Concentrations In Brown Rice Research Articles

γ-Oryzanol Enhances Adipocyte Differentiation and Glucose Uptake.

Recent studies show that brown rice improves glucose intolerance and potentially the risk of diabetes, although the underlying molecular mechanisms remain unclear. One of the phytochemicals found in high concentration in brown rice is γ-oryzanol (Orz), a group of ferulic acid esters of phytosterols and triterpene alcohols. Here, we found that Orz stimulated differentiation of 3T3-L1 preadipocytes and increased the protein expression of adipogenic marker genes such as peroxisome proliferator-activated receptor gamma (PPAR-γ) and CCAAT/enhanced binding protein alpha (C/EBPα). Moreover, Orz significantly increased the glucose uptake in insulin-resistant cells and translocation of glucose transporter type 4 (GLUT4) from the cytosol to the cell surface. To investigate the mechanism by which Orz stimulated cell differentiation, we examined its effects on cellular signaling of the mammalian target of rapamycin complex 1 (mTORC1), a central mediator of cellular growth and proliferation. The Orz treatment increased mTORC1 kinase activity based on phosphorylation of 70-kDa ribosomal S6 kinase 1 (S6K1). The effect of Orz on adipocyte differentiation was dependent on mTORC1 activity because rapamycin blocks cell differentiation in Orz-treated cells. Collectively, our results indicate that Orz stimulates adipocyte differentiation, enhances glucose uptake, and may be associated with cellular signaling mediated by PPAR-γ and mTORC1.

Effects of tire rubber ash and zinc sulfate on crop productivity and cadmium accumulation in five rice cultivars under field conditions.

Cadmium (Cd) is among the most widespread and toxic heavy metals becoming a severe threat to humans. A field study was conducted to examine the role of various zinc (Zn) fertilization treatments and cultivars on crop productivity and Zn and Cd concentrations in brown rice and rice straw. The Zn fertilization treatments included an unfertilized control, foliar applied Zn sulfate (ZnSO4) at panicle initiation stage, foliar applied ZnSO4 at milky stage, soil application of rubber ash, and soil-applied ZnSO4, while five rice cultivars were Swat-1, Shadab, Shua-92, Swat-2, and Sada Hayat. All the Zn fertilization treatments resulted in significantly higher number of panicles, number of spikelets per panicles, spikelet fertility, 1,000-grain weight, grain yield, brown rice and rice straw Zn concentrations, and significantly lower Cd concentrations. Soil application of rubber ash remained the best among all Zn fertilization treatments as it resulted in 73% higher grain yield and reduced Cd concentration by 51% as compared with control. Variations were also apparent among cultivars, and Shua-92 and Swat-2 performed better in terms of all studied attributes as compared with other cultivars. Conclusively, cultivar selection and Zn application are effective strategies to improve rice grain yield as well as quality. Rubber ash appeared a viable source of Zn having the ability to increase yield along with reducing Cd accumulation.

Distribution of Radioactive Cesium (134Cs plus 137Cs) in Rice Fractions during Polishing and Cooking

We investigated the distribution of cesium-134 ((134)Cs) and cesium-137 ((137)Cs) during polishing and cooking of rice to obtain their processing factors (Pf) and food processing retention factors (Fr) to make the information available for an adequate understanding of radioactive Cs dynamics. Polishing brown rice resulted in a decreased radioactive Cs concentration of the polished rice, but the bran and germ (outer layers) exhibited higher concentrations than brown rice. The Pf values for 100% polished rice and outer layers ranged from 0.47 to 0.48 and 6.5 to 7.8, respectively. The Fr values for 100% polished rice and outer layers were 0.43 and 0.58 to 0.60, respectively. The distribution of radioactive Cs in polished rice and outer layers was estimated at approximately 40 and 60%, respectively. On the other hand, cooked rice showed significantly lower levels of radioactive Cs than polished rice, and transfer of radioactive Cs into wash water was observed. The Pf and Fr values for cooked rice were 0.28 and 0.65 to 0.66, respectively. From these results, we can calculate that if the radioactive Cs concentration in brown rice is 100 Bq/kg, the concentrations of Cs in polished rice and cooked rice will be 47 to 48 Bq/kg and 13 Bq/kg, respectively.

Effect of the concentration of radiocesium dissolved in irrigation water on the concentration of radiocesium in brown rice

In 2011, the radiocesium concentration of brown rice grown (Oryza sativa L.) in mountainous areas with irrigation water that flowed from a nearby mountain forest, in Fukushima Prefecture, Japan, exceeded 500 Bq kg–1. Migration of radiocesium from contaminated irrigation water was suspected. Here, we investigated the migration of dissolved radiocesium (137Cs) from irrigation water into brown rice by determining the concentration of 137Cs in brown rice grown in pots irrigated with water containing dissolved 137Cs (0.1, 1.0 or 10 Bq L–1 137Cs). The treatment water was prepared by extracting 137Cs from conifer branches collected from the contaminated area and diluting the stock solution with tap water. We used two Gray Lowland soils (soils A and B) collected from two paddy fields in Fukushima Prefecture. Rice plants (Oryza sativa L. cv. Hitomebore) were grown in pots and treatment water was kept at a depth of 3–5 cm throughout the growing season. We calculated the amount of 137Cs absorbed by the plants by subtracting 137Cs concentrations in brown rice grown with tap water from that in brown rice grown with treatment water. The concentration of 137Cs in brown rice increased in proportion to that in the treatment water. The concentration of 137Cs in brown rice grown with water containing 10 Bq L–1 137Cs in soil A was 4.9 times that in brown rice grown in soil B, but the concentration of 137Cs in brown rice grown in either soil was not significantly different when grown with water containing 0.1 Bq L–1 137Cs. Before plants were grown, the exchangeable potassium in soil B was 3.8 times that in soil A. At least, even with irrigation water containing about 0.1 Bq L–1 of radiocesium, the migration of radiocesium into brown rice is negligible for the provisional regulation value for radiocesium in brown rice under the condition of our experiment.

Exchangeable Cs/K ratio in soil is an index to estimate accumulation of radioactive and stable Cs in rice plant

Pot and field experiments were conducted to clarify the effect of soil exchangeable potassium (K) and cesium-137 (137Cs) on 137Cs accumulation and to establish soil index in rice (Oryza sativa L.). Four paddy soils in Fukushima Prefecture, Japan, showing different transfer factors for radioactive Cs derived from the accident of Fukushima Daiichi Nuclear Power Station in the field were compared in terms of 137Cs accumulation in rice in a pot experiment. 137Cs accumulation in shoots and brown rice widely varied among soils with the transfer factor ranging from 0.018 to 0.068 for shoots and 0.004 to 0.065 for brown rice. 137Cs concentration in brown rice and shoots tended to decrease with higher levels of soil exchangeable K, and they were more closely related to the exchangeable Cs/K ratio. Similar relationships between the Cs/K ratio and Cs accumulation in plants were obtained for the stable isotope cesium-133 (133Cs). The distributions of 137Cs and 133Cs in grains were also similar and variable among soils. The transfer factors obtained in pot experiments mostly agreed with field observations. The results imply that the exchangeable 137Cs/K can be a potential soil index to estimate 137Cs accumulation in rice.

Comparative analysis of the relationship between Cs and K in soil and plant parts toward control of Cs accumulation in rice

The effect of soil exchangeable potassium (K) and cesium (Cs) levels on Cs uptake and accumulation in different parts of rice (Oryza sativa L.) plants were examined using paddy soils with diverse exchangeable K and Cs in pot experiments. Aboveground Cs uptake decreased with higher exchangeable K and was linearly correlated with exchangeable Cs/K ratios, indicating competitive absorption of these elements by roots. Variation in Cs concentration in brown rice among soils was also related to the exchangeable Cs/K ratio. The exchangeable Cs/K ratio was positively reflected in the Cs/K concentration ratio in each plant part, with a specific slope, suggesting that Cs transport was coordinated with K transport and that there were regulated discriminations of Cs against K in the translocation process among parts. The Cs/K ratio was higher in brown rice and dead leaves than in active leaves, stems and husks. The distribution of Cs accumulation in brown rice was 14.5% on average, but it was variable and negatively related to K concentration in the stem. The Cs distribution in aboveground plant parts also decreased with higher K concentration in the root. These results imply the importance of the competitiveness with K in the root absorption and translocation of Cs within the plant. Based on the observed relationship between Cs and K, effective K management and other measures to control Cs accumulation in plant parts are discussed.

Difference in Cs-137 concentration of brown rice between the years of 2011 and 2012 in Fukushima Prefecture

The objective of this study was to understand the effect of decrease in available radiocesium independently of the potassium and zeolite application effect on the uptake of radiocesium by rice. Brown rice produced in seven paddy fields located at four different sites of Fukushima Prefecture were sampled in 2011 and 2012. Any decontamination treatment was not conducted in these fields during the 2-year period. The Cs-137 concentrations in brown rice was 30 % lower in 2012 (1.3–160 Bq kg−1) compared to those in 2011 (2.8–290 Bq kg−1) with neither decontamination nor additional application of potassium and/or zeolite.

In situ field-scale remediation of Cd polluted paddy soil using sepiolite and palygorskite

At present, the remediation of heavy-metal polluted soil is a considerable problem. In this study, in situ immobilization field experiments were conducted by planting rice (Oryza sativa L.) in Cd contaminated paddy soil to determine the optimal remediation mode that would reduce the accumulation of Cd in brown grain. Sepiolite and palygorskite were utilized as amendments, while ordinary and low Cd-accumulating rice cultivars were selected as model plants. The remediation effects of the amendments on the soil and rice were investigated and the potential immobilization mechanisms were analyzed using X-ray diffraction and X-ray photoelectron spectroscopy. The application of sepiolite and palygorskite was found to increase the pH value of the paddy soil, by varying amounts, and significantly reduce the HCl, TCLP, CaCl2, and NH4OAc-extractable Cd concentrations resulting in a notable decrease in the Cd concentration in brown rice. Both sepiolite and palygorskite were found to reduce exchangeable Cd concentrations and increase the carbonate-bound and residual fractions in paddy soil. Precipitation of Cd as carbonates or hydroxides and surface complexation were the main immobilization mechanisms for sepiolite and palygorskite. The concentration of Cd in brown rice of the low Cd-accumulating cultivar from the control plot was 0.72mg·kg−1. Sepiolite treatment reduced the value to 0.18mg·kg−1 below the maximum levels reported by Codex Stan 193-1995 and the national standard of China. It was concluded that chemical immobilization combined with crop cultivar selection could be a suitable proposal for crop safety regulation and sustainable agriculture.

Influence of Sulfur Supply on the Iron Accumulation in Rice Plants

The influence of sulfur (S) (0, 30, 60, and 120 mg S kg−1 soil) supply on iron (Fe) accumulation in rice was investigated in a soil (soil/sand = 4:1) culture experiment. Results showed that Fe concentration in brown rice stem/leaf increased initially and then decreased with the increase in S concentration from 30 to 120 mg kg−1. The greatest Fe concentration was achieved at 60 mg S kg−1, whereas Fe concentration in the roots decreased with the increase in S concentration. Possible mechanisms of S supply on Fe accumulation in rice were proposed. These results suggest that S fertilization is important in developing approaches to increase Fe accumulation in brown rice when cultivated in low-S soils. However, the S input in farmland, such as S-containing fertilizers (e.g., calcium superphosphate) and atmospheric S deposition may decrease Fe accumulation in brown rice when cultivated in high-S soils.

Evaluation of the radioactive Cs concentration in brown rice based on the K nutritional status of shoots

The radioactive cesium ((134,137)Cs) concentration in brown rice is correlated with that in the straw/husk. The distribution of (134,137)Cs, resembles that of potassium (K), a homologous element of Cs, in the rice plant body. The relative isotopic abundance of (40)K is 0.0117 %; thus, 1 g K contains 30.4 Bq ⁴⁰K, and the mass of 4,000 Bq (40)K is 0.0154 g, indicating that the K concentration can be calculated from (40)K concentration. We examined if the radioactive Cs concentration in brown rice can be estimated from (40)K concentrations in straw, and especially might be predicted from the (40)K:(134,137)Cs ratio in straw. We determined the concentrations of (40)K and radioactive Cs in straw and brown rice, and found a strong correlated-equation (y = 72.922 x(-0.759); r = 0.907) between the radioactive Cs concentration in brown rice and the ⁴⁰K:(134,137)Cs ratio in straw. The estimated-radioactive Cs concentration in brown rice can be as much as double, depending on the K nutritional status changing the ⁴⁰K:(134,137)Cs ratio in straw. We herein propose a nutritional diagnosis that radioactive Cs concentrations in brown rice can be predicted from the ⁴⁰K:(134,137)Cs ratio in shoots.

Genetic Variation and Association Mapping of Protein Concentration in Brown Rice Using a Diverse Rice Germplasm Collection

ABSTRACTProtein is the second most abundant constituent in the rice grain next to starch. Association analysis for protein concentration in brown rice was performed using a “mini‐core” collection, which represents the germplasm diversity found in the USDA rice world collection. Protein concentration was determined in replicated trials conducted in two southern U.S. locations, and association mapping was performed by using 157 genomewide DNA markers. Protein concentration ranged from 5.4 to 11.9% among the 202 accessions. Protein variation owing to accession and accession × location interaction were highly significant. Ample variation was seen within each subpopulation by ancestry, as well as within the 14 geographic regions where the accessions originated. Accessions from Eastern Europe had the highest level of protein. Ten markers on eight chromosomes were significantly associated with protein concentration. Five of these markers occurred near known protein precursor genes or quantitative trait loci, and the other five markers were novel for the association with protein concentration in rice. The germplasm and genetic markers identified in this study will assist breeders in developing cultivars tailored for applications requiring specific protein concentration in the rice grain. The research results contribute to the potential discovery of novel rice storage protein pathways in the endosperm.

Water management affects arsenic and cadmium accumulation in different rice cultivars

Paddy rice (Oryza sativa L.) is a staple food and one of the major sources of dietary arsenic (As) and cadmium (Cd) in Asia. A field experiment was conducted to investigate the effects of four water management regimes (aerobic, intermittent irrigation, conventional irrigation and flooding) on As and Cd accumulation in seven major rice cultivars grown in Zhejiang province, east China. With increasing irrigation from aerobic to flooded conditions, the soil HCl-extractable As concentrations increased significantly and the HCl-extractable Cd concentrations decreased significantly. These trends were consistent with the As and Cd concentrations in the straw, husk and brown rice. Water management both before and after the full tillering stage affected As and Cd accumulation in the grains. The intermittent and conventional treatments produced higher grain yields than the aerobic and flooded treatments. Cd concentrations in brown rice varied 13.1-40.8 times and As varied 1.75-8.80 times among the four water management regimes. Cd and As accumulation in brown rice varied among the rice cultivars, with Guodao 6 (GD6) was a low Cd but high-As-accumulating cultivar while Indonesia (IR) and Yongyou 9 (YY9) were low As but high-Cd-accumulating cultivars. Brown rice Cd and As concentrations in the 7 cultivars were significantly negatively correlated. The results indicate that As and Cd accumulated in rice grains with opposite trends that were influenced by both water management and rice cultivar. Production of 'safe' rice with respect to As and Cd might be possible by balancing water management and rice cultivar according to the severity of soil pollution.

Excessive sulfur supply reduces arsenic accumulation in brown rice

The objective of this study was to investigate the influence of excessive sulfur (S) supply on iron plaque formation and arsenic (As) accumulation in rice plants. A combined soil-sand pot experiment was conducted by using two As levels (0, 20 mg/kg) combined with three S concentrations (0, 60, 120 mg/kg). The results showed that excessive S supply significantly decreased As concentration in brown rice, but As concentration in root increased with increasing rate of S supply. Moreover, bioconcentration factors for leaves and stems were 8–35 fold of that for brown rice, indicating that As was mainly accumulated in rice leaves and stems instead of brown rice. Furthermore, excessive S supply significantly decreased translocation factor of As compared to treatment without S supply. These results indicated that excessive S may reduce As translocation from soils and roots to grain. The mechanism could be ascribed to excessive S that induced the decrease of As availability, the increase of iron plaque formation under As stress, and the increase of glutathione in rice leaves and roots. Therefore, excessive S can reduce As accumulation in brown rice exposed to As contaminated soils though it may result in loss of rice yield.

Effects of Different Cultivation Methods and Straw Incorporation on Grain Yield and Nutrition Quality of Rice

Plastic film mulching cultivation (PFMC) under non-flooded condition has been considered as a new water-saving technique in rice production, while yield decline from continuous cropping of aerobic rice is a constraint to the widespread adoption of PFMC. Rice straw incorporation has been proposed to counter this negative effect in recent decades. This study examined the effects of three cultivation methods and rice straw incorporation on rice grain yield and quality using Liangyoupeijiu (an indica hybrid). The three cultivation treatments were: conventional flooding cultivation (CFC); non-flooded plastic film mulching cultivation (PFMC); no mulching cultivation in non-flooded condition (NMC). Compared with that under CFC, average rice grain yield under PFMC from 2008 to 2010 was significantly improved by 8.0%, while total amino acids content was decreased by 3.5%, no obvious effect was observed on rice protein, Fe and Zn concentrations in rice; under NMC, the reduction in yield, protein, total amino acids and Fe concentrations were 5.1%, 4.4%, 9.3%, and 11.8%, respectively. With rice straw incorporation, grain yield was improved by 113.6, 142.6, and 522.1 kg ha 1 under CFC, NMC, and PFMC, respectively. Average rice grain yield, Fe and Zn contents in brown rice were significantly improved by 3.3%, 3.1%, and 6.4% with rice straw incorporation. The results of the three years showed the same trend in rice grain yield and nutrition quality. The results indicated that PFMC could improve not only grain yield, but also part of rice nutrition quality. Rice straw incorporation could significantly improved rice grain yield as well as Fe and Zn concentrations in brown rice, which would be a good method to overcome grain yield decline under long term PFMC.

Increasing iron and zinc in rice grains using deep water rices and wild species - identifying genomic segments and candidate genes

Large genetic variation exists for grain iron and zinc in rice germplasm including wild species and deep water rices. Conventional breeding is an easy and acceptable approach to biofortify rice. Analysis of 126 rice accessions using atomic absorption spectrophotometry showed that Fe concentration in brown rice ranged from 6 ppm in Athira to 72 ppm in O. nivara and Zn concentration from 27 ppm in Jyothi to 67 ppm in O. rufipogon. Quantitative trait loci (QTL) for high Fe and Zn concentration in grains were mapped from 3 wild progenitors and 2 deep water rices with the aim of gene discovery and also to develop iron/zinc-rich lines of two widely grown, popular rice varieties Swarna (MTU7029) and Samba Mahsuri (BPT5204) through conventional breeding approaches. Three advanced backcross mapping populations were developed using 3 wild accessions: Swarna x O.nivara IRGC81832, Swarna x O.nivara IRGC81848 and Samba Mahsuri x O.rufipogon WR119. In addition, F7 recombinant inbred lines (RILs) were developed from two crosses: Madhukar x Swarna and Jalmagna x Swarna. Madhukar and Jalmagna are deep-water rice varieties with high grain iron and zinc. Overall, Fe concentration ranged from 0.2 to 224 ppm and Zn concentration from 0.4 to 104 ppm in the 5 mapping populations. QTLs for Fe and Zn concentration in polished rice were mapped from two Swarna x O. nivara BC2F3 mapping populations using accession IRGC81848- 227 families, 100 SSR markers and accession IRGC81832- 245 families, 75 SSR markers. qFe2.1, qFe3.1, qFe8.1 and qFe8.2 coincided in the two populations. QTLs for Fe and Zn concentration coincided on chromosomes 2, 3, 8 and 12. Five QTLs for Fe and 3 QTLs for Zn each explained more than 15% phenotypic variance. QTLs were also mapped for Fe and Zn concentration in brown rice from Madhukar x Swarna F7 RILs using 110 SSR markers including 9 gene specific markers. Seven QTLs for Fe and six QTLs for Zn were identified each explaining >30% phenotypic variance. QTLs for Fe and Zn concentration coincided on chromosomes 7 and 12. Madhukar allele increased Fe in qFe7.1 and qFe7.2 and Swarna allele increased Zn in qZn12.1 and qZn12.2. Only two QTL flanking markers RM243 for qFe1.1 and RM517 for qZn3.1 were common in the 3 mapping populations. Genotyping of 2 populations is in progress. Candidate genes OsYSL1, OsNAC, OsYSL16, OsZIP4, OsYSL17 and OsNAAT1 underlie the Fe or Zn QTLs mapped in the Swarna x O.nivara mapping population. Likewise, OsYSL1, OsMTP1, OsNAS1, OsNAS3, OsNRAMP1, heavy metal ion transporter, OsAPRT underly QTLs for Fe and Zn mapped in the Madhukar x Swarna mapping population. In all, 20 elite lines with >80 ppm iron and >50ppm zinc in brown rice were identified from 5 mapping populations. These non-transgenic rice lines with high iron, high zinc or both are a useful resource for functional genomics and biofortification programmes.

Effects of iron and zinc foliar applications on rice plants and their grain accumulation and grain nutritional quality

Foliar sprays of iron (Fe) and zinc (Zn) fertilisers are known to be an effective way to improve Fe and Zn concentrations in rice grain. However, results can differ significantly among different rice cultivars and/or types of foliar fertiliser. In this study, several Fe-rich rice cultivars were used to identify an effective foliar fertiliser for optimal Fe and Zn enrichment of rice grain. Foliar Fe amino acid (Fe-AA) fertiliser significantly improved the Fe concentration in brown rice of most cultivars. Compared with the control, the average Fe concentration in all tested cultivars was increased by 14.5%. The average Fe concentration was increased by 32.5% when 1% (w/v) nicotianamine (NA) was added to Fe-AA, while the average Zn concentration was increased by 42.4% when 0.5% (w/v) ZnSO₄ · 7H₂O was added to Fe-AA. The results suggested that NA at a suitable concentration added to Fe-AA fertiliser could accelerate Fe accumulation in rice grain. A relatively low concentration of ZnSO₄ · 7H₂O added to Fe-AA significantly increased Fe and Zn accumulation in rice grain. The study identified some useful foliar fertilisers for enhancing the levels of Fe and Zn in selected Fe-rich rice cultivars.

Selection of Cd-Excluder Rice in Shenyang Region of China for Food Safety

It is one of very important technologies of phytoremediation using low accumulative plant especially excluder crop to safely product food in contaminated soil. In order to identify some excluder crop cultivars, a pot experiment was conducted to compare Cd accumulation differences among of 26 normal and 4 hybrid rice cultivars (Japonica) in Shenyang region of China for food safety aim. The results showed that only Cd concentration in brown rice of Shendao 4 among of 30 rice cultivars was lower than 0.2 mg kg-1 (agricultural trade standard of non-pollution food for rice of China, NY 5115-2008) at a lower level of Cd exposure spiked at 2.5 mg kg-1. When soil Cd spiked at 5 mg kg-1, Cd concentration in brown rice of Shendao 4 was lower either compared to other cultivars, and its enrichment factors (EFs) and translocation factors (TFs) were lower than 1.0 and 0.5, respectively. Furthermore, the yields of grains and the biomasses of aboveground of Shendao 4 didn’t decrease significantly compared to the control (p<0.05), indicating it was a Cd-excluder cultivar. This is a new and important found in Northeast China rice production and may have an important interest in exploring crop exclusion mechanism.

Biofortification of rice grain with zinc through zinc fertilization in different countries

Increasing zinc (Zn) concentration of rice seed has potential benefits for human nutrition and health. Enhanced levels of Zn in grain also contributes greatly to crop production through better germination and seedling vigor of rice plants grown on soils with limited Zn supply. This study evaluated the effect of soil and/or foliar Zn fertilizer application on grain yield and grain Zn concentration of rice grown in 17 field trials conducted in 2008 to 2010 in China, India, Lao PDR, Thailand and Turkey on soils ranging in pH from 4.8 to 8.8 and DTPA- extractable Zn from 0.5 to 6.5 mg kg−1. Zinc fertilization had little effect on rice grain yield with the exception of increases of up to 10 % in some locations in China and India. As an average of all trials, Zn application increased grain yield by about 5 %. Grain Zn concentrations were, however, more effectively increased by Zn fertilization, especially with foliar Zn applications. On average, Zn concentration in brown rice (whole caryopsis with husk removed) was increased by 25 % and 32 % by foliar and foliar + soil Zn applications, respectively, and only 2.4 % by soil Zn application. The Zn concentration of un-husked rice (whole grain with husk), which was increased by 66 % by foliar Zn, showed a close association with the Zn in brown and white rice, indicating a possible penetration of Zn from the husk into the inner layers of the rice endosperm. Increase in grain Zn concentration by foliar Zn spray was significantly affected by the timing of the foliar application. More distinct increases in grain Zn by foliar Zn application were achieved when Zn was applied after flowering time, e.g., at early milk plus dough stages. Foliar Zn spray offers a practical and useful means for an effective biofortification of rice grain with Zn. This practice consistently and significantly contributed to increases in grain Zn of rice irrespective of cultivars, environmental conditions and management practices in 5 different countries.

Potential Risks of Copper, Zinc, and Cadmium Pollution due to Pig Manure Application in a Soil–Rice System under Intensive Farming: A Case Study of Nanhu, China

Heavy metal (copper [Cu], zinc [Zn], and cadmium [Cd]) pollution of soils from pig manures in soil-rice ( L.) systems under intensive farming was investigated, taking Nanhu, China, as the case study area. Two hundred pig manures and 154 rice straws, brown rice samples, and corresponding surface soil (0-15 cm) samples were collected in paddy fields from 150 farms in 16 major villages within the study area. The mean Cu and Zn concentrations in pig manures consistently exceeded the related standard. About 44 and 60% of soil samples exceed the Chinese Soil Cu and Cd Environmental Quality Standards, respectively. The concentration of Cu, Zn, and Cd in brown rice did not exceed the Chinese Food Hygiene Standard. There was a significant positive correlation between total Cu and Zn contents in soil and application rate of pig manures. Strong correlation was observed between the extractable Cu, Zn, and Cd in soil and the Cu, Zn, and Cd contents in the brown rice. The spatial distribution maps of Cu and Zn concentrations in brown rice, straw, and extractable soil Cu and Zn concentration also showed similar geographical trends. Further analyses on heavy metals loading flux and accumulation rates from pig manure applied suggested that Cu and Cd contents in soil currently have already exceeded the maximum permissible limit, and Zn, if still at current manure application rates, will reach the ceiling concentration limits in 9 yr. This study assists in understanding the risk of heavy metals accumulating from pig manure applications to agricultural soils.

Immunochromatography for the rapid determination of cadmium concentrations in wheat grain and eggplant

A simple and quick on-site test for trace levels of cadmium (Cd) in food is needed because of the human toxicity of this heavy metal. We developed an immunochromatography kit which uses the antigen-antibody complex reaction between the Cd-ethylenediaminetetraacetic acid (Cd-EDTA) complex and an anti-Cd-EDTA antibody. We previously reported the successful use of this kit to determine Cd concentrations in brown rice with respect to the international standard: 0.4 mg kg⁻¹. Here, we measured, using this immunochromatography kit, Cd concentrations in crops with lower international standards than rice. Cadmium extracted with 0.1 mol L⁻¹ HCl from wheat grain and fresh eggplant was purified sufficiently using an ion-exchange column treatment. Appropriate HCl extraction rates and dilution rates for the column eluate were selected; Cd concentrations in wheat grain and fresh eggplant were determined successfully by immunochromatography with respect to the international standards of 0.2 mg kg⁻¹ and 0.05 mg kg⁻¹ fresh weight, respectively. Approximate Cd concentrations in wheat grain and fresh eggplant can be monitored easily and quickly by this method at locations where facilities for acid digestion and precision analysis are not available.