Significant Nutritional Gaps in Tibetan Adults Living in Agricultural Counties Along Yarlung Zangbo River.

Background: Dietary intake and nutritional assessing data from a representative sample of adult population living in an agricultural zone on Tibet Plateau are still lacking nowadays. This study aimed to assess the daily dietary intakes and respective food sources in 552 local residents (≥ 18 years old, 277 men and 275 women) living in 14 agricultural counties along the Yarlung Zangbo River on Tibet Plateau. Methods: Food consumption data were collected using a validated cultural-specific food frequency questionnaire that contained all local Tibetan foods and analyzed with three fixed factors: gender, age, and region. Nutrient intakes were calculated using Chinese food composition tables. Nutritional gaps and the percentages of participants who had inadequate and excessive nutrient intakes were calculated by estimated average requirement (EAR) cut-point methods. Results: Compared with the dietary reference intakes, 68.4% of nutrient intakes were inadequate. Fiber, Ca, I, Zn, Se, and vitamin (Va, Vc, and folic acid) intakes appeared to be particularly deficient. The dietary energy intake was 7838.8 ± 537.1 KJ/d, with 78 and 84% of EAR values for men and women, respectively. The dietary intakes of most nutrients were below the estimated energy requirement/EAR or adequate intake values, while more than 70% of the participants had excessive intake of carbohydrate, especially the elderly (aged ≥ 51 years). The nutritional gap of Cu was more than 300%. Almost 100% of the participants was vulnerable to fiber, Se, and Va shortfalls due to the deficiency in sole food sources. The top five food sources of Se intake were highland barley (34.2%), meat (13%), rice (12.4%), eggs (12.2%), and cultural-specific beverages (7.8%). Eggs (42.1%), tubers (62.2%), vegetables (66.4%), and highland barley (49.7%) were the first contributors of Va, Ve, Vc, and folic acid, respectively. Conclusion: The dietary intake of a large sample of Tibetan adult population living in agricultural counties of Tibetan Autonomous Region is alarmingly insufficient. Gender inequality is common, and regional difference is widespread due to rapid urbanization. Young Tibetan adults aged 18-30 years are particularly vulnerable to micronutrient shortfalls and currently facing the risk of nutrition-insecurity-related dietary inadequacy. The respondents who belong to the elderly category (≥51 years of age) are facing the risk of "double burden of malnutrition" characterized by the coexistence of undernutrition, including micronutrient deficiencies and overweight or obesity.

Fertilizer and pesticide reduction in cherry tomato production to achieve multiple environmental benefits in Guangxi, China.

Cherry tomatoes, as a highly profitable vegetable, consume a substantial amount of fertilizer and pesticide compared with other staple crops, which leads to remarkably negative environmental impacts. The optimization of these agricultural inputs to mitigate these environmental burdens and improve cherry tomato yield has drawn little attention. This study used life cycle assessment (LCA) combined with a field investigation to analyze the environmental benefits under optimized fertilizer and pesticide inputs (i.e., reduction of 24.7% nitrogen, 35.6% phosphorus pentoxide, 18.8% potassium oxide, 17.1% organic fertilizer, and 30.9% pesticides) compared to traditional farmer inputs. Results showed that: (1) compared to traditional farmer management, optimized inputs reduced the energy depletion by 24.7%, water depletion by 6.4%, global warming by 28.8%, acidification by 23.7%, aquatic eutrophication by 34.2%, human toxicity by 34.8%, aquatic eco-toxicity by 34.8%, and soil eco-toxicity by 26.7%, respectively; (2) among them, aquatic eco-toxicity and aquatic eutrophication were the major environmental impacts in cherry tomato production and were mainly attributed to chlorothalonil and phosphate fertilizer use, respectively; and (3) optimized inputs decreased the total environmental index and environmental damage cost by 33.8% and 28.1%, respectively, without compromising the yield. These findings provide insight into optimizing fertilizer and pesticide usage to alleviate multiple environmental impacts while maintaining cherry tomato yield and improving economic benefits. Further studies should focus mainly on less harmful pesticide utilization and phosphate use efficiency improvement, which may achieve vegetable production system sustainability in China and also provide a reference value for vegetable production systems in the Global South.

Harvesting more grain zinc of wheat for human health.

Increasing grain zinc (Zn) concentration of cereals for minimizing Zn malnutrition in two billion people represents an important global humanitarian challenge. Grain Zn in field-grown wheat at the global scale ranges from 20.4 to 30.5 mg kg-1, showing a solid gap to the biofortification target for human health (40 mg kg-1). Through a group of field experiments, we found that the low grain Zn was not closely linked to historical replacements of varieties during the Green Revolution, but greatly aggravated by phosphorus (P) overuse or insufficient nitrogen (N) application. We also conducted a total of 320-pair plots field experiments and found an average increase of 10.5 mg kg-1 by foliar Zn application. We conclude that an integrated strategy, including not only Zn-responsive genotypes, but of a similar importance, Zn application and field N and P management, are required to harvest more grain Zn and meanwhile ensure better yield in wheat-dominant areas.

[Reactive nitrogen loss pathways and their effective factors in paddy field in southern China].

Based on the literature data, the N20 emission, N leaching, N runoff and NH3 volatilization were compared from different rice production regions and their effective factors were evaluated. The results showed that N2 0 emission, N leaching and N runoff in single rice in Yangtze River basin were higher than in other rice production regions, with N loss of 1.89, 6.4 and 10.4 kg N · hm(-2), and N loss rate of 0.8%, 3.8% and 5.3%, respectively. The high N20 emission, N leaching and N runoff in these regions might be attributed to high-rate N application and dry-wet alternation. The NH3 volatilization was the highest in late rice in southern China, with N loss of 54.9 kg N · hm(-2) and N loss rate of 35.2% due to higher temperature at late rice growing stage. In the field, the practice often decreased one reactive N loss but increased another one, indicating that intergated practical management is necessary to reduce reactive N loss. Reactive N loss often increase with increasing grian yield, which is associed with the high-rate N application. The N20 emission, N leaching and N runoff decreased with increasing the partial factor productivity of applied N (PFP). Therefore, reducing N losses per unit of yield is necessary for integrating higher yield with minimum environmental pollution.

Intercropping enhances soil carbon and nitrogen.

Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4% ± 1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 184 ± 86 kg C ha(-1) yr(-1). Soil organic N content in the top 20 cm was 11% ± 1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 45 ± 10 kg N ha(-1) yr(-1). Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil δ(15) N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration.

Plant diversity and overyielding: insights from belowground facilitation of intercropping in agriculture.

Despite increasing evidence that plant diversity in experimental systems may enhance ecosystem productivity, the mechanisms causing this overyielding remain debated. Here, we review studies of overyielding observed in agricultural intercropping systems, and show that a potentially important mechanism underlying such facilitation is the ability of some crop species to chemically mobilize otherwise-unavailable forms of one or more limiting soil nutrients such as phosphorus (P) and micronutrients (iron (Fe), zinc (Zn) and manganese (Mn)). Phosphorus-mobilizing crop species improve P nutrition for themselves and neighboring non-P-mobilizing species by releasing acid phosphatases, protons and/or carboxylates into the rhizosphere which increases the concentration of soluble inorganic P in soil. Similarly, on calcareous soils with a very low availability of Fe and Zn, Fe- and Zn-mobilizing species, such as graminaceous monocotyledonous and cluster-rooted species, benefit themselves, and also reduce Fe or Zn deficiency in neighboring species, by releasing chelating substances. Based on this review, we hypothesize that mobilization-based facilitative interactions may be an unsuspected, but potentially important mechanism enhancing productivity in both natural ecosystems and biodiversity experiments. We discuss cases in which nutrient mobilization might be occurring in natural ecosystems, and suggest that the nutrient mobilization hypothesis merits formal testing in natural ecosystems.

New technologies reduce greenhouse gas emissions from nitrogenous fertilizer in China.

Synthetic nitrogen (N) fertilizer has played a key role in enhancing food production and keeping half of the world's population adequately fed. However, decades of N fertilizer overuse in many parts of the world have contributed to soil, water, and air pollution; reducing excessive N losses and emissions is a central environmental challenge in the 21st century. China's participation is essential to global efforts in reducing N-related greenhouse gas (GHG) emissions because China is the largest producer and consumer of fertilizer N. To evaluate the impact of China's use of N fertilizer, we quantify the carbon footprint of China's N fertilizer production and consumption chain using life cycle analysis. For every ton of N fertilizer manufactured and used, 13.5 tons of CO2-equivalent (eq) (t CO2-eq) is emitted, compared with 9.7 t CO2-eq in Europe. Emissions in China tripled from 1980 [131 terrogram (Tg) of CO2-eq (Tg CO2-eq)] to 2010 (452 Tg CO2-eq). N fertilizer-related emissions constitute about 7% of GHG emissions from the entire Chinese economy and exceed soil carbon gain resulting from N fertilizer use by several-fold. We identified potential emission reductions by comparing prevailing technologies and management practices in China with more advanced options worldwide. Mitigation opportunities include improving methane recovery during coal mining, enhancing energy efficiency in fertilizer manufacture, and minimizing N overuse in field-level crop production. We find that use of advanced technologies could cut N fertilizer-related emissions by 20-63%, amounting to 102-357 Tg CO2-eq annually. Such reduction would decrease China's total GHG emissions by 2-6%, which is significant on a global scale.

Characterization of root response to phosphorus supply from morphology to gene analysis in field-grown wheat.

The adaptations of root morphology, physiology, and biochemistry to phosphorus supply have been characterized intensively. However, characterizing these adaptations at molecular level is largely neglected under field conditions. Here, two consecutive field experiments were carried out to investigate the agronomic traits and root traits of wheat (Triticum aestivum L.) at six P-fertilizer rates. Root samples were collected at flowering to investigate root dry weight, root length density, arbusular-mycorrhizal colonization rate, acid phosphatase activity in rhizosphere soil, and expression levels of genes encoding phosphate transporter, phosphatase, ribonucleases, and expansin. These root traits exhibited inducible, inhibitory, or combined responses to P deficiency, and the change point for responses to P supply was at or near the optimal P supply for maximum grain yield. This research improves the understanding of mechanisms of plant adaptation to soil P in intensive agriculture and provides useful information for optimizing P management based on the interactions between soil P dynamics and root processes.

Greenhouse gas emissions from a wheat-maize double cropping system with different nitrogen fertilization regimes.

Here, we report on a two-years field experiment aimed at the quantification of the emissions of nitrous oxide (N2O) and methane (CH4) from the dominant wheat-maize double cropping system in North China Plain. The experiment had 6 different fertilization strategies, including a control treatment, recommended fertilization, with and without straw and manure applications, and nitrification inhibitor and slow release urea. Application of N fertilizer slightly decreased CH4 uptake by soil. Direct N2O emissions derived from recommended urea application was 0.39% of the annual urea-N input. Both straw and manure had relatively low N2O emissions factors. Slow release urea had a relatively high emission factor. Addition of nitrification inhibitor reduced N2O emission by 55%. We conclude that use of nitrification inhibitors is a promising strategy for N2O mitigation for the intensive wheat-maize double cropping systems.

Genotypic differences in zinc efficiency of Chinese maize evaluated in a pot experiment.

BACKGROUND: Zinc (Zn) deficiency, a major problem limiting crop production worldwide, is common on calcareous soils of China. Using such a Zn-deficient soil supplied adequately with plant mineral nutrients, with or without Zn, 30 Chinese maize genotypes were grown for 30 days in a greenhouse pot experiment and assessed for Zn efficiency (ZE), measured as relative biomass under Zn-limiting compared with non-limiting conditions. RESULTS: Substantial variation in tolerance to low Zn nutritional status was observed within the maize genotypes. Tolerant genotypes did not show Zn deficiency symptoms at the studied early seedling growth, and there was a well-defined relationship between shoot dry matter and the ZE trait. ZE values ranged on average from 45 to 100% for shoot dry weight. Under low available soil Zn conditions, shoot and root dry weights, shoot Zn concentration and content, leaf superoxide dismutase (SOD) activity, leaf area and plant height were all correlated with ZE. Shoot Zn and phosphorus (P) concentrations were negatively correlated. CONCLUSION: Three genotypes (L55 × 178, L114 × 178 and Zhongnong 99) were identified as highly Zn-efficient and three (L53 × 178, L105 × 178 and L99 × 178) as very low in ZE. This selection allows further work to evaluate ZE based on grain yield and grain Zn concentration, including field experiments likely to benefit farmers producing maize on Chinese soils low in available Zn.

Integrated soil-crop system management for food security.

China and other rapidly developing economies face the dual challenge of substantially increasing yields of cereal grains while at the same time reducing the very substantial environmental impacts of intensive agriculture. We used a model-driven integrated soil-crop system management approach to develop a maize production system that achieved mean maize yields of 13.0 t ha(-1) on 66 on-farm experimental plots--nearly twice the yield of current farmers' practices--with no increase in N fertilizer use. Such integrated soil-crop system management systems represent a priority for agricultural research and implementation, especially in rapidly growing economies.

Localized application of soil organic matter shifts distribution of cluster roots of white lupin in the soil profile due to localized release of phosphorus.

BACKGROUND AND AIMS: Phosphorus (P) is a major factor controlling cluster-root formation. Cluster-root proliferation tends to concentrate in organic matter (OM)-rich surface-soil layers, but the nature of this response of cluster-root formation to OM is not clear. Cluster-root proliferation in response to localized application of OM was characterized in Lupinus albus (white lupin) grown in stratified soil columns to test if the stimulating effect of OM on cluster-root formation was due to (a) P release from breakdown of OM; (b) a decrease in soil density; or (c) effects of micro-organisms other than releasing P from OM. METHODS: Lupin plants were grown in three-layer stratified soil columns where P was applied at 0 or 330 mg P kg(-1) to create a P-deficient or P-sufficient background, and OM, phytate mixed with OM, or perlite was applied to the top or middle layers with or without sterilization. KEY RESULTS: Non-sterile OM stimulated cluster-root proliferation and root length, and this effect became greater when phytate was supplied in the presence of OM. Both sterile OM and perlite significantly decreased cluster-root formation in the localized layers. The OM position did not change the proportion of total cluster roots to total roots in dry biomass among no-P treatments, but more cluster roots were concentrated in the OM layers with a decreased proportion in other places. CONCLUSIONS: Localized application of non-sterile OM or phytate plus OM stimulated cluster-root proliferation of L. albus in the localized layers. This effect is predominantly accounted for by P release from breakdown of OM or phytate, but not due to a change in soil density associated with OM. No evidence was found for effects of micro-organisms in OM other than those responsible for P release.

[Nitrogen status diagnosis of rice by using a digital camera].

In the present research, a field experiment with different N application rate was conducted to study the possibility of using visible band color analysis methods to monitor the N status of rice canopy. The Correlations of visible spectrum band color intensity between rice canopy image acquired from a digital camera and conventional nitrogen status diagnosis parameters of leaf SPAD chlorophyll meter readings, total N content, upland biomass and N uptake were studied. The results showed that the red color intensity (R), green color intensity (G) and normalized redness intensity (NRI) have significant inverse linear correlations with the conventional N diagnosis parameters of SPAD readings, total N content, upland biomass and total N uptake. The correlation coefficient values (r) were from -0.561 to -0.714 for red band (R), from -0.452 to -0.505 for green band (G), and from -0.541 to 0.817 for normalized redness intensity (NRI). But the normalized greenness intensity (NGI) showed a significant positive correlation with conventional N parameters and the correlation coefficient values (r) were from 0.505 to 0.559. Compared with SPAD readings, the normalized redness intensity (NRI), with a high r value of 0.541-0.780 with conventional N parameters, could better express the N status of rice. The digital image color analysis method showed the potential of being used in rice N status diagnosis in the future.

[Influence of interpolation method and sampling number on spatial prediction accuracy of soil Olsen-P].

Different from the large scale farm management in Europe and America, the scattered farmland management in China made the spatial variability of soil nutrients at county scale in this country more challenging. Taking soil Olsen-P in Wuhu County as an example, the influence of interpolation method and sampling number on the spatial prediction accuracy of soil nutrients was evaluated systematically. The results showed that local polynomial method, ordinary kriging, simple kriging, and disjunctive kriging had higher spatial prediction accuracy than the other interpolation methods. Considering of its simplicity, ordinary kriging was recommended to evaluate the spatial variability of soil Olsen-P within a county. The spatial prediction accuracy would increase with increasing soil sampling number. Taking the spatial prediction accuracy and soil sampling cost into consideration, the optimal sampling number should be from 500 to 1000 to evaluate the spatial variability of soil Olsen-P at county scale.

[Application of ICP-AES to detecting nutrients in grain of wheat core collection of China].

Deficiency of micronutrients, especially iron and zinc, has been a serious malnutrition problem worldwide in human health. Increasing Fe and Zn concentrations in grains by means of plant breeding is a sustainable, effective and important way to improve human mineral nutrition and health. However, little information on grain Fe and Zn concentrations in Chinese wheat genotypes is available. Therefore, to determine the nutrients status especially these of micronutrients in wheat grain is necessary and very useful. Two hundred sixty two genotypes were selected from the wheat mini-core collections, which contained 23090 wheat genotypes in China and represented 72.2% of total genetic variation. All 262 genotypes were grown in soils of similar geographical and climate location in order to minimize the environmental effect. After harvesting, the grains were washed with deionized water and dried (around 70 degrees C), then digested in HNO3 solution using a microwave accelerating reaction system (MARS). Nutrient concentrations in stock solution were analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Remarkable genetic variations among grain nutrient concentrations (Fe, Mn, Cu, Zn, Mg, Ca, K and P ) in the tested genotypes were detected. The concentrations of Fe, Zn, Mn, Cu, Ca, Mg, K and P in wheat grain were in the ranges of 34.2-61.2, 26.3-76.0, 20.9-56.7, 3.4-9.8, 290-976, 1129-2210 mg x kg(-1); 0.34%-0.85% and 0.296%-0.580%, respectively. The corresponding average values were 45.1, 50.2, 37.9, 6.5, 515, 1772 mg x kg(-1), 0.55% and 0.451%, respectively. Significant positive correlations between micronutrients (Fe, Mn, Zn, and Cu) in wheat grains were detected, and the correlation coefficients were 0.395** (Fe and Mn), 0.424** (Fe and Zn), 0.574** (Fe and Cu), and 0.474** (Mn and Cu), respectively. However, no significant difference was found in grain nutrient concentrations between spring-wheat and winter-wheat genotypes. This study provides valuable and important information for breeding wheat genotypes which are enriched with minerals in grains, especially Fe and Zn

[Contents of nutrient elements in NH4(+)-N fertilizer and urea].

Fertilizer contains not only one compound or one element, so it is important to determine the contents of other elements necessitous and beneficial to plant. All the other nutrient elements for plant, including necessitous elements and beneficial elements in ammonia nitrogen fertilizer ((NH4)2SO4) and CO(NH2)2, were analyzed by method of ICP-MS. The results showed that ammonia nitrogen fertilizer ((NH4)2SO4) and CO(NH2)2 both contain many necessitous elements, Mg, P, K, Ca, Mn, Fe, Ni, Cu, Zn and Mo, thereinto the contents of Mg, P, K, Ca, Mn and Fe were on microg x g(-1) the level, and Ni, Cu, Zn and Mo were on the ng x g(-1) level; compared with CO(NH2)2, ammonia nitrogen fertilizer ((NH4)2SO4) contains more necessitous elements and beneficial elements except Mo and Si. All the above elements could influence the results of nitrogen fertilizer efficiency experiments, so pure fertilizer should be used in the future nitrogen fertilizer efficiency experiments and the comparative experiments of different form nitrogen fertilizer.

[The content of nutrient elements of plant in KCl fertilizer].

Potassium is one of the three most important plant nutrient elements, so many researchers pay attention on its fertilizer efficiency. But fertilizers were all industrial products containing many other nutrient elements in most experiments of fertilizer efficiency. All the other nutrient elements, including necessitous elements and beneficial elements in potassium fertilizer (KCl) were analyzed by method of ICP-MS. The results showed that KCl fertilizer contained many necessitous elements (Mg, Ca, Mn, Fe, Ni, Cu, Zn and Mo), the concentrations of them are 50.51, 1 309.48, 5.44, 500.83 microg x g(-1) and 65.54, 238.85, 212.44, 10.40 ng x g(-1) respectively; beneficial elements (Na, Al, Si, Co and Se) are 25 095.89, 3.83, 3.40 microg x g(-1) and 13.12, 23.25 ng x g(-1) respectively. All the above elements could influence the results of potassium fertilizer efficiency experiments, so pure fertilizer should be used in the future potassium fertilizer efficiency experiments.

[Effects of forms and level of nitrogen fertilizer on the content of chlorophyll in leaves of maize seedling].

The level and form of nitrogen fertilizer could significantly influence the growth and development of plant. The present paper studied the content of chlorophyll by the instrument SPAD-502 after treated with different nitrogen fertilizer level and different nitrogen fertilizer form. The results showed that the contents of chlorophyll in the last expanding leaf of maize seedling treated by levels of 0, 100 and 200 kgN x hm(-2) respectively had no significant difference, with the value of SPAD ranging from 43.3 to 43.7, but when the nitrogen fertilizer level got to 400 kgN x hm(-2), the content of chlorophyll in the last expanding leaf of maize seedling increased significantly, which can be caused by other components in the nitrogen fertilizer, which needs to be further studied. The experiments of nitrogen form showed that maize seedling treated by ammonia nitrogen ((NH4)2SO4) contained more chlorophyll than that treated by saltpeter nitrogen (Ca(NO3)2), and the statistical analysis was significant. The reason for the effect of nitrogen form on the content of chlorophyll of maize seedling leaf could be: (1) it is easier for plants to absorb ammonia nitrogen ((NH4)2SO4) than saltpeter nitrogen (Ca(NO3)2); (2) ammonia nitrogen ((NH4)2SO4) contains more trace elements which can promote the growth and development of plants.

[Nitrogen status diagnosis of summer maize by using visible spectral analysis technology].

In the present paper, a field experiment with different N rates was conducted to study the possibility of using the visible spectrum of crop canopy to diagnose N status for the summer maize. Visible spectrum parameters were compared with the leaf SPAD readings, total N concentration and vein nitrate concentration. Field measurement data showed that the greenness intensity, blueness intensity, normalized redness intensity, normalized greenness intensity and normalized blueness intensity of the maize canopy have significant relationships with leaf SPAD readings, total N concentration and vein nitrate concentration (under a low N input condition, with vein nitrate concentration < 2 000 mg x L(-1)) at summer maize 10 leaves unfold stage. The greenness intensity, blueness intensity, normalized greenness intensity and normalized blueness intensity have significant relationship with the vein nitrate concentration under a low N input condition (vein nitrate concentration < 2 000 mg x L(-1)). But when the maize vein nitrate concentration is above 2 000 mg x L(-1), there is no spectral parameter showing significant relationship with the vein nitrate concentration. The visible spectrum parameters reached a plateau with the vein nitrate concentration increasing. To sum up, the normalized greenness intensity (NGI) and normalized blueness intensity (NBI) have higher r values (0.45-0.66) than other parameters.

[Distribution of six trace elements in Fuji apple].

Trace elements are important nutritional elements for human health. Six trace elements in Fuji apple skin and pulp were analyzed by the method of ICP-MS. The results showed that the concentrations of Ca, Mn, Fe, Se, Mo and I were 197 910, 1 623, 14 400, 2, 47 and 91 ng x g(-1) x FW in apple skin respectively; and 58 360, 281, 550, 4, 18 and 24 ng x g(-1) x FW respectively in apple pulp. The concentrations of most trace elements (Ca, Mn, Fe, Mo and I) in apple skin were several times higher than those in apple pulp, especially the concentrations of Fe, Mn and I in skin was 25.18, 4.78 and 2.79 times higher than those in pulp, except Se (2 ng x g(-1) x FW in skin and 4 ng x g(-1) x FW in pulp). So we should not peel apples before we eat them from regions where were not polluted by pesticides and heavy metals.