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Zinc (Zn)–efficient wheat genotypes yield well on Zn-deficient soil. In this study, two Chinese wheat genotypes, Kenong9204 and Han6172, and two reference genotypes, Bezostaja (Zn efficient) and BDME10 (Zn inefficient), from Turkey were conducted to measure their physiological responses to Zn deficiency in the greenhouse. Results showed obvious genetic variation among the genotypes with Zn efficiency from 76% to 105%. Bezostaja and Kenong9204 had greater shoot dry weight and accumulated more shoot Zn content than BDME10 and Han6172 without Zn application. In one aspect of enzyme activities, Bezostaja and Kenong9204 presented significantly greater activities of superoxide dismutase while maintaining similar activities of catalase, ascorbate peroxidase, and glutathione reductase compared with inefficient genotypes BDME10 and Han6172 under Zn-deficient condition. Zinc-efficient genotypes are recommended to satisfy the sustainable grain yield in China and other areas, where Zn deficiency in soil is spread and...

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.

An automated system for continuous measurement of N₂O fluxes on an hourly basis was employed to study N₂O emissions in an intensively managed low carbon calcareous soil under sub-humid temperate monsoon conditions. N₂O emissions occurred mainly within two weeks of application of NH₄(+) based fertilizer and total N₂O emissions in wheat (average 0.35 or 0.21 kg N ha⁻¹ season⁻¹) and maize (average 1.47 or 0.49 kg N ha⁻¹ season⁻¹) under conventional and optimum N fertilization (300 and 50-122 kg N ha⁻¹, respectively) were lower than previously reported from low frequency measurements. Results from closed static chamber showed that N₂O was produced mainly from nitrification of NH₄(+)-based fertilizer, with little denitrification occurring due to limited readily oxidizable carbon and low soil moisture despite consistently high soil nitrate-N concentrations. Significant reductions in N₂O emissions can be achieved by optimizing fertilizer N rates, using nitrification inhibitors, or changing from NH₄(+)- to NO₃(-)-based fertilizers.

Nitrogen (N) supply is the most important factor affecting yield and quality of flue-cured tobacco (FCT). A field experiment and an in situ incubation method were used to study the effects of soil N mineralization in the later stages of growth on yield and nicotine content of FCT in Fenggang and Jinsha, Guizhou Province. The yield and market value of FCT at Fenggang were much lower than those at Jinsha. However, the nicotine content of middle and upper leaves was much higher at Fenggang than at Jinsha when the same rate of fertilizer N was applied, which might be due to a higher N supply capacity at the Fenggang site. At later stages of growth (7–16 weeks after transplanting), the soil net N mineralization at Fenggang (56 kg N ha−1) was almost double that at Jinsha (30 kg N ha−1). While soil NH4-N and NO3-N were almost exhausted by the plants or leached 5 weeks after transplanting, the N taken up at the later growth stages at Fenggang were mainly derived from soil N mineralization, which contributed to a high nicotine content in the upper leaves. The order of soil N contribution to N buildup in different leaves was: upper leaves > middle leaves > lower leaves. Thus, soil N mineralization at late growth stages was an important factor affecting N accumulation and therefore the nicotine content in the upper leaves.

Our previous experiment revealed that apex-removed plants have larger root systems but a lower K+-uptake rates than intact tobacco plants. Since the apex is not only a center of growth and metabolism, but also an important place of auxin synthesis and export, the aims of this study were to distinguish whether the apex demand or auxin synthesized in the apex regulates assimilate and nutrients partitioning within plant, and to explain the reason for the lower K+-uptake rate of the apex-removed plant. In comparison with the control plant, covering the shoot apex with a black transparent plastic bag reduced net increases in dry matter and nutrients; however, the distribution of the dry matter and nutrients between shoot and roots and nutrient-uptake rates were not changed. Removal of the shoot apex shifted the dry mass and nutrients distributions to roots, and reduced the rate of nutrient uptake. Application of 1-naphthylacetic acid (NAA) could partly replace the role of the removed apex, stimulated assimilate and nutrient deposition into the treated tissue, and enhanced the reduced plasma membrane ATPase activity of roots to the control level. However, treatment of the apex-removed plants with NAA could not rescue the reduced nutrient uptake rate and the shifted assimilates and nutrients partitioning caused by excision of the apex. Higher nutrient uptake rate of the intact plants could not be explained by root growth parameters, such as total root surface area and number of root tips. The results from the present study indicate that strong apex demand determined assimilates and nutrients partitioning and nutrient-uptake rate in tobacco (Nicotiana tabacum) plants.

The sequential growth of winter wheat and corn within one year is the main cropping rotation system in northern China, excess nitrogen (N) fertilizer application to this system is a common problem. Four field experiments with four or five N rates were conducted in Beijing City and Henan province to study the optimal N rate for this system. The results of this study clearly indicate that the high rates of fertilization recommended by the quadratic model were less profitable than the lower rates recommended by the LRP and QRP models. The amounts of N in above-ground plant tissue tended to increase with increase in rate of N application but the percentage recovery of N in each increment decreased with each additional increment of fertilizer applied, and higher percentage recoveries were observed in wheat than in corn. Soil nitrate concentrations increased with increasing rates of N application. Average of 30% of the soil mineral N deficit can be accounted for uptake of N by wheat, but linear regress...

Based on field measurements, the effects of atmospheric reactive nitrogen (ARN) on the middle/trace element concentrations in the leaves of wild plant humulus scandens were analyzed. Leaves of H. scandens were collected from six sites around Beijing in the North China Plain, and the concentrations of Ca, Mg, S, Fe, Mn, Cu, Zn, B, and Na in the leaves were determined with inductively coupled plasma atomic emission spectrometry (ICP-AES). The results showed that element concentrations in leaves ranked as Ca (41 106)S (8 370)Mg (6 628)Fe(476)Na (92)B (78)Mn (49)Zn (38)Cu (15) mg x kg(-1) dry matter; There were no significant difference in any of the individual element in the H. scandens leaves along the gradient of ARN, suggesting that the increasing demand of H. scandens for middle/trace elements, induced by the enhanced nitrogen availability from ARN, was not yet beyond the nutrient-supply limits of the local soils. This study offers reference to scientific assessments of the middle/trace element status in terrestrial herbaceous plants under the global background of increasing nitrogen deposition.

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.

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.

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

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.

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.

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 concentration2 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 concentration2 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.

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.

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.

Phosphate fertilizer is one of the most important fertilizers. The authors determined nine kinds of major elements in superphosphate, the most important phosphate fertilizer, by X-ray fluorescence spectrometry. The detection range of SiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 is 15.0%-90.0%, 0.20%-25.0%, 0.20%-25.0%, 0.01%-0.35%, 0.20%-40.0%, 0.10%-35.0%, 0.10%-7.50%, 0.05%-7.50% and 1.00%-100.00% respectively, and the precision of the method for SiO2, Al2O3, TFe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 range from 0.20% to 0.005%, so the method of X-ray fluorescence spectrometry is a fast and effectual method for detecting the composition of phosphate fertilizer. The contents of the above elements showed (1) the detected superphosphate content is 18.101% of P2O5, which is accordant to the labeled level (or = 16%); (2) the detected superphosphate contains much SiO2, TFe2O3, MgO, CaO and K2O, which are necessary for plant growth and the content of which is 16.954%, 1.495%, 1.580%, 21.428% and 1.585% respectively. These data showed that phosphate fertilizer sometimes can supply some trace elements for plants, but we should eliminate the interference effect of these elements when we research the role of phosphorus; (3) superphosphate contains 3.225% of Al2O3, so the authors should attention to the aluminium poison when superphosphate is used chronically.

Environmental safety has been the focus worldwide, where involved are the pollutions of heavy metals, pesticides and persistent organic pollutants. Fertilizer has become one of the polluting sources of heavy metals, which are very deleterious to human health and environmental safety. Heavy metals are difficult to metabolize in human body and very harmful, so research on the pollution of heavy metals is considered increasingly important. The pollution sources of heavy metals include waste residue, waste water and exhaust gas from industry and automobile, and garbage from human life. The heavy metals in fertilizer can endanger the human body by the crop containing heavy metals. Two kinds of nitrogen fertilizer were analyzed in terms of the content of heavy metals by ICP-MS, and the results showed that the content of 10 kinds of heavy metals (Al, Ti, Cr, Ni, Cu, Zn, As, Cd, Hg and Pb) in (NH4)2SO4 was 1345.13, 35.12, 2539.27, 287.26, 674.05, 270.79, 42.54, 22.13, 27.20 and 123.87 ng x g(-1) respectively; and in CO(NH2)2 it is 71.59, 5.36, 1167.71, 188.60, 7.46, 64.45, 10.55, 0.00, 0.09 and 3.71 ng x g(-1) respectively. All the data showed that CO(NH2)2 contained much less heavy metals than (NH4)2SO4, so we should select CO(NH2)2 as the nitrogen fertilizer in agricultural production.

With the rapid development of society, more and more attention has been focused on environmental safety, especially on the pollutions of heavy metals, pesticides, persistent organic pollutants and deleterious microorganism. Heavy metals are difficult to metabolize in human body are quite harmful, so research on the pollution of heavy metals is increasingly important. There are many pollution sources of heavy metals, including waste residue, waste water and exhaust gas from industry and automobile, and garbage from human life. The contents of 10 kinds of heavy metals (Cr, Ni, Cu, As, Cd, Sn, Sb, Hg, Tl and Pb) in potassium fertilizer (KCl) from Russia were analyzed by ICP-MS. The results showed that potassium fertilizer (KCl) contained less heavy metals than organic-inorganic compound fertilizer; the content of heavy metals Cr, Ni, Cu, As, Cd, Sn, Sb, Hg, Tl and Pb is 0.00, 65.54, 238.85, 190.60, 0.98, 14.98, 2.97, 10.04, 1.28 and 97.42 ng x g(-1), respectively, which accords with the correlative standards. All the data showed that if potassium fertilizer (KCl) is manufactured through normal channel, the content of heavy metals should be little and safe.

The role of the root apoplasm for iron acquisition was studied in wheat (Triticum aestivum L. cv Ares) grown in nutrient solution under controlled environmental conditions. To obtain different levels of Fe in the root apoplasm, plants were supplied in the dark for 5 hours (preloading period) with various (59)Fe-labeled Fe compounds [Fe(III) hydroxide; microbial siderophores: Fe rhodotorulic acid (FeRDA) and ferrioxamin (FeDesferal(3)), and synthetic Fe chelate (FeEDDHA)], each at a concentration of 5 micromolar. Large pools of apoplasmic Fe were formed after supplying Fe(III) hydroxide or FeRDA, but no such pools were observed after supplying FeDesferal or FeEDDHA. Depending on plant Fe nutritional status (preculture +/- 0.1 millimolar FeEDTA), apoplasmic Fe was used to different extent for translocation to the shoot. Under Fe deficiency, a much greater fraction of the apoplasmic Fe was utilized than in Fe-sufficient plants, as a result of the different rates of phytosiderophore release. Because of the diurnal rhythm in release of phytosiderophores in Fe-deficient plants, the utilization of the apoplasmic Fe for translocation into the shoot started 2 hours after onset of the light period and was dependent on the concentration of Fe in the apoplasm, which followed the order: Fe(III) hydroxide >> FeRDA >> FeDesferal = FeEDDHA. From these results, it can be concluded that in soil-grown plants the apoplasmic Fe pool loaded by various indigenous Fe compounds such as siderophores in the soil solution can be an important Fe source in graminaceous species, particularly during periods of limited Fe supply from the soil.

The diurnal rhythm of release of phytosiderophores and uptake rate of zinc (Zn) was studied in iron (Fe) deficient wheat (Triticum aestivum L. cv. Ares) plants grown in nutrient solution under controlled environmental conditions. Different forms of Zn (e.g. ZnSO4, ZnEDTA) were used to obtain different degrees of loading of the root apoplasmic pool with Zn. In the Fe-deficient plants the release of phytosiderophores from the roots followed a distinct diurnal rhythm with a steep peak about 4 h after the onset of the light period. These plants also showed a similar pattern in the rates of Zn uptake over the 24 h day-night cycle. During the light period there was a steep transient peak (factor 3.8) in Zn uptake rate in the Fe-deficient plants supplied with ZnSO4. This transient peak was much less distinct in plants supplied with ZnEDTA (factor 1.8) and absent in plants supplied with ZnEDTA plus free chelator (+ NaEDTA) in excess. The peak in Zn uptake coincided with the maximum rate of phytosideropho...

This paper reports the effects of different nitrogen (N) fertilizer levels on the growth of maize (Zea mays L.) under field conditions. The N supply was found to influence the growth of the plants, especially the roots. A high N supply significantly inhibited root elongation, and was associated with reduced root dry weight compared to controls and to plants grown with smaller supplies of N. However, no differences were seen in lateral primary root density under the different N supply conditions, nor did plant N concentration increase with high N supply. In conclusion, a high N supply not only wastes resources and pollutes the environment, it may also inhibit root growth., Se llevaron a cabo experimentos de campo para estudiar el efecto de los niveles de fertilizante de nitrógeno (N) sobre el crecimiento de maíz (Zea mays L.). Los resultados demostraron que el suministro de nitrógeno puede influir en el crecimiento de las plantas, especialmente en las raíces. En condiciones de campo, un elevado suministro de N inhibió significativamente la elongación de las raíces. El peso seco de las raíces que crecieron bajo un elevado suministro de N disminuyó comparado con controles o con plantas que crecieron con niveles inferiores de N. Sin embargo, la densidad de las raíces laterales primarias se mantuvo constante cuando las plantas crecieron con diversos niveles de N, y la concentración interna de N de las plantas no aumentó con un elevado suministro de N en el suelo. Un aporte elevado de N no solo desperdicia recursos y contamina el medio ambiente, sino que también puede impedir el crecimiento de las raíces.

With field plot experiment, this paper studied the effects of different nitrogen application rate (0, 90, 180 and 270 kg x hm(-2)) on the rhizosphere microbial community and its diversity in wheat-faba bean intercropping ecosystem. The results indicated that the amount of rhizosphere microbes fluctuated with crop growth stages, being the highest at the flowering stage of test crops. Comparing with monocropping, intercropping significantly increased the total amount of microbes and the numbers of bacteria, fungi and actinomyces in the rhizosphere of both wheat and faba bean, but decreased the microbial diversity in the rhizosphere of faba bean at its flowering and maturing stages. Under no nitrogen and low nitrogen application rate, a larger difference was observed in the amount of rhizosphere microbes between intercropping and monocropping. The promotion effect of intercropping in increasing the amount of rhizosphere microbes was more apparent at tillering and flowering stages, but declined significantly at maturing stage. With increasing nitrogen application rate, the amount of microbes in wheat rhizosphere increased first and decreased then, with the peak appeared at 180 kg N x hm(-2), and the effect was more obvious on monocropped wheat than on intercropped one. Nitrogen application rate had no significant effects on the numbers of bacteria, fungi and actinomyces and the microbial diversity in faba bean rhizosphere, but decreased the total amount of microbes in the rhizosphere of intercropped faba bean. Rational nitrogen application could regulate rhizosphere microbial community effectively, and there was an obvious correlation between aboveground plant diversity and belowground microbial community.

With the rapid development of transgenic cotton, people begin to focus on its physiology and ecology. The present paper studied the contents of heavy metals and microelements in transgenic cotton fibre by ICP-MS/ICP-AES. The results showed that the contents of most microelements (B, Mg, Mn, Fe, Co, Ni, Cu, Zn, Se and Mo) detected in transgenic cotton fibre were lower those in regular cotton fibre, especially the contents of Zn which was several times lower. But the concentrations of Na, Si, P, K and Ca in transgenic cotton fibre were higher than those of regular cotton fibre, especially for Si. The concentrations of the heavy metals detected (Al, Pb, Cr, Cd, Sb, Tl and As) in transgenic cotton fibre were all lower than those in regular cotton fibre. All the data showed that the accumulation patterns of heavy metals and microelements in transgenic cotton fibre were clanged by the insertion of foreign genes.

Paddy rice-upland crop rotation system is a major cropping system in China, and practiced widely along the Yangtze River basin. A unique feature of this system is the annual conversion of soil from aerobic to anaerobic and then back to aerobic condition, which can result in the changes of soil physical, chemical, and biological prosperities among seasons, making a special agroecosystem. The major challenges faced by this system include declining or stagnating productivity, increasing shortage of irrigation water, improper management of nutrients, low efficiency of resource utilization, and environmental pollution. Based on an overview of the characteristics and problems of paddy rice-upland crop rotation system, this paper put forward a strategy of practicing integrated nutrient management to solve the contradictions between nutrient input, crop production and environmental risk. The key points of this strategy included nutrient management from the whole rotation system perspective, integrated use of nutrients from various sources (chemical fertilizers, organic fertilizers, and nutrients from the environment), synchronization of nutrient supply and crop nutrient demand, application of different management technologies based on the characteristics of different nutrient resources, and integration of nutrient management with other cropping system technologies like water saving and high-yielding cultivation, etc.

With the rapid development of transgenic cotton, people begin to focus on its physiology and ecology. The present paper studied the contents of heavy metals and microelements in transgenic cotton seeds by ICP-MS/ICP-AES. The results showed that the content of most microelements detected in transgenic cotton seeds, B, Na, Si, P, K, Ca, Mn, Co, Ni, Zn, Se and Mo was lower than that in regular cotton seeds, except Mg, Fe and Cu. And the content of most heavy metals detected in transgenic cotton seeds, Al, As, Cd, Sb, Tl, Pb and Bi, was higher than that in regular cotton seeds, except Cr and Hg. All the data showed that the accumulation of heavy metals and microelements in transgenic cotton seeds is disadvantageous to itself.

Fruit of elm has been a popular food in Chinese county for many years. With the rapid development of food nutrition and food safety, more and more people begin to pay attention to its content of trace elements and heavy metals. The wild fruit of elm was studied by ICP-MS/ICP-AES to detect the 22 trace elements. The results showed that the fruit of elm contained many trace elements which are necessary to human health: The concentrations of Mg, Ca, Mn, Fe, Cu, Zn, Sr and Rb were 224.57, 269.73, 9.23, 64.93, 1.68, 4.79, 7.68 and 2.21 microg x g(-1) (FW) respectively; while those of Li, B, V, Co, Ni, Se, Br, Mo and Sn were 318.43, 518.83, 265.52, 108.50, 411.21, 34.51, 51.72, 109.90 and 31.51 ng x g(-1) (FW), respectively. Except the wholesome trace elements, contents of heavy metals (As, Cr, Pb and Cd) are also the important standard to identify the quality of food, and the results showed that the concentrations of heavy metals, Pb, Cd, As, Hg and Cr were respectively 557.87, 8.81, 345.55, 0.78 and 347.97 ng x g(-1) (FW) in fruit of elm, which meet the national hygiene standards.

Nanfeng orange is a world famous fruits, but its quality changes remarkably with the producing area. The present paper studied the contents of heavy metal mineral elements and microelements in soil planting Nanfeng orange by ICP-MS/ICP-AES and in order to find the dominant factors that affect the quality of Nanfeng orange in soil. The results showed that the contents of B, P, K, Mg and Ca, especially B, P and K were much higher in soil where the quality of Nanfeng orange is palatable than those where Nanfeng orange is unpalatable; but the contents of Fe, Mn, Si, Cu and Zn were lower in soil where the quality of Nanfeng orange is palatable than those where Nanfeng orange is unpalatable. These data indicate that B, P, K, Mg and Ca, especially B, P and K, affect the quality of Nanfeng orange significantly.

A field experiment with 12-level N fertilization in winter wheat growth season and zero-N in summer maize growth season was conducted to study the appropriate soil nitrate N content for a winter wheat/summer maize rotation system in North China Plain. The results showed that when the soil mineral N content before sowing was higher, a split application of 150 kg N x hm(-2) in winter wheat growth season could meet the N demand of both winter wheat and summer maize in the rotation system. The N use efficiency of winter wheat in different N treatments was only from 11% to 23%, while the residual N use efficiency of summer maize ranged from 30% to 52%. When the nitrate N content in top 90 cm soil layer before maize sowing was up to 82 and 151 kg x hm(-2), respectively, the N demand of summer maize at its ten-leaf stage and in its whole growth season could be met with no N application. However, when the nitrate N content in top 90 cm soil layer was less than 46 and 65 kg x hm(-2) at maize ten-leaf stage and after harvest, respectively, no N application could impact maize growth, and decrease its grain yield. With the maize yield and environmental protection considered comprehensively, the nitrate N content in top 90 cm soil layer should be maintained at an appropriate level from 65 to 151 kg x hm(-2) during maize growth season.

In a water culture experiment, rice seedlings were grown in a nutrient solution containing 10 micromol Cd x L(-1), and harvested after different durations of growth. Two treatments were installed, i. e. , adding 50 mg Fe2+ x L(-1) to induce the formation of iron coating on seedlings root surface (treatment Fe50), and the control. The study on the dynamics of the Cd adsorption on root surface and of the Cd uptake by plant showed that both in the treatment Fe50 and in the control, the amount of adsorbed Cd on root surface was the highest in the first 2 hours, decreased dramatically then and remained relatively stable thereafter, while the Cd concentrations in roots and shoots increased slowly within the first 8 hours and rapidly then. The increment of Cd concentrations in roots and shoots was smaller in treatment Fe50 than in the control, and the amounts of adsorbed and absorbed Cd also showed the same picture, suggesting that the iron coating on rice root surface had little effect on the dynamics of Cd content in different parts of rice seedlings, and the reduced Cd uptake in treatment Fe50 was probably relevant with the Fe concentration in roots.

The influence of nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP) on nitrate accumulation in greengrocery (Brassica campestris L. ssp. chinensis) and vegetable soil at surface layer were investigated in field experiments in 2002 and 2003. Results showed that NI DMPP took no significant effect on yields of edible parts of greengrocery, but it could significantly decrease NO(3-)-N concentration in greengrocery and in vegetable soil at surface layer. In addition, NI DMPP could reduce the NO(3-)-N concentration during the prophase stage of storage.

Growth of lateral roots is regulated by both environmental factors and nitrate (NO(-)(3)) content of the plant. The mechanism involved is not clearly understood. Two maize (Zea mays L.) inbred lines (478 and Wu312) were used to study the effect of different nitrate supply on lateral root (LR) growth by a whole plants agar culture. The results showed that increasing NO(-)(3)concentration in nutrient solution from 0.01 to 1.0 mmol/L significantly increased the LR length and root biomass. Lateral root density changed little with NO(-)(3) increase up to 5x10(-3) mol/L (for Wu312) - 10x10(-3) mol/L (for 478), then decreased significantly with increasing NO(-)(3). The inhibitory effect of high NO(-)(3) on root growth was weaker in 478 than in Wu312. The growth of lateral roots in Wu312 was completely inhibited by NO(-)(3) at a concentration of 10x10(-3) mol/L, whereas LR density of 478 could reach 30% (axial) and 50% (radicle) of its maximum even at NO(-)(3) 20x10(-3) mol/L. Both the shoot total N and shoot nitrate content increased with increasing NO(-)(3) level. They had similar mathematic functions with shoot/root ratio (Exponential Decay), LR density (Gaussian) and LR length (Parabola). When shoot N content exceed about 1.6 mol/kg and NO(-)(3) content exceed 0.22 mol/kg, shoot/root ratio increased rapidly; when the shoot N content exceed about 1.5 and NO(-)(3) exceed 0.16 mol/kg, LR densities began to decrease; when shoot N content reached about 1 mol/kg and NO(-)(3) content reached 0.10 mol/kg, the LR lengths began to decrease. The possible relationship between shoot NO(-)(3) content and lateral root growth was discussed.

It has been shown previously (Treeby et al., 1989) that phytosiderophores, released by roots of iron deficient grasses (Gramineae), mobilize from calcareous soils not only iron (Fe) but also zinc (Zn), manganese (Mn) and copper (Cu). Mobilization of Fe may therefore be impaired by other micronutrient cations. This has been studied in both, model experiments with Fe hydroxide and with a calcareous soil (15% CaCO3, pH 8.6) amended with micronutrients as sulfate salts.