植物叶片电容与含水量间关系研究

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树叶介电常数

树叶介电常数研究与分析一、引言1.1 研究背景随着科技的发展，电磁波在农业领域的应用越来越广泛，例如使用无线电波进行土壤湿度监测、植物生长状态监测等。

树叶作为植物的重要组成部分，其电磁特性对电磁波的传播和反射有着显著影响。

因此，研究树叶的介电常数对于提高这些技术的准确性和效率具有重要意义。

1.2 研究目的本研究的目的是系统地分析树叶的介电常数，探索其在不同环境条件下的变化规律，以及如何准确测量这一参数。

通过这些研究，我们希望能够为相关领域提供更为精确的数据支持。

二、树叶介电常数的定义与理论基础2.1 介电常数的定义介电常数（ε）是一个无量纲的物理量，用于描述材料在电场中存储电荷的能力。

它定义为材料的电容率与真空电容率的比值。

对于树叶而言，介电常数反映了其细胞结构、含水量和其他生物化学成分对电场的影响。

2.2 理论基础介电常数的测量基于电磁理论，特别是电容率和电导率的概念。

在交变电场中，介电常数通常是一个复数，其实部代表能量存储的能力，虚部代表能量耗散的能力。

三、树叶介电常数的测量方法3.1 传统测量方法传统的介电常数测量方法包括平行板电容器法、波导法和共振腔法等。

这些方法通常需要将树叶样本置于特定的电磁场中，通过测量电容或反射系数来确定介电常数。

3.2 现代测量技术随着技术的发展，出现了一些非破坏性的测量技术，如自由空间法、时域反射法和微波成像技术。

这些方法可以在不损伤树叶的情况下进行测量，更适合于活体植物的研究。

四、影响树叶介电常数的因素4.1 内在因素- 细胞结构：树叶的细胞排列方式和大小会影响其介电常数。

- 含水量：水分是决定介电常数的重要因素，因为水的介电常数远高于大多数其他物质。

- 生物化学成分：树叶中的糖分、蛋白质和其他有机物质也会影响其介电特性。

4.2 外在因素- 温度：温度的变化会影响树叶中水分子的活动性，进而影响介电常数。

- 频率：不同频率下，树叶的介电常数会有所不同，这是由于不同频率下分子极化机制的差异。

葡萄砧木叶片含水量和相对含水量的研究

关键词：葡萄砧木；叶片；含水量；相对含水量；抗旱性
中图分类号：￥６６３．１文献标识码：ＡＤＯＩ编码：１０．３９６９／ｊ．ｉｓｓｎ．１００６ — ６５００．２０１３．０２．００５
天津农业科学孔耐ｉｎＡｇｒｉｃｕｌｔｕｒａ！Ｓｃｉｅｎｃｅｓ
・植物生理与生物技术

葡萄砧木叶片含水量和相对含水量的研究
王爱玲，蔡军社，白世践，陈光，赵荣华
（新疆维吾尔自治区葡萄瓜果开发研究中心，新疆鄯善８３８２００）
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叶片相对含水量计算公式

叶片相对含水量计算公式叶片相对含水量计算公式是测量植物水分状况的一种方法。

植物的生长和发育受到环境水分的影响，因此植物的水分状况的评估十分重要。

叶片相对含水量反映的是叶片中的水分量与饱和状态下的水分量之间的比例。

在实际的植物研究中，需要通过测量叶片含水量来评估植物的水分状态。

下面将详细介绍叶片相对含水量计算公式及其应用。

1. 叶片相对含水量的定义叶片相对含水量是指叶片中的水分量与饱和状态下的水分量之间的比例，通常用百分比表示。

在计算中，需要测量叶片的干重、鲜重和再生重，并根据公式计算叶片相对含水量。

2. 叶片相对含水量计算公式叶片相对含水量计算公式为：RWC = （FW - DW）/ （TW - DW） * 100%其中，RWC表示叶片相对含水量，FW表示叶片的鲜重，DW表示叶片的干重，TW表示叶片的再生重。

在实际的测量中，为保证准确度，同一片叶子需要重复测量三次，并取平均值。

同时，需要避免对叶片造成损伤，尽可能减少测量误差。

3. 叶片相对含水量计算公式的应用叶片相对含水量可以反映植物的水分状况，对于研究植物的抗干旱性、抗病性和抗逆性等具有重要意义。

在植物的种质资源评价中，叶片相对含水量是一个重要的指标。

通过测量不同植物品种的叶片相对含水量，可以评估植物的抗旱性和适应性。

此外，叶片相对含水量的测量还可以为植物的灌溉提供参考。

通过测量叶片相对含水量，可以评估植物的水分状况，并决定是否需要进行灌溉或调整灌溉量。

总之，叶片相对含水量的计算公式是植物研究的常用方法之一，对于评估植物的水分状况和适应性具有重要意义。

在实际的应用中，需要注意测量方法的准确度和遵循科学的测量流程。

叶片含水率

叶片含水率叶片含水率是指叶片中所含的水分占总重量的比例。

它是植物生长和发育的重要指标之一，也是衡量植物生理状态的重要参数。

叶片含水率的变化与植物的生长环境、生理代谢和生长阶段等因素密切相关。

叶片含水率的测定方法有多种，常用的是干重法和湿重法。

干重法是将新鲜叶片在105℃下烘干至恒重，然后计算干重与新鲜重的比值；湿重法是将新鲜叶片称重后直接计算其含水率。

两种方法各有优缺点，需要根据实际情况选择合适的方法。

叶片含水率的变化对植物生长和发育有着重要的影响。

在植物生长初期，叶片含水率较高，这是因为植物需要大量的水分来维持生长和代谢活动。

随着植物生长的进行，叶片含水率逐渐降低，这是因为植物逐渐形成了完整的根系和叶片，能够更好地吸收和利用土壤中的水分和养分。

叶片含水率的变化还与植物的生理代谢和生长阶段有关。

在植物生长的不同阶段，叶片含水率的变化也不同。

例如，在植物的生长旺盛期，叶片含水率较高，这是因为植物需要大量的水分来维持生长和代谢活动；而在植物的生长停滞期，叶片含水率则较低，这是因为植物的代谢活动减缓，需要的水分也相应减少。

叶片含水率的变化还与植物的生长环境有关。

在干旱和高温的环境下，植物的叶片含水率会降低，这是因为植物需要更多的水分来维持生长和代谢活动。

而在潮湿和低温的环境下，植物的叶片含水率则会增加，这是因为植物的水分蒸发速度较慢，能够更好地保持水分平衡。

叶片含水率是植物生长和发育的重要指标之一，它的变化与植物的生长环境、生理代谢和生长阶段等因素密切相关。

通过对叶片含水率的测定和分析，可以更好地了解植物的生长状态和生理代谢，为植物的生长和发育提供科学依据。

植物叶片电容与含水量间关系研究

叶片含水率快速无损检测技术研究与实践提供支持。
１材料与方法
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同一叶片含水量差异的原因_概述说明以及解释

同一叶片含水量差异的原因概述说明以及解释1. 引言1.1 概述本文旨在探讨同一叶片含水量差异的原因，并通过概述、解释和分析来揭示这一现象的影响和意义。

在植物生长和生态系统功能的研究中，叶片含水量作为一个重要的指标被广泛应用。

尽管同一叶片上不同部位水分含量不同是普遍存在的，但其具体原因仍然需要进一步深入研究。

1.2 文章结构本文首先将通过对同一叶片含水量差异基本原因进行探讨，以提供背景知识和全面了解。

然后，我们将阐述环境因素对叶片含水量的影响，包括温度、湿度、光照等。

接着，我们将介绍植物生理过程与叶片含水量之间的关系，包括蒸腾作用、根系活力以及渗透调节机制等。

最后，本文将通过对不同环境中叶片含水量差异具体原因进行解释，并总结分析结果。

1.3 目的本文旨在回答以下问题：为什么在同一叶片上会存在着较大的含水量差异？这种差异是如何受环境因素的影响的？同时，我们将讨论植物生理过程与叶片含水量之间的关系，并探讨渗透调节机制在其中扮演的角色。

通过深入研究和分析，我们希望揭示这些原因对植物生长和生态系统功能的意义，并为未来相关研究提供展望。

2. 正文：2.1 同一叶片含水量差异的基本原因同一叶片出现含水量差异的基本原因可以归结为以下几个方面。

首先，植物的生理代谢活动会导致不同部位之间含水量的差异。

比如，叶片上部分接近光照位置的区域通常较为干燥，而下部靠近土壤或环境湿度较高的位置相对更湿润。

其次，叶片表面形态结构的差异也会导致含水量变化。

例如，某些植物具有特殊的气孔密度和分布方式，在不同位置上形成了气孔聚集区和稀疏区，进而影响该区域水分蒸发速率。

此外，植被类型、树种特性以及植物个体间遗传差异也可能导致叶片含水量存在差异。

2.2 环境因素对叶片含水量的影响环境因素是导致同一叶片含水量差异的重要原因之一。

首先是光照强度和温度对叶片蒸腾作用和蒸发速率的影响。

在阳光明媚、高温的环境下，叶片上部会有更大程度的水分蒸发，导致该区域相对较干燥。

电容法微量水-概述说明以及解释

电容法微量水-概述说明以及解释1.引言1.1 概述电容法微量水是一种测量微量水含量的方法，在近年来得到了广泛的应用和研究。

随着人们对环境和健康的关注度不断提高，对水质和水含量的监测也越来越重要。

然而，传统的测量方法存在一些局限性，例如仪器较为庞大、昂贵、操作复杂等。

相比之下，电容法微量水具有仪器简单、成本低廉、响应迅速等优势，因此备受关注和青睐。

电容法微量水的原理是通过测量微量水对电容值的变化来判断水含量的多少。

当水分子存在于电容器的电极表面时，会改变电容器的电容值，这是因为水分子的极性特性使得其与电极产生相互作用。

通过测量电容器的电容值变化，我们能够准确地确定水含量的大小。

这种方法的应用领域非常广泛。

首先，电容法微量水在环境监测领域具有重要的意义。

它可以用于监测土壤中的水分含量，了解植物的生长状况以及土壤的湿度变化情况。

此外，它还可以用于监测大气中的湿度，为气象预报和能源调控提供依据。

其次，在食品工业中，电容法微量水也被广泛运用。

例如，在面包、饼干等食品的生产过程中，我们需要控制水含量以确保产品的质量，并避免因含水量不合适而导致的产品损失。

电容法微量水的应用可以提供及时、准确的水含量数据，有助于优化生产工艺和提高产品质量。

综上所述，电容法微量水作为一种测量微量水含量的方法，具有许多优点和广泛的应用领域。

它不仅能够简化测量流程，降低成本，还可以提供准确可靠的水含量数据，为各个领域的研究和生产提供有力支持。

随着技术的不断发展和应用的不断深入，相信电容法微量水的研究和应用将会取得更加广泛和深入的发展。

1.2 文章结构文章结构部分的内容：本文主要分为引言、正文和结论三个部分。

以下将详细介绍每个部分的内容。

引言部分将从概述、文章结构和目的三个方面展开。

首先，我们将概述电容法微量水的背景和基本原理。

其次，我们会介绍本文的文章结构，给读者一个整体的把握。

最后，我们明确本文的目的，即探讨电容法微量水在哪些领域有应用前景。

叶片饱和含水量_概述说明以及解释

叶片饱和含水量概述说明以及解释1. 引言1.1 概述本文旨在介绍叶片饱和含水量的概念、影响因素、测量方法，以及探讨叶片饱和含水量与植物生长、生态系统功能以及农业之间的关系。

通过对叶片饱和含水量的解释，我们可以深入了解其对植物适应环境的意义，并更好地理解叶片饱和含水量在温度调节、干旱适应以及光合作用中扮演的角色。

1.2 文章结构本文共分为五个部分进行讨论。

首先是引言部分，包括概述、文章结构以及目的等内容。

第二部分将详细介绍叶片饱和含水量的定义、影响因素以及测量方法。

第三部分将探讨叶片饱和含水量与植物生长、生态系统功能以及农业之间的关系。

第四部分将解释叶片饱和含水量对植物适应环境的意义，其中包括对温度调节、干旱适应以及光合作用等方面进行阐述。

最后一部分是结论，总结全文的主要观点并提出展望。

1.3 目的本文旨在系统介绍叶片饱和含水量的相关概念和知识，并深入分析其与植物生长、生态系统功能以及农业等方面的关系。

通过对叶片饱和含水量的解释和意义探讨，我们可以增进对此概念的理解，并为环境保护、农业发展等领域提供科学依据。

希望本文能够为读者提供全面而详尽的信息，从而增加人们对叶片饱和含水量研究的兴趣，并推动该领域的进一步发展和应用。

2. 叶片饱和含水量2.1 定义叶片饱和含水量是指叶片中所存储的最大数量的水分。

当叶片中包含的水分达到其最大持水能力时，就称为叶片饱和含水量。

该值通常以百分比或克每克叶片干重的形式来表示。

2.2 影响因素叶片饱和含水量受到多种因素的影响。

其中，植物物种、气候条件、土壤类型以及植物生长阶段都是决定叶片饱和含水量的重要因素。

不同物种具有不同的生理特性和适应机制，因此对于相同环境下不同植物物种来说，其叶片饱和含水量也可能存在较大差异。

2.3 测量方法测量叶片饱和含水量的常用方法包括烘干法、称重法和抽取法等。

其中，烘干法是最为常见的方法之一。

通过将新鲜采集的叶片样本在恒温恒湿条件下进行加热至高温以蒸发掉其中的所有可挥发性成分，并得出干燥后的质量与原始鲜重的差值，即可计算出叶片饱和含水量。

太赫兹波表征植物叶片的特性和含水量估算方法

太赫兹波表征植物叶⽚的特性和含⽔量估算⽅法Characterization and Water Content Estimation Method of Living Plant Leaves Using Terahertz Wavesby Adnan Zahid ,Hasan T. Abbas ,Muhammad A. Imran ,Khalid A. Qaraqe ,Akram Alomainy ,David R. S. Cumming and Qammer H. Abbasi James Watt School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK Department of Electrical and Computer Engineering, Texas A&M University, Doha 23874, Qatar School of Electronic Engineering and Computer Science, Queen Mary University of London, London E1 4NS, UKAuthors to whom correspondence should be addressed.Appl. Sci. 2019, 9(14), 2781; https:///10.3390/app9142781Received: 31 May 2019 / Revised: 4 July 2019 / Accepted: 8 July 2019 / Published: 10 July 2019(This article belongs to the Special Issue Terahertz Communications: Present and Future )AbstractAn increasing global aridification due to climate change has made the health monitoring of vegetation indispensable to maintaining the food supply chain. Cost-effective and smart irrigation systems are required not only to ensure the efficient distribution of water, but also to track the moisture of plant leaves, which is an important marker of the overall health of the plant. This paper presents a novel electromagnetic method to monitor the water content (WC) and characterisation in plant leaves using the absorption spectra of water molecules in the terahertz (THz) frequency for four consecutive days. We extracted the material properties of leaves of eight types of pot herbs from the scattering parameters, measured using a materialcharacterisation kit in the frequency range of 0.75 to 1.1 THz. From the computed permittivity, it is deduced that the leaf specimens increasinglybecome transparent to the THz waves as they dry out with the passage of days. Moreover, the loss in weight and thickness of leaves were observed due to the natural evaporation of leaf moisture cells and change occurred in the morphology of fresh and water-stressed leaves. It is also illustrated that loss observed in WC on day 1 was in the range of 5% to 22%, and increased from 83.12% to 99.33% on day 4. Furthermore, we observed anexponential decaying trend in the peaks of the real part of the permittivity from day 1 to 4, which was reminiscent of the trend observed in the weight of all leaves. Thus, results in paper demonstrated that timely detection of water stress in leaves can help to take proactive action in relation to plants health monitoring, and for precision agriculture applications, which is of high importance to improve the overall productivity.Keywords: vegetation health monitoring ; leaf water content ; terahertz ; sensing ; plants health1. IntroductionOver the past decade, terahertz (THz) technology has seen an increased amount of interest in the scientific community chiefly due to its non-ionising and less pervasive radiation properties [1]. There has been significant progress in tapping the so-called THz gap 0.3 to 3 of the electromagnetic spectrum. The THz technology has found extensive use in applications such as the imaging of concealed items [2], material characterisation [1], diagnostic applications including treatment of skin and dental care [3,4], effective and quality control of food [5], and telecommunication [1,6,7]. Furthermore, a distinguishing feature of the THz waves is that the water molecules exhibit a strong absorption spectrum in the pertinent frequency range, leading to novel bio-sensing applications.Despite these substantial contributions, the utility of the THz technology in the environmental control/monitoring systems has not been explored in depth, especially for vegetation monitoring [8,9]. Unlike the microwave-based remote sensing techniques, the THz technology can provide detailed insight into the health of a plant specimen in terms of the water content (WC) in the leaves [10]. Plant leaves comprise of a composite biological structure of tissues, distinct bio-molecules like cellulose and synthesis compounds including proteins, carbohydrates and many other molecular weight compounds, as illustrated in Figure 1. On an individual basis, they vastly differ in terms of material properties such as relative permittivity [11].Furthermore, water is not only an essential component but an important nutrient to the process of photosynthesis, and transpiration in the overall process of growth [12]. Due to the high sensitivity and strong penetration feature of THz, it has a strong potential to disseminate through plants leaves at cellular level as shown in Figure 1 and can yield significant information of WC in leaves. Hence, it is significant to highlight the frequency dependence of the permittivity of leaves. Designing a smart and plant-specific irrigation system that monitors the leaf WC in a non-invasive manner is, therefore,critical in the current circumstances governed by global climate change that demand water conservation. Over the years, significant contributions have been made [9,10,11,12,13], that address estimating the leaf’s WC. There are techniques that offer high reliability, yet they are unsuitable for long-term studies of the same plant leaves because of validity of measurements cannot be guaranteed [11,14,15,16,17].Figure 1. Internal morphology of fresh and water stressed leaf using THz sensing.Thermogravimetric analysis has been used for the quantification of WC in plants leaves. However, due to its destructive nature and problems owing to its harmfulness to specimens have markedly reduced the usefulness, and thus is not suitable for estimation of WC in plants leaves. On the other hand, some non-destructive methods have previously been used to determine the water status in plant leaves, which include thermal and hyper-spectral imaging [18,19], infrared [20] and magnetic resonance imaging (MRI) [21]. However, these techniques are limited by the resolution and thus, cannot provide any cellular-scale information about the plants [19]. In addition, these technique do not consider any environmental influence due to its low photon energy [14,19]. Lately, there has been a growing trend in the field of plant physiology and characterisation of liquid to use THz time-domain spectroscopy (TDS) [11,22], which is considered a non-invasive technique, and has been deployed in the field of plant physiology to detect anomalies proactively. Moreover, it has an enormous potential to measure the leaf water status under certain conditions, such as drought stress [11,13,15,23,24]and dehydration kinetics [19]. In addition, THz-TDS technique can also investigate the structural behaviour and complex traits of leaves under any environment [14,19]. As compared to others, THz-TDS technique has proven to be more effective and reliable. However, the experimental setup of THz spectroscopy is not portable and requires a complex configuration of lasers [22].In this paper, we present a novel, non-invasive approach to monitoring the WC of plant leaves using the scattering parameters of a THz ing a well-known material extraction algorithm, we computed permittivity from the scattering parameters for eight types of leaves, which we observed for four consecutive days. The WC was then gauged from the decrease in the permittivity as the days passed. This paper is an expansion and presents a detailed analysis of our earlier work [8]. The rest of the paper is structured as follows: Section 2 describes the experimental setup followed by the 1,* 1 1 2 2,3 1 1,*123*THz THzmaterial characterisation methods of plants leaves. Section 3 presents the measurement results and different parameters are discussed such as permittivity, the effect of weight and thickness, followed by a comparison of transmission response of all eight leaves between day 1 and 4. Finally,conclusion is discussed in Section 4.2. Methods2.1. Experimental SetupWe used a Swissto12 material characterisation kit (MCK) operating in the THz frequency range to obtain the scattering parameters of the plant leaves. The MCK was attached to a Keysight Technologies N5224A microwave network analyser (NA), the frequency range of which was shifted in the THz frequency range via a Virginia Diode vector NA extender module WM-250 (WR 1.0), enabling operation in the frequency range of 0.75 to 1.1 THz with a resolution of 2 GHz. The MCK comprised of two conical waveguide horn transitions with further two sections of the low-loss corrugated waveguide. A small aperture between the two low-loss corrugated waveguides allows the material samples to be inserted into the system during the measurement. Moreover, each half of the MCK comprises a waveguide which transitions from a rectangular waveguide at one end to a corrugated circular waveguide at the other. Furthermore, one half of the MCK, is fixed, while the other half is movable (to easily accommodate the insertion of the sample to be measured). To avoid any structural damage while the leaf specimen was clamped in the MCK for observation, we used two PTFE caps that enabled a uniform compression of the samples as shown in Figure 2. Prior to the measurement, the setup was configured using the two-port short-open-load-thru (SOLT) calibration technique.Figure 2. Schematic representation of experimental setup used for measurement of leaf sample. The leafsample is placed between the two PTFE caps fitted to waveguide.2.2. Sample DetailsEight different kinds of pot herbs were used, namely coffea arabica, aromatic coriander, basil, baby-leaf, pea-shoot, parsley, lamb’s lettuce, and baby spinach. The fresh leaves were detached from the plants and placed in the laboratory for four consecutive days. The environment temperature for the measurements of leaves was 18.0 °C ± 0.1 °C, and the humidity was between 30% ± 2%. In this study, the weight and thickness of leaves were determined for four consecutive days using a precision electronic scale and Vernier caliper respectively. The leaves’ thickness and weight were measured every 2 h during the natural evaporation of leaf moisture. We used a Vernier scale to measure the leaf thickness and this process was repeated to determine thicknesses at three different locations to ensure the thickness was consistent across the surface of a leaf, which was in the range of 40 µ to 4 . The weight of leaf was measured using a digital kitchen scale with a least count of 0.1 mg. All leaves were measured at three different locations and on every location, four various orientations were considered to investigate the behaviour of leaves. From these observations, the purpose was mainly to determine any unevenness in the surface of leaves that may result in a change in the scattering response. For further illustration, Figure 3 shows the response of coffea leaf at three different locations which suggests that the orientation of leaf does not affect the measurements.Figure 3. Real part of permittivity of coffea leaves at three different locations taken on days 1 and 4.2.3. Material Characterization of Plant LeavesThe Nicholson-Ross-Weir (NRW) method [25] is the most common technique in which the dielectric parameters and of a planar material are extracted from a two-port vector NA measurement in which the transmission and reflection coefficients are obtainedthrough the S-parameters. This method belongs to the category of frequency-by-frequency material extraction in which every point from the frequency sweep is used. In general, the NRW method generates both the complex permittivity and permeability, of the specimen under test. Here, we assume that the leaves are non-magnetic and compute only the permittivity. One of the intrinsic problems of the NRW method is the periodicity of the phase of the electromagnetic wave that leads to ambiguous results. This problem has been discussedat length in other works [26,27,28]. To rectify this, we follow the step-wise approach in which the phase ambiguity is removed by using the phase delay information from the previous frequency point [29]. In this paper, we consider a plant leaf as a planar slab of thickness d which is positioned between two air-filled circular waveguides. With the help of an equivalent transmission line model, the reflection () and transmission (T ) coefficients of a semi-infinite slab are expressed in terms of the measured s-parameters, and as [30],(1)where the intermediate variable is defined as . In the case of the slab with a finite thickness d , the transmission coefficient T can be described in terms of the propagation constant, as, , which can subsequently be written in the Euler form as where denotes the phase term. The propagation constant is then determined using [28],(2)which results in an infinite number of branches of the complex valued root due to the logarithmic function, demonstrated by the presence of theterm. The problem of selecting the proper branch is solved by the technique proposed in [29] in which at each frequency point, the phase delay information is recovered from the previous frequency point. If the phase difference, (3)3. Results and Discussion In this paper, we aimed to determine the electromagnetic properties of leaves including permittivity, and physiological features such as weight and thickness that can affect the WC of leaves. In addition, a strong correlation between the determined properties and WC of leaves was observed.Furthermore, the transmission response of all eight leaves were investigated for four consecutive days.3.1. Permittivity of LeavesThe complex-valued permittivity of eight different types leaves were extracted from measurements taken from three various locations with different percentage of WC in them. Furthermore, on every location, measurements were recorded using four different orientations of the leaves to observe any anisotropic behaviour. Figure 3a shows that for a coffea arabica leaf, neither the location, nor the leaf orientation had any effect on the real part of permittivity on day 1. However, the effect of location was notable on the day 4 as shown in Figure 3b. We believe that the drastic decrease in the leaf thickness is responsible for this behaviour.m mm εr µr =−j εr ε′′r ε′r =−j µr µ′r µ′′r ΓS 11S 21Γ=χ±,−1√χ2−−−−−T =,+−Γ1−(+)ΓS 11S 21S 11S 21χ(−+1)/2S 211S 221S 11γT =exp (−γd)|T|exp (−j)γ={−log (|T|)−j +j2πn}where n ∈Z 1d 2πn , the method ensures the current branch is selected.The permittivity is then calculated by [31],−<</span>πi i−1=[].εrγγ01−Γ1+ΓSimilar patterns were observed for other types of leaves as well. Figure 4 shows the real part of the permittivity for all the leaves measured on four consecutive days. It is significant to observe that all the leaves revealed the highest permittivity on day 1 when the WC in fresh leaves was the highest,and as the days progressed, permittivity showed a decrement when leaves became water stressed. Hence, dielectric parameter measurements differed significantly on days 1 and 4 for fresh, and water-stressed leaves. From these observations, it also showed a clear correlation between the permittivity and WC of leaves, i.e., fresh leaves with a higher amount of WC would have a high permittivity and vice versa. From Figure 5, it is evident that the real part of permittivity shows a strong decaying correlation with WC. As observed in Figure 4, various leaves also showed distinct decreasing responses from each other, attributed to different lead composition and structure. In another study, we have shown that the real part of permittivity can be used to classify leaves, that are described here with an accuracy of 98.2%.Figure 4. Real part of permittivity of all eight leaves measured on four consecutive days. Leaves becometransparent to electromagnetic waves with the passage of days as seen by the decrease in the permittivity.Figure 5. Correlation of permittivity with loss of WC in leaves.3.2. Estimating Leaf Water ContentIn this study, WC in leaves was observed by determining the physical parameters such as weight and thickness. Referring to the weight of leaves,initially on the first day, the time duration between the two weight measurements were maintained from two to three hours. On the second day, this was extended to four hours and finally, on the third and fourth day, it was increased to 6 hours. It was noted that there was significant decrease in the weights of some leaves as shown in Figure 6 on day 1, i.e., basil, baby-leaf and pea-shoot, whereas, other leaves displayed a slow decreasing trend in weight loss of leaves as days progressed.Figure 6. Change in the physical properties of leaves with time.This clearly indicated that the moisture in leaves evaporated more rapidly on the day 1 and 2 compared to day 3 and 4, thereby creating more air cavities in the leaves. To assess the variation of leaf WC during the leaf’s water evaporation process, the measurements were translated into WC using[17,32],(4)where is the weight of the fresh leaf, is the weight of a leaf measured over time and is the weight of a dry leaf. In the beginning, the WC loss observed between the two hours on day 1 was found in the range of 5% to 22%. At the end of the investigation on day 4, thisloss increased during the natural evaporation of leaf moisture and was established in the range of 83.12% to 99.33%. The obtained percentages loss of WC can be validated with Figure 6a. Considering this discussion, it also showed a significant correlation with the real part of the permittivity which was the highest on the first day when the weight of leaves was considerably high compared with the fourth day as shown in Figure 4. The thickness of all the leaves was carefully determined to avoid any excess pressure to the samples that would cause disturbances in the morphological structure of the leaves, changing the dielectric properties of the samples as a result. As seen in Figure 6b, the thickness of leaves was considerably higher on day 1,implying a greater WC in fresh leaves compared to day 4 when mostly, all leaves were dried out. From this significant and meaningful observation, it was concluded that dehydration of leaves with passing days affected the thicknesses to a substantial degree. On day 4, some leaves stayed invariant or slight changes occurred in the thickness of leaves i.e., coriander and spinach as shown in Figure 6a. These transformations in the thickness of leaves evidently showed that WC in coriander and spinach leaves had evaporated to the maximum on day 4 and no further variations could be observed in thickness of leaves.3.3. Evaluation of Leaf Transmission ResponseIn this section, transmission responses of all leaves were observed on day 1 and 4 as shown in Figure 7. It was noticed that on day 1, attenuations of all leaves were substantially high due to the presence of higher WC in tissues of leaves, which resulted in a higher absorption and lower transmission response. Moreover, on day 4, a substantial degree of increment in transmission response was observed as WC in leaves had evaporated to large extent, which resulted in a decrement of weight and thickness of leaves and eventually, less absorption occurred at this time. Figure 7 exhibited a strong correlation of transmission response with WC, weight and thickness of leaves. Baby-leaf exhibited a lower transmission response on day 1compared to others, reflecting a higher presence of WC in leaf, which resulted in higher absorption. Contrarily, parsley displayed an increment in transmission response due to the presence of less WC in the leaf and hence, producing low absorption compared to other leaves.Figure 7. Transmission response of leaves on first and fourth days.4. ConclusionsIn this paper, a novel, non-invasive technique for characterising the water content (WC), and in turn the health of plant leaves was proposed using THz waves. The electromagnetic properties of eight types of leaves were determined for four consecutive days through the measured scattering parameters. The weight and thickness of the leaves were also recorded at the same time. We observed that the leaves became increasingly transparent to the terahertz (THz) waves through the course of four days experiment, as seen by the peaks in the real part of permittivity. Similar decaying trends were observed in the peak values of the real part of the extracted relative permittivity as the decreasing weight due to loss of WC. The significance of this paper lies in the simple, cost-effective technique and other advantages such as: (a) This paper proposes a unique technique to characterise and estimate WC of eight various leaves in terms of electromagnetic parameters at THz frequency range from 0.75 to 1.1 THz. (b) The electromagnetic parameters are measured in simple, fast, and non-invasive manner using a THz material characterisation kit. Moreover, The structural integrity and configuration of leaves were also considered by employing two polytetrafluoroethylene (PTFE) caps which were fitted internally to the waveguide. (c) This paper establishes a notable correlation between electromagnetic parameters with WC in leaves i.e., change in the WC of leaves is reflected in the electromagnetic parameters at certain frequencies. In the age of a climate change driven water conservation, the proposed scheme can be used to design efficient irrigation systems on-site without any need to remove the leaves from plants.Author ContributionsConceptualization, A.Z., H.T.A. and Q.H.A.; software, A.Z. and H.T.A.; resources, D.R.S.C. and K.A.Q.; writing–original draft preparation, A.Z. and H.T.A.; writing–review and editing, Q.H.A., M.A.I. and A.A.; supervision, Q.H.A. and M.A.I.; project administration, Q.H.A.FundingWC =×100−W time W dry W fresh W fresh W time W dryThis research was funded under EPSRC DTA studentship which is awarded to Adnan Zahid for his PhD.Conflicts of InterestThe authors declare no conflict of interest.References© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (/licenses/by/4.0/).。

植物叶片水分利用效率研究综述

植物叶片水分利用效率研究综述
目录
01 一、植物叶片水分利用效率的定义
02 二、影响植物叶片水分利用效率的因素
03 三、研究植物叶片水分利用效率的方法
04 四、应用
05 参考内容
植物叶片是植物体内水分和养分交换的主要部位，其水分利用效率对于植物的生长和生存具有重要意义。近年来，植物叶片水分利用效率已成为生态学、农学和林学等领域的研究热点。本次演示将从植物叶片水分利用效率的定义、影响因素、研究方法和应用等方面进行综述。
2、土壤水分：土壤水分是影响植物水分利用效率的重要因素。在干旱条件下，植物会通过调节气孔开度和光合速率等来降低水分消耗，提高水分利用效率。
3、气候条件：气候条件对植物的水分利用效率有很大影响。高温、高辐射和高风速等条件会使植物水分损失增加，从而降低水分利用效率。
4、生态位：生态位反映了植物竞争能力和利用资源的能力也会有所不同，从而影响水分利用效率。
结论
植物水分利用效率研究已经取得了显著进展，但仍存在诸多挑战和需要进一步探讨的问题。未来的研究应继续以下几个方面：
1、拓展植物水分利用效率研究范围，加强对非农作物和生态系统的研究； 2、研发更加高效、简便、低成本的研究方法，提高研究的可操作性和普及性；
3、综合考虑环境因素和遗传因素，深入探究植物水分利用效率的内在机制； 4、结合现代科技手段，制定更加精确的节水措施，提高植物水分利用效率。
2、生态保护：在生态系统中，植物的水分利用效率与生态系统的物质循环和能量流动密切相关。研究植物的水分利用效率有助于了解生态系统的功能和稳定性，为生态保护提供理论支撑。
3、气候变化：气候变化对植物的水分利用效率具有显著影响。研究植物的水分利用效率可以评估气候变化对植物生长和生态系统功能的影响，为应对气候变化提供科学依据。

茶树叶片蒸腾速率气孔导度和水分利用率的研究

茶树叶片蒸腾速率气孔导度和水分利用率的研究近年来，茶树的研究得到了广泛的关注，尤其是茶树叶片的蒸腾速率气孔导度和水分利用率的研究。

本文聚焦于茶树叶片蒸腾速率气孔导度和水分利用率的研究，通过对理论模型收集并分析国内外有关文献，以及采用播种碗法测定茶树叶片的气孔导度和水分利用率的实验，分析茶树叶片的蒸腾速率气孔导度和水分利用率的影响因素及其关系。

一、茶树叶片蒸腾速率气孔导度及其影响因素1. 气孔导度的影响因素：温度、湿度、光照等环境因素都会影响茶树叶片的气孔导度。

当环境温度升高时，叶片的气孔导度也会随之升高，叶片表面温度升高可以提高叶片蒸腾及气孔动力学效应，从而提高叶片气孔导度。

湿度一定时，当光照加强时气孔导度也会提高，而降低光照会使气孔导度降低，因而对气孔导度有显著影响。

2. 气孔导度的优化技术：调控叶片气孔导度，可以从气孔结构的调控入手，开展遗传育种，选择抗旱型和适应多变环境的品种，以便改造品种的气孔结构，增加茶树的抗旱能力；同时，科学施肥，限制茶树根系的活动和活动，可以有效减少气孔受损，促进茶树蓄水和加速气孔膨胀，从而保持气孔导度。

二、茶树叶片水分利用率及其影响因素1.茶树叶片水分利用率的影响因素：除了环境因素外，茶树叶片水分利用率还受到土壤条件、水分累积、营养元素等因素的影响。

土壤水分充足时，茶树叶片碳水化合物的合成速率高，利用率也会随之提高;当有机质累积丰富时，可充分利用土壤水分，有利于提高叶片水分利用率。

而养分含量不足时，会降低叶片水分利用率。

2. 水分利用率的优化技术：调控茶树叶片水分利用率，需要采用适时调节施肥、灌溉、防治病虫害等技术，以提高根系的吸力，降低叶片的叶肥比，增加叶片水汽对流量，以提高叶片水分利用率。

此外，加强茶树的遗传育种，可以改造茶树的根系结构，从而增加水分的吸收量，从而提高叶片水分利用率。

植物光合作用与水分利用

植物光合作用与水分利用植物光合作用与水分利用是生物学中一个重要的研究领域，它们之间存在着密切的关系。

植物通过光合作用将太阳能转化为化学能，并在此过程中消耗水分。

本文将从光合作用和水分利用两个方面进行讨论。

一、光合作用光合作用是植物利用光能将二氧化碳和水转化为有机物质和氧气的过程。

它主要发生在植物叶绿体中的叶绿体色素分子上。

光合作用的过程可以分为光能吸收、光能转化和光能固定三个阶段。

1. 光能吸收植物叶片上的叶绿素是光能吸收的主要色素。

当叶绿素吸收到光子后，光能会被转化为电子能，进而在叶绿体中发生一系列复杂的光能转换过程。

2. 光能转化光能转化阶段包括光合电子传递和ATP合成。

在光合电子传递过程中，光能被叶绿体系统Ⅱ吸收，通过一系列电子传递体系最终转移到叶绿体系统Ⅰ上，期间产生的电子通过细胞色素b6/f复合体进行传递。

在ATP合成阶段，通过光合电子传递所产生的质子梯度推动ATP 合成酶进行磷酸化反应，最终合成ATP。

3. 光能固定光能固定阶段是指植物将CO2转化为有机物质的过程，也是光合作用的最终目标。

通过光能转化过程所合成的ATP和NADPH提供能量和还原力，将二氧化碳固定为有机物质，其中最为重要的产物是葡萄糖。

二、水分利用植物在进行光合作用的过程中需要吸收大量的水分。

水分通过植物的根系吸收，并通过导管系统运输到叶片中的叶绿体。

在叶片内部，水分参与到光合作用的反应过程中，同时也起到保持细胞张力和输送养分的作用。

1. 水分吸收植物的根吸收系统包括根毛和根尖。

根毛是由根表皮细胞发育而成的突起，能够增加吸收表面积，增强吸收能力。

根尖则担负着诸如水分吸收、根向土壤深层延伸等功能。

2. 水分运输植物中的导管系统是水分运输的主要通道。

主要包括xylem和phloem。

xylem主要负责水分的上行运输，其内部由一系列形成壁孔的细胞组成，通过原生质溶胶张力和毛细现象将水分从根部上运输到地上部分。

3. 水分利用植物通过开启和关闭气孔来控制水分利用。

玉米叶片生理电容与含水率表达模型的研究

玉米叶片生理电容与含水率表达模型的研究张兵;韩霞;庄斌;吴春雨【摘要】为了能对玉米水分亏缺进行准确的判断，进而做出适时适量的灌溉，对玉米电特性与叶片含水率进行了深入的研究。

通过叶片非离体和离体实验数据采集及数据分析处理，得到在100Hz、1kHz、10kHz3种不同频率下，非离体与离体玉米叶片电容都随着时间推移逐渐变小，非离体玉米叶片电容的变化曲线相对离体玉米叶片的变化曲线更加平缓，且100 Hz频率下玉米叶片电容值的变化幅度最大。

离体玉米在夜间电容值没有延续之前趋势一直下降，甚至有了提高，这与晚间叶片停止光合作用，叶片会适当吸收空气中的水分有关。

通过对叶片电容与含水量实验数据的拟合，拟合检验值R2为0．96327，可以得到叶片含水量与叶片电容呈线性关系。

%In order to make accurate judgment on the corn moisturedeficit , make appropriate and timely irrigation .This paper studied thecorn electrical characteristics and leaf water content , through data acquisition and data processing of the leaves in vivo and in vitro .In the100HZ,, 1kHZ and 10kHZ three kinds of different frequencies , in vivo andin vitro leaf capacitance with the passage of time gradually become smaller , variation curve in curve body corn leaf capaci-tance relative isolated maize leaf is more gentle ,the range of capacitance of maize leaves under the frequency of 100Hz is greatest .Isolated corn in the night has not according to the trend of the capacitance value been declining , even with the increase , this has something to do with the evening leaf photosynthesis will be stopped and leaf will be appropriate to ab -sorb the moisture in the air .The leaf capacitance and water content of experimentaldata fitting , fitting test value R2 0 . 96327 , can get the leaf water content and leaf capacitance linearly .【期刊名称】《农机化研究》【年(卷),期】2015(000)005【总页数】4页(P200-203)【关键词】介电特性;作物需水量;叶片电容;含水率【作者】张兵;韩霞;庄斌;吴春雨【作者单位】农业部旱作节水农业重点实验室，北京 100081; 常州工学院电子信息与电气工程学院，江苏常州 213002;常州工学院电子信息与电气工程学院，江苏常州 213002;常州工学院电子信息与电气工程学院，江苏常州 213002;常州工学院电子信息与电气工程学院，江苏常州 213002【正文语种】中文【中图分类】S121为了更好地表达作物需水与介电特性间的关系，研究人员使用微电脑、有限元等先进技术，利用数字电桥仪进行数据的测量分析。

基于变介电常数的植物叶片含水率无损检测装置设计

基于变介电常数的植物叶片含水率无损检测装置设计ZHANG Lianwang;WANG Luyao;YUN Yuliang【摘要】以AT89 C51单片机为核心,结合数字电子技术相关电路,设计了一款基于变介电常数的植物叶片含水率无损检测装置.该装置采用夹持型平行极板电容器与555定时器搭建多谐振荡器,以待测叶片作为电容极间介质,通过待测叶片水分变化影响介电常数,进而改变多谐振荡器频率,再由单片机完成数据读取与处理,以此来检测叶片含水率.并采用鸢尾、望春玉兰、紫荆和海州常山四种植物叶片进行测量试验,试验结果表明,该装置可以实现植物叶片含水率无损检测,具有一定的应用价值.【期刊名称】《青岛农业大学学报（自然科学版）》【年(卷),期】2019(036)003【总页数】5页(P230-234)【关键词】单片机;叶片含水率;变介电常数;无损检测【作者】ZHANG Lianwang;WANG Luyao;YUN Yuliang【作者单位】;;【正文语种】中文【中图分类】S24中国植物种类繁多，不同植物需要的生存环境不同。

水是植物最不可或缺的生存条件之一，但是在各类植物的生长过程中，往往会因为各种自然因素和人为因素造成水量的短缺与减少，不能满足植物最基本的要求，影响其发育生长。

当今中国水资源已经严重短缺，科学有效的管理农作物，使用最适当的水量进行灌溉对农业科学管理发展有重要的意义。

所以能够实时、准确、快速的检测植物叶片含水率可以帮助人类做出最适合植物生长的灌溉方案。

目前叶片含水率检测方法多样，主要包括电阻法、微波法、射线法、干燥法与介电法。

其中介电法测量相较于其他方法更加方便、快速和准确。

由于不同植物叶片内部结构是不同的，所以每一种植物都有其特有的介电特性常数，利用该介电特性常数可以进行不同植物叶片含水率的检测[1]。

本文分别对鸢尾、望春玉兰、紫荆和海州常山四种植物叶片进行测量试验，研究并构建叶片含水率与其生理电容值之间的线性关系，进而设计实现了一种基于变介电常数的植物叶片含水率无损检测装置。

基于电容特性的植物叶片含水率无损检测仪设计

Non-destructive Moisture Detector for Plant Leaves Based on Capacitance
Guo Wenchuan1 Liu Dongxue1 Zhou Chaochao1 Han Wenting2,3
(1. College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China; 2. Institute of Water and Soil Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China; 3. Institute of Water Saving Agriculture in Arid Areas of China, Northwest A&F University, Yangling, Shaanxi 712100, China)
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图 4 压力检测电路 Fig.4 Pressure detection circuit
压阻式压力传感器 FSR402 的电源端接参考电压 Uref，其输出端接运算放大器 LM324 的反相输入端，此时 LM324 的输出电压 Uo 为[22]

离体叶片保水力测定

离体叶片保水力测定
植物组织含水量和相对含水量（RWC）的测定
一、原理：
叶片在离体条件下具有保持原有水分的能力。

其保水力的大小与植物遗传性、细胞特性和原生质胶体性质有关。

因此，离体叶片的保水力可以反应植物原生质的耐脱水能力和叶片角质层的保水能力。

在一定时间内含水量越高，表明叶片保水力越强，抗旱性也越强。

二、仪器设备：
（1）千分之一天平；（2）小烧杯
三、材料：
上述溶液培养的小麦或玉米叶片。

四、方法步骤：
1、剪取各处理小麦叶片10片（不带叶鞘）并称重（组织
鲜重），迅速将叶片插入蒸馏水中饱和（2－3 h）取出叶片剪
去叶鞘，称其重量（饱和鲜重）。

然后将叶片悬于室内，使其在
空气中缓慢脱水，并每隔1－3小时称重一次，（共称3－4次）。

然后24 H 后再称重一次。

将叶片在80o C下烘干称取干重。

根
据所得数据计算出每次称重时的叶片含水量，再以脱水时间对
叶片含水量作图，即可看出各处理叶片保水力的差异。

2、根据：组织鲜重和饱和鲜重及干重计算出
植物组织含水量和相对含水量（RWC）。

实验流程：
取样（每处理各10片不带叶鞘）→称重（组织鲜重）→饱和（2－3h）→称重(饱和鲜重)→自然脱水，并称重（每隔1h称重一次，共3－4次，24h
后再称重一次）→烘干（80o C下烘止恒重）→称取干重。

注：1、样品处理：中午9－10点用PEG-6000;(0.5MPa) 处理2h；
中午12点称重（自然鲜重）并立即饱和（2－3
小时）下午2点上课。

2、记录：室温T、RH 值。

叶片饱和含水量

叶片饱和含水量全文共四篇示例，供读者参考第一篇示例：叶片饱和含水量是指叶片所能吸收的最大水量。

对于大多数植物来说，叶片饱和含水量通常是叶片干重的50％至75％。

叶片是植物中非常重要的部分，它们通过光合作用将太阳能转化为化学能，从而提供植物生长和发育所需的能量。

叶片的水分含量对植物的生长发育至关重要。

水分能够帮助植物吸收养分、调节温度、维持细胞结构的完整性等。

而叶片饱和含水量则是叶片所能容纳的水分的极限值。

叶片的含水量会受到多种因素的影响，包括植物的种类、环境条件、季节等。

植物种类不同，叶片的饱和含水量也会有所不同。

一般来说，生长在干旱地区的植物叶片的饱和含水量会比生长在湿润地区的植物要低，因为在干旱环境中，植物需要更有效地保存水分以适应干旱条件。

环境条件也会对叶片的饱和含水量产生影响。

温度、湿度、光照等因素都会影响植物的水分吸收和蒸腾速率，从而影响叶片的含水量。

在高温干燥的环境中，植物需要更多的水分来保持细胞的正常功能，因此叶片的饱和含水量可能会比较高。

叶片的饱和含水量不仅对植物生长发育有重要影响，也对植物的抗逆性和适应性起到关键作用。

过高或过低的叶片饱和含水量都会导致植物生长不良甚至死亡。

了解和控制叶片的饱和含水量对于植物的生长和发育至关重要。

为了保持叶片的健康，我们可以通过合理浇水、适当遮荫、增加通风等方式来帮助植物调节叶片的含水量。

定期检查叶片的饱和含水量，及时调整管理措施，可以帮助植物更好地适应环境变化，保持健康生长。

叶片饱和含水量是植物生长发育中一个重要的参数，它直接影响植物的生长、适应性和抗逆性。

了解和控制叶片的饱和含水量对于植物的生长和发育至关重要，希望通过本文的介绍能够增加大家对于这一方面的了解，从而更好地照顾植物，促进植物的健康生长。

第二篇示例：叶片饱和含水量指的是植物叶片中所含水的量达到饱和状态时的水分含量。

水分是植物生长的重要因素之一，叶片中的水分含量直接影响着植物的生长发育和生理代谢。