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1.
基于介电特征的苹果霉心病检测方法   总被引:1,自引:0,他引:1  
针对苹果霉心病无法有效根据外表进行识别,且传统检测方法具有设备复杂、成本高昂等问题,本研究通过采集苹果介电参数构建苹果霉心病检测模型,从而实现简单快速的苹果霉心病无损检测。基于LCR测量仪采集220个苹果的108项介电指标(9个频率下的12项介电指标)作为原始参数,使用数据标准化、主成分分析算法等对数据进行预处理,并利用BP神经网络、支持向量机、随机森林算法构建霉心病果检测模型。试验结果表明,基于随机森林算法构建的霉心病果检测模型性能最佳,在150个苹果构建的训练集和70个苹果构建的测试集中分类准确率分别达到96.66%和95.71%;基于采用BP神经网络构建的霉心病果检测模型效果次之,分类准确率分别可达到94.66%和94.29%;基于使用支持向量机构建的模型检测效果相对较差,分类准确率分别为93.33%和91.43%。试验结果表明,使用随机森林构建的模型可以更有效地识别霉心病果和好果。本研究可为苹果病虫害及苹果品质无损检测等提供参考。  相似文献   
2.
为鉴定评价我国向日葵(Helianthus annuus L.)种质资源在南方地区的表现,筛选构建向日葵核心种质,以422份向日葵种质为材料,在进行2年鉴定观察的基础上,采用描述性统计、相关性分析、主成分分析等方法对11个表型农艺性状进行分析评价。结果表明,原始群体的这些农艺性状具有较大的变异幅度,其变异系数(CV)为3.60%~83.32%,平均变异系数为20.93%,其中分枝株率(0%~62.5%)、单株粒重(9.70~232.35 g)、百粒重(4.60~14.92 g)、叶片数(14.40~48.38个)和株高(103.75~260.00 cm)变异幅度较大;性状间表现出显著的相关性,主成分分析表明,影响性状的4个主要成分解释了总方差的71.72%。采用QGAstation 2.0软件构建了72组核心种质候选群体,并根据均值差异百分数(MD)、方差差异百分率(VD),极差符合率(CR)和变异系数百分率(VR),获得组获得1组包含84份材料的最佳核心种质群体。聚类分析将84份核心资源分为5大类,与原群体相比,所选核心种质均值无显著差异,方差显著提高,能最大限度代表原始油葵种质资源保存和利用。  相似文献   
3.
The use of soil fumigants and fungicides to control soilborne pathogens is reduced due to awareness of their negative drawbacks. Long-term application of such agrochemicals negatively affects soil microbiota and reduces natural soil suppressiveness. We investigated long-term impacts of biochar and not-pyrogenic organic amendment (OAs: manure, alfalfa straw and glucose), on disease suppression compared with conventional management in three pathosystems: Fusarium oxysporum f. sp. lactucae (FOL)–lettuce, Rhizoctonia solani–tomato and Sclerotinia sclerotiorum–lettuce, by conditioning soil for 2 years. Soil analyses included pH, electrical conductivity, organic carbon, total nitrogen, C:N ratio, N-NO3, N-NH4+, cation exchange capacity, available phosphorus, Ca2+, Mg2+, K+, Na+, fluorescein diacetate (FDA), and total and active limestone. Soil microbiota was characterized by combining BIOLOG EcoPlates with next-generation sequencing of 16S and 18S rRNA genes. Soil amended with OAs generally suppressed disease by S. sclerotiorum and FOL compared to fumigants and synthetic fertilizers. However, the incidence of R. solani infection was lower in soil treated with synthetic fertilizers than soil amended with OAs. EC, pH, C:N, N-NO3, N-NH4+, FDA and BIOLOG were significantly correlated with disease, depending on pathosystem. Bacterial richness and diversity, presence of some genera like Acidobacteria, Chloracidobacteria, Solibacteres, Anaerolineae, Nitrospira and Deltaproteobacteria were negatively related to disease incidence of FOL and S. sclerotiorum, whereas damping-off caused by R. solani was negatively affected by the presence of Flavobacterium and Chitinofagha. Therefore, we concluded that long-term application of OAs can effectively improve soil suppressiveness and reduce disease incidence against root pathogens, although the effects vary considerably depending upon pathosystem.  相似文献   
4.
基于核心竞争力视角,设计农产品加工业人力资源管理问卷和访谈进行数据搜集,结合数理统计分析,对铜仁市农产品加工业的人力资源管理进行分析。结果表明,被调查企业的人力资源管理存在管理模式较为粗放、管理理念相对落后、制度不够完善、“无法可依”和“有法不依”2种现象同时并存、从业人员素质偏低、年龄结构分布不合理、薪酬制度不合理等问题,并就存在的问题提出相应的对策。  相似文献   
5.
为了高效快速地区分浙茄类型茄子品种,并为鉴定浙茄品种的特异性和真实性提供依据,利用46份茄子材料,对48个单核苷酸多态性(SNP)标记进行核心SNP标记筛选,并利用筛选到的核心SNP标记,构建了6个浙茄类型茄子品种的SNP指纹图谱。结果表明:48个SNP标记均可转化为KASP标记,对46份茄子材料进行SNP标记的KASP分型,根据分型结果和多态性信息含量,34个SNP标记可作为核心标记,利用这些核心标记构建了6个浙茄类型茄子品种的指纹图谱;通过指纹图谱可以快速高效区分6个浙茄类型茄子品种,为茄子品种鉴定和知识产权的保护提供了理论依据。  相似文献   
6.
Desmet, Gumpert, and Ort?n have analyzed regional development using the Ricardian model or the Heckscher–Ohlin theorem. However, aspects such as consideration of combined wages, substitution elasticities, marginal costs, fixed costs, and number of companies were completely ignored. This study investigates the underdevelopment of regions in light of Krugman`s core–peripheral model. The extension of the model is intended to analyze the aspects that have so far been ignored and their influence on the benefits of the two regions. The following aspects characterize the model. Two regions with two sectors are considered for the model. The regions are characterized by different technological equipment. The first region is industrial. The second region has an agricultural character. When a new technology is available, both regions can benefit under certain conditions. The financial transfers lead to a convergence of wages.  相似文献   
7.
旨在构建以乙肝核心抗原(HBcAg)为载体呈现猪流行性腹泻病毒(PEDV)S1抗原表位的病毒样颗粒。将PEDV S1蛋白中含B细胞表位的270 bp片段插入到HBcAg主要免疫显性区域(MIR),构建重组质粒pET-32a(+)-HBcAg-PEDV S1,转化到感受态细胞BL21(DE3)中,经IPTG诱导表达,SDS-PAGE鉴定纯化后的重组蛋白,通过透射电镜观察其形态结构。结果显示,成功构建重组质粒pET-32a(+)-HBcAg-PEDV S1,并在BL21(DE3)中以包涵体形式表达,纯化、复性后的重组蛋白经过2%磷钨酸负染后透射电子显微镜检测到病毒样颗粒结构。HBcAg-PEDV S1重组蛋白能够自发形成病毒样颗粒,在原核表达中,乙肝核心抗原可作为载体呈现PEDV S1抗原表位,为今后新型PED疫苗的研究提供了思路。  相似文献   
8.
基于声振信号对称极坐标图像的苹果霉心病早期检测   总被引:1,自引:1,他引:0  
赵康  查志华  李贺  吴杰 《农业工程学报》2021,37(18):290-298
为实现苹果早期霉心病较高精度的检测,该研究采用对称极坐标法(Symmetrized Dot Pattern,SDP)将苹果声振信号变换为雪花图,然后采用AlexNet、VGG16和ResNet50卷积神经网络以迁移学习方式深度挖掘SDP雪花图像的特征信息,将其输入到支持向量机(Support Vector Machine,SVM)分类器,对霉心程度≤7%的苹果进行检测。研究结果表明,当时间间隔系数为25和角度放大因子为50°时,健康果与早期霉心果声振信号的SDP图形状特征差异最大,在此条件下获取的SDP图经卷积神经网络AlexNet、VGG16和ResNet50提取特征并构建了不同核函数的SVM霉心果检测模型,在各类SVM模型中,ResNet50-SVM-gaus(高斯基)模型用相对较少的训练时间和参数量可取得训练集霉心果较高分类准确率,经超参数优化训练该模型对健康果和早期霉心果测试集不平衡样本(10∶1)的总体分类准确率达到96.97%,平均查准率、平均查全率、平均加权调和均值、Kappa系数和马修斯相关系数值分别为80.19%、90.36%、86.21%,82.54%和82.68%,该模型不仅对多数类的健康果保持较高分类准确率,而且对少数类的早期霉心果也具有较高判别能力。这些研究结果为声振法应用于果蔬内部病害的早期在线检测系统研发提供了技术支撑。  相似文献   
9.
ABSTRACT

Sucker production of important clones belonging to different ploidy levels and genomic groups were assessed in three different planting seasons at Kerala Agricultural University, Thrissur, India. The study revealed that morphological characters such as plant height, collar girth, and total number of leaves recorded very strong, significant, and positive correlation with sucker production characters but negative correlation was observed with average leaf production interval and bunch weight. The number of dead suckers was found to be positively correlated with plant height, collar girth, “D” leaf area, bunch weight, and average leaf production interval. In a cluster analysis, six banana varieties that were planted in different three seasons (18 entries) and their pooled data (6 entries) were grouped into four distinct clusters each. In factor/principle component analysis, the first three major factors/principle components amounted to a total of 85.9% of the variability. The communality values of the factor analysis revealed that collar girth was the major relative contributory trait for deciding the sucker yield and production in banana.

Abbreviations: EVS: Early vegetative stage; AVS: Active vegetative stage; FBI: Flower bud initiation; FBD: Flower bud differentiation; PCA: Principle component analysis; FA: Factor analysis  相似文献   
10.
Our objective was to detect single nucleotide polymorphisms (SNPs) associated with resistance to the salmon louse in the Saint John River aquacultural population of North American Atlantic salmon using estimated breeding values (EBVs) and 6K genotypes from the parent‐generation and lice count phenotypes from the challenged, but ungenotyped, offspring‐generation. In 2011 and 2012, we challenged recent smolts with approximately 100 copepodids each. Fish were euthanized once the lice reached the chalimus stages and lice count, sex, tank and salt water weight were recorded. We used a multiple trait model to estimate breeding values for the parent‐generation using their own fresh water weights and the salt water weights and lice counts of the offspring‐generation. Salmon lice count heritability for untransformed and transformed data was 0.17 and 0.29 respectively. Two different genome‐wide association study methods were compared: (i) forward multiple linear regression and (ii) a mixed linear model using principal components to correct for population stratification as implemented in the egscore function of GenABEL. The two methods detected different SNPs located on different chromosomes. The multiple regression method incorporated 70 SNPs found on chromosomes 2, 7, 9, 12, 14, 15, 21, 22, 1p/23, 24. Many SNPs entered into the forward multiple regression are likely to be false positives from not correcting for the observed population stratification and cryptic relatedness. In contrast, the mixed linear model identified only two SNPs, one on chromosome 1p/23 (6.9%) and one on chromosome 1q (6.1%) consistent with louse‐resistance being a quantitative trait.  相似文献   
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