Comparative Metabolomic Analysis of Four Fabaceae and Relationship to In Vitro Nematicidal Activity against Xiphinema index

The grapevine fanleaf virus (GFLV), responsible for fanleaf degeneration, is spread in vineyards by the soil nematode Xiphinema index. Nematicide molecules were used to limit the spread of the disease until they were banned due to negative environmental impacts. Therefore, there is a growing interest in alternative methods, including plant-derived products with antagonistic effects to X. index. In this work, we evaluated the nematicidal potential of the aerial parts and roots of four Fabaceae: sainfoin (Onobrychis viciifolia), birdsfoot trefoil (Lotus corniculatus), sweet clover (Melilotus albus), and red clover (Trifolium pratense), as well as that of sainfoin-based commercial pellets. For all tested plants, either aerial or root parts, or both of them, exhibited a nematicidal effect on X. index in vitro, pellets being as effective as freshly harvested plants. Comparative metabolomic analyses did not reveal molecules or molecule families specifically associated with antagonistic properties toward X. index, suggesting that the nematicidal effect is the result of a combination of different molecules rather than associated with a single compound. Finally, scanning electron microscope observations did not reveal the visible impact of O. viciifolia extract on X. index cuticle, suggesting that alteration of the cuticle may not be the primary cause of their nematicidal effect.     

高光谱遥感模型对亚洲小车蝗危害程度研究

对内蒙古自治区锡林郭勒盟亚洲小车蝗危害进行了高光谱遥感监测,利用地面高光谱数据,分析和比较了正常羊草和亚洲小车蝗危害羊草冠层反射光谱和高光谱特征参数的差异,建立了高光谱特征参数与羊草叶面积指数的关系模型。结果表明：LAI和3个高光谱参数有极显著相关性,其中以红边峰值区(620～760 nm )一阶微分总和与蓝边峰值区(430～470 nm )一阶微分总和的比值为变量的虫害光谱指数(DI)模型精度最高,最适于反映研究区蝗虫的危害程度。从模型可以看出,DI介于51.57～79.83,蝗虫轻度发生;DI小于51.57,蝗虫严重发生。模型的预测值与实际值相关系数为0.948,平均相对误差为3.928%,表明模型的预测效果较好。     

基于现场光谱的翅碱蓬生物量遥感反演方法研究

利用便携式地物光谱仪和植被冠层分析仪测定辽东湾双台河口盐沼植被翅碱蓬的光谱数据和叶面积指数(LAI),建立翅碱蓬光谱反射率曲线;探讨翅碱蓬的植被指数与叶面积指数和生物量的相关关系,得到以下结论:(1)9月底翅碱蓬在630nm红光波长出现明显的反射峰值,反射率达到了12%～15%,在680～700nm,有明显的"红谷"形态,在760nm左右有明显的"红边",反射率达到25%～30%。(2)翅碱蓬植被指数及叶面积指数的回归分析中,SAVI和MSAVI指数与LAI的相关关系较其他指数好,最高的R2值达到0.711。对比不同指数的Linear回归方程发现,SAVI和MSAVI指数与LAI的相关关系R2值达到0.696,0.695;其次为RVI值0.664,NDVI值0.649及PVI值0.466。(3)翅碱蓬生物量(Biomass)与PVI,SAVI和MSAVI的相关系数R2较高,直线回归方程相关系数分别达到0.626,0.698和0.679;对数方程相关系数为0.592,0.706和0.683;二次方程相关系数分别为0.688,0.711和0.683。     

基于热点效应的不同株型小麦LAI反演

针对小麦株型对LAI反演精度的制约,利用地面实测的多角度数据,提出采用热点指数反演高精度的不同株型小麦LAI。通过分析京411紧凑型和中优9507披散型两种株型小麦在红光(670 nm)和近红外波段(800和860 nm)的二向反射光谱特征,借鉴热暗点指数HDS和归一化热暗点信息指数NDHD,构建了改进的归一化热暗点指数MNDHD和热暗点比值指数HDRI两个新热点指数。将HDS,NDHD,MNDHD和HDRI与NDVI,SR和EVI相乘得到的热点组合指数用于不同株型小麦LAI的反演。分析得出对紧凑型小麦京411,由860 nm近红外波段的NDVI与MNDHD和HDRI的组合指数反演的LAI精度分别为0.943 1和0.909 2;对披散型小麦中优9507,由800 nm近红外波段的SR与HDRI和MNDHD的组合指数获得的LAI反演精度分别为0.964 8和0.895 6。表明基于冠层的热点效应反演不同株型小麦LAI的方法可行,多角度遥感数据在作物结构参数提取方面比常规观测数据更具优势。     

冬小麦叶面积指数遥感反演方法比较研究

叶面积指数(leaf area index, LAI)是反映作物生长状况和进行产量预测预报的主要指标之一,对诊断作物生长状况具有重要意义。遥感技术为大面积、快速监测植被LAI提供了有效途径。利用高光谱遥感影像,结合田间同步实验数据,探讨不同方法对冬小麦叶面积指数遥感反演的能力。介绍了支持向量机、离散小波变换、连续小波变换和主成分分析四种LAI反演方法。分别利用上述四种方法构建冬小麦LAI反演模型,并对不同算法反演的LAI模型进行了真实性检验。结果显示,支持向量机非线性回归模型精度最高,对冬小麦LAI估算能力最强,反演值与实测值拟合的决定系数为0.823 4、均方根误差为0.419 5。离散小波变换法和主成分分析法都是基于特征提取和数据降维,其多元变量回归分析对LAI估算能力相近,决定系数分别为0.697 1和0.692 4,均方根误差分别为0.605 8和0.554 1。连续小波变换法回归模型精度最低,不适宜直接用其小波系数来反演LAI。结果表明,非线性支持向量机模型最适宜用于研究区域的冬小麦LAI反演。     

GF-6 WFV光谱植被指数模型的叶面积指数反演

农业是国家经济发展的基础支柱,同时也是社会发展的基础产业。我国农业遥感技术的进步和发展,大量遥感卫星发射升空,如高分1号、 2号和6号等,为我国农情监测、作物长势、农业产业结构调整提供了重要技术支撑。农业遥感成为农业科技创新和精准农业的重要手段。叶面积指数(LAI)是一种可用来衡量植被冠层生理与生化的关键指标,不仅可以用来评估植被冠层表面的最初能量交换情况,提供相应的结构定量数据,还能反映植被冠层的光谱能量信息。同时,在陆地气候变化情况下,叶面积指数是陆地生态系统和土地利用过程生产力模型的关键输入。此外,研究发现植被冠层受人为活动和气候变化的直接或间接影响时,叶面积指数也是陆地生态系统应对气候变化十分重要的衡量标准。因此,针对GF-6 WFV遥感影像叶面积指数反演研究较少和传统光谱植被指数模型机理性、稳定性较弱的问题。基于GF-6 WFV遥感影像以栾城县为试验区,通过光谱植被指数与实测叶面积指数构造5种传统光谱植被指数模型和15种红边参与的光谱植被指数模型反演乳熟期叶面积指数,采用R²和RMSE进行模型评价,同时利用未参与建模的实测叶面积指数和MODIS LAI产...     

基于支持向量机的水稻叶面积指数高光谱估算模型研究

为了研究支持向量机(SVM)对于作物农学参数高光谱估算的能力,通过大田小区试验,测定了2个品种、3个供氮水平处理的水稻在不同生长期的冠层高光谱反射率(350～2 500 nm)。依据Ladsat-5的TM传感器波段宽度,将高光谱反射率转换为10种不同的植被指数。利用所有样本的植被指数和水稻叶面积指数(LAI),通过不同统计模型的模拟分析,依据模型的R2选取了三种相关性较高的统计关系(包括NDVI_green的指数关系、TCARI/OSAVI的乘幂关系和RVI₂的乘幂关系)。对这三种关系,通过具有不同核函数的SVM模型和相应统计模型对LAI进行估算。结果表明：所有的SVM模型都具有较低的均方根误差值,估算精度都高于相应的统计模型;基于TCARI/OSAVI的POLY核SVM具有最高的估算精度,其RMSE比相应的统计模型降低近11个百分点。因此,SVM方法用于水稻LAI高光谱估算具有良好的学习能力和鲁棒性。     

TRANSFORMATION OF Lotus corniculatus L.MEDIATED BY Agrobacterium tumefaciens

A simple and effective system for the transformation and regeneration of a leguminous plant has been developed. The cotyledon explants of Lotus corniculatus (var. Leo) were infected by Agrobacterium tumefaciens that contained a non-oncogenic Ti plasmid vector. The vector carried a chimaeric npt-Ⅱ gene and a nopaline synthase gene (nos). On the selective medium that contained kanamycin, 40% of the explants formed buds within 3 weeks. Developed shoots were cut off and transferred to rooting medium. Normal-looking plants were recovered and grew well after being transplanted into soil, bloomed and set seeds. Foreign genes were integrated onto the L. corniculatus genome, expressed, and inherited through sexual reproduction, which was proven by nopaline detection, NPT-Ⅱ enzyme activity detection and DNA hybridization test of the transformed plants and the nopaline detection of the progeny.     

Conductimetric analysis of the ion binding properties of three leaf extracts of chestnut (Castanea sativa), Eucalyptus (Eucalyptus globulus) and oak (Quercus robur)

Humic materials extracted from tree leaves of chestnut (Castanea sativa), eucalyptus (Eucalyptus globulus) and oak (Quercus robur) were analyzed by performing conductimetric titrations. Values between about 84 and 236 μS cm⁻¹ for the molar conductivity and between 0.42 and 0.74 for the charge distribution parameter were obtained when the concentrations of the extract are increased from 40 to 100 mg 1⁻¹. These variations were explained by using the counterion condensation theory, and the distance between the charged groups of the polyions, the volume of the counterion condensation and the Debye-Hückel potential were also calculated.     

α-glucosidase inhibitory,antioxidant activity,and GC/MS analysis of Descurainia sophia methanolic extract: In vitro,in vivo,and in silico studies

Due to the presence of various phenolic compounds in D.sophia, this plant may have an inhibitory effect on α-Glc and ultimately diabetes control. Therefore, this work aims to scrutinize total phenolic, flavonoid contents, antioxidant capacity, and α-Glc inhibitory activity in aerial parts of methanolic D.sophia extract. The methanolic flower extracts were selected from among aerial parts for the experimental study of anti-diabetic effects by α-Glc inhibitory assays. The flower extracts were also studied by GC/MS to detect the compounds. The total phenolic and flavonoid contents were 21.38 ± 0.93 GAE/g and 96.2 ± 0.20 QE/g, respectively. The IC₅₀ value of flower extract for α-Glc inhibition with mixed (Competitive/non-competitive) mode was found to be 20.34 ± 0.11 mg/ml. Furthermore, in-vivo studies showed that the blood glucose level reduced after consumption of flower extract compared to the control group. Twenty-one compounds were identified by GC/MS technique. These compounds were assessed for high docking scores against α-Glc in silico. Docking score calculations exhibited that the DES-α-Glc complex had a significantly higher binding energy (-6.13 Kcal/mol) than other compounds. The DES-α-Glc complex which displayed a higher docking energy value than the ACR was subjected to MDs studies. The findings of this study suggest that the flower extract of D.sophia can be used as a suitable additive in syrups or foods with anti-diabetic capacity.