基于朴素贝叶斯分类器的棉花盲椿象危害等级识别

针对自然条件下棉花盲椿象危害区域提取和危害等级识别难的问题,提出了棉花盲椿象危害等级自动识别方法。该方法以自然条件下采集的不同盲椿象危害等级棉叶图像为对象,利用最大类间方差阈值分割和多颜色分量组合方法进行作物与土壤分离和病斑分割,并利用分水岭分割方法对粘连棉叶进行分离并提取盲椿象危害棉叶区域,提取图像的颜色、纹理和形状特征,结合朴素贝叶斯分类器,依据划分的棉花盲椿象危害等级标准,对盲椿象危害等级进行识别。不同盲椿象危害等级识别试验结果表明:该模型平均识别正确率达90.0%,通过比较试验表明,该模型在识别精度比BP神经网络高2.5%,运行速度比支持向量机高11.7%,可较好的对棉花盲椿象危害等级进行识别,可为棉花盲椿象的防治提供技术支持。     

基于显著和模糊检测的浅景深作物病害图像分割

大多数现有的基于图像的作物病害诊断方法往往对输入图像的质量具有很高的要求,例如要求背景简单、大景深等等。因此这些方法的预处理过程中需要去除复杂背景,然而这个预处理较难获得理想的结果。此外,当作物病斑面积较小时,会使得获取的图像景深较浅,也导致了这些方法难以抽取精确的病斑区域。为了解决上述问题,该文提出一种利用目标检测来分割病斑图像的方法。首先,该方法对抽取的结构特征和颜色特征进行整合并对特征空间进行量化,从而得到作物病害图像的显著区域。该方法不需要进行去除复杂背景的预处理过程即可得到病斑区域的图像;同时,为了处理浅景深的病害图像,引入了模糊检测方法用以进一步过滤背景和模糊区域的图像。试验中利用多种黄瓜和水稻病害的图片,将该方法与阈值法、图切割法进行了对比,结果表明该方法在效率不明显降低时,其分割效果明显优于阈值法;在分割效果差异不大时,其运行效率明显高于图切割方法;同时,该方法能够对浅景深的作物病害图像的病斑区域进行有效的分割。     

基于显著和模糊检测的浅景深作物病害图像分割（英文）

大多数现有的基于图像的作物病害诊断方法往往对输入图像的质量具有很高的要求,例如要求背景简单、大景深等等。因此这些方法的预处理过程中需要去除复杂背景,然而这个预处理较难获得理想的结果。此外,当作物病斑面积较小时,会使得获取的图像景深较浅,也导致了这些方法难以抽取精确的病斑区域。为了解决上述问题,该文提出一种利用目标检测来分割病斑图像的方法。首先,该方法对抽取的结构特征和颜色特征进行整合并对特征空间进行量化,从而得到作物病害图像的显著区域。该方法不需要进行去除复杂背景的预处理过程即可得到病斑区域的图像;同时,为了处理浅景深的病害图像,引入了模糊检测方法用以进一步过滤背景和模糊区域的图像。试验中利用多种黄瓜和水稻病害的图片,将该方法与阈值法、图切割法进行了对比,结果表明该方法在效率不明显降低时,其分割效果明显优于阈值法;在分割效果差异不大时,其运行效率明显高于图切割方法;同时,该方法能够对浅景深的作物病害图像的病斑区域进行有效的分割。     

基于MDMP-LSM算法的黄瓜叶片病斑分割方法

在复杂背景中有效分割作物病斑是解决作物病害识别的关键问题。针对这一问题,该文提出了一种全新的多域多相水平集方法。利用病斑在空间位置上处于叶片轮廓内的特点,构造出基于内部顺序的多相水平集模型。为了加强该模型对复杂背景下作物叶片病斑的分割能力,首次在该模型中引入多个空间域,构造出新的多域多相水平集模型,使内外水平集函数分别在不同空间域中进行演化。试验结果平均分割准确率为93.3%,较好地从复杂背景图片中提取出病斑,为病害诊断奠定了基础。     

改进自适应分水岭方法分割棉花叶部粘连病斑

针对棉花叶部病斑相互之间存在粘连问题,该文提出了一种自适应分水岭分割方法。该方法在H-minima分水岭分割方法基础上,结合最小二乘圆法误差理论,对图像中每个连通分量进行最小二乘圆拟合,并计算最小二乘圆误差值,通过最小二乘圆误差值大小判断每个连通分量的轮廓不规则度,针对不同轮廓不规则度确定H-minima变换的极小值阈值,根据不同极小值阈值实现棉花叶部粘连病斑的分水岭分割。不同数量粘连病斑分割试验结果表明:该方法实现了棉花叶部粘连病斑数量从2个粘连至5个粘连病斑的自动分割,分割准确率为91.25%,平均运行时间为0.088 s。不同分割方法对比结果显示:该方法能实现对棉花轮纹病、褐斑病、炭疽病、叶斑病和棉铃疫病共5种病害的粘连病斑自动分割,并将距离分水岭分割方法、梯度分水岭分割方法、标记分水岭分割方法、Chan-Vese方法、高斯混合方法与该文方法比较,正确分割率分别为67.8%、36.4%、83.7%、70.3%、82.1%、93.5%,该方法优于其他5种分割方法,有效抑制了过分割问题;在复杂背景、光照不均匀、病斑大小不一致等复杂条件下,该文方法也能较好地实现粘连病斑的分割。该方法不仅能对棉花叶部粘连病斑自动分割,也能为其他作物叶片粘连病斑分割提供参考。     

基于逻辑回归算法的复杂背景棉田冠层图像自适应阈值分割

棉田冠层覆盖度是监测棉田棉花长势的重要指标,针对棉田复杂环境中冠层图像难以准确分割的问题,该文提出了一种基于逻辑回归算法的复杂背景棉田冠层图像自适应阈值分割方法。首先将棉田冠层图像像素分成叶片冠层和地表背景2类,在HSV颜色空间中分别提取两类像素的H通道值,在RGB颜色空间中分别提取绿色占比值(G/(G+R+B))作为颜色特征;再利用逻辑回归算法确定出各颜色特征的分割阈值,通过H通道分割阈值实现图像的初次分割;再对初次分割结果中的低亮像素使用逻辑回归算法计算出的超绿特征阈值进行低亮像素分割,同时采用绿色占比分割阈值对图像高亮像素及低亮像素分割结果整体实现二次分割,最后采用形态学滤波方法对分割结果进行优化。为评价该分割方法,利用从新疆棉花产区采集到的320幅棉田冠层图像进行试验。结果表明,该方法可在棉田复杂自然背景下,有效分割出棉田冠层区域,平均相对目标面积误差率仅为5.46%,总体平均匹配率达到93.07%;优于超绿特征OTSU分割方法(平均相对目标面积误差率11.78%,总体平均匹配率76.43%)、四分量分割方法(平均相对目标面积误差率24.11%,总体平均匹配率71.67%)、显著性分割方法(平均相对目标面积误差率36.92%,总体平均匹配率66.92%)。该方法的平均处理时间为4.63 s,相对于超绿特征OTSU法(3.84 s)和四分量分割法(2.56 s),耗时多一些,但与显著性分割法(6.25 s)对比,花费时间要少。研究结果可为棉田自然复杂环境下机器视觉技术监测棉花覆盖度提供一种有效途径。     

基于水平集的作物病叶图像分割方法

针对具有复杂背景的作物病叶图像中的叶片提取问题,提出了一种基于先验信息的水平集模型。首先,在LBF模型中引入纹理信息——结构张量,构造新的水平集模型;其次,采用水平集方法表示目标叶片形状,并将先验形状信息以能量泛函的表达形式引入到上述新的水平集模型中,得到新的基于先验信息的水平集模型;最后,利用该模型对具有复杂背景的黄瓜病叶图像进行分割。结果表明,该方法能准确地提取具有复杂背景黄瓜病叶图像中的病叶,为后续的病斑提取、识别和诊断奠定前期基础。     

基于卷积神经网络的温室黄瓜病害识别系统

基于图像处理和深度学习技术,该研究构建了一个基于卷积神经网络的温室黄瓜病害识别系统。针对温室现场采集的黄瓜病害图像中含有较多光照不均匀和复杂背景等噪声的情况,采用了一种复合颜色特征(combinations of color features,CCF)及其检测方法,通过将该颜色特征与传统区域生长算法结合,实现了温室黄瓜病斑图像的准确分割。基于温室黄瓜病斑图像,构建了温室黄瓜病害识别分类器的输入数据集,并采用数据增强方法将输入数据集的数据量扩充了12倍。基于扩充后的数据集,构建了基于卷积神经网络的病害识别分类器并利用梯度下降算法进行模型训练、验证与测试。系统试验结果表明,针对含有光照不均匀和复杂背景等噪声的黄瓜病害图像,该系统能够快速、准确的实现温室黄瓜病斑图像分割,分割准确率为97.29%;基于分割后的温室黄瓜病斑图像,该系统能够实现准确的病害识别,识别准确率为95.7%,其中,霜霉病识别准确率为93.1%,白粉病识别准确率为98.4%。     

基于粗糙集和BP神经网络的棉花病害识别

为了提高棉花病害的识别率,提出了一种在自然环境条件下基于粗糙集和BP神经网络的棉花病害识别方法。该方法以轮纹病、角斑病、褐斑病和盲椿象为研究对象,将病害棉花图像从RGB颜色空间转换到HSI和L*a*b*颜色空间,应用Otsu算法对H分量、a*分量和b*分量进行阈值分割,通过H+a*+b*分量与原始图像的交集提取棉花病斑区域,利用颜色矩和灰度共生矩阵分别提取病斑的颜色和纹理特征,并结合粗糙集理论和BP神经网络,实现特征向量的优选,和棉花病害的识别。通过比较试验发现,粗糙集理论能有效减少特征维数,使提取的全部特征向量16个减少到5个,使BP神经网络的训练时间缩短到原来的1/4,且棉花病害平均识别正确率达到92.72%。研究结果表明,该方法准确识别了4种棉花病害,为棉花病害的防治提供了有效的技术支持。     

基于高斯分布的改进C-V模型植物病斑彩色图像分割

为了使C-V模型能够准确快速分割植物病斑图像,该文引入高斯混合模型来构建C-V模型,针对基于加权颜色信息的C-V模型处理时间长,R、G、B通道能量系数难确定等问题,结合高斯混合模型和C-V模型对病叶图像进行分割。先选中病斑区域中一点,以其3×3邻域像素均值作为C-V模型中曲线的内部能量均值;利用高斯混合模型对病斑图像建模,并采用高斯混合模型先验概率初始化C-V模型的水平集函数;最后分别以图像R、G、B通道中目标和背景像素均值的比例作为3个通道的权值,演化水平集函数的分割曲线。试验结果表明,该方法能够有效地分割出植物病斑,并在分割性能上优于基于加权颜色信息的C-V模型及传统C-V模型。本文的研究结果可为植物病斑分割提供参考。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.