• Volume 48,Issue 5,2011 Table of Contents
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    • Correlative evaluation of pedodiversity and land use diversity based on Shannon entropy

      2011, 48(5):893-903. DOI: 10.11766/trxb201012100523

      Abstract (2934) HTML (0) PDF 1022.15 K (1319) Comment (0) Favorites

      Abstract:A case study of Nanjing City was conducted using diversity theories and methods to evaluate correlation between soil and land use. Based on the remote sensing data of the city in 1986 and 2003, its land uses were classified, and constituent diversity index and spatial distribution diversity index in different grid scales of each soil and each land use pattern was worked out and a connection index was proposed to evaluate the relationship between soil and land use pattern. Furtheron, the connection indice between 3 typical types of soils and 9 land use patterns in the city were calculated at a 5 km-grid scale. Results show that during the years from 1986 to 2003, significant changes took place in land use composition with constituent diversity increased from 0.361 in 1986 to 0.444 in 2003. The spatial distribution discreteness of land use patterns was significantly higher in 2003, and so was the spatial distribution diversity of 5 major types of land use. The calculation of the connection indice between typical types of soils and various land use patterns indicate that quite a number of pairs of connection indice varied in a similar trend, so it could be inferred that compared to the situation in 1986, the correlations between soils and land use patterns in Nanjing City were more complicated and varied in 2003.

    • Composition and distribution of soil salts in profiles of saline-sodic soil under different land use patterns

      2011, 48(5):904-911. DOI: 10.11766/trxb200912050552

      Abstract (2458) HTML (0) PDF 650.54 K (1649) Comment (0) Favorites

      Abstract:Through field investigation, sampling and laboratory analysis, morphological characteristics of the profiles of saline-sodic soils under different land use patterns in the Songnen Plain and variations of content and composition of the soluble salts therein were studied. Results show that under different land use patterns, the soil profiles differed sharply in thickness of humus horizon and organic matter content in the plow layer and the humus horizon. In the four profiles under fenced grassland, upland field, 3-year-old paddy field and 20-year-old paddy field, separately, total content of soil soluble salts, pH and ESP were all higher in the middle layers than in the upper and lower layers. The soluble salts were mostly composed of K++Na+, HCO3- and CO32-, which indicate that all the four land use patterns tend to inhibit surface accumulation of sodic salt in the top layer. In grazing grassland, the total content of soil soluble salts increased with the decreasing soil depth in the profiles, showing a significant phenomenon of salt surface accumulation. In the profile under 20-year-old paddy field, the soluble salt content, pH and ESP decreased to 0.21%, 7.56% and 9.1% respectively, which suggests that in alkali- saline land growing paddy rice is more contributive to soil desalinization and solodization than managing the land as grassland and upland field.

    • Spatial variation of soil electric resistivity of a typical slope in the Xiangshuihe watershed of Liupan Mountains, Northwest China

      2011, 48(5):912-921. DOI: 10.11766/trxb201004190146

      Abstract (2834) HTML (0) PDF 448.00 K (1380) Comment (0) Favorites

      Abstract:To understand the spatial distribution of soil hydrological characteristics along slopes, the method of multi-electrode electrical resistivity tomography (ERT) was used in a study started in early May 2009 on a typical mountain slope in the Xiangshuihe watershed of the Liupan Mountains in Northwest China. The slope is 600 m long and covered with an artificial larch (Larix principis-rupprechtii) plantation. A longitudinal transect line was set up from the top to the foot of the slope and three transect lines at different slope positions to detect horizontal variation of the soil electrical resistivity. Results showed that along the longitudinal line, soil electric resistivity, on the whole, though remaining spatially continuous, varied to some extent. It decreased from the slope top to the mid slope and then restoratively increased on the slope downward. As a result of the uneven distribution of soil characteristics, surface topography and vegetation along slope, the longitudinal variation of soil electrical resistivity was greater than its horizontal variation. The electrical resistivity increased with soil depth as gravel and rock content increased with depth. A close relationship was observed between the soil electrical resistivity and soil porosity as well as the volumetric soil water content. The more close relation with the soil water content suggested that it is feasible to determine the spatial variation of soil characters such as the soil moisture through measuring spatial distribution of soil electric resistivity on slope.

    • Effect of irrigation with water diverted from the Yellow River on carbon sequestration in soils of different types in Ningxia Irrigation Zone

      2011, 48(5):922-930. DOI: 10.11766/trxb201103040076

      Abstract (2755) HTML (0) PDF 520.87 K (1266) Comment (0) Favorites

      Abstract:Irrigation and cultivation are two important driving forces of variation of soil organic carbon density (SOCD). The Ningxia Irrigation Zone using water diverted from the Yellow River in irrigation was selected as a case for study, and 48 sampling points were set up in five types of soils to study characteristics of soil organic carbon (SOC) and SOCD in these soils under different cultivation and irrigation time series, and analyze differences among the soils in effect of irrigation and cultivation on carbon sequestration. Results show that the effect of irrigation and cultivation on carbon sequestration varied with the soil. The same in irrigation and cultivation history, the five types of soils followed a decreasing order of Irrigated-alluvial soils> Fluvo-aquic soils >Fluvent soils > Aeolian sandy soil > Sierozem soil in SOCD. Irrigation and cultivation increased SOCD to a varying degree in these soils, which followed Aeolian sandy soil > Fluvo-aquic soils >Irrigated-alluvial soils> Sierozem soil > Fluvent soil. The differences among the soils in effect of irrigation and cultivation on carbon sequestration are significant in the Ningxia Irrigation Zone.

    • Change in surface micro-relief during the course of sheet erosion and inter-rill erosion

      2011, 48(5):931-937. DOI: 10.11766/trxb201004120133

      Abstract (3211) HTML (0) PDF 422.54 K (1258) Comment (0) Favorites

      Abstract:A study was carried out using the method of indoor simulated rainfall combined with geostatistical analysis to investigate characteristics of the change in surface micro-relief under four different kinds of management during the course of sheet erosion and inter-rill erosion. Results show that under the effect of rainfall, regardless of intensity, the surface micro-relieves of slopelands, regardless of management pattern, all demonstrated a certain extent of irregularity and inter-grade transfer in elevation in the process of sheet erosion and inter-rill erosion. GradeⅠ and GradeⅡ were dominated with moving-out, and only a little was transferred back into Grade Ⅰand GradeⅡ even after the inter-rill erosion phase. Little elevation of the surface micro-relief of Grade III moved out, but instead, most of the elevations of other grades moved into Grade Ⅲ, suggesting that in the regions between 0~0.01 m and 0.01~0.03 m deposition of silts occurs readily during the process of sheet erosion and inter-rill erosion.

    • A soil sampling method based on representativeness grade of sampling points

      2011, 48(5):938-946. DOI: 10.11766/trxb201011270494

      Abstract (3618) HTML (0) PDF 646.35 K (1532) Comment (0) Favorites

      Abstract:Sampling design plays a critical role in capturing information about spatial distribution of soils, influences directly the accuracy of samples-based soil mapping. The commonly used methods are often confronted with such problems as the need for large amounts of samples and low sampling efficiency. When the resources available are inadequate for accomplishing a large volume of sampling once for all, additional sampling has to be done many times and in batches. However, the present in-batches sampling methods mostly take into account supplementality of the batches of sampling points in geographic space, which lead to overlapping of the sampling points in attribute space, affecting efficient utilization of the resources. In view of this, clustering analysis of soil environmental co-variates was performed to explore for sampling points representative of different grades of soil spatial distribution and to formulate a sampling designing method based on representativeness grade. This proposed method was applied to the study area located in Heshan Farm, Nenjiang County, Heilongjiang Province, and digital soil mapping was done using selected sampling points of different representativeness grades for verification of the methods. Results show that only a small number of sampling points of the highest grade could obtain most of the main soil types (sub-order in Chinese Soil Taxonomy) and soil mapping was high in accuracy; and addition of sampling points lower in representative grade could raise the accuracy of soil mapping; but the accuracy did not improve much when the number of sampling points added exceeded a certain level. Therefore, compared with the number of sampling points, representativeness grade of the points was more important to accuracy of soil mapping. The representativeness grade system proposed in this paper can be used as reference for sequencing of sampling points and is contributive to formulation of high-efficiency stepwise sampling design.

    • Evaluation of soil water flux estimates from heat pulse technique

      2011, 48(5):947-956. DOI: 10.11766/trxb200912310604

      Abstract (2606) HTML (0) PDF 1019.22 K (1232) Comment (0) Favorites

      Abstract:Soil water flux (Jw) is an important hydrological parameter which determines soil infiltration, runoff and solute transport, yet no corresponding practical techniques are available for its real-time measurement in situ. In this study, heat-pulse measurements were performed of deferent water fluxes in packed soil columns different in texture. Based on temperature changes between upstream and downstream locations from the heat-pulse probe, water flux was then calculated with the MDTD method (maximum dimensionless temperature increase difference), and the Td /Tu method (ratio of temperature changes between downstream and upstream positions), and a modified Td /Tu method along other known parameters. Results indicated that strong linear relationships ( R 2>0.99) existed between the estimated and the measured water fluxes (up to 6×10-5 m s-1). Though, the three methods all down-estimated, however, the Td /Tu method was highest precise and simplest in calculation, and needed the least number of additional parameters. In coarse sand, the Td /Tu method was relatively more accurate in estimation of Jw, yet in fine sandy clay loam, especially when Jw was greater, obvious discrepancies were observed between the estimated and the measured, reaching 20%. Besides, the reason of underestimation of Jw with the heat-pulse technique is explored and presented as a basis for further development of the heat-pulse technique.

    • Interaction between low-molecular Weight organic reducing substances and soils Ⅱ.Chemical reactions of low-molecular weight reducing substances with soils

      2011, 48(5):957-963. DOI: 10.11766/trxb200912310603

      Abstract (2741) HTML (0) PDF 417.20 K (1369) Comment (0) Favorites

      Abstract:A study on chemical reactions concerning adsorption, oxidation-reduction and complexation of low-molecular weight organic reducing substances with soil was carried out. Results show as follows: About 60%~75% of the total organic reducing substances added was adsorbed by the soil, consisting roughly by half and half of strongly and weakly reducing organic substances. The adsorption of negatively charged substances varied with the content of Fe/Mn oxides and the negative charge they bear in the form of electrostatic adsorption. The adsorption of –COOH/-C=O -NH2 containing functional groups demonstrated existence of complexation on the solid surface; In redox equilibrium organic reducing substances acted as electron donor reducing Fe2O3 and MnO2 and got oxidated themselves; The complexation process was controlled by chelation-dissociation equilibrium in the solution and strongly affected by the amount of ligands and the amount of complex radicals that compete for ligands with hydrogen ions.

    • Effect of electrolyte concentration on release of hydrogen ions from soils adsorbing copper ions

      2011, 48(5):964-970. DOI: 10.11766/trxb200912310602

      Abstract (3400) HTML (0) PDF 508.61 K (1321) Comment (0) Favorites

      Abstract:Effect of H+ release from four constant charge soils and two variable charge soils on pH of their soil suspensions different in Cu ion concentration and in concentration of electrolyte was studied. Results indicate that for all the six samples, except for yellow brown soil, the higher their Fe content the lower the △pHmax caused by adsorption of copper ions. The adsorption of copper ions showed no significant effect on neutralization curves. When the copper ion was low in concentration, H+ release was low, but when the copper ion was high in concentration and the pH value of the system exceeded a certain threshold, a large volume of H+ was release. The presence of iron oxide was found to be the main cause for difference in H+ release between constant charge soils and variable charge soils. The effect of electrolyte concentration on the neutralization curves of constant charge soils and variable charge soils after adsorption of Cu ions varied greatly. The higher the iron oxide content, the lower the effect of electrolyte concentration on post-Cu-ion-adsorption H+ release.

    • Nitrous oxide emissions from wheat field at wheat jointing-maturing stage as affected by timing of topdressing

      2011, 48(5):971-978. DOI: 10.11766/trxb201001130018

      Abstract (2788) HTML (0) PDF 444.56 K (1344) Comment (0) Favorites

      Abstract:To study effect of timing of topdressing on N2O emission from wheat fields during the period from the jointing stage till the maturing stage of wheat, a field experiment was conducted to have three topdressing schedules (topdressing before rain, topdressing during rain and topdressing after rain) in jointing-maturing stage of wheat from 2007 to 2008. Results show that N2O emission was 37%~67% and 22%~46% less in fields topdressed after rain, than in fields topdressed before rain and during rain, respectively. No significant difference was observed between the treatments in wheat grain yield (p>0.05). Soil water content was the key factor affecting N2O emission during that wheat growing season. Topdressing after rain which brings enough moisture to the soil is an appropriate topdressing method, which may decrease N2O emission significantly in the wheat-growing season with no adverse effect on wheat yield.

    • Characteristics of mineralization of soil organic carbon in paddy and upland with rice straw incorporated and differences

      2011, 48(5):979-987. DOI: 10.11766/trxb201011030456

      Abstract (3500) HTML (0) PDF 450.90 K (1467) Comment (0) Favorites

      Abstract:To improve the farmland soil fertility and provide suggestions for better field management for more carbon sequestration, effects of land use and rice straw incorporation models on mineralization of soil organic carbon were quantitatively investigated. The CO2-C evolved from the soil was measured during incubation of the undisturbed soil column mulched or incorporated with 14C labeled rice straw over a 100-day period. Results show that straw carbon participated in carbon mineralization, contributing 34.74% in paddy mulched with straw (SM), 17.85% in paddy incorporated with straw (SI), 35.68% in upland (SM) and 36.06% in upland (SI) of the 14C-labelled rice straw carbon applied in either way after 100 d incubation. Meanwhile, 0.99%~1.17% and 2.25%~2.53% of the native soil organic carbon (SOC) in the paddy and upland soil was mineralized, respectively. Rice straw application model and land use and their interaction all showed significant effects on mineralization rate and accumulative mineralization rate of applied rice straw carbon (p<0.01). However, only land use (p<0.01) did on mineralization rate of SOC and accumulative mineralization rate of SOC. Application of rice straw did not affect much the total soil accumulative carbon mineralization rate except in upland (SI) because straw in the soil inhibited decomposition of native SOC, thus reducing the 100d cumulative mineralization rate by 13.95% in paddy (SM), 15.68% in paddy (SI), 11.04% in upland (SM) and 3.34% in upland (SI). Comparatively, Straw incorporation in paddy fields and straw mulch in upland fields are better straw application models and more favorable to accumulation of SOC. The mineralization rate of either applied rice straw carbon or native SOC in paddy soil is obviously lower in paddy soil than in upland soil, which is one of the main reasons why the content of soil organic carbon is generally higher in paddy soil than in upland soil within the same landscape.

    • Effects of nitrogen management on nitrogen leaching of paddy soil in Taihu Lake region

      2011, 48(5):988-995. DOI: 10.11766/trxb201009050362

      Abstract (2823) HTML (0) PDF 720.07 K (1253) Comment (0) Favorites

      Abstract:A field experiment, directed against non-point source pollution brought about by nitrogen leaching from paddy field in Taihu Lake region, was conducted to study effects of nitrogen management on on nitrogen leaching from paddy field at depths of 20~40 cm, 40~60 cm, 60~80 cm and 100~120 cm. The experiment was designed to five patterns of nitrogen management, i.e. Case-specific nitrogen application (CSN), Organic & chemical N combined application (OCN), Controlled release urea application (CRU), Reduced chemical N application (RCN) and Farmer’s common N application (FN). It was found show that in the soil layer (20~40 cm), TN in the leachate was positively related to N application rate depth, and CRU has more TN leakage amount. Compared with the other treatments, FN treatment had a higher concentration at 40~60 cm than 20~40 cm depth. DON was the prime form of N leaking into ground water floor. NH4+-N concentration would decrease 37%~50% if N input was reduced by 33%. Thus it can be seen that reduced N input and use organic N with chemical N would be environment-friendly nitrogen management methods for Taihu Lake region.

    • Effects of protective management of navel orange orchards on slope land on structure of and carbon, nitrogen and phosphorus contents in soil aggregates

      2011, 48(5):996-1005. DOI: 10.11766/trxb201008230334

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      Abstract:Based on the 8-year long experiment at the Zigui Ecological and Environmental Experiment Station for the Three-Gorge Project, effects of five citrus orchard protective management practices were studied on structure of and nutrient (C, N and P) distributions in soil aggregates in navel orange orchards located on slopeland. It was found that Treatment CM (interplantation of citrus trees with white clover, Trifolium repens Linn.) and Treatment SM (mulching of crop straws) were obviously higher than the other treatments in content of > 0.25 mm water stable aggregates (WSA), aggregate mean weight diameter (MWD) and nitrogen content in > 0.25 mm WSA in surface soil (0 ~ 5 cm), and Treatment SM was higher than all the other treatments in phosphate content in > 0.25 mm WSA in surface soil (0 ~ 5 cm); Treatment CH (interplantation with day lily, Hemerocallis citrina Baroni, or contour hedgerow) and Treatment MM (counter embedment of impermeable membrane) were significantly higher than CK (conventional management) and Treatment PC (interplantation with Wheat (Triticum aestivum Linn.) - Peanut (Arachis hypogaea)) in > 0.25 mm WSA and Treatment CH was also significantly higher than CK and PC treatments in aggregate MWD. Compared with CK, Treatment PC did not have any significant effect on > 0.25 mm WSA, MWD, soil carbon in aggregate and soil nitrogen in aggregate in the surface soil (0 ~ 5 cm), but increased soil phosphorus in aggregates in the 5 ~ 20 cm soil layer. Aggregate MWD was significantly related to contents of > 0.25 mm WSA and nitrogen in aggregates.

    • Response of rice plants different in response to nitrate to enhanced nitrate supply in root growth at the seedling stage

      2011, 48(5):1006-1012. DOI: 10.11766/trxb201003170096

      Abstract (2421) HTML (0) PDF 309.57 K (1062) Comment (0) Favorites

      Abstract:Nitrogen is one of the most important nutrients affecting production of cereal crops. Evidence available shows that although nitrate (NO3-) enhances growth of rice, the crop prefers ammonium (NH4+ ) to NO3-. A hydroponic experiment was carried out to study effects of two NH4+/NO3- ratio (100/0 and 75/25) on response of rice different in responsivility to nitrate in root growth at the seedling stage. Four rice genotypes were tested, i.e. Nanguang, Elio (low in NO3- responsivity), Shanghai-97 (low in nitrate responsivity) and Liaojing (low in nitrate responsivity). Compared to supply of sole NH4+, enhanced NO3- supply increased root biomass and nitrogen accumulation of Nanguang (high in NO3- responsivity) by 50% and 79%,respectively, and the total length and number of roots, adventitious roots and lateral roots of the plant increased significantly, however, the mean length of adventitious and lateral roots did not vary much. No such significant effects were observed on other three genotypes of rice. It is clearly indicated that enhanced NO3- nutrient stimulates emergence of adventitious and lateral roots only, but does not promote their elongation. From the findings it is inferred that responsivity of rice to NO3- in root development differs with the genotype and is one of the factors that affect nitrogen use efficiency by rice.

    • Phyto-accumullation of heavy metals and characteristics of rhizospere microbes in heavy metal contaminated soils Qixia, Nanjing

      2011, 48(5):1013-1020. DOI: 10.11766/trxb201004090126

      Abstract (4094) HTML (0) PDF 476.19 K (1650) Comment (0) Favorites

      Abstract:Five species of plants and their rhizospheric soils were sampled and collected from heavy metal contaminated soils in Qixia, Nanjing for analysis and exploration of characteristics of phyto-accumulation and relationships of contents of heavy metals with population of bacteria and activity of soil enzymes in the soil. It was found that the heavy metal pollutant in the rhizosphere was dominated with Zn and Cd; and the plants growing therein were quite high in heavy metal absorbing capacity. Beckmannia grass and Solanum nigrum featured the characteristics of a heavy metal hyperaccumulator plant. The numbers of bacteria and Pb-resistant bacteria in the rhizospheric soil both reached up to 107 CFU g-1 of soil. The activities of soil enzymes were little inhibited. Significant positive relationships were observed of heavy metals contents in the plant with contents and forms of the heavy metals in the soil, soil enzymes activity, and Pb-resistant bacteria. Soil bacteria in the rhizosphere, heavy metal-resistant bacteria in particular, may improve bioavailability of heavy metals in soil, thus promoting uptake and transport of heavy metals by plants.

    • Effects of different fertilization on soil fertility quality, fertilizer use efficiency, and bamboo shoot yields of Phyllostachys praecox stand

      2011, 48(5):1021-1028. DOI: 10.11766/trxb201011290499

      Abstract (3127) HTML (0) PDF 479.04 K (1477) Comment (0) Favorites

      Abstract:A field experiment was conducted on a Phyllostachys praecox stand of Lin’an county, Zhejiang Province, China in 2009 to compare the effects of conventional fertilization (CF), controlled-release fertilizer (CRF), special compound fertilizer (SCF),and microbial fertilizer (MF) on soil fertility quality, fertility use efficiency, and bamboo shoot yields of Phyllostachys praecox stand. The results showed the degrees of excessive-accumulation of available N, P, and K in the soil and soil acidification induced by fertilization followed the order of : CF>SF≈CRF>MF. The lowest fertilizer agronomic efficiency was obtained from CF and its agronomic efficiencies of N, P, and K were 4.7, 23.6, and 14.2 kg fresh shoot • kg-1. As Compared to the CF, application of SCF and CRF increased agronomic efficiencies of N, P, and K by 40.4%~53.2%, 50.8%~90.7%, and 35.5%~39.5%, respectively, whereas application of MF increased agronomic efficiencies of N, P, and K by 38.9、0.68 and 2.0 times, respectively. Compared to the control, CF increased bamboo shoot yields and economic benefit by 29.6% and 14.3%, respectively,where application of SCF,CRF, and WF increased bamboo shoot yields and economic benefit by 27.55%~29.0% and 14.6%~17.8%, respectively.with high rates of CF and its agronomic efficiencies of N, P, and K were 4.7 , 23.6, and 14.2 kg fresh shoot • kg-1. Application of SCF and CRF increased agronomic efficiencies of N, P, and K by 40.4-53, 87.3-90.7, and 35.5-39.6%, respectively, whereas application of MF increased agronomic efficiencies of N, P, and K by 38.9、o.68 and 2.0 times, respectively. Conventional fertilization increased bamboo shoot yields and economic benefit by 29.6 and 14.3%, respectively, compared to the control. Application of SCF and CRF with median rates of CF as well as WF with low rates of CF only reduced bamboo shoot yields 0.5 and 1.7, and 1.4%, respectively compared to the conventional fertilization treatment. However, these three treatments improved economic benefit 3.0, 0.5, and 2.7%, respectively. The results obtained in this study showed that great reduction of CF rates and application of SCF, CRF, and MF in the phyllostachys praecox production nut only maintained higher bamboo shoot yields and economic benefit, but also greatly improved fertilizer agronomic efficiency.

    • Uptake and translocation of chlorpyrifos residues by soil in Brassica chinensi

      2011, 48(5):1029-1034. DOI: 10.11766/trxb201004010115

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      Abstract:A pot experiment with fortified soils was carried out exploring effect of chlorpyrifos on growth of Brassica chinensi, degradation rate of the pesticide in different culture soils, and its uptake and translocation in the plant, so as to provide a theoretical basis for risk assessment of its residue in vegetables and production of safety vegetables. Results show that chlorpyrifos high in concentration (>50.0 mg kg-1) inhibited significantly growth of the plant, as compared to control. Chlorpyrifos differed in half-life in soil between treatments, ranging from 23.03 to 77.43 d, and its residue in the soils could be absorbed by the roots of Brassica chinensi and translocated to shoots. With the pesticide in the soil rising in concentration, its residue in vegetable root, stem and leaf increased, being the highest in the roots and the least in the leaf. Amount of chlorpyrifos residues in root was the maximum, but in leaf was minimum. The residues of chlorpyrifos in vegetable root, stem and leaf displayed a significant positive linear relationship with the primary residue in the soil, which could be expressed in the following equations: Croot= 0.0251Csoil- 0.2358,Cstem = 0.0123Csoil - 0.0517,Cleaf=0.0007Csoil+ 0.0115. To realize end-to-end control of pesticide residue in vegetables from from field to table, and to ensure production and supply of hazard-free safety vegetables, it is critical to monitor pesticide residues in the soils of the production bases for control at the source.

    • Difference between Suaeda physophora and Gossypium hirsutum in low affinity absorption rate under salt stress and its physiological analysis

      2011, 48(5):1035-1043. DOI: 10.11766/trxb201002250065

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      Abstract:NO3-low affinity absorption dynamics of Suaeda physophora Pall. and mechanism of the high NO3- absorption efficiency were studied using the conventional ion depletion method with Gossypium hirsutum L. as control in the nutrient solutions different in Cl- and NO3--N concentration. Results show that the NO3- uptake rate of S. physophora and G. hirsutum increased linearly with KNO3 concentration from 1 to 50 mmol L-1 in the solution. But the net NO3- uptake rate and nitrate reductase activity were significantly higher in S. physophora than in G. hirsutum, which implies that S. physophora has a higher demand for nitrate than G. hirsutum does. After 2 h of pre-treatment with 10 mmol L-1 KNO3, the total nitrogen concentrations increased by 30.6% and 36.8% in the shoots of G. hirsutum and S. physophora, respectively, meanwhile, the net NO3- uptake rates of the two reduced by 46.6% and 45.5%, respectively, which suggests that N uptake of the two species were regulated by negative feedback of the N nutrition of these plants. When G. hirsutum and S. physophora were put under NaCl stress for 30 days, NO3- uptake was significantly inhibited, more in G. hirsutum than in S. physophora. The net NO3- uptake rate exhibited a significant negative correlation with Cl- concentration in the roots of G. hirsutum and S. physophora, indicating that the ablility of the root of S. physophora to resist Cl- was higher than that of G. hirsutum. Temporary NaCl or KCl stress for 2 hours did not affect much the net NO3- uptake of S. physophora, but did decrease that of G. hirsutum by 43.8% and 37.5%, respectively. The findings indicate that the high-efficiency nitrate uptake by S. physophora roots is related to the high N demand and Cl- accumulation of the plant, and Cl- concentration in the nutrient solution does not have much impact on NO3- low-affinity transport system.

    • Effects of SNP on photosynthesis and alkaloid content of Catharanthus roseus seedlings under NaCl stress

      2011, 48(5):1044-1050. DOI: 10.11766/trxb201011220483

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      Abstract:A sand culture experiment was conducted in greenhouse to study effects of exogenous nitric oxide donor(SNP) on growth, photosynthetic characteristics and alkaloids contents of Catharanthus roseusseedlings under 50 mmol L-1 NaCl stress. Results show: (1) 0.1 mmol L-1 SNP was the highest in effect of alleviating the stress caused by 50 mmol L-1 NaCl, and significantly increased fresh weight, dry weight, Pn, Gs, Tr and POD activity by 18.8%, 13.9%, 20.7%, 19.1%, 8.5% and 32.6% respectively, but decreased Ci by 10.3% as against Treatment S1 (50 mmol L-1 NaCl). (2) In Treatment S4, where the concentration of SNP increased to 0.5 mmol L-1, the TDC activity, total indole alkaloids, Vinblastine, Catharanthine, Vincristine and Vindolin contents of the Catharanthus roseuswere the highest, compared with Treatment S1, they increased 33.4%, 26.9%, 32.3%, 27.4%, 68.8% and 50.2% respectively. To sum up, 0.1 mmol L-1SNP is the best at increasing photosynthesis, promoting growth and raising biomass, however 0.5 mmol L-1 SNP is the best at improving synthesis of total indole alkaloids and four main kinds of alkaloids.

    • Responses of Different Varieties of Oil Sunflower to Salt Stress

      2011, 48(5):1051-1058. DOI: 10.11766/trxb201010110418

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      Abstract:A pot experiment was conducted to study effects of salt stress on emergence, growth, yield and absorption of Na+ and K+ of oil sunflower in order to clarify differences in response to salt stress between different varieties of oil sunflower. Results show that increased soil salt concentration decreased emergence rate, plant height, yield and biomass of oil sunflower, regardless of varieties, and the inhibitory effects were more apparent with Variety XK-6 than with Varieties LK-1 and FA15. Oil sunflower was much more tolerant to salt stress at the germination stage than at any later stages, and lower salt stress was somewhat beneficial to emergence and growth of oil sunflower. It was found that when the relative inhibition rate of salt stress reached over 40% at the seedling stage, the plant could not complete its life cycle, and when over 50%, it could not survive the budding or flowering stage. Na+ content in oil sunflower plants increased multiplied with increasing soil salt concentration, but K+ content did not change much, thus lowering K+/Na+ ratio drastically. So, proper salt concentration may promote K+ absorption by oil sunflower, but big differences exist between the varieties. The oil sunflower plants under the same salt stree followed an order of LK-1 < FA15 < XK-6 in Na+ content, and a reverse order in K+ content and K+/Na+ ratio. In terms of sensitivity of the plant at different stages to salt stress, a decreasing order of flowering stage and budding stage > emergence stage > maturity stage was worked out. Therefore, it seems to be a major mechanism of oil sunflower tolerating salt to reduce Na+ absorption, keep K+ stability and maintain higher K+/Na+ ratio in plants. The three varieties show a decreasing order of LK-1 > FA15 > XK-6 in salt tolerance.

    • >Reviews and Comments
    • Status quo and prospects of the study on soil quality standards in China

      2011, 48(5):1059-1071. DOI: 10.11766/trxb201012060512

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      Abstract:Development and application of soil quality-related standards in China were reviewed in this paper. By far, China has 26 national standards already published and 34 under development. A majority of them are concerned with chemical methods for assessing soil quality and only a minority deal with evaluation and collation of criteria and terminologies, biological methods and physical methods, and none talks about sampling, assessment, remediation and cultivation of soils. Although progresses have been made in the field of soil quality standards, problems do exist. In view of the status quo of soil quality standards and the existing problems, the paper puts forward a preliminary framework of the soil quality standard systme and orientation of soil quality standardization in China, taking into account the 12th five-year-plan science and technology program.

    • Development of remote-sensing monitoring of coastal saline soil

      2011, 48(5):1072-1079. DOI: 10.11766/trxb201009050361

      Abstract (2823) HTML (0) PDF 757.84 K (1584) Comment (0) Favorites

      Abstract:This review elaborates contents of remote-sensing monitoring of coastal saline soil and advancement in monitoring technology at home and abroad, while pointing out existing problems and future development trendr. In recent years, the technology of space identification in remote-sensing monitoring of coastal saline soil has gradually evolved from visual interpretation based on image spectrum and hue characteristics towards computer automated interpretation; in inverting coastal saline soil properties, from statistical modeling based on discrete samples to spatially continuous intelligent inversion; in monitoring salinization degree, from mere characterization of salinization degree with soil physical and chemical properties to monitoring of overall coastal ecosystems. However, remote-sensing of the coastal saline soil is deeply affected by factors, like soil moisture, vegetation, etc., and subject to large spatial uncertainty. Therefore, the research still has much room for development in inversion accuracy, model universality and data management. To sum up, the remote-sensing monitoring of coastal saline soil is developing towards of timeliness, dynamicity and intelligentization. It is an inevitable trend of the research in this field in future to build up a multi-scaled general model for inversion of quality of coastal saline soil and efficient mechanism for management of mega-store of saline soil remote-sensing data.

    • >Research Notes
    • Assessment of soil erosion risk in watersheds typical of eroded red soil region, south China

      2011, 48(5):1080-1082. DOI: 10.11766/trxb200912240589

      Abstract (2368) HTML (0) PDF 441.24 K (1615) Comment (0) Favorites

      Abstract:

    • Determination of soil organic matter in red soils using VIS-NIR diffuse reflectance spectroscopy and selection of optimal spectral bands

      2011, 48(5):1083-1089. DOI: 10.11766/trxb201006110237

      Abstract (3395) HTML (0) PDF 429.85 K (1306) Comment (0) Favorites

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    • A comparative study on two mehteds for determination of ammonia volatilization

      2011, 48(5):1090-1095. DOI: 10.11766/trxb201003050082

      Abstract (3234) HTML (0) PDF 499.36 K (2132) Comment (0) Favorites

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    • Analysis of soil fungal community structure of Stipa steppes in Hulunbuir, Inner Mongolia

      2011, 48(5):1096-1102. DOI: 10.11766/trxb201010120420

      Abstract (3085) HTML (0) PDF 659.42 K (1586) Comment (0) Favorites

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    • Effect of downslope vegetation distribution on sediment yield of slope-gully system exposed to runoff scouring

      2011, 48(5):1103-1107. DOI: 10.11766/trxb200912030546

      Abstract (2723) HTML (0) PDF 295.67 K (1280) Comment (0) Favorites

      Abstract:

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