Effect of bensulfuron-methyl (a sulfonylurea herbicide) on the soil bacterial community of a paddy soil microcosm   总被引：2，自引：0，他引：2  

Masao?Saeki  Koki?ToyotaEmail author 《Biology and Fertility of Soils》2004,40(2):110-118

The effect of bensulfuron-methyl (BSM) on a soil microbial community in a model paddy microcosm was studied. Total bacterial numbers in the overlying water and surface soil were monitored for 2 months after the application of BSM at the field rate and a ten-fold field rate. Pentachlorophenol (PCP) was used for comparison. Neither chemical affected the total bacterial numbers remarkably, either in the overlying water or in the surface soil. In contrast, the nitrification potential was significantly suppressed by the BSM application. The bacterial community structure, as evaluated by the denaturing gradient gel electrophoresis (DGGE) of PCR amplification products from bacterial 16S rDNA, was unaffected by the BSM treatments over 8 weeks in the surface soil, compared with the control (no pesticide). In contrast, the surface soil exposed to PCP at a ten-fold field rate showed different patterns from the controls at 4 weeks and 8 weeks after application. The DGGE patterns of the overlying water were much more variable than those of the surface soil in any treatments. Cluster analysis showed that the BSM plots were classified within the same group as the control at 1 week after application and that the BSM and PCP plots from 2 weeks onward after application were grouped differently from the control. Of 22 clones excised from the DGGE gels, 20 clones belonged to the Proteobacteria and two belonged to the Verrucomicrobia. It was considered that the impact of BSM on the overall microbial community (total numbers, community structure of soil) was negligible, although BSM had an impact on some specific functions of the soil microbial community (nitrification) and a part of the community (overlying water).  相似文献   

Small-scale heterogeneity in carbon dioxide, nitrous oxide and methane production from aggregates of a cultivated sandy-loam soil   总被引：2，自引：0，他引：2  

Benjamin K. Sey  Ameur M. Manceur  Joann K. Whalen  Edward G. Gregorich  Philippe Rochette 《Soil biology & biochemistry》2008,40(9):2468

Spatial variability in carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄) emissions from soil is related to the distribution of microsites where these gases are produced. Porous soil aggregates may possess aerobic and anaerobic microsites, depending on the water content of pores. The purpose of this study was to determine how production of CO₂, N₂O and CH₄ was affected by aggregate size and soil water content. An air-dry sandy loam soil was sieved to generate three aggregate fractions (<0.25 mm, 0.25–2 mm and 2–6 mm) and bulk soil (<2 mm). Aggregate fractions and bulk soil were moistened (60% water-filled pore space, WFPS) and pre-incubated to restore microbial activity, then gradually dried or moistened to 20%, 40%, 60% or 80% WFPS and incubated at 25 °C for 48 h. Soil respiration peaked at 40% WFPS, presumably because this was the optimum level for heterotrophic microorganisms, and at 80% WFPS, which corresponded to the peak N₂O production. More CO₂ was produced by microaggregates (<0.25 mm) than macroaggregate (>0.25 mm) fractions. Incubation of aggregate fractions and soil at 80% WFPS with acetylene (10 Pa and 10 kPa) and without acetylene showed that denitrification was responsible for 95% of N₂O production from microaggregates, while nitrification accounted for 97–99% of the N₂O produced by macroaggregates and bulk soil. This suggests that oxygen (O₂) diffusion into and around microaggregates was constrained, whereas macroaggregates remained aerobic at 80% WFPS. Methane consumption and production were measured in aggregates, reaching 1.1–6.4 ng CH₄–C kg⁻¹ soil h⁻¹ as aggregate fractions and soil became wetter. For the sandy-loam soil studied, we conclude that nitrification in aerobic microsites contributed importantly to total N₂O production, even when the soil water content permitted denitrification and CH₄ production in anaerobic microsites. The relevance of these findings to microbial processes controlling N₂O production at the field scale remains to be confirmed.  相似文献   

水稻病害孢子多光谱衍射识别与病害源定位方法研究     

杨宁  张天纬  张钊源  张晓东  毛罕平  袁寿其 《农业机械学报》2023,54(4):250-258

水稻真菌病害主要依赖真菌孢子在空气中进行传播。然而各种水稻病害孢子的形态相近,传统孢子捕捉仪和显微图像法难以对其进行区分。为了能够准确识别目标病害孢子并进行病害源定位,提出了一种水稻病害孢子多光谱衍射识别与病害源定位方法。为了解决传统衍射方法无法识别形态相似的缺点,设计了一种大视场、无透镜的多光谱衍射成像传感器。通过分析病害孢子衍射指纹图谱,解析稻瘟病菌、稻曲病菌孢子多光谱衍射成像特征规律。融合孢子的形态特征和吸收特性,提出指纹分离强度和相对峰差两个特征参数,建立孢子的多光谱衍射识别模型。通过仿真计算实验分析孢子传播规律,耦合环境信息建立孢子传播过程中的扩散模型。在无定向风及有定向风条件下分析孢子的空间分布情况,提出病害爆发源迭代质心定位算法。实验结果表明,本文方法对水稻病害孢子的识别率达到98.5%,对无定向风条件下的定位误差最低为4.9%,对有定向风条件下的定位误差最低为7.1%。  相似文献   

知识扩散何以影响稻作系统转型实践?——基于结构方程模型的链式中介效应     

张康洁  李福夺  尹昌斌 《中国农业大学学报》2023,28(1):48-66

促进水稻—冬闲农作系统向绿肥稻作系统转型是强化区域耕地质量保护与提升、保障国家粮食安全的有效措施。基于南方稻作区安徽、湖南、广西三省区934份农户调查数据,采用PLS-SEM模型和Bootstrap检验方法,分析知识扩散对农户绿肥稻作系统采纳意愿的影响效果与作用路径,并进一步运用Ordered logit模型揭示异质性农户禀赋对其参与农业知识扩散活动的影响。结果表明：知识扩散对农户绿肥稻作系统采纳意愿具有显著正向的直接影响;外部风险感知与组织信任、生态服务价值感知与组织信任分别在知识扩散对农户绿肥稻作系统采纳意愿的影响中存在链式中介作用;知识扩散通过农户障碍感知对农户绿肥稻作系统采纳意愿产生显著的间接作用;参加合作社、务农经验、教育程度、家庭收入、身体健康状况均对农户参加知识扩散活动具有显著的正向影响。据此,本研究提出开展系统性宣讲培训活动、提高农户组织信任、改善农户禀赋条件等政策建议。  相似文献   

豚草(Ambrosia artemisiifolia)不同器官与不同发育期中过氧化物酶同工酶分析     

顾之中  董闻达  熊友发  蒋鸟琴 《江西农业大学学报》1991,(4)

本文用凝胶电泳法测定了豚草根、茎、叶不同器官过氧化物酶同工酶酶谱,按其酶带相对迁移率(R_m),可分为11条酶带.豚草植株过氧化物酶同工酶与其他植物一样,有明显的器官特异性和阶段发育特异性.结果表明豚草茎叶中过氧化物酶酶谱在开花前后有明显的变化:(1)开花期较开花前酶带明显地增多;(2)开花期在主茎或叶片中,都会出现一条颜色较浅的,该器官花期特有的酶带;(3)豚草株体内一条主酶带(E 带)在开花期明显变浅.上述过氧化物酶同工酶的三种变化,为判断豚草植株体内开花前后生理生化变化提供了一种生化指标.  相似文献   

2450MHz频率下含盐凝胶琼脂的介电特性   总被引：1，自引：0，他引：1  

程裕东  酒井升 《上海水产大学学报》1999,8(4):337-341

本文通过对水分含量９９％的含盐琼脂（盐浓度：０．１,０．２,０．３,０．４,０．５,１,１．５,２）的介电特性值测定,研究了在１０～７５℃范围中盐浓度对高水分凝胶琼脂在介电特性所产生的影响,并进一步讨论了食品微波加热中,采用含盐琼脂在介电性质上对真实食品进行模拟的可能性,扩大在液晶感温法进行食品内温度分布研究的适用范围。  相似文献   

玉米种子清蛋白 PAGE 谱带稳定性及玉米杂交种纯度检验     

陈景堂  池书敏  刘志增 《河北农业大学学报》2000,23(4):29-32

利用改进的聚丙烯酰胺凝胶电泳（ＰＡＧＥ）技术对１１个不同玉米（Ｚｅａ ｍａｙｓ Ｌ．）自交系和杂交种种子清蛋白（ａｌｂｕｍｉｎ）进行了电泳分析。结果表明,改进的聚丙烯酰胺凝胶电泳技术对玉米种子清蛋白具有较高的分辨率;玉米种子清蛋白存在丰富的多态性,各自交系和杂交种的电泳图均具有鲜明特征,并构成其独特的生化“指纹”;电泳谱带具有相对稳定性,基本不受产地和收获早晚的影响。  相似文献   

硅胶表面霉酚酸分子印迹聚合物的合成及应用     

彭侃霖  周豪  刘戎  孙坚  丘镜莉  熊仁萍  贺利民 《华南农业大学学报》2022,43(2):19-25

【目的】合成一种对霉酚酸具有特异性识别的分子印迹聚合物吸附材料,用于青贮饲料中霉酚酸的净化、富集和分析检测。【方法】以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(γ-MPS)改性的硅胶为载体、霉酚酸酯为虚拟模板,合成硅胶表面接枝分子印迹聚合物,采用扫描电镜对制备材料进行表征,通过平衡吸附试验评价材料吸附特性。建立基于合成的分子印迹聚合物固相萃取-高效液相色谱(High performance liquid chromatography,HPLC)法检测青贮饲料中霉酚酸。【结果】改性硅胶表面成功包裹一层印迹聚合物。静态吸附试验表明,印迹材料饱和吸附量为4.5 mg/g;动态吸附试验表明,该材料吸附速率快,60 min内即达到吸附平衡。基于该印迹材料作为固相萃取吸附剂建立了HPLC法,霉酚酸的回收率为76.0%～81.2%,相对标准偏差小于7%,检测限达60μg/kg。【结论】制备的硅胶表面霉酚酸分子印迹聚合物可特异性吸附霉酚酸,建立的分子印迹聚合物固相萃取–HPLC法可用于日常青贮饲料中霉酚酸的分析测定,了解青贮饲料被霉菌毒素污染的状况。研究结果可为青贮饲料的质量安全控制提供指导。  相似文献   

白桦雄花序发育初期蛋白质的双向电泳图谱分析   总被引：7，自引：2，他引：7  

杨传平  姜静  梁艳  刘桂丰  王大海  李慧玉 《东北林业大学学报》2004,32(1):1-4

对发育初期2个时期的白桦雄花序进行的蛋白质双向电泳(two-dimemional electrophoresis，2-DE)研究结果表明，2个时期的2-DE图谱，有275个蛋白点在表达上有明显的质和量的变化。其中：162个蛋白点在5月31日雄花序2-DE图谱中的表达量均高于5月28日，110个蛋白点的表达量低于5月28日；2个蛋白点为5月28日雄花序2-DE图谱所特有；1个蛋白点为5月31日雄花序2-DE图谱所特有。这些结果为进一步获得与雄花序发育时期的相关蛋白，进而得到相关的特异基因，在分子水平上揭示白桦雄花序发育机理奠定重要基础。  相似文献   

A Parametric Transfer Function for Grain-Flow Within a Conventional Combine Harvester     

Whelan  Brett M.  McBratney  Alex. B. 《Precision Agriculture》2002,3(2):123-134

Grain yield monitoring is an integral tool in the Precision Agriculture management system. When used in conjunction with a satellite-based navigation system, it provides spatial information on output variability, output response to managed inputs and is used to identify limiting resources in the crop production process. Accurately matching measured yield quantities with spatial units within a field is therefore important. At present, a simple linear time shift is employed by all commercial monitoring systems to account for the delay between GPS recorded positions and subsequent yield measurements. This study examines the internal process of grain transport to the sensor by monitoring the flow of strategically coloured grain. The flow is shown to be significantly influenced by mixing induced by threshing and auger transport processes. In contrast to the common assumption that grain moves as a spatially related cohort through to the sensor, the results suggest that a diffusion process is more realistic. A parametric model for the diffusion process is provided which suggests that from each individual yield measurement a maximum 20% of the mass could be assigned to a single spatial unit of the size that is typically allocated. The results imply that for further analyses, the inconclusive spatial origin and artificially smoothed quantities of instantaneous yield measurements should be considered.  相似文献