespread use, this practice appears to have little benefit for most of soybean producers; across the entire region, a partial economic analysis further showed inconsistent evidence of a break-even cost of FST or FST + NST. These results demonstrate that the current widespread prophylactic use of NST in the key soybean-producing areas of the US should be re-evaluated by producers and regulators alike.

Carboxin and its major metabolites residues in peanuts: Levels, dietary intake and chronic intake risk assessment.

We developed an ultra-performance liquid chromatography-tandem mass spectral method to determine the fungicide carboxin and its metabolites, oxycarboxin and carboxin sulfoxide in peanut samples. The method was used to detect the concentration of the analytes in the samples from fields and markets. The total residue quantities in peanut kernels were used to evaluate the chronic dietary risk of total carboxin upon peanut consumption. The estimated dietary intake of carboxin from peanuts whose seeds had been treated with carboxin at the recommended dose was between 0.020% and 0.344% of acceptable daily intake and the risk was found to be negligible. The chronic dietary risk assessment from markets and commercial field samples for various groups of humans indicated that the group with the greatest degree of exposure was 45 to 75-year-old women who lived in rural areas. However, their acceptable daily intake percentage was 0.006%, meaning that their health risk was extremely small.

Methods for the Simple and Reliable Assessment of Barley Sensitivity to Abiotic Stresses During Early Development.

Physiological assays that facilitate screening for various types of responses to abiotic stresses are well established for model plants such as Arabidopsis; however, there is a need to optimize similar tests for cereal crops, including barley. We have developed a set of stress assays to characterize the response of different barley lines during two stages of development-seed germination and seedling growth. The assays presented, including the response to osmotic, salt, oxidative stresses, and exogenously applied abscisic acid, can be used for forward screening of populations after mutagenesis as well as for phenotyping of already isolated mutants, cultivars, or breeding lines. As well as protocols for stress treatments, we also provide methods for plant stress response evaluation, such as chlorophyll a fluorescence (ChlF) and image analysis.

Toxicity assessment of cobalt ferrite nanoparticles on wheat plants.

Cobalt ferrite nanoparticles (NPs) have received increasing attention due to their widespread therapeutic and agricultural applicability. In the environmental field, dry powder- and ferrofluid-suspended cobalt ferrite NPs were found to be useful for removing heavy metals and metalloids from water, while diluted suspensions of cobalt ferrite NP have been promisingly applied in medicine. However, the potential toxicological implications of widespread exposure are still unknown. Since cobalt ferrite NPs are considered residual wastes of environmental or medical applications, plants may serve as a point-of-entry for engineered nanomaterials as a result of consumption of these plants. Thus, the aim of this study was to assess the effects of dry powder and fresh cobalt ferrite NP on wheat plants. Seven-day assays were conducted, using quartz sand as the plant growth substrate. The toxicity end points measured were seed germination, root and shoot lengths, total cobalt (Co) and iron (Fe) accumulation, photosynthetic pigment production, protein (PRT) production, and activities of catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX). Increasing total Co and Fe in plant tissues indicated that wheat plants were exposed to cobalt ferrite NP. Seed germination and shoot length were not sufficiently sensitive toxicity end points. The effective concentration (EC50) that diminished root length of plants by 50% was 1963 mg/kg for fresh ferrite NPs and 5023 mg/kg for powder ferrite NP. Hence, fresh ferrite NPs were more toxic than powder NP. Plant stress was indicated by a significant decrease in photosynthetic pigments. CAT, APX, and GPX antioxidant enzymatic activity suggested the generation of reactive oxygen species and oxidative damage induced by cobalt ferrite NP. More studies are thus necessary to determine whether the benefits of using these NPs outweigh the risks.

Phytotoxicity assessment of olive mill solid wastes and the influence of phenolic compounds.

The main objective of this work is to evaluate the phytotoxicity of olive mill solid wastes (OMW) produced in two different centrifugation technologies and also the toxicity associated with specific phenolic compounds. Two samples of waste were collected in two-phase (2P-OMW) and three-phase (3P-OMW) centrifugation olive oil production processes, and cress bioassays with Lepidium sativum L. were employed to evaluate phytotoxicity. Although both OMW have similar total phenolic content (TPh), results confirmed that 2P-OMW is more phytotoxic than 3P-OMW. When extracts from 2P-OMW at liquid to solid ratio of 10 L kg-1 were applied none of the seeds germinated, i.e. germination index (GI) was 0%, while for 3P-OMW GI was 94.3%. Growth tests in soil and mixtures with OMW also led to more favorable results for 3P-OMW, whereas worse results than those obtained in the control experiments were observed. In order to discriminate the individual influence of eleven phenolic compounds, gallic acid, protocatechuic acid, cinnamic acid, syringic acid, 3,4,5-trimethoxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, p-coumaric acid, caffeic acid, veratric acid and phenol were tested in the concentration range of 5-500 mg L-1. Results showed that cinnamic acid is the most phytotoxic, with EC50 of 60 mg L-1, which is related with its hydrophobicity. Moreover, increasing -OH and -OCH3 groups in these molecules seem to reduce phytotoxicity. Tests with a mixture of six phenolic compounds demonstrated there are neither synergistic nor additive effects. The phytotoxicity appears to be determined by the presence of the most lipophilic phenolic molecule.

Assessment of toxicity and biochemical mechanisms underlying the insecticidal activity of chemically characterized Boswellia carterii essential oil against insect pest of legume seeds.

The present study was undertaken to investigate the insecticidal activity of chemically characterized Boswellia carterii essential oil (EO) and its mode of action against the pulse beetle Callosobruchus chinensis and C. maculatus. GC-MS analysis depicted α-thujene (69.16%), α-Pinene (7.20) and α-Phellandrene (6.78%) as the major components of test EO. EO exhibited absolute toxicity at 0.10µl/ml air against both C. chinensis and C. maculatus following 24h exposure. EO caused a significant reduction in oviposition and further reproductive development at LC50 doses (0.050µl/ml to 0.066µl/ml in air). Compared to control, a significant elevation in ROS level accompanied with impairment in enzymatic (SOD and CAT) and non-enzymatic (GSH/GSSH) antioxidant defense system has been observed in EO exposed insect pest. However, EO has no significant effect on in vivo AChE activity. An absolute protection of Vigna radiata seeds samples exposed to EO at LC90 doses was observed without affecting seed germination. The findings revealed that the B. carterii EO has strong insecticidal potential, hence, it could be recommended as a biorational alternative to synthetic insecticides.

Field trial of insect-resistant and herbicide-tolerant genetically modified cotton (Gossypium hirsutum L.) for environmental risk assessment in Japan.

Japan imports cottonseed mainly from Australia and the USA where more than 96% of all cotton varieties grown are genetically modified (GM). GM crops undergo an environmental risk assessment (ERA) under the Law Concerning the Conservation and Sustainable Use of Biological Diversity before import into Japan. Potential adverse effects on biodiversity are comprehensively assessed based on competitiveness, production of harmful substances and outcrossing ability. Even though imported cottonseed is intended for food and feed uses and not for cultivation, the potential risks from seed spillage during transport must be evaluated. In most cases, the ERA requires data collected from in-country field trials to demonstrate how the GM crop behaves in Japan's environment. Confined field trials in Japan were conducted for the ERA of Lepidoptera-resistant and glufosinate-tolerant GM cotton (Gossypium hirsutum L.) lines GHB119 and T304-40. These lines were compared with conventional varieties for growth habit, morphological characteristics, seed dormancy, and allelopathic activity associated with competitiveness and production of harmful substances. Outcrossing ability was not a concern due to the absence of sexually compatible wild relatives in Japan. Although slight statistical differences were observed between the GM line and its conventional comparator for some morphological characteristics, transgenes or transformation were not considered to be responsible for these differences. The trial demonstrated that competitiveness and production of harmful substances by these GM cotton lines were equivalent to conventional cotton varieties that have a long history of safe use, and no potential adverse effects to biosafety in Japan were observed.

Toxicity assessment of multi-walled carbon nanotubes on Cucurbita pepo L. under well-watered and water-stressed conditions.

The rapid increase in the production and application of various types of nanomaterials increases the possibility of their presence in total environment, which subsequently raises concerns about their potential threats to the first trophic level of organisms, specifically under varying environmental constraints. In this work, seeds of Cucurbita pepo L. were cultured in MS basal medium exposed to multi-walled carbon nanotubes (MWCNTs) at different concentrations (0, 125, 250, 500 and 1000µgmL-1) under two levels of water potential, well-watered (0MPa) and water stress (-1.5MPa) induced by polyethylene glycol (PEG 6000) for 14 days. Seeds exposed to MWCNTs showed reduction in germination percentage, root and shoot length, biomass accumulation and vigor index in a dose-dependent manner. However, seedlings germinated in MWCNTs-fortified media had significantly lower germination and growth attributes than those of control under water stress conditions. This happened due to increased oxidative injury indices including hydrogen peroxide (H2O2), and malondialdehyde (MDA) contents, as well as electrolyte leakage index (ELI) of tissues. The impaired morpho-physiological and biochemical processes of seedlings exposed to different concentrations of MWCNTs under both PEG-induced stress and non-stress growing conditions were consequence of changes in the activation of various cellular antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (POD). Taken together, our findings reveal that MWCNTs played negative role on seed germination and subsequent growth of C. pepo L. seedlings under both levels of water potential.

Translocation of the neonicotinoid seed treatment clothianidin in maize.

Neonicotinoid seed treatments, typically clothianidin or thiamethoxam, are routinely applied to >80% of maize (corn) seed grown in North America where they are marketed as a targeted pesticide delivery system. Despite this widespread use, the amount of compound translocated into plant tissue from the initial seed treatment to provide protection has not been reported. Our two year field study compared concentrations of clothianidin seed treatments in maize to that of maize without neonicotinoid seed treatments and found neonicotinoids present in root tissues up to 34 days post planting. Plant-bound clothianidin concentrations followed an exponential decay pattern with initially high values followed by a rapid decrease within the first ~20 days post planting. A maximum of 1.34% of the initial seed treatment was successfully recovered from plant tissues in both study years and a maximum of 0.26% was recovered from root tissue. Our findings show neonicotinoid seed treatments may provide protection from some early season secondary maize pests. However, the proportion of the neonicotinoid seed treatment clothianidin translocated into plant tissues throughout the growing season is low overall and this observation may provide a mechanism to explain reports of inconsistent efficacy of this pest management approach and increasing detections of environmental neonicotinoids.