Discrimination of corn,grasses and dicot weeds by their UV-induced fluorescence spectral signature

Real-time spot spraying of weed patches requires the development of sensors for the automatic detection of weeds within a crop. In this context, the potential of UV-induced fluorescence of green plants for corn-weed discrimination was evaluated. A total of 1 440 spectral signatures of fluorescence were recorded in a greenhouse from three plant groups (four corn hybrids, four dicotyledonous weed species and four monocotyledonous weed species) grown in a growth chamber. With multi-variate analysis, the full information contained in each spectrum was first reduced to the scores calculated from five principal components. Then, a linear discriminant analysis was applied on these scores to classify spectra on a species/hybrids basis and, subsequently, the resulting classes were aggregated according to the three plant groups. This two-step process minimized the error generated by heterogeneous groups such as dicotyledonous weeds. The output of this classification shows the significant potential of UV-induced fluorescence for plant group discrimination as the success rate reached 91.8%. No error was observed between corn and dicot weeds and most of the errors between corn and grasses came from confusion between the hybrid Pioneer 39Y85 and Setaria glauca L. (Beauv.). Analysis also determined that the position of the fluorescence sensor on the leaf and the plant age had negligible effects on the efficiency of fluorescence to discriminate plant groups. The factors to consider for transferring the results about UV-induced fluoro-sensing from laboratory to the field are discussed.     

基于近红外图像的杂草识别研究

利用近红外图像识别杂草,使用均值法和最大方差自动取阈值法去除土壤背景,利用作物和杂草的形态差异识别杂草。结果表明,利用近红外图像进行土壤背景分割,相对误差小于0.049 0;应用形态学方法可有效识别作物和杂草,识别精度为85.0%-98.8%。     

An evaluation of the contribution of ultraviolet in fused multispectral images for invertebrate detection on green leaves

Real-time detection and identification of invertebrates on crops is a useful capability for integrated pest management, however, this challenging task has not been solved. Compared with other technologies, a machine vision system (MVS) could provide a more flexible solution. To date, most studies have focused on counting and identifying specimens in sample containers, glass slides or traps where the illumination and background reflection can be well controlled; few studies have been conducted to detect pests on plants. In the context of invertebrate detection or identification, the spectra of visible light, near infrared (NIR) and soft X-ray have been well studied, while the spectrum of ultraviolet (UV) is still untouched. Many species of bird prey on invertebrate pests and have adaptations in their visual system to enhance detection of targets. These birds can use both UV and visible light to hunt. If the mechanisms of bird vision could be transferred to a technological visual system, it might improve the capability for invertebrate detection. This study provides an initial estimation of the contribution of UV for invertebrate detection on green leaves. By fusing the UV images into the visible light and NIR images, the MVS can detect nine invertebrate species on leaves of plants and the UV images can significantly reduce segmentation errors. The initial experiment was conducted in a laboratory, however, this study shows promise for infield applications.     

江苏省长江以北地区麦田杂草群落的定量分析

用 7级目测法调查江苏省长江以北地区 6 9个样点的 6 38块麦田共计约 5 4 5hm2 的草害情况 ,数据转化成综合值后 ,进行主成分分析 ,并赋予生态学意义上的解释。研究结果表明 ,决定江苏长江以北地区麦田杂草发生、分布和危害的主要因素是土壤水分、土壤性质 地带性气候因素 ;主成分分析结果表明 ,生境相似 ,杂草群落有趋同性 ;可将 6 9个样点划分为 3个聚类群 ,即沿海旱茬麦类群、内陆旱茬麦类群和稻茬麦类群 ,各聚类群均有相应的优势杂草 ,粘毛卷耳、波斯婆婆纳、刺儿菜、猪殃殃等为沿海旱茬麦田优势杂草 ,内陆旱茬麦田的主要杂草是播娘蒿和麦家公 ,稻茬麦田的杂草优势种为硬草、棒头草 ,并就该地区杂草发生的特点提出了综合治理的建议     

哈尔滨市田间阔叶杂草生物学特性及群落调查

实验调查了哈尔滨市及其周边地区旱田、水田和蔬菜田阔叶杂草的发生情况、杂草种类、杂草密度和主要优势杂草,掌握了不同作物田间阔叶杂草群落分布概况。结果表明,旱田(玉米,大豆,小麦)主要阔叶杂草有12科20种;水田以禾本科和莎草科杂草为主且危害较重,阔叶杂草种类虽多但危害不大,共有10科12种;蔬菜田7科8种。各作物田以一年生杂草为主,不同作物田杂草群落有显著差异。     

农作措施对油菜田杂草的生态控制作用

研究了稻草覆盖、增加作物种植密度及开沟深度等农作措施对油菜田杂草的控制作用。结果表明。稻草覆盖总体控草效果可达85％以以上，使油菜株间光照强度显著上升。增加油菜种植密度，可以增强植株整体竞争能力，对田间杂草的控制效果也逐步提高。油菜田开沟改变了田间的水湿条件，能显著降低田间恶性杂草牛繁缕、看麦娘及茼草的发生数量。农作措施在有效控制田间杂草危害的同时，使油菜产量显著提高。     

合肥地区油菜田杂草种群分布及生态位特征的初步研究

运用七级目测法对合肥地区三县(肥东县、肥西县、长丰县)的油菜田样点进行了深入的调查,根据相对盖度、相对高度、相对多度等计测重要值、生态位宽度、生态相似系数,结果表明:合肥地区油菜田常见杂草有31种,隶属18个科,生态位宽度前10位的杂草分别是野老鹳草、日本看麦娘、粘毛卷耳、猪殃殃、一年蓬、看麦娘、酸膜叶蓼、罔草、大巢菜、抱茎苦苣菜.各样点间的相似系数较高,由于各杂草间普遍存在生态位的重叠,群落组成的稳定性是相对的.     

小麦播种量对杂草群落及小麦产量的影响

农田生态系统中杂草与作物争光、争水、争肥,也是各种害虫的寄主,最终影响作物的产量和品质.该文分析小麦绵农6号不同播种量对农田杂草发生种类、发展规律及小麦经济产量的影响,为实现农田杂草的生态管理提供参考.结果表明:麦田杂草群落主要由看麦娘、荠菜、猪殃殃、蔊菜、短辐水芹、碎米荠和野薄荷等构成,其中看麦娘、荠菜、猪殃殃和野薄荷等为主要杂草.在低播种量B1(4.47g/m2)时,杂草生物量较高,增大播种量B4(17.88g/m2)可抑制麦田中杂草数量的发生.适宜的小麦播种量B2(8.94g/m2)和B3(13.41g/m2)能抑制麦田杂草的发生,降低生产成本,获得较高的经济产量.     

云南外来入侵农田杂草发生与危害特点

云南省农科院环资所杂草研究室于1996年至2010年间开展了云南农田杂草的野外调查,共发现云南外来入侵农田杂草有186种,隶属41科,122属。外来杂草数量最多的是菊科和禾本科,分别有37种和35种,数量较多的科有豆科19种,苋科12种,茄科9种,大戟科8种。草本杂草有172种,占外来杂草植物种数的92.5%。1年生杂草植物有79种,占外来杂草植物种数的42.5%;2年和多年生杂草植物有85种,占外来杂草植物种数的45.7%。分布区域主要集中于滇南和滇中的各有122种和102种,分别占外来杂草种数的65.6%和54.8%;属于全省分布的有23种,占外来杂草植物种数的12.4%。绝大多数的外来杂草属于一般性杂草,危害的农作物主要是蔬菜、玉米和果园。调查结果表明,云南外来农田杂草的种类、数量、危害范围和严重性居全国之首。为此,各相关部门应高度重视,采取强有力的措施防止其入侵和危害进一步加剧。     

Image Processing Performance Assessment Using Crop Weed Competition Models

Precision treatment of both crops and weeds requires the accurate identification of both types of plant. However both identification and treatment methods are subject to error and it is important to understand how misclassification errors affect crop yield. This paper describes the use of a conductance growth model to quantify the effect of misclassification errors caused by an image analysis system.Colour, morphology and knowledge about planting patterns have been combined, in an image analysis algorithm, to distinguish crop plants from weeds. As the crop growth stage advances, the algorithm is forced to trade improved crop recognition for reduced weed classification. Depending on the chosen method of weed removal, misclassification may result in inadvertent damage to the crop or even complete removal of crop plants and subsequent loss of yield. However incomplete removal of weeds might result in competition and subsequent yield reduction. The plant competition model allows prediction of final crop yield after weed or crop removal. The competition model also allows the investigation of the impact on yield of misclassification in the presence of both aggressive and benign weed types. The competition model and the image analysis algorithm have been linked successfully to investigate a range of misclassification scenarios in scenes containing cabbage plants.     

Hydrogen peroxide on the surface of Europa

Spatially resolved infrared and ultraviolet wavelength spectra of Europa's leading, anti-jovian quadrant observed from the Galileo spacecraft show absorption features resulting from hydrogen peroxide. Comparisons with laboratory measurements indicate surface hydrogen peroxide concentrations of about 0.13 percent, by number, relative to water ice. The inferred abundance is consistent with radiolytic production of hydrogen peroxide by intense energetic particle bombardment and demonstrates that Europa's surface chemistry is dominated by radiolysis.     

Performance evaluation of a crop/weed discriminating microsprayer

An intelligent real-time microspraying weed control system was developed. The system distinguishes between weed and crop plants and a herbicide (glyphosate) is selectively applied to the detected weed plants. The vision system captures 40 RGB images per second, each covering 140 mm by 105 mm with an image resolution of 800 × 600 pixels. From the captured images the forward velocity is estimated and the spraycommands for the microsprayer are calculated. Crop and weed plants are identified in the image, and weed plants are sprayed. Performance of the microsprayer system was evaluated under laboratory conditions simulating field conditions. A combination of maize (Zea mays L.), oilseed rape (Brassica napus L.) and scentless mayweed (Matricaria inodora L.) plants, in growth stage BBCH10, was placed in pots, which were then treated by the microspray system. Maize simulated crop plants, while the other species simulated weeds. The experiment were conducted at a velocity of 0.5 m/s. Two weeks after spraying, the fraction of injured plants was determined visually. None of the crop plants were harmed while 94% of the oilseed rape and 37% of the scentless mayweed plants were significantly limited in their growth. Given the size and shape of the scentless mayweed plants and the microsprayer geometry it was calculated that the microsprayer could only hit 64% of the scentless mayweed plants. The system was able to effectively control weeds larger than 11 mm × 11 mm.     

硬茬复播玉米和大豆田主要杂草及化学防除技术研究

硬茬复播田杂草种类达15科27种。采用除草剂JNH－1,JNH－2或JNH－3进行苗前土壤处理,对已出苗和未出苗的杂草皆有极显著防效,一次用药不仅可保证作物苗期免遭草害,而且对作物生育后期的杂草也可达到有效控制。所用除草剂均对玉米、大豆安全。由于有效减轻了草害和虫害,大豆平均增产19．4％,玉米平均增产26．2％。     

不同除草剂对冬油菜田间杂草控制和产量的影响

采用一锄、乙草胺、油力和草除·精喹混剂、10.0%油力以及17.5%草除·精喹EC 5种除草剂分别对大田冬油菜进行处理.研究不同除草剂对冬油菜田间杂革的控制作用及对田间透光率和油菜产量的影响.结果表明,17.5%草除·精喹EC对油菜田杂草具有较好的防除效果,苗期杂草的总体防效达到95%以上,随着时间的延长药效略有下降,成熟期时控草效果仍可达90%以上.各除草剂处理均能提高油菜产量(增5.1%～36.4%).其中以一锄和17.5%草除·精喹EC处理产量增幅最高,并能显著提高油菜田间的透光率、植株的一次有效分枝数、主花序有效角果数以及单株有效角果数.     

Potential of a terrestrial LiDAR-based system to characterise weed vegetation in maize crops

LiDAR (Light Detection And Ranging) is a remote-sensing technique for the measurement of the distance between the sensor and a target. A LiDAR-based detection procedure was tested for characterisation of the weed vegetation present in the inter-row area of a maize field. This procedure was based on the hypothesis that weed species with different heights can be precisely detected and discriminated using non-contact ranging sensors such as LiDAR. The sensor was placed in the front of an all-terrain vehicle, scanning downwards in a vertical plane, perpendicular to the ground, in order to detect the profile of the vegetation (crop and weeds) above the ground. Measurements were taken on a maize field on 3 m wide (0.45 m²) plots at the time of post-emergence herbicide treatments. Four replications were assessed for each of the four major weed species: Sorghum halepense, Cyperus rotundus, Datura ferox and Xanthium strumarium. The sensor readings were correlated with actual, manually determined, height values (r² = 0.88). With canonical discriminant analysis the high capabilities of the system to discriminate tall weeds (S. halepense) from shorter ones were quantified. The classification table showed 77.7% of the original grouped cases (i.e., 4800 sampling units) correctly classified for S. halepense. These results indicate that LiDAR sensors are a promising tool for weed detection and discrimination, presenting significant advantages over other types of non-contact ranging sensors such as a higher sampling resolution and its ability to scan at high sampling rates.     

生物多样性及其在农田作物生产中的意义和作用

从生物多样性这一现代研究课题了出发，论述了作物在多样性。作物与杂草关系的意义。     

杂草对作物产量损失预测的复合函数模型

本文根据杂草与作物在田间竞争所表现出的三大特征，应用幂函数与双曲线函数的复合模型（y=d^r/（a＋bd^l）来模拟杂草密度与作物产量间的关系，通过对7组不同来源的杂草与作物竞争资料的模拟，证明幂双曲线函数复合模型具有实际的生物学意义，能准确地描述多种杂草和多种作物间的竞争关系，预测杂草为害作物可能造成的产量损失。为杂草的经济防除和进一步建立杂草防除的生态经济阚值模型提供科学的依据。     

开荒作物对后茬作物产量、杂草群落及土壤理化性质的影响

【目的】探讨传统农业中利用芝麻作为开荒作物的作用机理。【方法】采用大田种植方式,在南方红壤新垦荒地以芝麻作为先锋作物,大豆和玉米作为对照,调查不同作物对后茬作物玉豆和萝卜产量、土壤理化性质以及田间杂草的影响。【结果】新垦荒地种植芝麻对后茬玉豆和萝卜单株产量增产率分别为44.25%和148.48%;对土壤p H、有机碳和速效磷含量有增加效应,使土壤碱解氮和速效钾分别减少了89.93%和47.95%;种植芝麻后未发现原生境中的杂草粗耳草,但出现优势杂草凹头苋和三叶鬼针草;杂草种类和生物量受后茬作物种类的影响差异较大,其中芝麻-自然长草处理杂草种类为5.67种,与芝麻-萝卜处理11.67种和芝麻-玉豆处理10种相比差异达显著水平,杂草的地上部净质量为萝卜(1 639.13 g·m~(-2))玉豆(976.89 g·m~(-2))自然长草(944.13 g·m~(-2));芝麻-长草与长草-长草处理相比,杂草种类由4种增加到5.67种,但杂草生物量由2 698.6 g·m~(-2)减少到944.13 g·m~(-2)。【结论】芝麻可以提高后茬作物产量,对杂草的生长有抑制作用,适宜作为开荒作物。芝麻凋落物和残茬易腐解,导致土壤有机质和速效磷增加,这可能是后茬作物增产的主要原因。     

阴山北麓保护性耕作油菜田间杂草控制试验

据调查,阴山北麓保护性耕作油菜田初期杂草密度增加,田间杂草发生时间提前,上下茬农田杂草重叠发生,多年生杂草为害加重。采用化学除草、机械除草、人工除草、农业轮作等单因素和多因素除草技术进行研究。结果表明,采用综合除草"深松+高特克+胺苯磺隆+龙拳"和"中耕+高特克+胺苯磺隆+龙拳"除草效果好,杂草株防除率和鲜质量防除率均达90%以上。     

杂草密度与作物产量损失预测的一种新方法

引入幂指函数模型［ｙ＝ ｙＬＭｅｘｐ（－ ｂｄｒ）］模拟杂草密度与作物产量间的关系,通过１０组不同来源的杂草与作物竞争资料的模拟,证明幂指函数模型具有实际的生物学意义,能准确地描述多种杂草和多种作物间的竞争关系,预测杂草为害作物可能造成的产量损失。为杂草的经济防除提供了一种新的研究方法。