基于点云数据的植物叶片曲面重构方法

叶子是植物最重要的器官之一,建立植物叶片的高精度曲面模型对于开展植物叶片形态特征分析和冠层光分布计算等研究具有重要意义。该文提出了一种基于点云数据的植物叶片曲面重构方法,该方法首先对原始点云数据进行噪声点剔除和数据精简,然后采用Delaunay三角剖分方法生成初始网格曲面,再对网格曲面进行优化处理。结果表明该方法能够基于激光扫描三维点云数据快速重构出植物叶片的高精度网格曲面,包括萎蔫和枯萎等复杂形态。该研究可为植物建模与可视化相关研究提供参考。     

植物三维信息采集方法研究

精确的植物三维形态结构模型可用来研究与植物空间结构相关的性质,是虚拟植物、植物建模等相关研究的一个重要方面。该文主要研究了采用基于结构光技术的三维信息采集系统,结合必要的旋转装置,快速无损地获取植物点云数据,从而获取植物三维形态结构的方法。为解决这种三维信息采集时点云数据无法良好配准的问题,该文提出了一种基于改进的外部附加结构的配准技术,使得配准精度、稳定性及处理速度都有显著提高。该研究结果可为深入研究植物虚拟生长建模技术奠定良好的基础。     

基于可视化类库的植株三维形态配准方法及点云可视化

精确的植物三维静态形态结构模型有助于植物空间结构相关的各种研究,是虚拟植物、植物建模等问题研究的一个重要方面。研究植物生长过程中的三维信息的获取可以获得作物生长过程中各参数的动态数据,可为精细农业植物生长模型建立等提供依据。该文以植物为研究对象,介绍了虚拟植物及植物三维可视化的研究现状,讨论了植物叶片三维可视化的可行性及必要性。针对植物三维点云的采集与处理上,讨论了三维扫描仪的精度测定方法,并针对基于基准体的植株点云配准问题,提出采用基准体点云平均法向量计算的方法,去除了部分基准体表面的噪声点,提高了植株体的配准精度;采用迭代最近点（iterative closest point,ICP）算法,对植株叶片进行进一步的高精度配准。最后采用基于可视化类库VTK(visualization toolkit)实现了植物点云配准与三维可视化。     

基于体着色的植物构型三维重建和可视化模拟

对植物进行三维重建通常利用立体视觉原理,由于立体匹配无法自动完成,加大了对植物构型时空变化的研究难度。根据体素颜色赋值法,设计了记录植物空间变化的体素三维重建系统,并利用其重建出植物点云数据,提出了针对植物体素点云数据进行滤波、分类及提取植物构型信息的算法,基于OpenAlea利用植物构型信息,建立植物构型模型并实现可视化模拟。采用阴香（Cinnamomum burmannii）枝条作为样本对该三维重建系统进行验证,结果表明,该系统能够自动重建枝条构型组织茎叶的点云,抽取植物构型信息的算法能快速正确得到枝     

基于点云的作物地下变态根可视化模拟

为研究作物地下变态根的可视化模拟,以肉质直根和块根为模拟对象,采用体着色三维重建的方法获取变态根点云,提出并实现了去除变态根点云噪声、离群点和修补孔洞的预处理通道,并对预处理后的点云进行曲面重建,构建曲面模型,进而提取变态根的构型参数,最后对重建后的曲面模型进行可视化模拟。以胡萝卜和马铃薯为试验对象进行了可视化模拟,结果表明,去除变态根点云噪声、离群点和修补孔洞的预处理通道,能有效得到完整、均匀和光顺的点云模型,从曲面模型提取的体积误差小于10%,利用重建得到的曲面模型可平滑逼真的可视化变态根形态。该文研究为植物变态根构型模拟提供了一种新方法。     

植物三维建模ICP点云配准优化

构建精确三维模型无损获取植物表型特征信息,对研究农作物的精准化种植、可视化管理和智能化操控具有实际意义。针对当前植物三维建模过程点云数据量大、配准精度不高的问题,该研究提出基于轻量化处理的迭代最近点算法（Iterative Closest Point,ICP）点云配准优化方法。首先以人机交互算法对获取的植株点云图像进行背景滤除,然后利用高效近邻搜索算法判别点云的离群点进行噪声去噪;通过引入辅助特征坐标参数解决ICP算法配准过程中易陷于局部最优解的问题,获取多组点云的精确配准;最后提出体素化网格法,在保证点云三维形态特征的前提下有效滤除冗余点云数据点。试验结果表明,单株和多植株的精简配准效果良好,表型清晰明显,细节易区分,精简后的植株点云冗余数据减少96.90%～97.35%。精简后的植物点云表型可有效重构植株的形态特征,单植株的株高误差为0.20%～0.45%,冠幅误差为0.17%～0.47%,多植株的株高误差为0.25%～0.60%,冠幅误差为0.42%～0.80%。优化后的ICP算法实现滴水莲点云数据精准融合时间为124.3 s,较暴力算法提升26.75%,冗余点云数据精简了96.90%～97.20%,为植物表型的三维建模轻量化处理提供参考。     

基于运动恢复结构算法的油菜NDVI三维分布

植物形态伴随着植物生长过程而发生变化,植物的三维重建对研究植物形态对植物生物量估测、植物病害虫害、基因型表达等有着很重要的意义。目前三维重建方法重建出的三维点云多包含植物的形态、颜色等特征,无法反应植物营养状况（如叶绿素含量）、病虫害胁迫等原因造成有机质空间三维分布改变,同时以往手段都需要专门仪器,携带和作业都受到很大限制。多光谱图像能够反应有机质含量等化学值的分布,在近地面遥感、农产品质量无损检测等发面取得了广泛的应用。该文通过采集31张4叶龄油菜的多光谱图像,使用运动恢复结构算法（structure from motion）方法对其进行空间三维重建,得到油菜的三维点云,并对点云中噪声点进行滤除。以控制点和控制长度对所得模型进行评价,得到长度最大偏差在0.1023 cm,RMSE=0.052599,证明该方法重建所得模型具有较好的空间均匀性与准确性,最后计算NDVI指数空间分布。证明所得模型对将来研究植物营养与病虫害胁迫空间分布有着重要意义。     

葡萄树地上部形态结构数据获取方法

葡萄树为多年蔓生植物,其形态结构复杂且受人工修剪及架势的影响。获取葡萄树地上部植株及器官的形态结构及纹理数据,有助于建立3D可视化模型以表征该植株的品种遗传特征、受环境、架式和人工修剪等因素的影响。该文针对葡萄树形态结构数据获取工作量大、效率低、依靠单一手段所获取数据缺乏完整性等特点,提出一种高效的葡萄树地上部形态结构数据获取方法,首先对葡萄树进行拓扑结构解析和数字化表达实现复杂结构的显示表达;然后针对目标植株进行葡萄树三维形态数据采集,包括植株拓扑结构三维数字化数据采集、品种一致性与差异性分析的DUS(植物新品种特异性(distinctness)、一致性(uniformity)和稳定性(stability)的栽培鉴定试验或室内分析测试)数据采集,器官的形态参数测量,三维扫描与纹理数据采集,目标植株的栽培环境及人工管理措施等信息的采集。结果表明,基于所获取形态结构数据结合植物参数化建模方法重建的葡萄树器官与植株几何模型具有较高的真实感。在葡萄树形态结构数据获取方法的基础上,对植物地上部形态结构数据获取标准化流程进行探讨,以期为其他植物主要器官与植株的形态结构数据获取提供方法参考。     

基于相位相关的温室番茄植株多模态三维重建方法

为实现温室番茄植株多模态三维重建,解决多光谱反射率配准和多视角点云三维重建问题,基于相位相关原理将多光谱反射率配准至RGB-D图像坐标系中,建立了基于Kinect传感器测量位姿自主标定的多视角RGB-D图像三维重建方法,实现植株RGB三维点云模型和多光谱反射率点云模型重建,通过归一化灰度相似系数、配准区域光谱重叠率、互信息值3个指标客观评价二维多光谱图像配准质量,采用豪斯多夫距离客观评价植株三维点云重建精度。结果表明:30株温室番茄,每株4个重建视角,视角间隔为90°,配准区域光谱重叠率和归一化灰度相似系数的平均值分别为0.920 6和0.908 5,异源图像配准后互信息值比配准前互信息值平均提升了9.81%,植株冠层多光谱图像能够准确配准至深度坐标系,番茄植株三维重建点云距离集小于0.6 cm的比例为78.39%,小于1.0 cm的比例为91.13%,番茄距离集均值的平均值为0.37 cm,表明植株三维点云模型重建精度较高,能够应用于温室番茄植株多模态三维重建。植株多模态三维模型是实现三维形态测量与生理诊断的关键要素,为高通量植株表型测量提供高效精准的测量方法,对植物表型组学等研究领域的发展具有重要的意义。     

基于TOF深度传感的植物三维点云数据获取与去噪方法

为提高植物三维重建的精度,更好地实现植物数字化研究,提出了基于TOF(time of flight)深度传感的植物三维点云数据获取与去噪方法。首先通过TOF深度传感来获取植物点云数据,采用直通滤波器对点云数据进行预处理,减少背景噪声;其次采用改进密度分析的离群点去噪算法,该算法通过结合邻近点平均距离和邻域点数数量2个特征参数,对点云数据中的离群点噪声进行检测和去除;最后采用双边滤波算法对点云内部的小尺寸噪声进行检测和去除。以番茄植株进行相关试验,试验结果表明:与传统双边滤波算法比较,该文算法最大误差降低了11.2%,平均误差降低了23.2%;与拉普拉斯滤波算法比较,最大误差降低了20.6%,平均误差降低了39.2%,表明该文提出的算法在保持点云特征的情况下,能简单高效地去除植物三维点云数据中的不同尺度噪声。     

Bragg soybeans grown on a southern coastal plains soil i. dry matter distribution,nodal growth analysis,and sample variability

Yields of soybean [Glycine max (L.) Merr.] are affected by the manner in which available resources are partitioned into component plant parts. Little is known about these partitioning processes and much of what has been reported describes indeterminate cultivars or comes from other than field studies. A field investigation was conducted, therefore, on a Goldsboro loamy sand (Aquic Paleudult) to characterize in detail the growth and development of a determinate soybean cultivar ‘Bragg’. Soybean were grown in well watered field plots in four replications from each of which 4 nested samples of 0.3 m² each were combined at each sampling. Leaf area, dry matter production, internode length, and sample variability were determined nodally at 10‐ to 14‐day intervals from 7 July to 17 October. Plant components at each node were separated into stems, leaf blades, pods, and petioles. Primary and secondary branches were combined in the petiole fraction.

Maximum above ground plant dry weight achieved was 1027 g/m² and maximum combined nodal dry weight was 92 g/m² (at node 8), both occurring at the R7 growth stage. Canopy dry weight distribution over time was unique for each plant part. Growth analyses showed that RGR, NAR, LAR, and LWR declined with plant age at a rate that could be described with either linear or exponential models. A maximum CGR of 16.24 g/m²/day occurred at mid‐podfill and declined thereafter due to maturity. Leaf area per node peaked between nodes 7 and 12, decreasing uniformly toward the top of the canopy. Maximum nodal LAI was 0.79 at node 7 on 31 August.

Distribution of dry weight among parts varied with plant age and node position. Maximum dry weights of stems (276 g/m²), petioles (253 g/m²), and leaves (263 g/m²) were found during mid‐podfill. During mid‐August, the dry weights of the stems, petioles, and leaves were similar and approximately 250 g/m². Stem dry weights had the lowest coefficients of variation of all plant fractions once maximum dry weight was achieved. Internode length varied along the stem with the maximum at node 12. By bloom, expansion of the internodes lower than 12 had ceased; expansion of the eight higher internodes ceased three weeks later. During vegetative growth, the ratio of stem internodal dry weight to internodal length had peak values at the lowest and highest internodes. During reproductive growth, the ratio decreased linearly with internode number. Coefficients of variation (CV) for the combined weight of plant parts, and for stems, petioles, leaves, and pods were relatively constant during the season and were 24.8, 23.4, 38.2, 25.5, and 26.8%, respectively. The CV's for the combined weight of plant parts were somewhat higher at the lowest and uppermost nodes. This variability resulted from the abscission of petioles and leaves in the lower nodes and the initiation of leaves, petioles, and pods in the upper nodes where rapid growth and development was occurring. Time from node initiation to achievement of lowest stable CV was determined for each node and plant part. Plant node position and morphological part with the lowest CV was identified for each sampling date (and growth stage).     

Rice (Oryza sativa L.) plant protection using dual biological control and plant growth-promoting agents: Current scenarios and future prospects

Various microorganisms live in association with different parts of plants and can be harmful, neutral, or beneficial to plant health. Some microbial inhabitants of plants can control plant diseases by contesting with, predating on, or antagonizing plant pathogens and by inducing systems for plant defense. A range of methods, including plant growth-promoting microorganisms(PGPMs) as biological control agents(BCAs)(BCA-PGPMs) are used for the biological management and control of plant pathogens. S...     

The influence of carbon dioxide on the growth,pigment, protein,carbohydrate, and mineral status of lettuce

Lettuce plants (Lactuca sativa L. cv. Grand Rapids) were grown in nutrient solution in controlled environment plant growth chambers to characterize certain qualitative responses to above ambient levels of CO₂. Increased plant material produced under high CO₂ levels did not differ nutritionally from plants grown under ambient levels. No differences were found in chloroplast pigment content, protein content, or in carbohydrate content on a weight basis. Sequential harvests did reveal, however, that there is a greater accumulation of carbohydrate, under high CO₂ conditions, prior to an increased growth rate as the plants reach maturity.     

Optimum N and P rates for greenhouse production of vegetative coleus using constant liquid feed

Many new coleus (C. hybridus cv.) cultivars are vegetatively propagated and require different fertilization practices from seed propagated cultivars. Two experiments were conducted to evaluate growth responses of Henna, Indian Summer, Mint Mocha, New Orleans Red, Red Head, and Trusty Rusty to 0, 70, 140, 280 and 420 mg·L^?1 nitrogen (N), and Henna, Mint Mocha, Red Head, and Trusty Rusty to 0, 6.2, 12.4, 24.8, or 49.6 mg·L^?1 phosphorus (P) to determine optimum constant liquid feed rates to produce marketable size plants from rooted cuttings. Positive growth responses in terms of biomass were found with increasing N rates but not P rates. For medium-sized cultivars such as Henna, Indian Summer, and New Orleans Red, quadratic responses were found in aboveground biomass, and N at 280 mg·L^?1 resulted in similar plant size and dry weight as those fertilized at 140 and 420 mg·L^?1 N. For large-sized cultivars such as Mint Mocha, Red Head and Trusty Rusty, plant dry weight responded linearly within the N range tested and were greatest at 420 mg·L^?1. However, plant visual quality was negatively affected by N rates at 280 and 420 mg·L^?1 in that, leaf color became less intense at these high N rates. Plants fertilized at 70 mg·L^?1 were smaller than those fertilized at 140 mg·L^?1, however, they received similar visual quality ratings because of more intense leaf color. Therefore, N at 70 to 140 mg·L^?1 can be used to grow most vegetative coleus for similar marketable quality. Mint Mocha and Henna were the only cultivars responded to P treatments that, 12.4 mg·L^?1 P rate resulted in greater biomass than the no-P control. All other cultivars had no response to supplemental P except a linear response in tissue P%. Therefore, supplemental P is not required during the 8 week production period when there is an initial P charge in the substrate. We found that substrate pH decreases with higher P rates, therefore supplemental P fertilizer can be used for adjusting pH. Both N and P rates found optimum in this study are lower than current industry practices (N at 150 to 250 mg·L^?1 and P at 24 mg·L^?1) and can significantly lower production cost and potential leaching of excessive nutrient into waterway. Nutrient treatments in further study on postharvest performance of vegetative coleus will be selected based on this study.     

The diagnosis of nitrogen deficiency in wheat by means of a critical nitrate concentration in stem bases

Abstract

Stem bases from wheat plants in a glasshouse pot experiment conducted under varying nitrogen and two water regimes, were analysed for nitrate (NO₃) concentration. The concentration of NO₃ at three stages of growth i.e. tillering, jointing and anthesis were related both to rates of applied nitrogen and to shoot dry matter yield at time of sampling. Plotted against rate of increasing nitrogen application, the response curve of NO₃ concentration in wheat stem bases was sigmoidal. The level of nitrogen application at which NO₃ began to accumulate in the plants was the supply at which plants reached maximum dry matter yield. The concentration of NO₃ at which plant yield was 90% of maximum dry matter was taken as the critical level. This concentration was around 1000 ppm NO₃‐N at all stages. Compared with plants supplied with unlimited water, plants under moderate water stress accumulated relatively more NO₃ but had a similar critical NO₃ concentration.

Maximum grain yield was obtained from plants which stayed above the critical level throughout the growing season.     

Fruit Quality and Nitrogen,Potassium, and Calcium Content of Apple as Influenced by Nitrate: Ammonium Ratios in Tree Nutrition

Evaluations of fruit quality and nitrogen, potassium, and calcium concentration of apple (Malus domestica Borkh. cvs. Gala and Golab) grown with five treatments of NO₃^?:NH₄⁺ ratios were made in pot culture. The concentrations of NO₃^?:NH₄⁺ ratios were 2.5:0.1, 6:1, 6:0.7, 6:0.5, 6:0.3 meq L^?1. Fruit size, percent dry matter, total dissolved solids, total acidity, or juice pH was not affected by increased ammonium in the ratio. Firmness decreased as the proportion of NH₄⁺ increased. Gala and Golab differed in some of these parameters. Concentrations of N and K increased as NH₄⁺ increased, whereas Ca had no trend or decreased. Generally, the treatment of 2.5:0.1 produced fruits with lower N but higher K and Ca concentrations than the other treatments. This research showed that some parameters such as fruit weight, length, and diameter, juice pH, and dry matter were not affected significantly by NH₄⁺ concentration whereas composition was affected.     

Nutrient deficiencies and toxicities in plants: Nitrogen

Current literature review and discussion of the N status of plants as related to their growth and yield and quality of produced product.     

Rapid and simple leaf tissue test for nitrate

Abstract

A simple and rapid procedure for the determination of nitrate in fresh leaf tissue, suitable for use by relatively untrained operators is presented. The method requires only 4 reagents and can be carried out in less than 20 min from start to finish. A 400 mg sample of fresh leaf tissue is macerated briefly with 5 drops of 10 N sulphuric acid, diluted with 10.0 ml of water and filtered. Nitrate‐N is estimated on an aliquot of the filtered extract by reducing the nitrate to nitrite by shaking with powdered zinc in ammonium hydroxide solution for 3 min. The reduced mixture is allowed to settle (5 min) and an aliquot is withdrawn through a cotton‐wool plug thus removing any particles of the zinc. The filtered aliquot is then reacted with a single colour reagent to yield a pink azo‐dye, the intensity of which is directly proportional to the amount of nitrate.

The method was found to have a coefficient of variation of about 4%. When compared with the phenoldisulphonic acid method for nitrate, on aliquots of the some plant extract, it yielded values which were on average 94.6% of those obtained with the former method. The coefficient of variation between the methods was 7%.     

植物营养生物学研究方向探讨

植物营养生物学是重点研究植物活化、吸收、转运与利用养分的生理、分子及遗传机制的科学。在过去的30年,我国植物营养生物学研究取得了长足的发展,但从国家自然科学基金资助情况分析,与相关学科相比,近10多年来植物营养生物学总体研究力量相对薄弱,缺乏新一代领军人才。一些研究更接近于“纯”植物生物学,与植物营养应用研究出现脱节,对农业绿色发展及化肥产业升级的支撑不够。植物营养生物学研究者应该重视与作物育种、耕作栽培、生态环境、植物保护及化肥产业的合作,跟踪这些领域的研究现状及生产中面临的技术需求,围绕这些领域的技术“瓶颈”开展植物营养基础研究,在提供解决途径的同时创新植物营养生物学机理,从而丰富植物营养学理论。在研究内容上,建议重视控制养分响应度的生理与遗传机制,养分信号与环境信号互作,养分×土壤×管理互作及其对根系生长的影响,养分供应与抗生物胁迫,高产高效的植物营养生理学基础,特种作物的营养机理,化肥产品升级的生物学途径等方向的研究。     

哈尔滨市不同绿地植物群落重金属分析与种植对策

采用野外调查与室内实验分析相结合的方法,以哈尔滨市街道广场绿地、单位附属绿地、苗圃生产绿地的“乔灌草密林、乔灌草疏林、灌木密林”植物群落为研究对象,综合评价不同植物群落土壤的重金属Zn、Cu、Pb含量与污染程度,对比分析不同植物群落的重金属修复效应及树木含水量、全氮、全磷含量与土壤重金属富集的相关性.结果表明:土壤重金属修复能力为乔灌草密林＞灌木密林＞乔灌草疏林;植物根系重金属富集能力最强,其中小根对锌、铜富集能力较强,大根、中根对铅富集能力较强;树种富集重金属能力显著不同,梓树、黄檗对铜富集能力较强,铺地柏、红皮云杉、小叶丁香对铅富集能力较强,紫丁香、胡桃楸对锌富集能力较强;树木富集铜和锌的能力与其叶片含水量、叶片全磷含量密切相关.为了有效修复土壤重金属污染,提出了优先选用耐重金属植物、努力提高乔灌木小根数量、科学营造乔灌草复层群落等种植对策.