利用网格法确定县域农田整治优先度

为了科学测算农田整治难度系数,合理确定不同评价单元整治的优先次序,该文根据研究区域农田整治特点,以江苏省宝应县为例,以规则网格为评价单元,从土地利用结构、农田空间格局、可提高生产能力、土壤环境质量、人口社会因素等5个影响因素,构建农田整治优先度评价指标体系。对研究区按1′×1′的经纬度网格划分的532个网格评价单元进行农田整治优先度测算,并根据计算结果,按整治优先顺序将整个研究区划分为近期、中期和远期网格单元,分别占42%、31%和27%。远期网格单元分布在宝应县中部和南部的平原区,该区域农田的连片性、细碎度和质量等别等优于其他区域。研究结果表明,该文提出的区域农田整治优先度评价方法,有助于确定农田整治先后顺序,明确优先开展整治区域和方向。该方法为区域土地整治规划提供支撑,也为中国各县市开展高标准基本农田建设提供科学参考。     

Biochar-induced changes in soil properties affected immobilization/mobilization of metals/metalloids in contaminated soils

Purpose

Remediation of metal contaminated soil with biochar is attracting extensive interest in recent years. Understanding the significance of variable biochar properties and soil types helps elucidating the meticulous roles of biochar in immobilizing/mobilizing metals/metalloids in contaminated soils.

Materials and methods

Six biochars were produced from widely available agricultural wastes (i.e., soybean stover, peanut shells and pine needles) at two pyrolysis temperatures of 300 and 700 °C, respectively. The Pb-, Cu-, and Sb-contaminated shooting range soils and Pb-, Zn-, and As-contaminated agricultural soils were amended with the produced biochars. The mobility of metals/metalloids was assessed by the standard batch leaching test, principal component analysis and speciation modeling.

Results and discussion

The changes in soil properties were correlated to feedstock types and pyrolysis temperatures of biochars based on the principal component analysis. Biochars produced at 300 °C were more efficient in decreasing Pb and Cu mobility (>93 %) in alkaline shooting range soil via surface complexation with carboxyl groups and Fe-/Al-minerals of biochars as well as metal-phosphates precipitation. By contrast, biochars produced at 700 °C outperformed their counterparts in decreasing Pb and Zn mobility (100 %) in acidic agricultural soil by metal-hydroxides precipitation due to biochar-induced pH increase. However, Sb and As mobility in both soils was unfavorably increased by biochar amendment, possibly due to the enhanced electrostatic repulsion and competition with phosphate.

Conclusions

It is noteworthy that the application of biochars is not equally effective in immobilizing metals or mobilizing metalloids in different soils. We should apply biochar to multi-metal contaminated soil with great caution and tailor biochar production for achieving desired outcome and avoiding adverse impact on soil ecosystem.

     

N2O production in the organic and mineral horizons of soil had different responses to increasing temperature

Journal of Soils and Sediments - The responses of N2O emission to increasing temperature in different soil horizons are not clearly understood yet. Here, we investigated the effects of increasing...     

不同改良剂对铅污染砖红壤的修复效果

在未污染的花岗岩砖红壤中加入重金属Pb，平衡两周后在污染土壤上施用不同水平的钙镁磷肥、牛粪、钙镁磷肥＋牛粪等改良剂，以小白菜作为指示作物，根据小白菜生长动态变化和收获后生物量、Pb吸收量、土壤pH、土壤中有效Pb含量等理化性质的差异，来评价各种改良剂对Pb污染砖红壤的改良效果，以便为海南花岗岩砖红壤Pb污染修复提供理论依据。实验结果表明：各改良剂对Pb污染土壤都有一定的修复效果，不同程度的减轻了小白菜的毒害症状，其中钙镁磷肥与牛粪配施处理效果最好，该处理的小白菜不仅生物量高，而且Pb含量较低；其次是钙镁磷肥处理，而改良效果最差的是牛粪，其植株叶片不仅稍有黄化症状，且Pb含量较高     

Identification of a RAPD marker linked to a brown planthopper resistance gene in rice

We report the tagging of a brown planthopper (BPH) resistance gene (Bph–1) in rice using RAPD and RFLP markers. The Korean rice variety ‘Gayabyeo’ has dominant duplicate genes including Bph–1 conferring resistance to biotype 1 of BPH. Bulked segregant RAPD analysis was employed for rapid identification of DNA markers linked to resistance genes. For tagging these two genes, an F2F3 population from a ‘Gayabyeo’ × ‘Nagdongbyeo’ cross was developed and evaluated for BPH resistance. Three bulked DNAs from two groups of homozygous BPH resistant (each for Bph–1 and the other unknown gene) and homozygous susceptible F2 plants were analyzed by RAPD using 140 random oligomers. One primer, OPD–7 yielded a 700-bp fragment that was present in Gayabyeo and resistant F2 plants (homozygous for Bph-1 locus) but absent in Nagdongbyeo and susceptible F2 plants. Cosegregation of this marker with Bph-1 was verified using an F2 population segregating for Bph-1. Chromosomal regions surrounding the Bph-1 were examined with additional RFLP and microsatellite markers on chromosome 12 to define the location of the RAPD marker and Bph-1. Use of this RAPD marker could facilitate early selection of resistant lines for BPH. This revised version was published online in July 2006 with corrections to the Cover Date.     

农业机械化对种植业经济增长贡献的实证分析——以辽宁省为例

在解决"三农"问题和建设新农村过程中,农业机械化的重要作用越来越显著.为此分析了影响农业经济增长的主要因素,运用项目有无法分析模型,测算了2006年农业机械化对辽宁省农业经济增长的贡献率.研究结果表明:农业机械化对农业经济增长的贡献率为20.6%,影响农业经济增长的主要因素有农业生产成本、种植面积、农作物产量和农业机械作业效率等.     

The effect of temperature on the energy budget of the Manila clam, <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>

In this study, the energy budget of the Manila clam, Ruditapes philippinarum, was evaluated after one-week acclimation periods at 5, 10, 15, 20, and 25°C. Small clams (151 ± 12 mg DW) and large clams (353 ± 16 mg DW) were fed with the microalgae, Isochrysis galbana. Filtration rate, ingestion rate, assimilation efficiency, oxygen-consumption rate, and ammonia excretion rate were measured. Both filtration rate and ingestion rate of small and large clams were found to be related to temperature. The highest Q ₁₀ values were measured in the range 15–20°C for both small and large clams. Assimilation efficiency of both small and large clams was not significantly influenced by temperature, although the maximum mean values were detected at 20°C. Oxygen consumption rate and ammonia excretion rate of small and large clams were found to be related directly to temperature over the entire range, with a maximum being detected at 25°C. The highest Q ₁₀ value was estimated in the range 10–15°C with regard to oxygen consumption rate, and in the range of 15–20°C with regard to ammonia excretion rate. Scope for growth (SFG) was positive at all temperatures, achieving a maximum value at 20°C in both small and large clams, primarily as a consequence of the enhanced ingestion rate which offset the concomitant elevation in the metabolic rate. In this study we have estimated the thermal optimum for this species at 20°C.     

转基因抗虫棉中棉所76高效制种技术规程

总结了优质抗虫棉中棉所76高效制种技术,包括：制种田的选择、前期准备、亲本种植与管理、制种程序及注意事项等关键技术。     

最小二乘法在水泵试验曲线拟合中的应用

根据目前国内外水泵测试软件中需要曲线拟合的要求,充分考虑了目前水泵试验软件曲线拟合的基础,我们将最小二乘法应用到水泵试验软件中.从软件中实现了流量-扬程曲线的拟合,流量一效率曲线的拟合,流量-功率曲线的拟合,以及流量-汽蚀余量曲线的拟合,并且拟合曲线的多项式方程的次方数和拟合精度可以手动或自动选择,有效避免了目前曲线拟合精度不高的问题.实际试验结果表明将最小二乘法应用在VB开发的水泵测试软件中,绘图准确,曲线美观大方,使用方便,符合国家相关标准的要求,保证了试验的测试精度.     

Monitoring biochemical changes in bacterial spore during thermal and pressure-assisted thermal processing using FT-IR spectroscopy

Pressure-assisted thermal processing (PATP) is being widely investigated for processing low acid foods. However, its microbial safety has not been well established and the mechanism of inactivation of pathogens and spores is not well understood. Fourier transform infrared (FT-IR) spectroscopy was used to study some of the biochemical changes in bacterial spores occurring during PATP and thermal processing (TP). Spore suspensions (approximately 10(9) CFU/mL of water) of Clostridium tyrobutyricum, Bacillus sphaericus, and three strains of Bacillus amyloliquefaciens were treated by PATP (121 degrees C and 700 MPa) for 0, 10, 20, and 30 s and TP (121 degrees C) for 0, 10, 20, and 30 s. Treated and untreated spore suspensions were analyzed using FT-IR in the mid-infrared region (4000-800 cm(-1)). Multivariate classification models based on soft independent modeling of class analogy (SIMCA) were developed using second derivative-transformed spectra. The spores could be differentiated up to the strain level due to differences in their biochemical composition, especially dipicolinic acid (DPA) and secondary structure of proteins. During PATP changes in alpha-helix and beta-sheets of secondary protein were evident in the spectral regions 1655 and 1626 cm(-1), respectively. Infrared absorption bands from DPA (1281, 1378, 1440, and 1568 cm(-1)) decreased significantly during the initial stages of PATP, indicating release of DPA. During TP changes were evident in the bands associated with secondary proteins. DPA bands showed little or no change during TP. A correlation was found between the spore's Ca-DPA content and its resistance to PATP. FT-IR spectroscopy could classify different strains of bacterial spores and determine some of the changes occurring during spore inactivation by PATP and TP. Furthermore, this technique shows great promise for rapid screening PATP-resistant bacterial spores.