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In situ optical meters are widely used to estimate leaf chlorophyll concentration, but non-uniform chlorophyll distribution causes optical measurements to vary widely among species for the same chlorophyll concentration. Over 30 studies have sought to quantify the in situ/in vitro (optical/absolute) relationship, but neither chlorophyll extraction nor measurement techniques for in vitro analysis have been consistent among studies. Here we: (1) review standard procedures for measurement of chlorophyll; (2) estimate the error associated with non-standard procedures; and (3) implement the most accurate methods to provide equations for conversion of optical to absolute chlorophyll for 22 species grown in multiple environments. Tests of five Minolta (model SPAD-502) and 25 Opti-Sciences (model CCM-200) meters, manufactured from 1992 to 2013, indicate that differences among replicate models are less than 5%. We thus developed equations for converting between units from these meter types. There was no significant effect of environment on the optical/absolute chlorophyll relationship. We derive the theoretical relationship between optical transmission ratios and absolute chlorophyll concentration and show how non-uniform distribution among species causes a variable, non-linear response. These results link in situ optical measurements with in vitro chlorophyll concentration and provide insight to strategies for radiation capture among diverse species., (© 2014 John Wiley & Sons Ltd.)

Various devices and applications are used for the rapid assessment of plant nitrogen nutrition, which give an approximate indication of leaf chlorophyll saturation by giving the relative chlorophyll content or leaf greenness intensity. In this study, chlorophyll content and leaf greenness determined by three devices were compared: SPAD-502 (spectrum technology), Hydro N-Tester, and Samsung smartphone (RGB app). Additionally, laboratory determination of chlorophyll content was compared to soil-plant analysis development (SPAD) values. Based on the results obtained, indices characterising the vegetative or direct state were calculated and the values obtained with these devices were compared. The crops tested were soya, potatoes, wheat and sunflower. The results show a close relationship between the size of the SPAD index and RGB light sources of colour the intensity of red (R), green (G) and blue (B). The indices IPCA and R+G-2B showed a very high negative correlation with SPAD readings (-0.82 and -0.83). Statistical analysis showed that SPAD readings obtained from the two chlorophyll meters showed a high correlation regardless of the crop species tested (R2 = 0.98). The correlation analysis also showed the possibility of substituting equipment and vegetation indices based on readings taken with a smartphone, with an accuracy not much inferior to standard chlorophyll meters. This situation could occur in case of failure or absence of the standard device. [ABSTRACT FROM AUTHOR]

Chlorophyll content in lichens is routinely used as an accurate indicator of lichen vigor, interspecific differences, and the effect of site-related environmental parameters. Traditional methods of chlorophyll extraction are destructive, time-consuming, expensive, and inoperable, especially when measuring large quantities of chlorophyll. However, non-destructive methods of measurement using portable chlorophyll meters are rarely used for lichens. Considering the characteristics of lichens such as rough blade surface and absence of chlorophyll b in cyanolichens, we compared the non-destructive methods with traditional methods and evaluated their applicability in studying lichen pigment content. Two instruments, SPAD-502 and CCM-300, were used to measure the pigment content of seven foliose lichen species. These pigment readings were compared with those determined using the dimethyl sulphoxide (DMSO) extraction method. Significant correlations were observed between SPAD/CCM values and pigments (chlorophyll and total carotenoids) extracted from chlorolichens, especially species with a smooth surface. The CCM-300 was more accurate in detecting the pigment content of foliose chlorolichens. However, both instruments showed certain limitations in the determination of pigment content in cyanolichens, especially gelatinous species. For example, CCM-300 often failed to give specific values for some cyanolichen samples, and both instruments showed low measurement accuracy for cyanolichens. Based on the high correlation observed between chlorophyll meter readings and pigments extracted from chlorolichens, equations obtained in this study enabled accurate prediction of pigment content in these lichens. [ABSTRACT FROM AUTHOR]

Efficient nutrient management requires estimating factual fertilizer requirements. This study was aimed to test the use of chlorophyll meter SPAD-502 to estimate the nitrogen status of tea maintenance leaf. The test was carried out by correlating the SPAD readings with destructively measured leaf nitrogen content using samples oGbtained from nitrogen fertilizer dosage experiments. Observations were made at 15, 32, 45 and 62 days after the application of N fertilizer treatments. The results showed that the SPAD readings and total nitrogen leaf content correlated significantly with the time of observation. Estimation of leaf N content based on the SPAD readings follows linear line equation y = 0.0311x + 1.5856 with coefficient determinant (R²) = 0.62 significantly at P<0.01. It was concluded that SPAD-502 chlorophyll meter is reliable to assess the leaf nitrogen content of tea maintenance leaf and is adequate to predict future nitrogen fertilizer requirements. [ABSTRACT FROM AUTHOR]

Aim of study: We evaluated the use of dimethylsulfoxide (DMSO) for the photometric determination of chlorophyll (Chla and Chlb) and carotenoids in Quercus ilex L. leaves by comparative analysis using aqueous-acetone extraction. Area of study: a Q. ilex dehesa in Las Majadas del Tietar, Cáceres, Spain Material and methods: Q. ilex leaves were sampled during two vegetative periods. Field SPAD-502 Chlorophyll measurements and photometric chlorophyll determinations were performed. Two procedures were used: extraction of intact foliar discs at 65ºC with DMSO and fine foliar powder with cold aqueous-acetone. Main results: DMSO produced Chlb overestimation and different fitting performance for SPAD vs pigment calibrations (R2=0.64, RMSE=0.20, p

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Total chlorophyll and nitrogen status in leaves of longkong and rambutan were evaluated by using the SPAD-502 meter. Leaves of both species were sampled from 10 year-old trees grown in an experimental plot at Prince of Songkla University, Hat Yai campus. The relationship between SPAD-502 meter reading (SPAD) and total chlorophyll content analyzed in the laboratory was evaluated in longkong and rambutan, and they were y = -2.68+0.21x, r2 = 0.77** and y = -1.11+0.18x, r2 = 0.77**, respectively. The data recorded by SPAD were also linearly related in a positive manner to nitrogen status in longkong (y = 1.27+0.20x, r2 = 0.82**) and rambutan (y = 1.17+0.02x, r2 = 0.79**). The results show that using the SPAD-502 meter is convenient and fast for the evaluation of total chlorophyll and nitrogen status in leaves of longkong and rambutan.

Perennial organ functions of trees living in seasonal environments exhibit temporal changes that can be classified as long-term interannual changes and seasonal fluctuations within single years. However, few studies have separately quantified these changes from longitudinal measurement data or analyzed the relationships between them. We developed a hierarchical Bayesian statistical model consisting of three parts: a long-term interannual change expressed by consecutive annual linear trends, seasonal fluctuations with 26 values for two-week periods in a year, and a random effect for repeated measurements. The model can extract long-term interannual changes and seasonal fluctuations from longitudinal repeated measure data. The pattern of seasonal fluctuation, the amount of seasonal fluctuation, and the net annual change are expressed by the estimated model parameters. We applied our model to foliar chlorophyll (Chl) and nitrogen (N) content measured repeatedly on more than 1-year-old leaves of saplings in four evergreen broad-leaved tree species using nondestructive optical methods. The model successfully explained large variations in the Chl and N content. In general, seasonal fluctuations corresponded to the phenology of current-year leaves; Chl and N tended to decrease from the opening to maturation of new leaves and increased during the rest period. The magnitude of the decrease in the Chl and N content in the growth period of current-year leaves (Δγ) did not decrease noticeably as leaves aged. For the Chl content, Δγ was positively correlated with the maximum value before leaf opening across species. For the N content, Δγ and the maximum value before leaf opening were not clearly correlated across species, but were positively correlated within some species. A model parameter for annual linear trends in Chl and N varied from positive (indicating increasing trends) to negative values (indicating decrease) depending on species and leaf age in years. [ABSTRACT FROM AUTHOR]

• Leaf chlorophyll content (LCC) is often assessed in-situ with the SPAD instrument. • We test this approach for herbs and grasses in temperate grasslands across seasons. • Potential uncertainties in the LCC-SPAD relationship were assessed. • Several species with distinct traits were not suitable for SPAD-LCC measures. • Related uncertainties in LCC assessments have to be considered in applications. Leaf chlorophyll content (LCC) is an important indicator of plant health. Earth observation facilitates LCC monitoring on large spatial scales and within short time intervals by retrieving canopy LCC from spectral signals. However, in-situ measurements are still necessary to validate the predicted values and the accurate quantification of LCC is labour-intensive and costly. Handheld leaf chlorophyll metres, such as the SPAD-502 (Konica Minolta) promise quick and non-destructive in-situ LCC estimates. SPAD values can be easily converted to LCC by established calibration curves that are based on measurements of single plant species. Due to these practical advantages, the application of SPAD-LCC calibration curves, originally derived in an agricultural context (Markwell et al., 1995), has become common practice in field studies. Although associated with a variety of uncertainties, the transfer of general SPAD-to-LCC calibration equations to natural ecosystems has not yet been comprehensively investigated. In this study, we test the reliability of SPAD-to-LCC conversions in three structurally different semi-natural grassland areas with mixed species compositions. We measured SPAD values in the field and determined the corresponding LCC of the very leaf samples via chemical extraction and spectrophotometry. Our results show that SPAD-to-LCC conversion equations lack accuracy in semi-natural grassland with mixed species compositions (n = 157, R2 = 0.046, p < 0.05, for all sites). This study highlights the uncertainties in optical approaches for in-situ LCC assessments. It further underlines the need to find feasible and reliable solutions for a quick and efficient chlorophyll determination in natural habitats with mixed species compositions towards a reliable monitoring of ecosystem properties. [ABSTRACT FROM AUTHOR]

Models were developed to estimate nondestructively chlorophyll (Chl) content per unit of leaf area (Chl area) and nitrogen content per unit of leaf area (N area) using readings of two optical meters for five warm-temperate, evergreen, broadleaved tree species ( Castanopsis sieboldii, Cinnamomum tenuifolium, Eurya japonica, Machilus thunbergii, and Neolitsea sericea). It was determined whether models should be adjusted seasonally. Readings (were obtained six times during a year period and Chl area and N area were determined using destructive methods. Bayesian inference was used to estimate parameters of models that related optical meter readings to Chl area or N area for each species. Deviance information criterion values were used to select the best among models, including the models with seasonal adjustment. The selected models were species-specific and predicted Chl area accurately ( R2 = 0.93–0.96). The best model included parameters with seasonal adjustments for one out of five species. Model-based estimates of N area were not as accurate as those for Chl area, but they were still adequate ( R2 = 0.64–0.82). For all species studied, the best models did not include parameters with seasonal adjustments. The estimation methods used in this study were rapid and nondestructive; thus, they could be used to assess a function of many leaves and/or repeatedly on individual leaves in the field. [ABSTRACT FROM AUTHOR]

Urban trees are frequently subjected to stress-causing environmental factors and cultural practices, requiring a permanent monitoring of their health condition. Stress detection in woody plants usually relies on a visual assessment of symptoms: inventories are mostly based on the parameters of the percentage of foliage reduction and leaf colour, both of which require a subjective interpretation. The main goal of this study was to detect whether the foliar chlorophyll (Chl) and nitrogen contents of linden trees, in an urban environment, can be useful and objective diagnostic indicators of the plant health and physiological performance, and whether it was possible to evaluate these data through a quick technique. Furthermore, as the ectomycorrhizal (ECM) community is a well-known bioindicator of the plant health status, its potential association with both variations in the Chl content and the different degrees of tree decline was verified. By determining the mathematical relationship between the instrument (SPAD-502) readings, the foliar Chl and nitrogen contents and the association with significant variations in the ECM community, the different stages of the visual symptoms of decline were accurately determined. This approach should help to integrate the methodology used for tree health inventories with new universal methods that do not entail individual interpretation. [ABSTRACT FROM AUTHOR]

The effectiveness of eight spectral reflectance indices for estimating chlorophyll (Chl) content in leaves of Eugenia uniflora L., a tropical tree species widely distributed throughout the world and a key species for ecosystem restoration projects, was evaluated. Spectral reflectance indices were tested using sun and shade leaves with a broad variation in leaf mass per area (LMA). Shortly after plants were exposed to chilling temperatures, there was a dramatic visible change in some sun leaves from green to red. Prior to testing Chl-related reflectance indices, the green and red leaves were separated according to the anthocyanin reflectance index (ARI). Slightly green to dark green leaves corresponded to an ARI value less than 0.11 ( n = 107), whereas slightly red to red leaves corresponded to an ARI value greater than 0.11 ( n = 35). To estimate leaf Chl, two simple reflectance indices (SR and SR), two normalized difference indices (ND and ND), two modified reflectance indices (mSR and mND705), a modified Chl absorption ratio index (mCARI) and an index insensitive to the presence of anthocyanins (CI) were evaluated. Good estimates of leaf Chl content were obtained using the reflectance indices tested regardless of the presence of anthocyanins and changes in LMA. Based on the coefficients of determination ( r) and the root mean square errors (RMSɛ) the best results were obtained with reflectance indices measured at wavelengths of 750 and 705 nm. Considering the performance of the models the best reflectance indices to estimate Chl contents in E. uniflora leaves with a broad variation in LMA and anthocyanin contents was SR and mCARI. [ABSTRACT FROM AUTHOR]

For Tunisian olive tree orchards, nitrogen deficiency is an important nutritional problem, in addition to the availability of water. Establishment of relationships between nutrients such as nitrogen and ecophysiological parameters is a promising method to manage fertilisation at orchard level. Therefore, a nitrogen stress experiment with one-year-old olive trees ( Olea europaea L. 'Koroneiki' and 'Meski') was conducted with trees respectively subjected to four nitrogen supply regimes (23.96 meq l, 9.58 meq l, 4.79 meq l and 0 meq l NO). The current paper focuses on the use of the SPAD-502 portable chlorophyll (Chl) meter, a nondestructive method for fertilisation management under nitrogen stress conditions of olive trees. Maximum net photosynthetic assimilation rates, chlorophyll fluorescence parameters and the SPAD Chl index were therefore measured simultaneously and the Chl and nitrogen content of the leaves were analysed. Significant correlations were established in the olive tree leaves between SPAD-502 readings on the one hand and Chl content, nitrogen content, photosynthetic assimilation rate, and Chl fluorescence parameters (Φ and ETR) on the other hand. [ABSTRACT FROM AUTHOR]

A hand-held SPAD-502 chlorophyll meter provides rapid and nondestructive measures of chlorophyll content. Integrating this meter into basil production can reduce costs and may improve basil quality. This study determined the relationship between SPAD-502 and the leaf chlorophyll (total, a, b). Over 500 leaf samples were collected from a field study conducted in 2006. Comparisons between chlorophyll contents and meter readings showed that SPAD meter readings were positively correlated to actual chlorophyll content. Regression analysis SPAD readings should be corrected by leaf area. Findings suggest that SPAD meter readings can be used as a tool to improve Basil quality and for assessing the relative chlorophyll content during the growing season. [ABSTRACT FROM AUTHOR]

Summary: Handheld chlorophyll meters have proven to be useful tools for rapid, non-destructive assessment of chlorophyll and nutrient status in various agricultural and arborescent plant species. We proposed that a SPAD-502 chlorophyll meter would provide valuable information when monitoring life cycle changes and intraspecific variation in endangered plant populations, whereby, destruction of plants to obtain this information is impractical. Further, use of this instrument would augment leaf morphometric measurements collected during controlled studies, circumventing the need for leaf harvest. We developed a regression model relating foliar chlorophyll concentration and content to SPAD chlorophyll content indices for a genetically diverse population of the federally listed Lindera melissifolia. Application of the regression to four additional L. melissifolia populations, and to the ecologically widespread congener L. benzoin, proved the SPAD-502 to be an effective tool for non-destructive estimation of total foliar chlorophyll concentration (r 2=0.8230) and content (r 2=0.9029) across a range of plant ages, growing conditions, and genotypes. [Copyright &y& Elsevier]

Copyright of Universidad & Ciencia is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chlorophyll content of butterhead lettuce leaves was estimated by correlations between the Minolta SPAD-502 and Minolta chroma meter CR 300. The SPAD-502 readings and extractable chlorophyll (Chl a, Chl b, and total Chlorophyll) contents were related. High linear correlations were obtained for chlorophyll a (R2=0.90), chlorophyll b (R2=0.85), and total chlorophyll (R2=0.92). After that, during the growth cycle of butterhead lettuce grown in soilless culture, leaves were selected and SPAD-502 and chroma meter readings were made. Finally, correlations between SPAD-502 readings and leaf color (L*, a*, b*, C*, and hue angle) determined by the chroma meter were calculated. Hue angle (H°; R2=0.75) and lightness index (L*; R2=0.68) were the parameters that better relate with SPAD-502 readings, so these parameters can also be used for rapid and nondestructive estimates of leaf chlorophyll in situ. [ABSTRACT FROM AUTHOR]

Chlorophyll contents in vegetation depend on soil nitrogen availability and on crop nitrogen uptake, which are important management factors in arable farming. Crop nitrogen uptake is important, as nitrogen is needed for chlorophyll formation, which is important for photosynthesis, i.e. the conversion of absorbed radiance into plant biomass. The objective of this study was to estimate leaf and canopy nitrogen contents by near and remote sensing observations and to link observations at leaf, plant and canopy level. A theoretical base is presented for scaling-up leaf optical properties to whole plants and crops, by linking different optical recording techniques at leaf, plant and canopy levels through the integration of vertical nitrogen distribution. Field data come from potato experiments in The Netherlands in 1997 and 1998, comprising two potato varieties: Eersteling and Bintje, receiving similar nitrogen treatments (0, 100, 200 and 300 kg N ha-1) in varying application schemes to create differences in canopy nitrogen status during the growing season. Ten standard destructive field samplings were performed to follow leaf area index and crop dry weight evolution. Samples were analysed for inorganic nitrogen and total nitrogen contents. At sampling dates, spectral measurements were taken both at leaf level and at canopy level.At leaf level, an exponential relation between SPAD-502 readings and leaf organic nitrogen contents with a high correlation factor of 0.91 was found. At canopy level, an exponential relation between canopy organic nitrogen contents and red edge position (λrep, nm) derived from reflectance measurements was found with a good correlation of 0.82. Spectral measurements (SPAD-502) at leaf level of a few square mm were related to canopy reflectance measurements (CropScan™) of approximately 0.44 m2. Statistical regression techniques were used to optimise theoretical vertical nitrogen profiles that allowed scaling-up leaf chlorophyll measurements to canopy nitrogen values. A nitrogen attenuation coefficient (kN) of 0.41 g N m-2 soil resulted in highest correlation coefficients for scaling-up nitrogen contents from leaf to canopy values. Remote sensing of canopy nitrogen (g N m-2 soil) did not require considering vertical nitrogen profiles, as canopy reflectance measurements were able to integrate organic nitrogen over total canopy depth. The integration of near sensing techniques, theories on the interpretation of reflectance signatures and vertical crop nitrogen distribution allowed scaling between leaf chlorophyll measurements and canopy nitrogen values. This results in more accurate quantification of the nitrogen status of a potato crop, which is important information in potato crop management. [Copyright &y& Elsevier]

The practicality of the portable, non-destructive type nitrogen meter ( Agriexpert PPW-3000) was tested on ten forest species. Also investigated was the potential relationship between leaf nitrogen and chlorophyll (Chl) contents and the readings taken with the PPW-3000 and a Chl meter ( SPAD-502). There was a significantly positive correlation between the readings of PPW-3000 and N content in the same leaves, whereas the correlation between leaf Chl content and the PPW-3000 values was less positive. Similarly there was a significant positive correlation between actual Chl content and the SPAD-502 readings and the less positive correlation between actual N content and the SPAD-502 readings. Thus using both the PPW-3000 and SPAD-502 enables to determine leaf N and Chl contents simply and non-destructively in the field. [ABSTRACT FROM AUTHOR]

A recent non-destructive technique allows estimation of leaf chlorophyll content using the portable SPAD-502 chlorophyll meter. Measurements were taken on four species (winter wheat, maize, soyabean and tobacco) subjected to different nitrogen regimes or senescence status and the non-destructive readings were compared with analytical results obtained by solvent extraction. In general, the relationship between the SPAD measurement and the analytical result was not linear and species was a factor in three out of four crops. Linear, quadratic and exponential curve fitting are presented; only the interpolation with a polynomial exponential function adequately describes the whole data set. The presence of statistically non-significant differences between the estimated values of wheat and maize on the one hand and significant points of difference between those of tobacco and soyabean on the other suggests distinct behaviour patterns for monocots and dicots. This type of response may be explained by differences in the optical properties of pigments with differing spatial distributions (sieve effect) and therefore by in vivo and in vitro different procedures and the structural diversity of leaves belonging to the two subclasses. [ABSTRACT FROM AUTHOR]