Cd Concentration In Grain Research Articles

Crucial roles of cadmium retention in nodeⅡ for restraining cadmium transport from straw to ear at reproductive period in a grain low-cadmium rice line (Oryza sativa L.)

Using an ideal parental line to breed hybrid rice with low cadmium (Cd) accumulation in grain is an environmental-friendly approach to reduce the risk of Cd contamination in field. A grain low-Cd rice line YaHui2816 has stably low Cd in grain but strong Cd accumulation in straw, revealing specific pattern of its straw-grain Cd remobilization is beneficial to effectively breed hybrid rice for safe production as well as phytoremediation. In this study, a pot experiment was conducted to investigate Cd partitioning of YaHui2816 at different stages by comparison with a common rice C268A. The Cd from lower nodes and leaves was restricted in nodeⅡ, this Cd retention led to weak Cd transport from straw to ear in YaHui2816. Cd concentration in nodeⅡ of YaHui2816 was 1.56-fold and 7.36-fold higher than C268A at filling and mature stages. Thus, glutathione (GSH) and phytochelatin (PC) concentration, PC synthase (OsPCS1), GSH S-Transferase (OsGST) and Cd-remobilization associated genes were measured at filling stage. OsHMA2 and OsCCX2 were up-regulated in nodeⅡ of YaHui2816, relative expression of them were significantly higher than C268A. PCs participated in Cd remobilization process, remarkable PC increase in nodeⅡ of YaHui2816 was found in response to Cd treatment under regulation of OsPCS1 and OsGST of which PC2 was dominant form. Taken as a whole, the Cd retention in nodeⅡ of YaHui2816 acts as a ‘firewall’ to restrain Cd transport to grain. This work provides more insight to understand possible function of alleles for reducing Cd concentration in grain as well as strengthening Cd accumulation in straw of YaHui2816.

Coupling phytoremediation of cadmium-contaminated soil with safe crop production based on a sorghum farming system

With increasing environmental pressure and soil pollution, sustainable energy and food production for a steadily growing world population is a grand challenge. Globally, nearly 12 million hectares of croplands are contaminated by cadmium (Cd), and how to develop a production system for the cleaning and utilisation of such contaminated land is essential for sustainability. Herein, a diverse panel of 166 sorghum accessions was grown in typical Cd-contaminated fields in two consecutive years, and the effect of different accessions and organs on the phytoremediation potential was evaluated by analysing the Cd concentrations of stems, leaves and grains at maturity. Both the bioaccumulation factors (BCFs) and the aboveground Cd accumulation varied substantially and the differences were up to 13–24 fold. The aboveground Cd accumulation was positively associated with important bioenergy traits including biomass, stem Brix, internode numbers and plant height, as envisaged by the high Cd concentration in sweet sorghum accessions, while BCF was significantly negatively correlated with relevant agronomic traits except Brix. The genetic regulation of Cd concentration in grains is different from those in leaves and stems, which allowed us to screen for three types of sorghum resources with the potential to couple soil phytoremediation with the production of bioethanol, safe grains and forage. A sorghum farming system was further proposed, which could reduce soil Cd concentration below the safe level within 12 years and obtain economic returns of about 70.5–169.5 million Chinese Yuan (CNY) by producing bioethanol, safe grains and forage in one season in 30% of the Cd-contaminated soil in China.

Development of nutritious rice with high zinc/selenium and low cadmium in grains through QTL pyramiding.

Enriching zinc (Zn) and selenium (Se) levels, while reducing cadmium (Cd) concentration in rice grains is of great benefit for human diet and health. Large natural variations in grain Zn, Se, and Cd concentrations in different rice accessions enable Zn/Se-biofortification and Cd-minimization through molecular breeding. Here, we report the development of new elite varieties by pyramiding major quantitative trait loci (QTLs) that significantly contribute to high Zn/Se and low Cd accumulation in grains. A chromosome segment substitution line CSSLGCC7 with the PA64s-derived GCC7 allele in the 93-11 background, exhibited steadily higher Mn and lower Cd concentrations in grains than those of 93-11. This elite chromosome segment substitution line (CSSL) was used as the core breeding material to cross with CSSLs harboring other major QTLs for essential mineral elements, especially CSSLGZC6 for grain Zn concentration and CSSLGSC5 for grain Se concentration. The CSSLGCC7+GZC6 and CSSLGCC7+GSC5 exhibited lower Cd concentration with higher Zn and Se concentrations in grains, respectively. Our study thus provides elite materials for rice breeding targeting high Zn/Se and low Cd concentrations in grains.

Sulfate application decreases translocation of arsenic and cadmium within wheat (Triticum aestivum L.) plant

Arsenic (As) and cadmium (Cd) typically exhibit divergent fates in soil, which complicates efforts to decrease As and Cd accumulation in the edible parts of crops. Here, we performed pot experiments to examine the effect of sulfate application on As and Cd accumulation in the grain of wheat grown in contaminated soil. Compared to the control (no sodium sulfate addition), application of 120 mg kg−1 sodium sulfate decreased the rhizosphere soil pH from 7.27 to 7.10 and increased the soil extractable Cd concentration; however, it did not significantly influence the soil extractable As concentration. However, sodium sulfate addition decreased As and Cd concentrations in wheat grain, in association with decreased As and Cd translocation from root and straw to grain, rather than from soil to root. Furthermore, sodium sulfate addition significantly decreased membrane lipid peroxidation and enhanced photosynthesis, while increasing the uptake of nitrogen, phosphorus, and sulfur. These effects increased the growth and grain weight of plants grown in As and Cd co-contaminated soil. Our findings provide insight into the mechanisms by which sulfate modulates As and Cd uptake and translocation in wheat; moreover, our findings will enable formulation of strategies to decrease As and Cd concentrations in the grain of wheat grown in As and Cd co-contaminated soil.

Effect of amendment of biochar supplemented with Si on Cd mobility and rice uptake over three rice growing seasons in an acidic Cd-tainted paddy from central South China

To examine the effect of rice straw biochar and the synergism with silicon on Cd immobilization, a Cd-contaminated acidic sandy loam paddy, polluted from emissions from industrial activity, was chosen in central South China. A field trial was conducted over three rice growing seasons during 2016–2017. Rice straw biochar (BR), produced by the pyrolysis of rice straw pellets at 450 °C, was amended at 10 t/ha (BR1), 20 t/ha (BR2), and supplemented with 0.75 t/ha sodium silicate (SS) at 10 t/ha, (BR1 + SS) and 20 t/ha (BR2 + SS), compared to the control without biochar and sodium silicate (BR0). BR supplemented with Si enhanced Cd soil immobilization and decreased Cd accumulation in rice plant within three rice seasons. Compared to BR0, BR + SS reduced Cd concentrations in grains by 19.5–73.7%, higher than that of 8.6–50.2% following BR. Cd bio-concentration factor of the root was reduced by an average of 54.6% from BR + SS and by 19.0% from BR, compared to BR0 in last two rice seasons. BR + SS significantly increased soil pH and available Si, and soil CaCl2-Cd was negatively related to soil available Si (p < 0.05). The synergistic effect of BR and Si induced liming effect and co-precipitation of Cd with Si compounds during the aging process of biochar. Thus, we suggest that an alkaline silicon supplementation is used as an amendment to BR, which could be used as a strategic approach for tackling Cd contamination in South China rice paddies.

Surface complexation model of Cd in paddy soil and its validation with bioavailability

In southern China, the paddy soils are mainly variable-charge soils, which have undergone high weathering processes and leaching processes. Due to deficiencies of carbonate and base cations, the variable-charge soil pH is normally less than 6.5, and decrease of soil pH can substantially enhance the mobility and bioavailability of heavy metals. Cadmium (Cd) is one of the most important pollutant influencing human health and environmental safety. Cd contamination is a serious problem in paddy soils, and the acidic condition could further aggravate the mobility and bioavailability of Cd. There is an urgent need to establish a model to investigate the adsorption characteristics of Cd and accurately assess the bioavailability of Cd in variable-charge paddy soils. In this study, the paddy soil was selected from agricultural regions in southern China. Batch experiments were conducted to investigate the Cd adsorption characteristics of the soils from pH 3 to 10. The results showed that Cd mainly existed in dissolved forms at pH 5.5, almost all Cd was adsorbed on the soil surface. Based on the potentiometric titration, the point of zero charge (pHpzc) was obtained when the surface charge density ( σ ) was equal to zero. The pHpzc of the paddy soil was 5.91. The 1-site/2-p K surface complexation model (SCM) was applied to further examine the acid-base properties of the soils by assuming the acid-base buffering system as a protonation-deprotonation process. The surface site concentration ( H s) and the surface site density ( D s) were obtained by Gran plot. The two acid equilibrium constants (p K a1 and p K a2) were determined by extrapolation and the calculated pHpzc were obtained by the average values of the p K a1 and p K a2. The value of pHpzc calculated from the model was 6.10, which was well matched with those from the potentiometric titration, indicating that it is feasible for the application of SCM to the variable-charge soils. The intrinsic equilibrium constants (lg K SOCd) was estimated from the Cd adsorption experimental data and acid-base parameters (p K a1, p K a2 and D s) using Visual MINTEQ software. The results showed that the adsorption of Cd on the paddy soil could be successfully modeled by the SCM. Based on the previous study, the pH was significantly negatively correlated with grain Cd content in paddy soil when pH was below 5.5 ( P 1 mol L−1 MgCl2 (exchangeable fraction) and 1 mol L−1 NaOAc/HOAc (bound to carbonate). Although the extracted Cd was positively correlated with Cd content in grain, the P value was much higher than 0.05, indicating the insignificant correlation. Compared with the extraction method, the dissolved Cd calculated from the SCM was significantly correlated with the grain Cd content (P

Rice vegetative organs alleviate cadmium toxicity by altering the chemical forms of cadmium and increasing the ratio of calcium to manganese

Altering Cd chemical form is one of the mechanisms to alleviate Cd toxicity in rice plant. Field experiments were carried out in this study to investigate the potential of rice vegetative organs in altering Cd into insoluble chemical forms in the natural environment. Experimental results showed that more than 80% of Cd in rice roots existed in the insoluble forms. Uppermost nodes altered Cd into insoluble form preferentially and generally had higher content of insoluble Cd than other organs. Rachises displayed a slow increasing trend in soluble Cd when total Cd in roots was less than 1.8 mg kg−1. However, when Cd content in roots exceeded 2.8 mg kg−1, the ratio of insoluble to soluble Cd remained stable at 85:15 in rachises and roots, and at 75:25 in uppermost nodes and flag leaves. Cd concentration in grains was greatly lower than that in vegetative organs, and closely correlated with the content of soluble Cd in rachises (r = 0.991**) as well as in uppermost nodes. Soluble Cd in the uppermost nodes displayed a much lower mobility than that in other organs. Accumulation of soluble Cd was always companied by decrease of Ca and increase of Mn in roots, uppermost nodes and rachises. A small increase of soluble Cd from 0.05 to 0.1 mg kg−1 caused a sharp decline of Ca:Mn ratio in roots and rachises. Roots and nodes had much higher Ca:Mn ratio than rachises when soluble Cd was less than 0.5 mg kg−1 in them. These results indicate that vegetative organs have a great potential to alter more than 75% Cd into insoluble forms and increasing Ca:Mn ratio may be another way to alleviate Cd toxicity by establishing new ionic homeostasis in rice plants.

Plant growth and Cd accumulation characteristics in different planting modes of maize and Amaranthus hypochondriacus.

To achieve the goal of remediation while producing for farmland contaminated by Cd, maize and grain amaranth (Amaranthus hypochondriacus) were planted on farmland contaminated by Cd in five different intercropping modes, including alternating wide-narrow-row of maize and single-row grain amaranth intercropped between wide rows (T1), alternating wide-narrow-row of maize and double-row grain amaranth intercropped between wide rows (T2), equidistant double-row maize and single-row grain amaranth intercropped between rows (T3), equidistant double-row maize and double-row grain amaranth intercropped between rows (T4), maize and grain amaranth intercropped with equal four rows (T5), while maize (CK1) and grain amaranth (CK2) single planted as control to explore the effects of different intercropping modes on growth and Cd accumulation of crops and hyper-accumulation plants (A. hypochondriacus). The results showed that: 1) Compared with mono-culture (CK1), grain yield of maize per plant showed an increasing trend in intercropping modes. The grain yield of maize in T1 increased by 10.5%, while that in T4 and T5 decreased by 6.3% and 5.4% respectively, and that in T2 or T3 did not change compared with monoculture of maize. The aboveground biomass per plant and yield per unit area of grain amaranth decreased by 69.5%-95.7% and 83.9%-96.9% in intercropping modes respectively compared with monoculture (CK2). 2) The Cd content of maize grain showed an increasing trend in intercropping modes compared with monoculture (CK1). The Cd content of grain amaranth showed a decreasing trend in intercropping modes compared with monoculture (CK2). 3) Compared with monoculture (CK2), the enrichment coefficient, transport coefficient, and effective transport coefficient of grain amaranth all showed an increasing trend in intercropping modes, while the aboveground Cd extraction amount per plant and per unit area of grain amaranth decreased by 40.4%-86.7% and 70.4%-88.9% in intercropping modes, respectively. The total amount of Cd extraction per unit area of maize and grain amaranth in intercropping modes was significantly higher than that in monoculture of maize and lower than that in monoculture of grain amaranth. 4) The content of available Cd in maize rhizosphere soil and the content of total/available Cd in grain amaranth rhizosphere soil both showed an increasing trend in intercropping modes compared with monoculture of both crop, but it had no significant effect on non-rhizosphere soil. In this study, T1 was beneficial to increase maize grain yield, while T5 was beneficial to maximize the Cd extraction amount of grain amaranth.

Calcium amendment improved the performance of fragrant rice and reduced metal uptake under cadmium toxicity.

Cadmium (Cd) toxicity has detrimental effects on plant metabolism and yield formation. This study examined the effects of Cd stress in rice and the possible role of calcium (Ca) in mitigating oxidative damage caused by Cd in two fragrant rice cultivars, i.e., Guixiangzhan and Meixiangzhan 2. The experimental treatments were composed of various Ca and Cd levels as individual, i.e., Ca at 2.5 and 5.0mg/kg soil (Ca1 and Ca2, respectively), Cd at 50 and 100mg/kg soil (Cd50 and Cd100, respectively), and combined, i.e., Ca1+Cd50, Ca1+Cd100, Ca2+Cd50, and Ca2+Cd100. Plants without Ca and Cd application were taken as control (CK). Results showed that Cd stress led to a substantial decline in the photosynthetic pigments, i.e., Chl a, Chl b, and carotenoids, while enhanced oxidative damage in terms of increased levels of hydrogen peroxide (H2O2) and malondialdehyde (MDA) and electrolyte leakage (EL) in both rice cultivars. Moreover, Cd stress hampered the activities of enzymatic antioxidants, i.e., superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), with lowest antioxidant activities were recorded at Cd100. The overall trend (lowest to highest) for antioxidant activities across treatments was recorded as Cd100 < Ca2+Cd100 < Cd50 < Ca1+Cd100 < CK < Ca1 < Ca1+Cd50 < Ca2+Cd50 < Ca2. Similarly, Ca amendment improved the proline, soluble protein, and soluble sugar contents in both rice cultivars under Cd stress condition. Comparing Ca2 with CK, the yield and related components, i.e., number of panicles, spikelets per panicle, seed setting rate, 1000 grain weight, and grain yield, were found to increase by 13.08, 2.39, 4.03, 5.86, and 27.53% for Guixiangzhan and 16.48, 5.19, 6.87, 15.44, and 51.16% for Meixiangzhan, respectively. Furthermore, Cd contents in roots, stems, leaves, and grains increased with increased Cd concentration applied and reduced with Ca amendment. The Cd contents in grains for all Ca+Cd levels are statistically at par with each other and significantly lower (P < 0.05) than those for individual Cd application. Hence, Ca amendment can be an appropriate approach to ameliorate the toxic effects of Cd in crops grown under Cd-contaminated soils.

Lanthanum reduces the cadmium accumulation by suppressing expression of transporter genes involved in cadmium uptake and translocation in wheat

Lanthanum (La) is attracting increasing attention due to its effects in enhancing yields and reducing cadmium (Cd) accumulation in crops. Although a few transporter genes are reportedly involved in regulating the Cd accumulation in plants, the mechanisms of La-decreased Cd accumulation in plants remain poorly understood. Therefore, this study aimed to 1) investigate the effects of La on Cd accumulation and growth of wheat and 2) determine whether La regulates the Cd accumulation in wheat correlating with the expression of TaNramp5, TaHMA2 and TaHMA3. Hydroponics and pot experiments were conducted under Cd stressed conditions in the presence or absence of La, with special emphasis on the accumulation of Cd, the expression of TaNramp5, TaHMA2 and TaHMA3, and the growth of wheat. La supplementation decreased Cd accumulation in wheat, which resulted in better plant growth. Pre-treatment with La also decreased Cd accumulation in both roots and shoots. La supply resulted in a decreased Cd concentration in the root cell sap, cell wall and xylem sap, respectively. Furthermore, in the pot experiment, La application also reduced Cd accumulation in all tissues of wheat under Cd exposure, and the concentration of Cd in grains decreased by 35.0%. The expression levels of TaNramp5 and TaHMA2 were down-regulated by La supplementation. La could efficiently limit Cd accumulation in wheat. The La-decreased Cd accumulation in wheat is probably a consequence of both decreased Cd uptake due to the down-regulation of TaNramp5, and reduced root-to-shoot by the down-regulation of TaHMA2.

Silicon nanoparticles enhanced the growth and reduced the cadmium accumulation in grains of wheat (Triticum aestivum L.)

The application of silicon (Si) under heavy metal stress is well known, but the use of Si nanoparticles (NPs) under metal stress in not well documented. Thus, the experiments were performed to investigate the impacts of soil and foliar applied Si NPs on wheat (Triticum aestivum L.) growth and cadmium (Cd) accumulation in grains under Cd toxicity. The plants were grown under natural environmental conditions and were harvested after physiological maturity (124 days after sowing). The results demonstrated that Si NPs significantly improved, relative to the control, the dry biomass of shoots, roots, spikes and grains by 24–69%, 14–59%, 34–87%, and 31–96% in foliar spray and by 10–51%, 11–49%, 25–69%, and 27–74% in soil applied Si NPs, respectively. The Si NPs enhanced the leaf gas exchange attributes and chlorophyll a and b concentrations, whereas diminished the oxidative stress in leaves which was indicated by the reduced electrolyte leakage and enhancement in superoxide dismutase and peroxidase activities in leaf under Si NPs treatments over the control. When compared with the control, the foliar spray of Si NPs reduced the Cd contents in shoots, roots, and grains by 16–58%, 19–64%, and 20–82%, respectively, whereas soil applied Si NPs reduced the Cd concentrations in shoots, roots, and grains by 11–53%, 10–59%, and 22–83%, respectively. In comparison with the control, Si concentrations significantly (p ≤ 0.05) increased in the shoots and roots in both foliar and soil supplementation of Si NPs. Our results suggested that Si NPs could improve the yield of wheat and more importantly, reduce the Cd concentrations in the grains. Thus, the use of Si NPs might be a feasible approach in controlling Cd entry into the human body via crops.

Cadmium Concentrations in New Zealand Wheat: Effect of Cultivar Type, Soil Properties, and Crop Management.

Wheat ( L.) grain is a contributing source of dietary Cd in New Zealand, but despite this, there is a dearth of information on Cd concentrations in wheat and the factors that affect uptake. We measured Cd concentrations in 12 wheat cultivars grown in field sites across New Zealand and also assessed the soil, plant, and crop factors that have been reported to affect Cd uptake. We found there was a wide range in grain Cd concentrations (0.004 to 0.205 mg kg fresh weight [FW]). The overall mean concentration (0.066 mg kg FW) was below the maximum limit (ML) of 0.1 mg kg FW. Only 7% of grain samples across seven sites exceeded the ML. There were significant ( < 0.05) differences (2.5-fold) in Cd concentrations in wheat grain between cultivars. No strong significant relationships were found between soil properties and Cd concentrations in grain. Further, management factors affecting grain Cd concentrations were inconsistent. Given the lack of relationships between soils and management practices, the most effective way of limiting Cd uptake in wheat grain at sites where Cd exceeds MLs may be the use of low-Cd-accumulating cultivars. Further studies are required to explore specifically the influence of irrigation and effects of type and rate of fertilizer on Cd uptake in wheat, as well as to better understand the mechanisms of Cd uptake in wheat.

Response of Grain Quality to Alternate Wetting and Moderate Soil Drying Irrigation in Rice

Alternate wetting and moderate soil drying irrigation (WMD) has been widely adopted in rice (Oryza sativa L.) production for saving irrigation water and increasing grain yield. However, limited information is available about the effect of WMD on rice grain quality. The main purpose of this study was to evaluate the characteristics of grain quality in response to WMD. Two rice varieties, Yangdao 6 (YD6, indica) and Hanyou 8 (HY8, japonica), were grown in the field, with two water management treatments, well‐watered (WW) and WMD from 10 d after transplanting to maturity. In comparison with WW, WMD prominently increased grain yield by 7.57 to 9.72%, and improved some grain quality parameters such as milling, appearance, and eating and cooking qualities, including increases in head rice and decreases in chalkiness. The two varieties showed the same tendency. However, WMD had a negative impact on some nutritional quality traits in rice grains, such as reduction in the contents of amino acids and the micronutrient elements Cu, Fe, Mn, Mo, Se, and Zn. The WMD treatment also markedly decreased As content and exhibited no significant effect on Cd content in grains. The results demonstrated that WMD has an overall impact on rice grain quality with both positive and negative effects.

Changes of non-protein thiols in root and organic acids in xylem sap involved in cadmium translocation of cadmium-safe rice line (Oryza Sative L.)

The selection and breeding of low grain-cadmium (Cd)-accumulating rices is a promising approach for reducing the Cd concentration in grains. A cadmium-safe rice line designated D62B (Oryza Sative L.) accumulated a low Cd concentration in brown rice for safe consumption (< 0.2 mg kg−1). D62B was a great potential breeding material with a weaker translocation capacity of Cd to shoot compared with common rice lines. A prior understanding of the Cd translocation mechanisms in D62B offered theoretical basis for breeding new low-Cd-accumulating rice cultivars in the future. A pot experiment was conducted to investigate the changes of non-protein thiols in shoot and root of D62B in comparison with a common rice line (Luhui17), and then the relationship between the Cd translocation via xylem and organic acids in xylem sap of two rice lines was explored by a hydroponic experiment. D62B showed lower Cd translocated to shoot in comparison with Luhui17. The translocation factor (TF) of D62B varied from 0.11 to 0.15. Cd exposure promoted the synthesis of non-protein thiols in two rice lines, particularly in roots. Syntheses of glutathione (GSH) and phytochelatins (PCs) in root of D62B were greater than those of Luhui17. Cd concentration in xylem sap of D62B was significant positively correlated with the malic acid, citric acid and tartaric acid concentrations. The citric acid and tartaric acid concentrations in xylem sap of D62B were significantly lower than those of Luhui17. There was no significant difference for malic acid between two rice lines. More GSH and PCs in root of D62B was beneficial to Cd retention in root. Furthermore, the involvement of lower citric acid and tartaric acid in Cd translocated in xylem sap of D62B resulted in lower Cd accumulation in shoot.

Cadmium (Cd) concentration in wheat (Triticum aestivum) grown in Cd-spiked soil varies with the doses and biochar feedstock

Biochar is considered a promising amendment for the reduction of metal concentration in plants; however, the effects of biochar in terms of dose and feedstock on metal uptake by plants remain widely unclear. In the current study, three individual biochars were prepared at 450 °C from different feedstocks (wheat straw, sukh chain (Pongamia pinnata), and cotton sticks). The main aim was to evaluate their ability to remediate cadmium (Cd)-spiked soil in terms of growth response and Cd uptake by wheat (Triticum aestivum) tissues. Biochars were separately applied at 0, 1, and 2% (w/w) in Cd-spiked soil and wheat was grown until maturity in pots and then morphological and physiological parameters and Cd concentrations in grains, roots, and shoots were determined. The post-harvest soil was analyzed for extractable Cd concentrations. Plants grown in Cd-spiked soil treated with biochars had higher seed germination, lengths of roots, shoots, and spikes, grains per spike and leaf relative water contents, chlorophyll contents, and dry weight of roots, shoots, and grains as compared to the untreated control. Biochar treatments significantly decreased the Cd concentrations in shoots, roots, and grains as well as total Cd uptake by grains. Soil extractable Cd concentrations were significantly decreased with biochar treatments. The application of 2.0% wheat straw biochar was the most efficient treatment in increasing grain yield and decreasing Cd in grains as well as soil extractable Cd than the other two biochars and doses applied.

Effects of various warming patterns on Cd transfer in soil-rice systems under Free Air Temperature Increase (FATI) conditions

Global warming has become an important research topic in different disciplines around the world, especially in the fields of environment quality and food security. As a potential problem in soil environments, cadmium (Cd) contamination of rice under global warming conditions has not been thoroughly investigated. In this study, the fate of Cd in soil-rice systems under various warming patterns was studied via pot experiments under Free Air Temperature Increase (FATI) conditions. The patterns of warming included different temperatures (0.5 °C and 0.8 °C), different day-night durations (nighttime, daytime, and the whole day), and different warming stages (WSx) (including WS1 (seedling to tillering), WS2 (jointing to booting), WS3 (heading), WS4 (grain filling to milk ripening)). At harvest, samples of different rice tissues were collected and the Cd concentrations were measured. The results showed that warming significantly increased Cd concentrations in grain by 1.45 and 2.31 times, which was positively correlated with the two temperature increases (0.5 °C and 0.8 °C), respectively. Both daytime and nighttime warming significantly increased the Cd concentration in grain, and the daytime dominated Cd translocation from roots to shoots. In addition, warming in individual growth stages contributed to increases in Cd accumulation in grain by 31.6% (WS1), 15.0% (WS2), 20.6% (WS3), and 32.8% (WS4), respectively. Specifically, warming during the vegetative phase boosted Cd translocation from roots to shoots, while warming during maturation further increased Cd uptake and remobilization into grain. The projected results could provide a new and in-depth understanding of the fate of Cd in soil-rice systems under global warming conditions in Cd contaminated areas.

A novel method for predicting cadmium concentration in rice grain using genetic algorithm and back-propagation neural network based on soil properties

Heavy metal pollution is a global ecological safety issue, especially in crops, where it directly threatens regional ecological security and human health. In this study, the back-propagation (BP) neural network optimized by the genetic algorithm (GA) was used to predict the concentration of cadmium (Cd) in rice grain based on influencing factors. As an intelligent information processing system, the GA-BP neural network could learn the laws of Cd movement in the soil-crop system through its own training and use the soil properties to predict the concentration of Cd in grain with high accuracy. The total soil Cd concentration, clay content, Ni concentration, cation exchange capacity (CEC), organic matter (OM), and pH have important impacts and interactions on Cd concentration in rice grain were selected as input factors of the prediction model based on Pearson's correlation analysis and GeoDetector. By using GA to optimize the initial weight, the prediction accuracy of the GA-BP neural network model was optimal compared with the BP neural network model and multiple regression analysis. Based on the Cd concentration predicted in grain by the model, human exposure and health risk can be assessed quickly, enabling measures to be taken in time to reduce the transfer of Cd from soil to the food chain.

Influence of phosphate amendment and zinc foliar application on heavy metal accumulation in wheat and on soil extractability impacted by a lead smelter near Jiyuan, China

Higher concentrations of Pb and Cd in wheat grains harvested in several lead-smelting-polluted areas in northern China have been reported. This field experiment was conducted to investigate the effect of phosphate amendment and Zn foliar application on the accumulation of Pb and Cd in wheat grains grown in a lead-smelting impacted area in Jiyuan in northern China. The soil (total Pb and Cd are 261 and 2.65mgkg-1, respectively) was amended with superphosphate at P:Pb ratios (mol:mol) of 1.90 or 2.57 either during wheat (Triticum aestivum L.) planting or a split of 60% of the phosphate applied at planting, with remaining 40% applied at the jointing stage. Zn was sprayed on the canopy of the wheat plants at the jointing stage. The phosphate amendment resulted in lower DTPA (diethylene triamine pentaacetic acid)-extractable Pb (1.39-10.7% lower than the control) and Cd (0.040-7.12%) in the soil. No significant effect of split application of phosphate was found on Pb and Cd availability in soil; however, higher rates of P resulted in lower Pb and Cd availabilities in the soil. Grain Pb (5.41-21.5% lower than the control), Cd (3.62-6.76%), and Zn (4.29-9.02%) concentrations were negatively affected by the phosphate application, with higher rates of phosphate resulting in lower grain heavy metal concentrations. Foliar application had no statistically significant influence on Pb and Cd concentrations in the grain (p > 0.05). Although Pb and Cd concentrations in wheat grains were reduced by the phosphate application, their concentrations were still much higher than the maximum permissible concentrations for wheat in the national standards of China. The results suggest that it is feasible to reduce wheat grain concentrations of Pb and Cd in Pb-smelting-polluted areas in northern China by soil application of superphosphate; however, the split application of the phosphate and the foliar application of Zn compounds do not have substantial impact on reducing accumulation of Pb and Cd in the wheat grains.

Distribution of Cadmium in Sweet Corn Grown on a Peat Soil and Its Implication on Food Safety

Cadmium (Cd) is a heavy metal that can contaminate agricultural soils, in which one of the sources of Cd in agricultural soils is the use of phosphate fertilizers. Some plant species are known to have the ability to accumulate large amounts of Cd in their organs despite the Cd content in soil is relatively small. Cadmium distribution in various organs of plants also shows a diverse variation. Maize is able to accumulate Cd in its organs, either in roots, leaves or grains. This study aims to determine the distribution of Cd in sweet corn plants grown on a peat soil. Samples of maize plants were taken from nine maize fields in the village of Rasau Jaya 1, Rasau Jaya subdistrict, Kubu Raya district, West Kalimantan. The cultivars of sweet corn planted were Zea mays saccharata cultivar Bonanza and Zea mays saccharata cultivar Secada. Samples for roots, leaves, stems and panicles were taken at the stage of early grain filling. Grain samples were taken at the phase of fresh pod consumption. The Cd contents in the plant organ tissues were determined using dry ashing method. The results showed that the distribution of Cd in plant organs of sweet corn cultivars Secada and Bonanza follows the pattern of Cd in leaves &gt; roots &gt; grains &gt; panicles &gt; stems. The leaves contain the highest concentration of Cd, while the stems contain the lowest amount of Cd. The Cd concentration in leaves is about 3.5 times higher than that in grains, and 1.5 times higher than that in roots. The average Cd content in grains of sweet corn is 0.037 mg kg-1, which is still below the safe limit of Cd content in grains allowed by the Standar Nasional Indonesia, i.e. 0.2 mg kg-1.

Features of Cadmium absorption by plants of spring barley

The paper present result of research on the intensity of the absorption of cadmium from the soil by plants barley. The object of the study were plant spring barley varieties Peas in various stages of development. Сadmium was added to the soil (dark-grey podzolic) as a CdCl2·2,5H2O in the concentration of 3, 15 and 30 mg Cd+2 per kg of the soil. Сadmium is one of the heavy metals which occur in the environment as a result of antropogenic activities. The best solution for maintaining non-contaminated soils and plants is to remove the sources of Cd in the environment. Given that that is essentially impossible at this time, further research needs to determine how soil and plant factors affect Cd availability on polluted soils. Of all non-essential heavy metals, Cadmium (Cd) is perhaps the metal that has attracted the most attention in soil science and plant nutrition due to its potential toxicity to humans, and also its relative mobility in the soil-plant system. The Cadmium is for plants completely unnecessary element. Of particular concern for humans are the high concentrations of Cd in grain. Established that the Cadmium content in barley amended as follows: underground faction &gt; vegetative biomass fraction &gt; generative fraction (control and on the variant of contamination of soil in a dose 3 mg Cd+2 per kg of the soil) and underground faction &gt; generative fraction &gt; vegetative biomass fraction (on the variants of experience 5 and 10 maximum possible concentration of Cd+2). Сadmium absorbed most intensive barley in the flowering stage. Cadmium is characterized by subzero migratory ability in theorgans of barley. Roots are the main accumulators of this heavy metal. Every stress conditions are signal for a plant to initiate in its cells a number of different biochemical processes (e.g. changes of cytoplasm pH, changes of electrostatic potential of cell membranes, flow of ions). It is set that getting a clean straw and clean grain ispossible only on the variants of experien-ce 1 maximum possible concentration of Cd+2 and on control. The effect of сadmium and other heavy metals on plants depends not only on its form, but also on the presence and concentration of other elements and substances, the plant species and its developmental stage are also important. Several soil conditions, such as the pH value, calcium level, content of organic substances, particulaly humus etc., are decisive for the exchangeable and water soluble, available сadmium for plants.