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1.
The salt‐sensitive Glycine max N23674 cultivar, the salt‐born Glycine soja BB52 population, and their hybrid 4076 strain (F5) selected for salt tolerance generation by generation were used as the experimental materials in this study. First, the effects of NaCl stress on seed germination, tissue damage, and time‐course ionic absorption and transportation were compared. When qualitatively compared with seed germination appearance in culture dishes, and tissue damages on roots or leaves of seedlings, or quantitatively compared with the relative salt injury rate, the inhibition on N23674 was all the most remarkable. After the exposure of 140 mm NaCl for 1 h, 4 h, 8 h, 12 h, 2 days and 4 days, the content of Cl? gradually increased in the roots and leaves of seedlings of BB52, 4076 and 23674. Interestingly, the extents of the Cl? rise in roots of the three experimental soybean materials were BB52 > 4076 > N23674, whereas those in leaves were just on the contrary. Secondly, by using the scanning ion‐selective electrode technique (SIET), fluxes of Na+ and Cl? in roots and protoplasts isolated from roots and leaves were also investigated among the three experimental soybean materials. After 140 mm NaCl stress for 2, 4 and 6 days, and when compared with N23674, slighter net Cl? influxes were observed in root tissue and protoplasts of roots and leaves of BB52 and 4076 seedlings, especially at the cellular protoplast level. The results indicate that with regard to the ionic effect of NaCl stress, Cl? was the main determinant salt ion for salt tolerance in G. soja, G. max and their hybrid, and the difference in their Cl?/salt tolerance is mainly attributed to the capacity of Cl? restriction to the plant above‐ground parts such as leaves. 相似文献
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为促进企业发展使之取得良好的经济效益,讨论了排灌机械行业贯彻与应用标准的情况,分析了标准的作用。自从我国加入世贸组织,国际贸易量日益增大,熟悉和掌握与之相关的标准,参与市场竞争更显得非常重要。指出了标准在市场与营销及生产中的制约作用和利害关系。 相似文献
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Use of poor-quality groundwater has become inevitable for irrigation to compensate rapidly increasing water demands in many arid and semiarid regions. Salinity and sodicity are the principal soil and water quality concerns in such areas. Many saline–sodic and sodic soils have saline or saline–sodic subsurface drainage waters. Amelioration of these soils needs a source of calcium (Ca2+) that can replace the excess exchangeable sodium (Na+). Most of these soils, however, contain calcite (CaCO3) of extremely low solubility. The native calcite does not supply adequate levels of Ca2+ for soil amelioration as do other chemical amendments. Phytoremediation may help ameliorate such soils through cultivation of certain crops tolerant to ambient soil salinity and sodicity. This amelioration strategy works through plant root action to help dissolve CaCO3 to supply adequate Ca2+ without the application of an amendment. During a 3-year field experiment conducted under irrigated conditions, we evaluated phytoremediation against soil application of gypsum and farm manure, and water treatment with sulphuric acid on a calcareous saline–sodic soil (pHs=8.0–8.4, ECe=24–32 dS m−1, SAR=57–78, CaCO3=45–50 g kg−1 for the top 0.15 m depth; Calcic Haplosalids). A saline–sodic water (EC=2.9–3.4 dS m−1, SAR=12.0–19.4, RSC=4.6–10.0 mmolc l−1, SARadj=15.6–18.4) was used to irrigate the rice (Oryza sativa L.) and wheat (Triticum aestivum L.) crops grown in rotation. Active desalinisation and desodication processes were observed in all the treatments. After the final wheat crop, the 1.2 m soil profile ECe was 7±0.5 dS m−1 and SAR was 15±2 with non-significant treatment differences, indicating comparable soil amelioration effect of phytoremediation with other treatments. Better crop yields were obtained from the manure-treated plots, owing to its annual addition to the soil that possibly improved soil fertility. Phytoremediation needed minimum capital input because no initial investment was made to purchase the amendments. 相似文献
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由排灌机械行业的现状 ,结合江苏理工大学流体机械工程技术中心 15年来举办培训班的实践 ,提出了培养一大批掌握现代科学技术的工程技术人员和高素质员工是促进排灌事业发展最直接、最有效的措施 ,而制定和完善岗位培训制度是这一措施规范化、制度化、科学化的保证。文章阐述了岗位培训的概念 ,对建立岗位培训制度的原则、框架和体系作了探讨。 相似文献
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运用温室葡萄水热平衡观测资料,分析了东北日光温室葡萄的能量平衡和能量分量日变化、生育期变化以及分配规律,同时也分析了潜热通量(λET)对环境因子的响应。结果表明:水热通量各分量在整个生育期日变化总体上呈现为单峰趋势,净辐射(Rn)的峰值最大为618.75 W·m-2,λET峰值最大为242.73 W·m-2,感热通量(H)峰值最大为327.93 W·m-2;在新梢生长期,白天λET较小,为34.55 W·m-2,随着生育期推进,λET逐渐增大,在果实着色成熟期达到最大值(78.49 W·m-2)之后减小;H在各生育期能量中均占了绝大部分;白天潜热通量占净辐射的比例(λET/Rn)在新梢生长期最小,为25.28%,在果实着色成熟期最大,为44.17%;感热通量占净辐射比例(H/Rn)整个生育期几乎都达50%以上,土壤热通量占净辐射比例(G/Rn)相对较小,变化范围为4.46~12.32 W·m-2;在整个生育期能量比率大小依次为H/Rn>λET/Rn>G/Rn。在不同生育阶段瞬时尺度上,Rn是影响潜热变化最主要的气象因子,R2高达0.88。在日尺度上,各气象因子对潜热通量的影响在逐渐变弱,相对湿度(RH)与λET相关系数仅为0.28。但无论从瞬时尺度还是日尺度,Rn都是影响潜热通量最主要的气象因子。各气象因子对潜热通量的影响大小依次为:Rn>VPD>Ta>RH。 相似文献
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Measurements of the horizontal and vertical fluxes of energy and mass were taken at a crop canopy edge and downwind of it to examine the effects of inhomogeneity on surface-atmosphere exchange, for the ideal case of flat uniform terrain. Energy balance closure was also examined and the effects of the often-neglected advection terms on the energy budget were evaluated. The results show that neither vertical nor horizontal advection should be neglected for moderate distances downwind from heterogeneous boundaries, with the energy budget closure near the leading edge improved by more than 20% with the inclusion of the horizontal and vertical advection of latent and sensible heat. Significant mean advective horizontal and vertical flux divergences of water vapor and temperature were found even in typical daytime conditions. In stable conditions horizontal advection can be responsible for more than 15% of the scalar (water vapor) transport 136 canopy heights downwind of a change in water vapor source density and surface roughness. 相似文献
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Janaina Braga do Carmo Marisa de Cssia Piccolo Cristiano Alberto de Andrade Carlos Eduardo Pellegrino Cerri Brigitte Josefine Feigl Erclito Sousa Neto Carlos Clemente Cerri 《Soil & Tillage Research》2007,96(1-2):250-259
Anthropogenic conversion of primary forest to pasture for cattle production is still frequent in the Amazon Basin. Practices adopted by ranchers to restore productivity to degraded pasture have the potential to alter soil N availability and N gas losses from soils. We examined short-term (35 days) effects of tillage prior to pasture re-establishment on soil N availability, CO2, NO and N2O fluxes and microbial biomass C and N under degraded pasture at Nova Vida ranch, Rondônia, Brazilian Amazon. We collected soil samples and measured gas fluxes in tilled and control (non tilled pasture) 12 times at equally spaced intervals during October 2001 to quantify the effect of tillage. Maximum soil NH4+ and NO3− pools were 13.2 and 6.3 kg N ha−1 respectively after tillage compared to 0.24 and 6.3 kg N ha−1 in the control. Carbon dioxide flux ranged from 118 to 181 mg C–CO2 m2 h−1 in the control (non-tilled) and from 110 to 235 mg C–CO2 m2 h−1 when tilled. Microbial biomass C varied from 365 to 461 μg g−1 in the control and from 248 to 535 μg g−1 when tilled. The values for N2O fluxes ranged from 1.22 to 96.9 μg N m−2 h−1 in the tilled plots with a maximum 3 days after the second tilling. Variability in NO flux in the control and when tilled was consistent with previous measures of NO emissions from pasture at Nova Vida. When tilled, the NO/N2O ratio remained <1 after the first tilling suggesting that denitrification dominated N cycling. The effects of tilling on microbial parameters were less clear, except for a decrease in qCO2 and an increase in microbial biomass C/N immediately after tilling. Our results suggest that restoration of degraded pastures with tillage will lead to less C matter, at least initially. Further long-term research is needed. 相似文献
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J. lvaro-Fuentes C. Cantero-Martínez M.V. Lpez J.L. Arrúe 《Soil & Tillage Research》2007,96(1-2):331-341
In semiarid Mediterranean agroecosystems, low and erratic annual rainfall together with the widespread use of mouldboard ploughing (conventional tillage, CT), as the main traditional tillage practice, has led to a depletion of soil organic matter (SOM) and with increases in CO2 emissions from soil to the atmosphere. In this study, we evaluated the viability of conservation tillage: RT, reduced tillage (chisel and cultivator ploughing) and, especially, NT (no-tillage) to reduce short-term (from 0 to 48 h after a tillage operation) and mid-term (from 0 h to several days since tillage operation) tillage-induced CO2 emissions. The study was conducted in three long-term tillage experiments located at different sites of the Ebro river valley (NE Spain) across a precipitation gradient. Soils were classified as: Fluventic Xerocrept, Typic Xerofluvent and Xerollic Calciorthid. Soil temperature and water content were also measured in order to determine their influence on tillage-induced CO2 fluxes. The majority of the CO2 flux measured immediately after tillage ranged from 0.17 to 6 g CO2 m−2 h−1 and was from 3 to 15 times greater than the flux before tillage operations, except in NT where soil CO2 flux was low and steady during the whole study period. Mid-term CO2 emission showed a different trend depending on the time of the year in which tillage was implemented. Microclimatic soil conditions (soil temperature and water content) had little impact on soil CO2 emission following tillage. In the semiarid Mediterranean agroecosystems studied, NT had low short-term soil CO2 efflux compared with other soil tillage systems (e.g., conventional and reduced tillage) and therefore can be recommended to better manage C in soil. 相似文献