基于高光谱图像的黄瓜叶片叶绿素含量分布检测

植物叶片叶绿素含量及分布是植物营养信息表达的重要指标。为了给大棚黄瓜营养元素的控制提供理论依据,该研究利用高光谱图像建立简单实用的光谱值和叶绿素含量关系的模型,从而实时、无损地检测叶片的叶绿素分布。选取黄瓜叶片的高光谱图像数据块中450~850 nm波段作为研究波段。选取8个具有代表性的植被指数,建立特征波长λ下相应的光谱反射值Rλ与黄瓜叶片叶绿素含量之间的关系模型。结果显示,基于最优指数(R695–705)-1-(R750–800)-1的模型可以很好地预测黄瓜叶片叶绿素的含量,校正集和预测集相关系数r分别为0.8410和0.8286,最小均方根误差RMSE分别为0.2045和0.2190 mg/g。最后根据最优模型预测叶片上任意位置叶绿素的含量,并通过伪彩手段描述叶绿素含量的分布。研究结果表明,利用高光谱图像技术分析黄瓜叶片叶绿素含量及其在叶面上的分布是可行的。另外,该研究确定的最优植被指数所包含的695~705和750~800 nm 2个波段可用于搭建更加简便实用的快速检测叶片叶绿素的便携式多光谱设备。     

近红外光谱技术快速无损诊断黄瓜植株氮、镁元素亏缺

为了快速无损诊断黄瓜植株氮、镁元素亏缺,以K-最近邻域法（k-nearest neighbors, KNN）模型识别率作为遗传算法中染色体的适应度值,采用遗传算法（genetic algorithm, GA）优选近红外光谱特征子区间,交互验证优化主成分因子数和K值后建立了特征子区间对应的GA-KNN诊断模型。通过控制营养液中氮和镁的含量,在温室大棚内以无土栽培方式培育氮、镁元素亏缺植株,并用近红外光谱仪采集缺氮、缺镁植株老叶的光谱信息。结果表明：原始光谱经过标准正交变换预处理和子区间总数优化后,均匀划分为     

三峡库区脐橙生长元素农业地球化学研究

利用田间试验研究了三峡库区福罗斯特脐橙(Citrus.sinensis)体内营养元素(N、P、K、Ca、Mg、Zn、Mn、Cu、Fe)的分布特征及其农业地球化学行为。结果表明:大量元素中,树干(枝)Ca含量最高,花器官中K含量最高,根系与叶片中大量元素含量分布基本相同,大量元素在脐橙中的含量分配与土壤中的分配基本一致,均为脐橙强烈摄取元素;微量元素Zn、Mn、Cu为中等摄取元素,Fe为极微弱摄取元素,土壤背景为营养元素的主要控制因素。叶、花、根为大量元素与微量元素较为富集的器官,而树干、果实对各营养元素的富集程度较弱。该地区土壤具有缺N、少P、富K的特点,因此需合理调整有机、无机肥的比例,提高土壤N、P的供应量。     

基于叶片光谱透过特性的植物氮素测定

该文通过不同施氮水平下营养液栽培的水稻和黄瓜叶片在300～1100 nm的分光光谱透过率,与其叶绿素含量和含氮量的相关性分析,确定了560、650和720 nm作为特征波长,940 nm作为参比波长可用于植物营养的快速无损诊断。以上述波长的光谱透过率构建的21组光谱特征参数中,(T940-T560)/(T940+T560)、log(T940/T560)和log(T940/T650)与水稻和黄瓜叶片的叶绿素含量和含氮量的相关性较好,且经回归估测检验的相对误差均小于8%。因此,上述光谱特征参数可作为植物氮素营养指标用于植物叶片的叶绿素含量和含氮量的快速无损估测,从而为植物营养无损诊断提供技术支持。     

铜胁迫对嫁接和自根黄瓜幼苗光合作用及营养元素吸收的影响

以"新泰密刺"黄瓜/黑籽南瓜嫁接苗和"新泰密剌"自根苗为材料,采用日光温室水培的方法研究了铜胁迫下嫁接对黄瓜幼苗光合作用和营养元素吸收的影响.结果表明,铜(Cu2+)胁迫6 d后,嫁接和自根黄瓜幼苗叶片叶绿素含量和类胡萝卜素含量显著降低;净光合速率和气孔导度显著下降,胞闻CO2浓度随Cu2+离子浓度的增加而降低,但各浓度处理间差异并不显著;电解质渗漏率明显升高,细胞膜透性发生改变;根系和叶片中的营养元素(N、K、Ca、Mg)含量明显降低.嫁接黄瓜幼苗叶片叶绿素和类胡萝卜素含量、净光合速率、营养元素含量显著高于自根黄瓜,电解质渗漏率显著低于自根黄瓜.嫁接黄瓜幼苗叶片中Cu2+含量显著低于自根黄瓜,表明嫁接能够明显减少Cu2+向叶片的运输,缓解Cu2+毒害作用.     

甘肃省元帅系苹果叶营养元素含量标准值研究

不同地区苹果不同品种叶营养元素适宜值存在差异,苹果叶片营养标准值的确定对养分管理具有指导意义.通过对甘肃省元帅系苹果叶片营养水平的研究表明,营养元素变异规律呈现常量营养元素＜微量元素;不同产量苹果园,高产园叶片N、P、Ca、Mg、Zn、Mn含量值显著高于低产园,而铁含量显著低于中、低产园,K、B含量差异不显著;叶片矿质营养N、P、K、Ca、Mg、B含量值遵从正态分布,而Cu、Fe、Mn、Zn呈偏态分布(x2分布).对符合正态分布的元素采用概率分级法1～5级分级,分别对应叶营养元素含量标准值中的缺乏、低值、正常值、高值、过高5个数值范围,各级出现的叶样概率分别为10％、20％、40％、20％和10％,叶分析值为(X-0.5246S)～(X+0.5246S)可作为标准值中的正常值范围,这与高产园分析值十分接近;对呈x2分布特征的元素,参照高产园的叶分析值对概率分级法进行矫正,制定出甘肃省元帅系苹果叶营养元素含量标准值.与国内外标准相比,甘肃元帅系苹果叶标准值表现出N、P、K、Mn、Zn、B水平正常,Ca、Mg、Cu偏高,Fe极高的特点.     

脐橙幼苗新老叶片养分含量对大、中量元素短期缺乏的差异性响应

  【目的】  对比大、中量养分短期缺乏下脐橙新、老叶片中11种必需元素含量及变化,并分析缺素导致的营养元素间的相互影响。  【方法】  以一年生枳砧纽荷尔脐橙幼苗为试材进行了砂培试验。以完全营养液为对照 (CK),设置缺氮 (?N)、缺磷 (?P)、缺钾 (?K)、缺钙 (?Ca)和缺镁 (?Mg)处理,测定不同处理脐橙叶片（老叶和新叶）生长指标及矿质元素含量。  【结果】  所有缺素处理均导致叶片叶绿素含量降低,生物量减少,以缺氮处理最为显著。缺氮降低了叶片N、Ca、Cu、Mo含量;缺磷降低了叶片P、K、Mo含量;缺钾降低了叶片K含量;缺钙降低了叶片N、Cu、Zn、Mo含量但增加了P含量;缺镁降低了叶片Ca、Mg、Zn、Mo含量但增加了K含量。以必需矿质元素为变量分别对各处理老叶和新叶进行主成分分析,老叶中第一主成分 (PC1)明显将缺钾处理与其他处理区分开,与对照相比,缺钾老叶离子组成变化为N (?3%)、P (+1%)、K (?71%)、Ca (+11%)、Mg (+39%)、B (+16%)、Mn (+11%)、Fe (+32%)、Cu (?7%)、Zn (+14%)、Mo (?63%);新叶中PC1明显将缺氮处理与其他处理区分开,缺氮新叶离子组成变化为N (?53%)、P (+8%)、K (+7%)、Ca (?14%)、Mg (+11%)、B (+55%)、Mn (+51%)、Fe (?14%)、Cu (?57%)、Zn (+4%)、Mo (?25%)。老叶和新叶中元素含量呈正相关的元素是N-Cu、N-Ca、Mg-Mn和Cu-Mo,呈负相关的是K-Zn。  【结论】  脐橙幼苗老叶对钾的短期缺乏反应最敏感,缺钾会显著降低老叶中K和Mo含量并增加Mg和Fe含量,而新叶对氮素的短期缺乏最敏感,缺氮显著降低新叶中N、Ca、Cu和Mo含量。短期缺少P、Ca和Mg对脐橙幼苗叶片中的养分含量影响较小。     

叶面营养对黄瓜生物效应的影响

采用盆栽和田间大棚小区试验，研究了施用不同叶面营养组分对黄瓜的养分吸收分配和叶片光合生理及果实产量与品质的影响。结果表明:（1）P、N、K三要素可被黄瓜（苗期）叶片快速吸收并显著提高其在体内的含量，天然植物生长活性物质具有促进黄瓜N、P、K养分，尤其是N、K的吸收功效。特别是当它与营养元素配合施用时，这种促进作用最为明显。（2）叶面施用适当浓度的该活性物质或硫酸铵或KH2PO4均有显著提高黄瓜处理叶绿素及其光合速率的作用。从总体上讲，三者的作用效果相当，其中活性物质的作用速度较快，但持续时间稍短。叶面施肥后48小时与72小时，不同处理间的叶片光合速率与叶绿素含量差异分别达到最大，一直到108小时，仍维持较稳定的显著差异。说明叶面营养对作物的光合作用的影响主要发生在施肥三天（72小时）以后。（3）叶面肥不同组分配施均能增加黄瓜的生物量与果实产量，提高果实蛋白质、Vc、可溶性糖的含量，降低脂合纤维的含量，而果实酸度则基本不受叶面施肥的影响。（4）在不同叶面营养处理中，无论是促进叶片光合作用还是提高果实产量与改善品质，均是营养元素与该种物质的合理团合达到最理想的效果，两者呈现极其显著的正交互作用。     

菊科花卉常见缺素症及植株养分含量变化探讨

通过溶液培养的方法,研究了3种主要菊科花卉（金盏菊、孔雀草、万寿菊）在缺N、P、K、Ca 、Mg、S条件下的缺素症状及其生物量与营养元素变化情况。结果表明,金盏菊、万寿菊缺N,孔雀草缺K时症状最为明显;缺N对金盏菊、孔雀草、万寿菊的植株生物量影响最大;与全素（CK）相比,金盏菊和万寿菊缺K处理植株N浓度增加,3种花卉缺N、缺K处理均增加植株的P含量,但缺P处理降低植株K浓度,缺K处理增加含Ca量,缺Ca处理增加含K量和含Mg量,金盏菊缺Mg处理的含K量增加,3种花卉缺S处理植株S含量降幅不大,孔雀草和万寿菊缺N、P、K、Ca处理均可导致植株S含量增加。     

基于计算机视觉的番茄缺素神经网络识别

提出了采用不受植株叶片大小和背景影响的色调域平均百分率直方图来提取番茄叶片的颜色特征,用于识别番茄是否缺乏营养元素;提出了采用基于最大差分算子的色调域百分率直方图法、灰度－梯度共生矩阵法和小波分析法提取番茄缺素叶片的纹理特征,用于识别番茄缺何种营养元素;设计了番茄缺N、缺Fe、缺Mg的BP神经网络系统,综合识别结果为：正常中叶、正常新叶、缺铁新叶,缺氮中叶、缺镁中叶的识别准确率依次为95％、92.5％、92.5％、87％、87％。     

Nondestructive diagnostics of magnesium deficiency based on distribution features of chlorophyll concentrations map on cucumber leaf

Abstract

A new and nondestructive method for diagnosing magnesium (Mg) deficiency based on chlorophyll concentration distribution features of cucumber leaves was proposed. Mg deficient cucumber plants and Control plants were grown under non-soil conditions with special nutrient supply. Cucumber leaves were employed to collect hyperspectral images using a visible and near infrared (VIS/NIR) hyperspectral imaging system (400–900?nm) and determine reference chlorophyll concentrations using high performance liquid chromatography (HPLC). An optimal chlorophyll concentration calibration model (Rp = 0.9087) was constructed and used to detect chlorophyll distribution maps of Mg deficient leaves and Control leaves. Results shown that chlorophyll content distributed more unevenly on Mg deficient leaves than Control leaves. The Standard Deviation (SD) value of the chlorophyll content at all the pixels on a chlorophyll distribution map was calculated for Mg deficient diagnostics. An Mg deficiency diagnostics model with satisfied performance (diagnostic rate 93.33%) was obtained. The result indicated the SD value of chlorophyll concentrations on the whole cucumber leaf could be employed to diagnose Mg deficiency nondestructively.     

柑桔叶片黄龙病光谱特征选择及检测模型

为探索高光谱技术诊断黄龙病及分类的可行性,通过变量筛选方法组合为高维数据实用化提供参考。采集柑桔叶片高光谱图像并进行普通(polymerase chain reaction,PCR)鉴别分为轻度、中度、重度、缺锌和正常5类样品。用无信息变量消除算法(uninformative variable elimination,UVE)剔除无关信息,组合遗传算法(genetic algorithm,GA)和连续投影算法(successive projections algorithm,SPA)筛选变量,对数据进行降维。结合极限学习机(extreme learning machine,ELM)和最小二乘支持向量机(least squares support vector machine,LS-SVM)构建柑桔黄龙病判别模型。对预测样品进行诊断分类,来评价模型判别能力。经对比发现,UVE组合SPA筛选变量后的LS-SVM模型效果最好,该模型以Link_kernel函数为核函数,惩罚因子(γ)最小为1.07,误判率最低为0。用全谱作输入变量时LS-SVM模型复杂程度最高且预测能力最差,误判率最高为11.9%,可能是包含无用信息和冗余信息变量造成的。研究显示,UVE组合SPA筛选变量,结合LS-SVM对柑桔黄龙病诊断并分类具有一定可行性,为高维度数据实用化提供一定参考价值。     

硝普钠对黄瓜幼苗缺镁和硝酸盐胁迫的缓解效应

【目的】设施栽培中土壤次生盐渍化严重,导致植株出现缺镁失绿症状。通过研究硝酸盐胁迫下外源NO供体(硝普钠,SNP)对缺镁黄瓜幼苗生长的影响,探究硝酸盐胁迫下外源NO对缺镁黄瓜幼苗的胁迫缓解效应,为解决设施生产中黄瓜幼苗的缺镁失绿症状提供理论指导。【方法】采用水培的方式培养黄瓜幼苗,幼苗长至三叶一心时进行处理。营养液采用山崎配方,镁离子浓度设两个水平为2 mmol/L(正常浓度)和1 mmol/L(缺镁胁迫);硝酸盐浓度设两个水平为14 mmol/L(正常浓度)和140 mmol/L(硝酸盐胁迫);硝酸盐和镁正常浓度为对照。用0.1mmol/L SNP分别缓解缺镁胁迫、硝酸盐胁迫以及缺镁和硝酸盐双重胁迫,用0.1 mmol/L SF(铁氰化钠)处理,观察SNP反应产物的影响;NO-3由Ca(NO3)2·4H2O和KNO3提供,各占1/2,p H由H2SO4调节,保持在5.5 6.5。【结果】1)缺镁胁迫下,黄瓜幼苗株高和叶面积增加值、干物质增长量较正常处理的黄瓜幼苗显著降低;电解质渗漏率、丙二醛含量和可溶性蛋白含量较正常处理的黄瓜幼苗显著升高。缺镁处理的黄瓜幼苗根茎叶中镁离子含量、叶片光合色素含量、光合特性指标、叶绿素荧光及抗氧化酶活性与正常处理的黄瓜幼苗相比明显降低。2)硝酸盐胁迫下,黄瓜幼苗株高和叶面积增加值、干物质增长量、黄瓜幼苗根茎叶中镁离子含量、叶片光合色素含量、光合特性指标、叶绿素荧光及抗氧化酶活性较正常处理的黄瓜幼苗显著降低;电解质渗漏率、丙二醛含量和可溶性蛋白含量较正常处理的黄瓜幼苗显著升高。3)缺镁和硝酸盐双重胁迫下,黄瓜幼苗的相关生长指标和抗逆指标较正常处理的黄瓜幼苗降低或增大更为显著。4)缺镁胁迫,硝酸盐胁迫以及缺镁和硝酸盐双重胁迫下,外施0.1 mmol/L SNP处理的黄瓜幼苗,株高和叶面积增加值、干物质增长量、幼苗根茎叶中镁离子含量、叶片光合色素含量、光合特性指标、叶绿素荧光、可溶性蛋白含量及抗氧化酶活性较未添加SNP处理的黄瓜幼苗显著提高,电解质渗漏率和丙二醛含量则明显降低。外施0.1 mmol/L SF则没有表现出明显的作用。【结论】硝酸盐胁迫下缺镁黄瓜幼苗生长受到明显抑制,出现失绿症状,通过添加0.1 mmol/L SNP,黄瓜幼苗的生长抑制得到明显缓解,说明在硝酸盐胁迫下外源NO对缺镁黄瓜幼苗的胁迫有显著缓解作用,增强黄瓜幼苗的耐盐性和对镁的吸收能力。     

缺镁对菜豆幼苗膜脂过氧化及体内活性氧清除酶系统的影响

营养液中培养菜豆幼苗,缺镁菜豆植株生长受抑,生物量显著低于正常供应镁的植株,体内镁浓度和镁的积累总量均较低。严重缺镁黄化叶片中叶绿素含量下降。完整叶绿体的希尔反应值在缺镁与正常植株间无差别。缺镁菜豆植株的根和叶膜造性（以相对电导率表示）增加,叶片中丙二醛含量升高。活性氧清除酶系统:SOD、POD、CAT活性在缺镁菜豆真叶中高于正常植株,老叶中抗坏血醒过氧化物酶（AsA-POD）活性增加程度也较大。     

高光谱图像技术诊断温室黄瓜病害的方法

利用高光谱图像技术研究了诊断温室黄瓜病害的方法,以提高诊断的准确性和效率。试验以黄瓜霜霉病、白粉病为研究对象,利用高光谱图像采集系统获取黄瓜病叶的高光谱图像数据,在450～900 nm范围内的高光谱图像数据中,选出特征波长下的图像;然后,对该图像进行去除噪声的滤波处理,并提取黄瓜病叶的色度矩纹理特征向量;最后采用支持向量机分类方法对黄瓜病害进行诊断。研究结果表明,采用高光谱图像新技术与线性核函数对黄瓜霜霉病、白粉病的正确诊断率达100%,采用高光谱图像技术可以实现对温室黄瓜病害进行快速、精确的分类诊断。     

Distribution of nutrient elements along the maize leaf: Alteration by iron deficiency

Distribution often elements along the maize leaf and the effect of iron (Fe) deficiency on these distributions were studied using plants grown in nutrient solution. In both the control and Fe‐deficient leaves, the concentrations of Fe, calcium (Ca), magnesium (Mg), manganese (Mn), zinc (Zn), and boron (B) increased and only that of potassium (K) decreased from leaf base to the leaf tip. Nitrogen (N) and copper (Cu) were the only two elements which showed no gradient of concentration along the entire leaf. Iron deficiency decreased the concentration of Fe by the same extent along the entire leaf length. However, it differentially accentuated the uneven distribution of some elements along the leaf length. For example, Fe deficiency increased the concentrations of Cu and N somewhat uniformly along the whole length the leaf; those of P and K were increased only along the lower two‐thirds of the leaves; and those of Ca, Mg, B, Zn, and Mn mostly along the upper one‐half to one‐third of the leaf length. Potassium was the only element whose concentration was lower at leaf tip than at the leaf base under both Fe‐sufficient and Fe‐deficient conditions. My results indicate that the basal half of maize leaf may be a more suitable part for diagnostic purposes since the concentration of most elements is less subject to alteration in this region, especially if a latent or obvious Fe deficiency is present. In view of these observations, the use of the entire maize leaf for diagnostic purposes may have to be reevaluated.     

Effect of Foliar Salicylic Acid Applications on Growth,Chlorophyll, and Mineral Content of Cucumber Grown Under Salt Stress

The objective of this study was to determine the effect of foliar salicylic acid (SA) applications on growth, chlorophyll, and mineral content of cucumber grown under salt stress. The study was conducted in pot experiments under greenhouse conditions. Cucumber seedlings were treated with foliar SA applications at different concentrations (0.0, 0.25, 0.50, and 1.00 mM). Salinity treatments were established by adding 0, 60, and 120 mM of sodium chloride (NaCl) to a base complete nutrient solution. The SA was applied with spraying two times as before and after transplanting. Salt stress negatively affected the growth, chlorophyll content and mineral uptake of cucumber plants. However, foliar applications of SA resulted in greater shoot fresh weight, shoot dry weight, root fresh weight, and root dry weight as well as higher plants under salt stress. Shoot diameter and leaf number per plant increased with SA treatments under salt stress. The greatest chlorophyll content was obtained with 1.00 mM SA treatment in both saline and non-saline conditions. Leaf water relative content (LWRC) reduced in response to salt stress while SA raised LWRC of salt stressed cucumber plants. Salinity treatments induced significant increases in electrolyte leakage. Plants treated with foliar SA had lower values of electrolyte leakage than non-treated ones. In regard to nutrient content, it can be interfered that foliar SA applications increased almost all nutrient content in leaves and roots of cucumber plants under salt stress. Generally, the greatest values were obtained from 1.00 mM SA application. Based on these findings, the SA treatments may help alleviate the negative effect of salinity on the growth of cucumber.     

高钾供应加剧了水稻叶片缺镁诱导的氧化胁迫

Magnesium （Mg） deficiency in plant affects photosynthesis and many other metabolic processes. Rice （Oryza sativa L. cv. ＇Wuyunjing 7＇） plants were grown in hydroponics culture at three Mg and two potassium （K） levels under greenhouse conditions to examine the induction of oxidative stress and consequent antioxidant responses in rice leaves due to Mg deficiency. At low Mg （0.2 mmol L 1 Mg supply for two weeks after transplanting） and high K （6 mmol L^-1） for 21 days, the rice plants showed severe Mg deficiency and a significant decreases in the dry matter production. The Mg deficiency in leaves decreased chlorophyll concentrations, photosynthetic activity, and soluble protein, but significantly increased the concentrations of soluble sugars and malondialdchyde （MDA） and the activities of superoxide dismutase （SOLD, EC 1.15.1.1）, catalase （CAT, EC 1.11.1.6） and peroxidase （POD, EC 1.11.1.7）. In addition, Mg concentrations in the leaves and in the shoot biomass were negatively related to the activities of the three antioxidative enzymes and the concentration of MDA in leaves. There were very significant interactive effects between Mg and K supplied in the culture solution on shoot biomass yield, chlorophyll content, photosynthesis rate, the activities of SOD, CAT and POD, and MDA content in the leaves of rice. It is suggested that the high K level in the nutrient solution aggravated the effect of low Mg supply-induced Mg deficiency and created the oxidative damage in rice plants.     

Evaluation of nutrient deficiencies in wheat seedlings by chlorophyll fluorescence

Chlorophyll fluorescence of plants is altered by conditions that affect photosynthesis and has proven useful in screening for resistance to environmental stresses. This study evaluated chlorophyll fluorescence for assessing the physiological impact of nutrient deficiencies and for diagnosing deficiencies of specific nutrients. Major nutrient (N,P,K) deficiency‐induced changes in chlorophyll fluorescence were determined in ‘Len’ hard red spring wheat (Triticum aestivum L.). Seedlings were grown in media containing 0, 1, 10, 50, or 100% of N and 0, 1, 10, or 100% of P and K in full‐strength Hoagland solution in a growth chamber for 22 d. Changes in initial (Fo), maximum (Fm), and variable (Fv) chlorophyll fluorescence of leaves and weight, height, and N, P, K, and Mg concentrations of shoots were measured. All chlorophyll fluorescence parameters declined significantly as N, P, and K concentrations declined, but thylakoid membrane efficiency (Fv/Fm and Fm/Fo) was stable at all nutrient levels. Relative units of Fo, Fm, and Fv were usually significantly and positively correlated with growth and. N,P,K, and Mg concentrations of shoots. Chlorophyll fluorescence may be a useful measure of severity of nutrient deficiencies. Use of chlorophyll fluorescence for diagnosing specific deficiencies may not be feasible, however, because of the similar effects of different nutrients.