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1.
To evaluate the available silicon (Si) content in agricultural soils in Japan and to investigate the determining factors of this content, we collected 180 soil samples from the surface layer of paddies and upland fields in Japan and determined their available Si contents. A phosphate buffer (PB; 0.02 M, pH 6.9) or an acetate buffer (AB; 0.1 M, pH 4.0) was used to extract available Si from the soil samples, and the Si concentrations in the extracts were determined by inductively coupled plasma-atomic emissions spectroscopy (ICP-AES). The total Si content and selected physicochemical properties were also determined for the soil samples. The median values of the available Si contents by the PB and AB methods were 48.8 and 79.7 mg kg?1 and corresponded to 0.017% and 0.027% of the total Si content, respectively. The overall data showed log-normal distributions. The available Si content of the upland soils was significantly higher than that of the paddy soils by both the PB (p < 0.01) and AB methods (p < 0.05). The available Si contents by the PB and AB methods had a significant positive correlation (p < 0.01) and they had significant negative correlation with the total Si content (p < 0.01). The values of the available Si contents by the PB and AB methods correlated positively with the pH, total carbon (C) content, and dithionite-citrate bicarbonate extractable iron (Fed) and aluminum (Ald), acid oxalate extractable iron (Feo) and aluminum (Alo), Fed-Feo and Alo+1/2Feo values (p < 0.01). A multi-regression analysis indicated that pH, amorphous minerals and crystalline iron (Fe) oxides were the dominant determining factors of available Si in the soils, and these three variables explained approximately two thirds of the variation of available Si content in agricultural soils in Japan. In terms of soil type, Terrestrial Regosols, Dark Red soils and Andosols had relatively high available Si contents, whereas Sand-dune Regosols, Red soils and Gray Lowland soils had relatively low contents. In terms of region, the soils in the Kanto and Okinawa regions had relatively high available Si contents and those in the Kinki, Shikoku and Chugoku regions had relatively low contents. In conclusion, the available Si content and its determining factors for agricultural soils in Japan were quantitatively elucidated, and this will contribute to the establishment of rational soil management?—including the application of silicate materials, taking into account the Si-supplying power of the relevant soils—for sustainable and productive agriculture in Japan.  相似文献   

2.
Abstract

To evaluate labile selenium (Se) content in agricultural soils in Japan and to investigate its determining factors, 178 soil samples were collected from the surface layer of paddy or upland fields in Japan and their soluble Se contents were determined. Two grams of soil was extracted with 20 mL of 0.1 mol L?1 sodium sulfate (Na2SO4) solution for 30 min in boiling water, and the released Se was reduced to Se (IV) after organic matter decomposition. The concentration of Se (IV) was then determined by high performance liquid chromatography (HPLC) with a fluorescence detector after treatment with 2,3-diaminonaphthalene (DAN) and extraction with cyclohexane. Soluble Se content ranged from 2.5 to 44.5 μg kg?1 with geometric and arithmetic means of 11.4 and 12.8 μg kg?1, respectively, and corresponded to 3.2% of the total Se on average. The overall data showed log-normal distribution. In terms of soil type, Non-allophanic Andosols and Volcanogenous Regosols had relatively high soluble Se content, and Wet Andosols and Lowland Paddy soils had relatively low soluble Se content. In terms of land use, upland soils had significantly higher soluble Se content than paddy soils (p < 0.01). The soluble Se content had significant positive correlation with total organic carbon (TOC) content of the extract, soil pH and total Se content (p < 0.01). In conclusion, total Se content in combination with soil pH was the main determining factor of the soluble Se content of agricultural soils in Japan.  相似文献   

3.
Abstract

To evaluate the content of nitrogen (N) fractions of agricultural soils in Java, Indonesia, in relation to soil type and land use, 46 surface soil samples, 23 from paddy and 23 from upland, were collected throughout Java to include various types of soils. Soil N was separated into four fractions according to form and availability: inorganic extractable nitrogen (Iex-N), fixed ammonium nitrogen (Ifix-N), organic mineralizable nitrogen (Omin-N) and organic stable nitrogen (Osta-N). The total-N content was determined by the dry combustion method. The Iex-N content was determined by extraction with a 2 mol L?1 potassium chloride (KCl) solution and the Ifix-N content by extraction with an hydrofluoric and hydrochloric acid (HF-HCl) solution after removal of organic-N. The Omin-N content was evaluated as the potentially mineralizable N based on a long-term incubation method. The Osta-N content was calculated as the difference between the contents of total-N and the three other fractions. The total-N content was 2.06 g kg?1 on average. The contents of Iex-N, Ifix-N, Omin-N and Osta-N were 25.8, 99.1, 103 and 1,832 mg kg?1, respectively, and corresponded to 1.3, 4.8, 5.0 and 88.9% of the total-N. Hence, available (Iex-N and Omin-N) and stable (Ifix-N and Osta-N) fractions accounted for 6.3% and 93.7% of the total-N, respectively. Correlation analysis indicated that the contents of total-N and Osta-N had positive correlation with (Alo + 1/2Feo) as an index of amorphous minerals (p < 0.01), suggesting strong influence of volcanic materials for the accumulation of organic matter in Java soils. The content of Ifix-N had a positive correlation with nonexchangeable potassium (K) content (p < 0.01), suggesting the contribution of 2:1 clay minerals which can fix both ammonium (NH4+) and K+ in their interlayer sites. On the contrary, Omin-N did not have any significant correlation with soil properties, implying the importance of management for the improvement of the available N level in soils, rather than intrinsic soil properties. Soil N status further showed strong topographical trends depending on the elevation where soil developed. The contents of total N, Iex-N, Ifix-N, Omin-N and Osta-N in Java soils were on average 80, 69, 90, 65 and 80% of those in Japanese soils, respectively, suggesting that the soil N level in Java was lower than that in Japan, probably due to accelerated decomposition of organic matter, especially degradable fractions, reflecting high temperature, but that the level was relatively high for tropical soils due to the effect of volcanic materials. In conclusion, these results should be taken into account for the sustainable management of soil N in agricultural fields in Java, Indonesia.  相似文献   

4.
Runoff may cause losses of micronutrients from soils. This can result in environmental problems such as contaminant transfers to water or a decrease in soil fertility. Appropriate soil management may reduce these micronutrient losses. This study examined the effect of applying crop residues to the soil surface on iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) losses by runoff. Runoff and sediment yield were measured on 1-m2 plots using a rainfall simulator with constant 65 mm h?1 intensity. Eight successive rainfall applications were performed at 65 mm each. Corn (Zea mays L.) straw was applied to plots at rates ranging from 0 to 8 t ha?1. Both total and dissolved concentrations of the micronutrients studied were decreased by corn straw applications. After 520 mm cumulative rainfall, total soil losses ranged from 150 to 15354 kg ha?1 depending on the amount of corn straw applied. Total micronutrient concentrations in runoff were as follows: Fe from 14.98 to 611.12 mg L?1, Mn from 0.03 to 0.61 mg L?1, Cu from 0.10 to 1.43 mg L?1, and Zn from 0.21 to 5.45 mg L?1. The relative contribution of the dissolved fraction to the total micronutrient content loss was low, but varied depending on the nutrient, being less than 1 percent for Fe and Mn and almost 10 percent for Zn. Total and dissolved concentrations in runoff of the studied elements decreased exponentially as the rate of applied corn straw increased. In conclusion, the addition of corn straw to soil reduced micronutrient losses.  相似文献   

5.

Purpose

The area of cadmium (Cd)-contaminated soil in China is increasing due to the rapid development of the Chinese economy. To ensure that the rice produced in China meets current food safety and quality standards, the current soil quality standards for paddy soils urgently need to be updated.

Materials and methods

We conducted a pot experiment with 19 representative paddy soils from different parts of China to study the effects of soil properties on bioaccumulation of Cd in rice grains. The experiment included a control, a low treatment concentration (0.3 mg kg–1 for pH?<?6.5 and 0.6 mg kg–1 for pH?≥?6.5), and a high treatment concentration (0.6 mg kg–1 for pH?<?6.5 and 1.2 mg kg–1 for pH?≥?6.5) of Cd salt added to soils.

Results and discussion

The results showed that the Cd content in grains of the control and low and high Cd treatments ranged from 0.021 to 0.14, 0.07 to 0.27, and 0.12 to 0.33 mg kg–1, respectively. Stepwise multiple regression analysis indicated that soil pH and organic carbon (OC) content could explain over 60 % of the variance in the (log-transformed) bioaccumulation coefficient (BCF) of Cd in grains across soils. Aggregated boosted trees analysis showed that soil pH and OC were the main factors controlling Cd bioavailability in paddy soils. Validation of the models against data from recent literature indicated that they were able to accurately predict the BCF in paddy soils.

Conclusions

These quantitative relationships between the BCF of Cd in grains and soil properties are helpful for developing soil-specific guidance on Cd safety threshold value for paddy soils.  相似文献   

6.
A pot experiment, in which composted pig manure was applied to soils at rates of 0%, 0.5%, 1.5%, 3.0%, and 5.0% (W/W) to simulate additions of different amounts of cadmium (Cd), copper (Cu), and zinc (Zn) to soil, was conducted to assess accumulation of metals by rice (Oryza sativa L.) plants from soils treated with manure. Results indicated that Cd concentrations in rice grains were more than the limit of 0.2 mg kg?1 when 0.14 mg kg?1 or more Cd was loaded to Ferralsols by manure application, but it was not more than the limit in Calcaric Cambisols. Zinc contents in polished rice grains did not exceed the permissible limit of 50 mg kg?1 in two soils. Copper concentrations in rice grain were slightly more than the limit of 10 mg kg?1 in Ferralsols but not in Calcaric Cambisols. Results suggested greater risk of heavy‐metal contamination from manure to paddy rice in Ferralsols than in Calcaric Cambisols.  相似文献   

7.
Available iron, zinc, copper and manganese were determined in six pedons located in upper slope, middle slope and valley bottom soils derived from Abeokuta geological materials in Nigeria. The soils had an average of 639.8 g kg?1 sand, 241.8 g kg?1 clay and 118.4 g kg?1 silt. The fertility status of the soils was low–medium with a strongly acid–neutral reaction, 1.3–15.1 g kg?1 organic carbon contents, moderate–high exchangeable bases and 1.38 mg kg?1 available phosphorus. Both Fe (122.50 mg kg?1) and Mn (111.40 mg kg?1) occurred at toxic levels, whereas the mean Cu (1.27 mg kg?1) and Zn (2.56 mg kg?1) contents were found to be adequate for most crops grown in the region. There were significant positive correlations among the micronutrients and also between soil pH, organic carbon, particle size fractions and micronutrients. The high levels of Fe and Mn were probably due to the presence of oolitic ironstone in the parent material.  相似文献   

8.
亚热带典型地貌下旱地和水田可溶性有机物化学组成特征   总被引：3，自引：1，他引：2  
郑小东  陈香碧  胡亚军  苏以荣 《土壤》2019,51(6):1114-1121
阐明亚热带典型地貌下旱地与水田土壤可溶性有机物(DOM)化学组成差异可为农田土壤DOM稳定性评价提供理论依据。研究采用XAD-8树脂分组和热裂解气质联用仪(Py-GCMS)技术,分析比较休闲期、耕作期亚热带喀斯特山区、丘陵区及平原湖区旱地和水田土壤DOM化学组成特征。结果表明:休闲期,亲、疏水性可溶性有机碳(DOC)含量以水田(10.2、33.4 mg/kg)显著高于旱地(4.15、12.8 mg/kg),耕作期无显著性差异。与休闲期相比,耕作期水田亲、疏水性DOC含量均显著降低,而旱地亲、疏水性组分DOC含量在两个时期间保持相对稳定。休闲期旱地和水田土壤DOM中有机酸相对比例分别为31.9%、35.6%,耕作期显著降至17.9%、20.0%(P0.05)。脂类相对比例趋势与有机酸相反,旱地和水田土壤DOM中脂类相对比例在休闲期分别为55.0%、49.5%,耕作期显著增至70.1%、62.9%(P0.05)。Adonis分析表明,亲、疏水性DOC含量在旱地和水田、休闲期和耕作期差异显著(P0.05);DOM化学组成在不同时期(休闲期和耕作期)及地貌(喀斯特山区和丘陵区、丘陵区和平原湖区)差异显著(P0.05)。Random Forest分析表明,有机酸和脂类参与微生物代谢过程,在休闲期和耕作期差异显著(P0.05);芳香化合物作为DOM稳定性组分,在不同地貌区差异较大(P0.05)。总体上,田间条件下水田DOC比旱地DOC对时期响应更敏感,且土壤DOM中微生物代谢相关组分(有机酸、脂类)和稳定性组分(芳香族化合物)在不同时期及地貌区的差异性不同,这对评价旱地和水田土壤DOM稳定性及土壤有机碳积累具有一定的参考意义。  相似文献   

9.
Abstract

In the course of a series of studies conducted to investigate the long-term behavior of 129I (which has a half-life of 16 million years) in the environment, seasonal variation in the concentration of stable iodine (127I) in precipitation and soil water to a depth of 2.5 m in a forest plot, an upland field and a paddy field in the upland area of Tsukuba, Japan, were determined. Iodine concentration in precipitation tended to increase during the summer (high air temperature) season and low-rainfall period, and a positive high correlation was observed between annual rainfall and the annual amount of iodine supplied by precipitation. No seasonal variations in iodine concentration in soil water were observed at any depth in the forest plot and upland field unlike at shallow depths (0.2 and 0.5 m) in the paddy field. In the paddy field, from the beginning of summer irrigation, under flooding conditions, iodine concentration in soil water at shallow depths (0.2 and 0.5 m) continuously increased, and immediately before mid-summer (intermittent) drainage and drainage, the maximum iodine concentration (approximately 50 µg L?1) and lowest Eh values (approximately ?150 to ?200 mV) were recorded. These high iodine concentration levels and low Eh values were ascribed to high air temperature (approximately > 25°C on average every 10 days) and the continuation of the groundwater level above the ground surface. As for the temporary winter irrigation period (mean daily air temperature 2?4°C), the iodine concentration was low (1.7–3.7 µg L?1) at all depths, as was the case in the non-irrigation period. After mid-summer drainage, and drainage, the iodine concentration in soil water at depths of 0.2 and 0.5 m decreased drastically as the groundwater level decreased. The mean annual amount of iodine accumulated in the surface soil horizons (0–0.67 m) in the forest plot was estimated to be approximately 2.9 mg m?2 (7.5 µg kg?1 dry soil), which coincided with the mean annual amount of iodine supplied to the earth surface by precipitation. A mildly oxidative subsurface 2Bw horizon (0.60–0.89 m) in the paddy field was estimated to illuviate approximately 3.1 mg m?2 (20 µg kg?1 dry soil) of iodine annually by retaining iodine in the soil water percolated to this horizon.  相似文献   

10.
Two greenhouse experiments were conducted simultaneously to evaluate polymer-coated and common urea in upland rice production. The nitrogen (N) levels used for both the N sources were from 0 to 400 mg kg?1 of soil. Maximum grain yield was obtained with the addition of 167 mg N kg?1 polymer-coated urea and 238 mg N kg?1 common urea. Maximum value of other plant traits was obtained with N applied from 233 to 313 mg kg?1 depending on plant traits and N source. Nitrogen-use efficiency (NUE) decreased with increasing N rate in the two N sources. Based on results of growth, yield, and yield components, and NUE it can be concluded that the N sources were equally effective in upland rice production. Base saturation, pH, and exchangeable calcium (Ca) increased with increasing N rates while iron (Fe), manganese (Mn), and copper (Cu) contents decreased with the increasing N rates.  相似文献   

11.
Abstract

Athyrium yokoscense, a type of fern that grows vigorously in mining areas in Japan, is well known as a Cd hyperaccumulator as well as a Cu, Pb and Zn tolerant plant. However, no information is available on As accumulation of A. yokoscense, although it often grows on soils containing high levels of both heavy metals and As. In this study, young ferns collected from a mine area were grown in media containing As-spiked soils or mine soil in a greenhouse for 21 weeks. Athyrium yokosense was highly tolerant to arsenate and survived in soils containing up to 500 mg As (V) kg?1. The addition of 100 mg As (V) kg?1 resulted in the highest fern biomass (1.95 g plant?1) among As-spiked soils. Although the As concentration of the fern was lower than other As hyperaccumulators, such as Pteris vittata, A. yokoscense could hyperaccumulate As in mature and old fronds. Arsenic was accumulated most efficiently in old fronds (922 mg kg?1) in the media containing 5 mg As (III) kg?1. Moreover, higher As accumulation was found in the roots of the ferns, with a range from 506 to 2,192 mg kg?1. In addition, in the mine soil with elevated concentrations of As and heavy metals, A. yokoscense not only hyperaccumulated As (242 mg As kg?1 in old fronds), but also accumulated Cd, Pb, Cu and Zn at concentrations much higher than those reported for other terrestrial plants. Athyrium yokoscense accumulated Cd mostly in fronds in high concentrations, up to 1095 mg kg?1, while it accumulated Cu, Zn and Pb mainly in the roots and the concentrations were 375, 2040 and 1165 mg kg?1, respectively.  相似文献   

12.
The effects of different grazing pressures (GPs) on soil properties are not sufficiently understood. The objectives were to analyse the effects of three different extensive GPs on stocks of soil organic C and total N, soil microbial biomass C, basal respiration and mineral N in three different soil depths of a long-term pasture in Central Germany (FORBIOBEN field trial). No significant (p ≤ 0.05) effects of GP on weighted stocks of soil organic C, total N, soil microbial biomass C, mineral N and basal respiration rate were observed, suggesting that the C and N cycles are coupled in the three grazing treatments. Oxalate soluble Fe contents explained a marked part of the variation of soil organic C (multiple linear regression: R2 = 0.64) and total N contents (R2 = 0.64) in the soils, whereas almost all of the variability of soil microbial biomass C contents and basal respiration was explained by soil organic C contents. Overall, variabilities of soil organic C and N contents were largely explained by oxalate soluble Fe contents, whereas grazing intensity did not affect the C and N dynamics.  相似文献   

13.
Eight fly ash samples collected from South African power stations were evaluated for various chemical properties, liming potential and metal species release under incubation. All fly ashes had alkaline pH ranging from 10.97 to 12.75 with much wider variations of electrical conductivity (range 0.46–8.27 dS m?1). Their total P content ranged from 553.3 to 1514 mg P kg?1 and Olsen extractable P from 130 to 345.5 mg P kg?1. Application of two of the fly ashes to three different soils showed a high ability to neutralize acidity, resulting in an average of 41% change in pH after 8 weeks of incubation. Across all three soils, the fly ash incorporation increased extractable P content from a P-deficient level to levels above 25 mg P kg?1 in two of the three soils. Except for Cu, all metal species (Cr, Pb, Ni and Fe) showed significantly (P ≤ 0.05) low extractability under fly ash treated soils compared to the soil alone control. These results suggest that the South African fly ashes studied are effective liming materials and can provide essential elements such as P with minimum risk of soil contamination from metal species release.  相似文献   

14.
Abstract

Denitrification products nitrous oxide ((N2O) and nitrogen (N2)) were measured in three flooded soils (paddy soil from Vietnam, PV; mangrove soil from Vietnam, MV; paddy soil from Japan, PJ) with different nitrate (NO3–) concentrations. Closed incubation experiments were conducted in 100-mL bottles for 7 d at 25°C. Each bottle contained 2 g of air-dried soil and 25 mL solution with NO3– (concentration 0, 5 or 10 mg N L?1) with or without acetylene (C2H2). The N2O + N2 emissions were estimated by the C2H2 inhibition method. Results showed that N2O + N2 emissions for 7 d were positively correlated with those of NO3– removal from solution with C2H2 (R2 = 0.9872), indicating that most removed NO3– was transformed to N2O and N2 by denitrification. In PJ soil, N2O and N2 emissions were increased significantly (P < 0.05) by the addition of greater NO3– concentrations. However, N2O and N2 emissions from PV and MV soils were increased by the addition of 0 to 5 mg N L?1, but not by 5 to 10 mg N L?1. At 10 mg N L?1, N2 emissions for 7 d were greater in PJ soil (pH 7.0) than in PV (pH 5.8) or MV (pH 4.3) soils, while N2O emissions were higher in PV and MV soils than in PJ soil. In MV soil, N2O was the main product throughout the experiment. In conclusion, NO3– concentration and soil pH affected N2O and N2 emissions from three flooded soils.  相似文献   

15.
A study was conducted with 24 piedmont soils of Arunachal Pradesh (India) to estimate the critical limit of available boron (B) in soil and cowpea plant for predicting the response of cowpea (Vigna unguiculata L. Walp.) to B application. The critical concentration of available B in these soils was established by graphical procedure at 0.48 mg kg?1 for soil and at 24.5 mg kg?1 in the plant tissues. Soil containing available B below the critical limit responded appreciably to B fertilization. A negative response to B application was also observed in soils at higher level of available B. The average dry matter yield increased with the increasing level of B application up to 1.5 mg kg?1. The yield response to B application in cowpea on B deficient soils was 34.5%. Based on the critical value of 0.48 mg kg?1, 10 soils were rated to be adequate and 20.0% soils belonging to this category responding to B application, whereas 85.7% soils below the critical value showed a positive response to B application. The hot water soluble B was significantly and positively correlated with organic carbon, cation exchange capacity and clay contents and negatively correlated with pH, silt and sand contents of soils.  相似文献   

16.
Abstract: In recent years, sulfur (S) deficiencies in winter wheat (Triticum aestivum L.) have become more common, particularly on coarse‐textured soils. In Study I, field experiments were conducted in 2001/2002 through 2003/2004 on Mississippi River alluvial soils (Experiment I) and an upland, loessial silt loam (Experiment II) to evaluate the influence of spring S rates of 0, 5.6, 11.2, and 22.4 kg ha?1 and a fall rate of 22.4 kg sulfate (SO4)‐S ha?1 on grain yield of three varieties. In Study II, field experiments were conducted in 2001/2002 and 2004/2005 on alluvial soils to evaluate the influence of spring S rates of 0, 5.6, 11.2, and 22.4 kg SO4‐S ha?1 in fields where S‐deficiency symptoms were present. Grain yield response to applied S occurred only on alluvial, coarse‐textured, very fine sandy loam soils (Study II) that had soil SO4‐S levels less than the critical level of 8 mg kg?1 and organic‐matter contents less than 1 g kg?1 in the 0‐ to 15‐, 15‐ to 30‐, and 30‐ to 45‐cm depths. Soil pH increased with soil depth. Optimum S rate was 11.2 kg SO4‐S ha?1 in 2001/2002 and 5.6 kg SO4‐S ha?1 in 2004/2005. On the upland, loessial silt loam soil, soil SO4‐S levels accumulated with depth, whereas organic‐matter content and pH decreased. In the loessial soils, average soil SO4‐S levels in the 15‐ to 30‐ and 30‐ to 45‐cm soil depths were 370% greater than SO4‐S in the surface horizon (0 to 15 cm).  相似文献   

17.
基因组学在作物抗逆性研究中的新进展   总被引：4，自引：0，他引：4  
自然环境中各种生物和非生物胁迫是影响作物产量的巨大威胁。随着现代分子生物学的发展,从分子水平研究作物抵御逆境的机理已成为生态农业研究的一个重要任务,分子遗传学与生态学的整合诞生了生态基因组学即用基因组学的技术和手段研究生态学领域的问题。基因组学按其研究内容分为功能基因组学、结构基因组学和比较基因组学,本文从这3方面分别阐述了作物抵抗生物胁迫和非生物胁迫的生态基因组学研究进展,总结了基因组学在植物抗逆性研究中的一些新技术和新手段,特别是基于近几年发展起来的二代深度测序所带来的一系列高通量的检测方法与结果。①功能基因组学包含转录组学、表观遗传学、蛋白组学、相互作用组学、代谢组学和表型组学,本文侧重从植物抗逆的功能基因表达水平上的研究展开,重点探讨了转录组学和表观遗传学在植物抗逆研究的新进展,介绍了一些转录组学和表观遗传学研究技术,如基因芯片技术、RNA测序技术、SAGE、cDNA-AFLP、SSH、亚硫酸盐法、ChIP-Chip、ChIP-seq等;例举了一些转录因子基因家族在植物抗逆反应中的作用,总结其作用共性,结果表明不少抗逆基因受到胁迫后基因转录激活上有一定相关性,大多受激素信号转导途径所调控,很多抗逆途径最终都涉及到ABA信号传导通路并与衰老相关;植物的抗逆性受多个信号通路调控,对同一逆境响应常常需要不同的转录因子共同参与,而同一转录因子也有可能参与2个以上的不同抗逆反应;表观遗传学则指在不改变基因序列前提下,对DNA甲基化修饰、组蛋白翻译后修饰及小RNA介导的信号传导等,有证据表明其存在遗传印记作用。②结构基因组学主要利用QTL定位和DNA测序技术,确定植物基因组的遗传图谱和物理图谱,二代深度测序平台的建立使许多植物的全基因组测序成为可能。迄今为止,已有超过40种植物完成全基因组测序,越来越多的植物全基因组计划正在实施中或预计实施。③比较基因组学是基于功能基因组学和结构基因组学进而比较不同物种或不同群体间的基因组差异和相关性的研究,可分析逆境响应相关基因在进化过程中及在地理位置分布中的作用和意义,也同时为QTL定位及功能基因组学研究提供丰富信息。此外,还简要介绍并列举了一些网络共享作物抗逆的生物信息资源数据库。虽然基因组学在如何正确处理海量数据等问题上还存在瓶颈,但它提供的大量作物抗逆方面的基因组信息已为植物抗逆研究提供了众多线索与依据,为今后改良作物抗逆性的遗传育种工作带来了新启示。  相似文献   

18.
Abstract

Soils under the main mangrove (Rhizophora racemosa and Avicennia germinans) forest in the Niger Delta, Nigeria, were characterized, and their capacities to retain heavy metals were examined by using soil column leaching experiments, using 20 mg L?1 Cu, 50 mg L?1 Zn, 20 mg L?1 Cd, and 100 mg L?1 Mn solutions. At the end of the leaching experiments, soil samples from each column were divided into two layers (0–5 cm and 5–10 cm) and analyzed for total metal retained. The fractionation of heavy metals in the surface soil samples (0–5 cm) was investigated by the sequential extraction technique. The study showed that the soils were influenced by tidal flow and characterized by the presence of very fine textured, thin (0–5 cm) to moderately thick (10–15 cm) layer of alluvium (mud) on the surface. The fibric soil material beneath the surface mud varies in thickness from about 70 to 100 cm, and beyond the histic layer is the plastic, very sticky, massive clay. In situ, the soils were neutral in reaction (pH 7.0–7.2), but became strongly acid (pH 3.3–4.8) upon drying. They are saline, high in soluble salts, highly reduced, with CEC that is low in the fibric layer, but high in the mineral, clayey subsoil horizon. The soils are saturated with water for much more than 30 days in a year and have fiber content that is more than 40 cm thick, with the fibric sphagnum constituting more than three‐fourths by volume to a depth greater than 90 cm. The soils, classified as Typic Sphagnofibrists, sequestered considerable amounts of copper (Cu), zinc (Zn), cadmium (Cd), and manganese (Mn) with most of the metals retained in the surface soils. The anthropogenic heavy metals were mostly adsorbed probably to the negatively charged sites of organics and clay. These loosely bound metals may be desorbed and reenter the aqueous phase, thus becoming a secondary source of metal pollution.  相似文献   

19.
Copper/zinc bioaccumulation and the effect of phytotoxicity on the growth of lettuce (Lactuca sativa L.) were studied in plastic vessels containing (i) non-contaminated soil, (ii) copper-contaminated soils at concentrations of 75.0 and 125.0 mg kg?1, (iii) zinc-contaminated soils at concentrations of 1200 and 2400 mg kg?1, and (iv) soil enriched with swine manure. Copper and zinc concentrations in lettuce leaves were determined by flame atomic absorption spectrometry during 42 days of growth. Copper concentrations from 0.92 to 13.06 mg kg?1 were found in lettuce leaves grown in copper-contaminated soils and zinc concentrations from 58.13 to 177.85 mg kg?1 were found in lettuce leaves grown in zinc-contaminated soils. Copper and zinc concentrations in lettuce leaves grown in swine manure-enriched soils ranged from 0.82 to 8.33 and 0.68 to 13.27 mg kg?1, respectively. Copper and zinc bioaccumulation caused a decrease in lettuce growth in metal-contaminated soils and an increase in phytotoxicity effects when compared to growth in non-contaminated and manure-enriched soils. These findings were confirmed by measuring leaf areas and biomasses. Copper was less toxic to lettuce than zinc due to the different concentrations in the soil. Lettuce growth and development was better in the swine manure-enriched soil than non-contaminated soil, which indicates that swine manure is a safe agricultural biofertilizer when used in appropriate amounts to avoid metal bioaccumulation in soil and plants.  相似文献   

20.
长期施磷稻田土壤磷素累积及其潜在环境风险   总被引：7，自引：1，他引：7  
应用常规化学分析法和数学统计方法,基于太湖地区13年的长期定位试验,研究长期不同施磷水平下[0(不施磷)、30 kg.hm 2.a 1(低磷)、60 kg.hm 2.a 1(适磷)、90 kg.hm 2.a 1(高磷)]稻麦轮作系统稻田土壤磷素累积规律及磷素流失引发的环境风险。在本试验区土壤环境条件下,可能发生稻田磷素淋溶及径流的土壤耕层(0~15 cm)Olsen-P临界值分别为26.0 mg.kg 1和24.8 mg.kg 1。连续13年适磷、高磷施肥,土壤耕层Olsen-P含量分别达到26.9 mg.kg 1和33.2 mg.kg 1,均高于临界值浓度,且已导致稻田田面水与30 cm渗漏水中总磷浓度显著升高,大大提高了稻田磷素淋溶及径流的风险。低磷施肥土壤Olsen-P长期稳定在(10.1±2.0)mg.kg 1水平,并且每年的稻麦产量与高磷、适磷处理相比并无显著差异,而长期低磷施肥土壤磷的流失风险也较小。因此,在太湖地区稻麦轮作体系下,磷肥不宜以常规适磷水平长期施用,建议以低磷水平(30 kg.hm 2.a 1)长期施用或以适磷水平(60 kg.hm 2.a 1)间歇式施用。  相似文献   

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