Persistence and Metabolism of Fipronil in Sugarcane Leaves and Juice

Fipronil gives effective control of early shoot borer and termites in sugarcane. The persistence and metabolism of fipronil in sugarcane leaves and juice were studied following application of fipronil (Regent 0.3 G) at 75 and 300 g a.i. ha^?1. Samples of sugarcane leaves were collected at various time intervals. Samples of sugarcane juice were collected at harvest. Residues of fipronil and its metabolites were quantified by gas liquid chromatograph. The limit of quantification of fipronil and its metabolites was 0.01 mg kg^?1 for sugarcane leaves and juice. Total residues of fipronil and its metabolites in sugarcane leaves after 7 days of its application at 75 and 300 g a.i. ha^?1 were 0.26 and 0.66 mg kg^?1, respectively. Residues could not be detected after 60 and 90 following fipronil application at either concentration. In sugarcane leaves, fipronil was found to be the main constituent, followed by its metabolites amide, desulfinyl, sulfone and sulfide. Samples of sugarcane juice did not reveal the presence of fipronil or its metabolites following its application at both the dosages at harvest.     

Persistence and Metabolism of Imidacloprid in Rice

Imidacloprid is a systemic insecticide which gives effective control of plant and leaf hoppers in rice. The persistence and metabolism of imidacloprid in paddy leaves, rice grains, bran, straw and husk were studied following two applications of imidacloprid (Confidor 17.8 SL) @ 20 and 80 g a.i. ha^?1 at an interval of 10 days. Samples of paddy leaves were collected at various time intervals. The samples of rice grains, bran, straw and husk were collected at the time of harvest. The limit of quantification of imidacloprid and its metabolites was worked out to be 0.01 mg kg^?1. The maximum residues of imidacloprid and its metabolites in paddy leaves after 0 day (1 h after last spray) of its application @ 20 and 80 g a.i. ha^?1 were found to be 4.57 and 13.94 mg kg^?1, respectively. These residues could not be detected after 60 and 90 days following last application of imidacloprid at lower and higher dosages, respectively. In rice, olefin metabolite was found to be the main constituent, followed by nitroguanidine, urea, 5-hydroxy, chloronicotinic acid and nitrosimine. The samples of rice grains, bran, straw and husk did not reveal the presence of imidacloprid or its metabolites following its application at both the dosages at harvest.     

Evaluation of Mercury Uptake and Distribution in Rice (Oryza sativa L.)

Bulletin of Environmental Contamination and Toxicology - Mercury (Hg) contamination in soil-rice systems from industry, mining and agriculture has received increasing attention recently in China....     

Effect of Three Insecticides and Two Herbicides on Rice (Oryza sativa) Seedling Germination and Growth

Rice (Oryza sativa L.) is one of the most important food crops worldwide. However, it is also a valuable tool in assessing toxicity of organic and inorganic compounds. For more than 20 years, it has been an approved species for standardized phytotoxicity experiments. The objective of this study is to determine germination and radicle (root) and coleoptile (shoot) growth of rice seeds exposed to three insecticides and two herbicides, commonly used in the agricultural production landscape. Although no germination effects of pesticide exposure were observed, significant growth effects were noted between pesticide treatments. Coleoptile growth was significantly (p ≤ 0.05) lowered in metolachlor/atrazine mixture, diazinon, and lambda-cyhalothrin exposures when compared with controls. Radicles of fipronil-exposed seeds were significantly larger (p ≤ 0.05) when compared with controls. This research contributes to the phytotoxicity assessment database, in addition to laying the foundation for the use of rice as a phytoremediation tool for agricultural pesticide runoff.     

Accumulation and phytotoxicity of microcystin-LR in rice (Oryza sativa)

Irrigation with eutrophic water containing microcystins-LR (MC-LR) poses a potential risk to crops. However, the accumulation of MC-LR in rice grains and the mechanism of MC-LR-induced inhibition in rice roots are not understood. In this study, we detected the accumulation of MC-LR in rice grains collected from Taihu Lake region. MC-LR could accumulate in rice grains, but the risk evaluation suggested that MC-LR levels in rice grains from Taihu Lake region may not pose a threat to human health currently. In addition, MC-LR with low concentrations did not affect the growth of rice roots. However, MC-LR with high concentrations impeded the rice root morphogenesis by inhibiting root elongation, crown root formation, and lateral root development from primordia. Treatment with high concentrations of MC-LR stimulated the production of reactive oxygen species (ROS) and inhibited the production of nitric oxide (NO) in rice roots. Exogenous NO treatment reversed the inhibition of rice root growth under MC-LR stress. These results indicated that ROS and NO played important roles in the development of rice roots in responding to MC-LR stress.     

Changes in Bone Metabolism and Antioxidant Defense Systems in Menopause-Induced Rats Fed Bran Extract from Dark Purple Rice (Oryza sativa L. Cv. Superjami)

Menopause is a matter of concern for women’s health due to a deficiency of female hormones; additionally, reactive oxygen species and aging can cause osteoporosis. Food becomes increasingly interesting as a menopausal woman’s alternative to hormone therapy. The effects of ethanol extracts from dark purple Superjami rice bran on bone metabolism and antioxidant defense systems in menopause-induced animal models were evaluated. Female rats underwent sham surgery or were ovariectomized to induce a menopause-like state. Rats were divided into a sham control group (SHAM), an ovariectomized control group (OVX), and an ovariectomized grou supplemented with Superjami rice bran extract group (OVX-S) and fed for 8 weeks. The OVX groups exhibited significantly more weight gain, amounts of bone turnover biochemical markers (alkaline phosphatase, osteocalcin, and C-terminal telopeptide), bone loss, lipid-peroxidation and oxidative stress than the SHAM group. However, Superjami bran extract added to the diet resulted in a significant reduction in body weight and lipid peroxidation, as well as enhanced bone metabolism and antioxidant enzyme activities, in ovariectomized rats. These results propound that extracts from Superjami rice bran have therapeutic potentiality against bone loss and oxidative stress in menopause-induced states and will be useful in preventing postmenopausal osteoporosis and oxidative damage.     

Arsenite Tolerance is Related to Proportional Thiolic Metabolite Synthesis in Rice (Oryza sativa L.)

Thiol metabolism is the primary detoxification strategy by which rice plants tolerate arsenic (As) stress. In light of this, it is important to understand the importance of harmonised thiol metabolism with As accumulation and tolerance in rice plant. For this aim, tolerant (T) and sensitive (S) genotypes were screened from 303 rice (Oryza sativa) genotypes on exposure to 10 and 25 μM arsenite (As^III) in hydroponic culture. On further As accumulation estimation, contrasting (13-fold difference) T (IC-340072) and S (IC-115730) genotypes were selected. This difference was further evaluated using biochemical and molecular approaches to understand involvement of thiolic metabolism vis-a-vis As accumulation in these two genotypes. Various phytochelatin (PC) species (PC₂, PC₃ and PC₄) were detected in both the genotypes with a dominance of PC₃. However, PC concentrations were greater in the S genotype, and it was noticed that the total PC (PC₂ + PC₃ + PC₄)–to–As^III molar ratio (PC-SH:As^III) was greater in T (2.35 and 1.36 in shoots and roots, respectively) than in the S genotype (0.90 and 0.15 in shoots and roots, respectively). Expression analysis of several metal(loid) stress–related genes showed significant upregulation of glutaredoxin, sulphate transporter, and ascorbate peroxidase in the S genotype. Furthermore, enzyme activity of phytochelatin synthase and cysteine synthase was greater on As accumulation in the S compared with the T genotype. It was concluded that the T genotype synthesizes adequate thiols to detoxify metalloid load, whereas the S genotype synthesizes greater but inadequate levels of thiols to tolerate an exceedingly greater load of metalloids, as evidenced by thiol-to-metalloid molar ratios, and therefore shows a phytotoxicity response.     

Cadmium Pollution in Paddy Soil as Affected by Different Rice (Oryza sativa L.) Cultivars

No abstract available.     

Potential Health Risk of Total Arsenic from Consumption of Farm Rice (Oryza sativa) from the Southern Caspian Sea Littoral and from Imported Rice in Iran

In this study, Arsenic (As) was measured in several varieties of imported and local cultivated rice. Soil samples collected from rice farms situated in south Caspian Sea (Iran) were also studied. The mean concentration of As in imported rice, local farmed rice and soil, were determined as 0.28, 0.39 and 3.80 μg g⁻¹ dry weight, respectively. Estimated daily intake of As through human consumption of imported and local produced rice was 0.77 and 1.074 μg day⁻¹ kg⁻¹ B.W., respectively. These values are much lower than the tolerable daily intakes estimated by JECFA. The As concentration in the soil (3.80 μg g⁻¹ dry) was below acceptable limit for agricultural soil of 20.0 mg kg⁻¹ as recommended by the European Community (EC). No correlation between the As concentrations in rice and soil samples was found (p > 0.05).     

The Effects of Oil Well Drill Cuttings on Soil and Rice Plant Development (Oryza sativa) Under Two Redox Conditions

Few studies have focused on the release of toxic elements from oil well drill cuttings and their effect on soil. The present study evaluated these effects using rice growth as the endpoint. Drill cuttings were collected from a Brazilian well and added in doses of 300, 3,000 and 6,000 mg kg^?1 soil, which was maintained at oxidized or reduced conditions. When the redox potential reached approximately ?250 mV, barium concentrations were determined by geochemical fractionation. Overall, doses of 300 and 3,000 mg kg^?1 promoted plant development, while a dose of 6,000 mg kg^?1 inhibited it due to the associated increase in electrical conductivity and exchangeable sodium concentration. In addition, the lower redox potential promoted solubilization of barite from the drill cuttings, which increased barium absorption by plants and translocation to grain, posing a risk to human health.     

Persistence and Dissipation of O-Sec-Butylphenyl N-Methylcarbamate (BPMC) in Rice Ecosystem

No abstract available.     

Tungsten (W) bioavailability in paddy rice soils and its accumulation in rice (Oryza sativa)

The aim of this study was to investigate the accumulation characteristics of tungsten (W) by different indica rice cultivars from the soil and to assess the potential risks to human health via dietary intake of W in rice consumption. A total of 153 rice (ear) samples of 15 cultivars and the corresponding surface soil samples were collected from 7 cities in Fujian Province of southeastern China. The available soil W were extracted using H₂C₂O₄·2H₂O-(NH₄)₂C₂O₄·H₂O at pH 3.3). Results showed that the total soil W ranged from 2.03 mg kg^?1 to 15.34 mg kg^?1 and available soil W ranged from 0.03 mg kg^?1 to 1.61 mg kg^?1. The W concentration in brown rice varied from 7 μg kg^?1 to 283 μg kg^?1 and was significantly correlated with the available soil W. The highest mean TF_avail (transfer factor based on available soil W) was 0.91 for Te-you 627 (hybrid, indica rice), whereas the lowest was 0.08 for Yi-you 673 (hybrid, indica rice). The TF_avail decreased with the increase in available soil W, clay content, and cation exchange capacity. The consumption of the brown rice produced from the investigated areas in some cultivars by the present study may cause risks to human health.     

Effects of Microplastics on the Mineral Elements Absorption and Accumulation in Hydroponic Rice Seedlings (Oryza sativa L.)

Environmental pollution caused by microplastics (MPs) have become a non-negligible environmental problem and come into our notice recently. Herein, the nutrient elemental signature (ionome) of rice seedlings exposed to four levels of polyethylene microplastics (PE-MPs), and was analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) or mass spectroscopy (ICP-MS) to determine the relationship between ionome and MPs. After 21 days of laboratory exposure, no shoots growth difference has shown among any doses of PE-MPs treatments, however, the roots growth was significantly inhibited after the medium and high doses of PE-MPs treatments. Further analysis showed that PE-MPs treatments could decrease the accumulation of one essential mineral element Mn and some non-essential mineral elements accumulation including As and Cd, while increase the accumulation of one essential mineral elements including Na in rice seedlings. This study is the first to document the variation of the rice seedlings ionome after exposing microplastics.

     

Biochemical and Physiological Responses of Rice (Oryza sativa L.) Grown on Different Sewage Sludge Amendments Rates

Using sewage sludge, a biological residue from sewage treatment processes, in agriculture is an alternative disposal technique of waste. To study the biochemical and physiological responses of Rice (Oryza sativa L.) grown on different sewage sludge amendments (SSA) rates a field experiment was conducted by mixing sewage sludge at 0, 3, 4.5, 6, 9, 12 kg m⁻² rate to the agricultural soil. Rate of photosynthesis and stomatal conductance increased in plants grown at different SSA rate. Chlorophyll and protein contents also increased due to different SSA rates. Lipid peroxidation, ascorbic acid, peroxidase activity and proline content increased, however, thiol and phenol content decreased in plants grown at different SSA rates. The study concludes that for rice plant sewage sludge amendment in soil may be a good option as plant has adequate heavy metal tolerance mechanism showed by increased rate of photosynthesis and chlorophyll content and various antioxidant levels.     

Cadmium Content of Commercial and Contaminated Rice, Oryza sativa, in Thailand and Potential Health Implications

Thailand is the number one global exporter and among the top five producers of rice in the world. A significant increase in anthropogenic contamination in agricultural soils over the past few decades has lead to concerns with cadmium and its uptake in rice. The cadmium levels in Thai rice from different sources/areas were determined and used to estimate the potential health risks to consumers. The cadmium concentration in the commercial rice samples ranged from below the detection limit to 0.016 mg/kg. The cadmium concentrations in the contaminated rice samples ranged from a low of 0.007 mg/kg to a high of 0.579 mg/kg. Five of the calculated values exceed the proposed PTWI, with one value almost three times higher and two values almost double. The three highly elevated values are certainly a concern from a health standpoint. Ultimately, action is required to address the health implications resulting from the cadmium contamination in agricultural soils used for rice production in a few select areas of Thailand. Overall, this study indicates that the vast majority of rice produced, consumed and exported by Thailand is safe pertaining to cadmium content.     

Inorganic mercury accumulation in rice (Oryza sativa L.)

To investigate the source and process of inorganic mercury (IHg) accumulation in rice, we monitored the concentrations of IHg in tissues of rice plants (Oryza sativa L.) from four experimental plantation plots. Biweekly during the rice-growing season, tissues of rice plants, corresponding soil, precipitation, and irrigation water samples were collected. The sampling data support the following: (1) the atmosphere is the principal source of IHg to the aboveground parts of the rice plant; (2) both the atmosphere and soil contribute to IHg content in stalks, but the former source tends to be more important; and (3) soil is the major source of root IHg content. These observations and the fact that the gradually increasing concentration and mass of IHg in stalks and leaves during the rice-growing season suggested that atmospheric Hg could be absorbed by and incorporated into the aboveground parts of the rice plant and that limited or no Hg emission to the air or translocation to the soil occurred after deposition of atmospheric Hg. The root surface acted as a potential Hg barrier and consequently reduced the translocation of Hg ion mass through the root system to the aboveground parts. Accumulated IHg in aboveground parts of rice plants cannot be transported to seeds, which is completely different from the case of methylmercury. Environ. Toxicol. Chem. 2012; 31: 2093-2098. ? 2012 SETAC.     

Profile of phenolic compounds in Indonesian rice (Oryza sativa) varieties throughout post-harvest practices

Apart from being a foremost source of calories for a large part of the world’s population, cultivated rice (Oryza sativa) provides beneficial effects for human health through several bioactive compounds, including phenolics. Therefore, to earn this advantage, it is essential to retain the phenolics through appropriate post-harvest practices. In this paper, the profile of 10 individual phenolic compounds contained by rice grains after drying, dehusking and polishing processes were studied. A number of Indonesian rice cultivars from indica and javanica subspecies were acquired from conventional (IR-64, Umbul-umbul and Pandanwangi) and organic farming (Batang Lembang, Pandanwangi, black- and red-pigmented rice) were studied. Additionally, the effect of polishing degree on individual phenolics content in the grain was also evaluated. The level of phenolics decreased, also their relative values dramatically changed throughout a series of post-harvest processes. Moreover, changes on the composition of phenolic acids and its aldehydes in the grain have been described. p-Coumaric acid reflects the greatest differences on the phenolic composition during the course of post-harvest practices that altered from 48% to 8% portion to the total phenolics in paddies and polished grains, respectively. However, phenolics content in black-pigmented rice appeared to be the most persistent in the rice matrix. Since the profile of individual phenolics has also been evaluated on different polishing degrees (70%, 80%, 90% and 100% bran removal), the distribution of these compounds in the whole grain rice was effectively disclosed. These variations in the compositions and quantities of phenolics revealed the effect of post-harvest practices, varietal differences as their distribution in the grain.     

Responses of Antioxidant Enzymes to Chronic Free-Air Ozone Stress in Rice (Oryza sativa L.) Cultivars with Different Ozone-Sensitivities

Bulletin of Environmental Contamination and Toxicology - Free-air O3 enrichment was used to investigate the responses of different antioxidant mechanisms in different rice (Oryza sativa L.)...     

Selenium (Se) Does Not Reduce Cadmium (Cd) Uptake and Translocation in Rice (Oryza sativa L.) in Naturally Occurred Se-Rich Paddy Fields with a High Geological Background of Cd

This study examined the selenium (Se) and cadmium (Cd) uptake by rice from soil and analyzed the relationship between Se and Cd in naturally occurred Se-rich paddy fields with a high geological background of Cd. Significant correlations were observed between soil Se and plant biomass Se, but not between soil Cd and plant biomass Cd. High concentrations of Cd were detected in rice plants and particularly in rice grains, suggesting potential health risks to human. Contrary to results from other previous studies, our results showed that high soil Se did not reduce Cd uptake by rice, although it decreased the availability of Cd in soil. Rather, soil Se and internal Se pool in rice were positively correlated to the transfer of Cd from root to straw. The effect of Se on the uptake and translocation of Cd in rice in field is therefore different from those in pot experiments.

     

Effect of Rice (Oryza sativa L.) Ceramides Supplementation on Improving Skin Barrier Functions and Depigmentation: An Open-Label Prospective Study

Ceramides plays a crucial role in maintaining skin barrier function. Although foregoing evidence supported beneficial effects of topical ceramides for restoration of the skin barrier, studies on oral ceramides are extremely scarce, with most published data collected from in vivo and in vitro models. Thus, this study aimed to evaluate the efficacy of rice ceramides (RC) supplementation to improve skin barrier function and as a depigmenting agent through comprehensive clinical assessments. This study investigated the beneficial effects of orally administered RC supplementation in 50 voluntary participants. Skin hydration, firmness and elasticity, transepidermal water loss (TEWL), melanin index (MI), erythema index (EI), sebum production, pH, and wrinkle severity were assessed at baseline and during monthly follow-up visits. RC supplementation was found to significantly (p < 0.01) improve skin hydration, sebum production, firmness and elasticity, and wrinkle severity for three assessed areas, namely the left cheek, dorsal neck, and right inner forearm. Additionally, RC significantly (p < 0.01) reduced the rates of TEWL, levels of MI and EI. Analyses of data indicated that participants at older age were more responsive towards the effect of RC supplementation. Our findings suggest that RC supplementation can effectively improve skin barrier function, reduce wrinkle severity, and reduce pigmentation.