Portable Chlorophyll Meter Research Articles

An evaluation of non-destructive methods to estimate total chlorophyll content

The portable chlorophyll (Chl) meter (CL-01, Hansatech) has been successfully used for a rapid and direct estimation of total Chl content in the leaves of some crops. We compared CL-01 meter readings (Chl value) and Chl contents in leaves of Zea mays, Cucumis sativus, Raphanus sativus, and Ceiba speciosa. Chl index was linearly and positively correlated to Chl content in all the species.

Determinação da necessidade de adubação nitrogenada de cobertura no feijoeiro irrigado com auxílio do clorofilômetro portátil

As pesquisas demonstram que as leituras de transmitância obtidas em clorofilômetro portátil podem indicar a época de maior demanda de nitrogênio (N) das plantas e se há ou não a necessidade de sua aplicação em cobertura. Este foi o objetivo do presente trabalho, que avaliou para a cultura do feijoeiro irrigado os seguintes manejos de N: M1: 240kg ha-1 de N (80kg na semeadura 80kg aos 15 dias após emergência (dae) + 80kg aos 30 dae), m²: 120kg ha-1 (30 de N na semeadura + 45kg aos 15 dae + 45kg aos 30 dae); M3: 30kg ha-1 de N na semeadura e aplicação em cobertura estabelecida com base no uso do clorofilômetro Minolta SPAD-502 e M4: testemunha sem a aplicação de N. O delineamento experimental foi o inteiramente casualizado com quatro tratamentos e cinco repetições. A produtividade de grãos no tratamento baseado nas leituras do clorofilômetro portátil (M3) foi semelhante a do tratamento normalmente recomendado para o feijoeiro irrigado (m²), porém, foram aplicados 60kg ha-1 de N a menos. Os níveis críticos mínimos de índice relativo de clorofila para obtenção de produtividade superior a 90% da máxima foram, respectivamente, de 43 e 46 aos 28 e 49 dias após emergência do feijoeiro.

Interactive Effects of Drought Stresses and Elevated CO2 Concentration on Photochemistry Efficiency of Cucumber Seedlings

To reveal and quantify the interactive effects of drought stresses and elevated CO2 concentration [CO2] on photochemistry efficiency of cucumber seedlings, the portable chlorophyll meter was used to measure the chlorophyll content, and the Imaging-PAM was used to image the chlorophyll fluorescence parameters and rapid light response curves (RLC) of leaves in two adjacent greenhouses. The results showed that chlorophyll content of leaves was reduced significantly with drought stress aggravated. Minimal fluorescence (Fo) was increased while maximal quantum yield of PSII (Fv/Fm) decreased significantly by severe drought stress. The significant decrease of effective quantum yield of PSII (Y(II)) accompanied by the significant increase of quantum yield of regulated energy dissipation (Y(NPQ)) was observed under severe drought stress condition, but there was no change of quantum yield of nonregulated energy dissipation (Y(NO)). We detected that the coefficient of photochemical quenching (qP) decreased, and non-photochemical quenching (NPQ) increased significantly under severe drought stress. Furthermore, we found that maximum apparent electron transport rate (ETR(max)) and saturating photosynthetically active radiation (PPFD(sat)) decreased significantly with drought stress aggravated. However, elevated [CO2] significantly increased Fv/Fm, qP and PPFD(sat), and decreased NPQ under all water conditions, although there were no significant effects on chlorophyll content, Fo, Y(II), Y(NPQ), Y(NO) and ETR(max). Therefore, it is concluded that CO2-fertilized greenhouses or elevated atmospheric [CO2] in the future could be favorable for cucumber growth and development, and beneficial to alleviate the negative effects of drought stresses to a certain extent.

Evaluation of a portable chlorophyll meter to estimate chlorophyll concentrations in leaves of tropical wood species from Amazonian forest

A portable chlorophyll meter can be an important tool to estimating chlorophyll contents in leaves of tree species under field conditions. The method is quick and non-destructive compared to the classic chemical methods of pigment extraction. The aim of this work was to evaluate the performance of a portable chlorophyll meter (CCM-200, Opti-Science) to estimate the concentrations of chloroplastid pigments and the fraction of photosynthetically active irradiance absorbed by leaves (α) in four tropical wood species from Amazonian forest. The results shown positive correlation between the chlorophyll contente index (CCI) readings and concentrations of Chl a (P < 0.0001; r² = 0.904), Chl b (P< 0.0001; r² = 0.803), Chl tot (P< 0.0001; r² = 0.923) and α (P< 0.0001; r² = 0.886), suggesting that the portable chlorophyll meter can be an effective tool for the relative estimation of chlorophyll concentrations and the fraction of the photosynthetically active irradiance absorbed by the leaves of tropical tree species.

Discriminação entre estágios nutricionais na cultura do trigo com técnicas de visão artificial e medidor portátil de clorofila

O ajuste da adubação nitrogenada é um tema que suscita preocupações econômicas e ambientais em todo o mundo. Isso decorre da elevada resposta das culturas, especialmente gramíneas, ao nitrogênio e da falta de métodos adequados de quantificação de sua disponibilidade no solo. Com o objetivo de avaliar a discriminação de três estágios nutricionais na cultura do trigo, foram utilizadas imagens digitais e um medidor portátil de clorofila (SPAD -502). Os dados foram coletados em três épocas (8; 14 e 20 dias após a adubação nitrogenada em cobertura - DAA), em parcelas de trigo submetidas a três doses de N (0; 30 e 60 kg ha-1). As imagens foram processadas para desenvolvimento dos classificadores multivariados, utilizando-se de nove índices espectrais com as combinações dos valores médios dos "pixels". Os dados de clorofila e N foliar foram utilizados para desenvolver classificadores univariados. Verificou-se que o sistema de visão artificial foi mais eficiente que o SPAD aos 8 DAA. Aos 14 e 20 DAA, a classificação univariada com os dados SPAD foi equivalente aos classificadores com dados de imagens. Com a utilização das imagens digitais, foi possível discriminar os estágios nutricionais oito dias após a primeira adubação nitrogenada em cobertura.

Use of a chlorophyll meter to determine the nitrogen status of winter barley (Hordeum vulgareL.)

Introduction The basis for the N top-dressing of winter barley may be the mineral N content of the 0– 60 cm soil layer, characteristic of the N supplying capacity of the soil, or plant analysis on the N concentration of the leaves (Nemeth 2006, Szentpetery et al. 2006). The N concentration of plant tissues is closely correlated with the N supplying capacity of the soil. However, there is also a close correlation between the plant N nutrition level and the leaf chlorophyll content. A determination of the chlorophyll content thus allows the N nutrition level of the plant, and indirectly the N supplying capacity of the soil, to be estimated. Portable chlorophyll meters for use in the field could be used by the fertiliser recommendation service to estimate the N nutrition level of the crop and to predict yield levels and crop quality (Berzsenyi 2005, Le Bail 2005, Arregui 2006). Naturally, these instruments must be calibrated for typical chlorophyll contents before use. The aim of the present research was to establish the relationship between the SPAD index characteristic of leaf chlorophyll content during the tillering of winter barley and the N concentration of the leaves, to evaluate the reliability of the instrument and its suitability for estimating the N nutrition level of winter barley for the purposes of fertiliser recommendations, and to supply the necessary data on how the chlorophyll content and N concentration of the leaf were correlated with the magnitude and yield as well as the quality of the yield.

Ultrastructure and Gene Mapping of the Albino Mutant al12 in Rice ( Oryza sativa L.)

Seedling albino mutation resistant to low temperature is an adaptability of rice ( Oryza sativa L.) to cold. The mutant, a conditional expression controlled by development and temperature, differs from other albino mutants. The chlorophyll content of the mutant was measured using a portable chlorophyll meter, and the ultrastructure of the chloroplast was observed using a transmission electron microscope. Chlorophyll content was 1.2 SPAD, and the chloroplast did not develop, with only small vesicle-like structures. A segregation analysis of the reciprocal crosses between the albino mutation line with the rice line 9311 demonstrated that the albino trait was controlled by a single recessive gene, which was flanked by SSR markers RM5068 and RM3702 on the short arm of chromosome 8 with a distance of 0.5-1.1 cM and 4.9 cM, respectively. This gene was mapped within a 6 cM interval region and was tentatively referred to as al12.

Growth, photosynthesis and chlorophyll fluorescence of sweet pepper plants as affected by the cultivation method

AbstractDifferent methods of sweet pepper cultivation (organic, integrated and conventional farming) were evaluated under greenhouse conditions. Organic treatment was defined as only 4‐kg manure application at the preplanting stage. Conventional and integrated treatments consisted of application of the manure dosage plus chemical fertiliser at 100% and 50% of the local farmers’ amount, respectively, to avoid nutrient depletion. Plant growth parameters such as shoot dry matter, total leaf area and leaf weight fraction were all reduced in the organic treatment compared with the conventional. Leaf expansion was dramatically reduced in the organic treatment 155 days after transplanting. Relative growth rates were significantly affected by the nitrogen concentration in each organ and were directly related to the cultivation method. Chlorophylls (a + b) contents in the leaves were reduced in the organic treatment and were directly correlated with the nondestructive quantification of chlorophylls using a portable chlorophyll meter. Net photosynthesis was also reduced in the organic treatment, but chlorophyll fluorescence was not affected. This study shows that biometric monitoring and fast and non‐invasive techniques of plant nutrient status analysis could help to improve growth as easy and useful tools to follow the nutrient status at different phenological stages, especially when no chemical fertilisers are applied.

Selection of discrepant maize genotypes for nitrogen use efficiency by a chlorophyll meter

The objective of the present study was to verify if it is possible to discriminate maize genotypes for their efficiency of nitrogen use by readings obtained with a portable chlorophyll meter. A total of 76 topcross hybrids and five previously tested controls were evaluated without sidedress nitrogen fertilization and 81 S1 families that only differed in relation to nitrogen sidedress fertilization (with and without). Readings were obtained by the chlorophyll meter in the phenological stages of four and eight fully unfolded leaves. Different negative selection pressures were simulated by the chlorophyll meter readings at each phenological stage and the genotypes were screened for grain yield and efficiency of N use. It was verified that the portable chlorophyll meter can be used to eliminate the least productive genotypes before flowering in quick tests, especially in environments without nitrogen sidedress, although the most effective genotypes regarding nitrogen use could not be discriminated this way.

Use of Chlorophyll Meter to Assess the Effect of Nitrogen on Sweet Pepper Development and Growth

The evolution of both leaf expansion and chlorophyll content was assessed in potted sweet pepper plants subjected to four different levels of nitrogen (mg N/kg of soil): N1 = 25 (basal dressing); N2 = 50 (basal dressing); N3 = 100 (basal dressing and one side dressing); and, N4 = 150 (basal dressing and two side dressings). In each plant, the first leaves (numbered 1–5) were chosen at the main stem and the next four ramifications. The relative chlorophyll content of leaves 1 to 5, from all treatments, was obtained by a portable chlorophyll meter, SPAD-502, twice a week. The SPAD readings were subsequently converted into total chlorophyll (μ g cm− 2). The plant dry weight, the number of fruits per plant, and the N content of leaves were measured at final harvest (70 d after transplantation, DAT). Until the first side dressing (35 DAT), the increase in chlorophyll content was similar in all treatments, decreasing afterward under the N1 and N2 treatments (leaves 1 and 2), while under the N3 and N4 treatments the increase in the chlorophyll content continued after the first side dressing. The application of the second side dressing (53 DAT) under the N4 treatment induced a subsequent increase in chlorophyll content in all leaves compared with those of N3. An early senescence was observed under the N1 and N2 treatments compared with the others. Applied N in side dressing led to an increase in leaf width (leaves 2–5) and longevity, mainly in leaves 2 and 3, and a subsequent increase under fruit number and fruit dry weight under the N3 and N4 treatments.

Predicting nitrogen fertilizer requirements for corn by chlorophyll meter under different N availability conditions

Nitrogen management strategies that enhance fertilizer use efficiency and maximize profitability in corn require a rapid and accurate method to determine the crop N needs of current hybrids. The objective of this study was to evaluate the potential of a portable chlorophyll meter for predicting N fertilizer requirements for corn grown under varying levels of N availability. Several crop management treatments were imposed in an attempt to create conditions ranging from low N availability (oily food waste application in spring and fall, application at different rates in spring) to high N availability (continuous fertilized corn, winter wheat cover crop). Different corn hybrids were sown at different sites (21 site yr) and varying N fertilizer application rates were applied. Chlorophyll meter readings (CMR) were taken at the 5th to 6th leaf stage (V6) using a SPAD-502 chlorophyll meter. The crop management treatments, corn hybrids and their interaction significantly affected the chlorophyll meter readings. A high inverse correlation between chlorophyll meter readings and maximum economic rate of nitrogen (MERN) was observed (r = −0.87). The main new and unique aspect of our research is the development of a linear model for using chlorophyll meter measurements to make N fertilizer recommendations (MERN = 348.47 − 8.5304 × CMR ) for corn production under varying degrees of N availability in Southern Ontario. Key words: Chlorophyll meter, soil organic carbon, nitrogen application

Growth, Nutrient Status, and Chlorophyll Meter Readings in Wheat as Affected by Nitrogen and Manganese

Mineral nutrition of wheat (Triticum aestivum L.) in highly calcareous soils low in available nitrogen (N) and manganese (Mn) requires further investigations. The purpose of this experiment was to determine the effect of N and Mn on the growth, nutrient concentration and uptake, and chlorophyll meter readings (CMR) in wheat grown in greenhouse conditions. The experiment was conducted on a highly calcareous soil (fine-loamy, carbonatic, thermic, Typic Calcixerepts) relatively low in available N and Mn. Treatments consisted of a factorial arrangement of five N rates (0, 50, 100, 200, and 400 mg kg−1 as NH4NO3) and three Mn levels (0, 15, and 30 mg kg−1 as MnSO4) in a completely randomized design with four replications. Plants were grown for 60 d and hand-held chlorophyll meter (Minolta SPAD-502) readings were used to evaluate dry matter (DMY) and N, Mn, iron (Fe), zinc (Zn), and copper (Cu) concentration of wheat in aerial parts. Applied N increased DMY and concentration and uptake of N, Mn, Fe, Zn, and Cu, and Mn:Fe ratios. A significant correlation was obtained between DMY and applied N (R2 = 0.75). Manganese had no significant effect on DMY, N, Zn, Cu concentration and uptake, and Fe uptake. However, Mn rate increased Mn concentration and uptake and Mn:Fe ratio and reduced Fe concentration. Interaction of N × Mn did not affect DMY, concentration, or uptake of any of the nutrients. The CMR increased significantly with N rate but was not influenced by Mn addition. Highly significant correlations were observed between CMR and DMY (R2 = 0.84), and the concentrations of N (R2 = 0.97), Mn (R2 = 0.70), Fe (R2 = 0.73), Zn (R2 = 0.93), and Cu (R2 = 0.90). It is concluded that portable chlorophyll meter is a quick, reliable, and nondestructive tool for assessing DMY and nutrients affecting leaf greenness in wheat. However, further investigation in field conditions is recommended.

Parâmetros de planta para aprimorar o manejo da adubação nitrogenada de cobertura em milho

O milho é uma das culturas mais exigentes em fertilizantes nitrogenados os quais proporcionam os maiores acréscimos no rendimento de grãos. Para manter a planta bem nutrida, há necessidade de estimar corretamente a quantidade de nitrogênio (N) que deve ser aplicada no solo, com intuito de satisfazer as suas necessidades durante todo o ciclo. No Rio Grande do Sul e Santa Catarina, o teor de matéria orgânica, a expectativa de rendimento de grãos e a contribuição da cultura antecedente como fonte de N são os parâmetros que têm servido como critério para recomendação de adubação nitrogenada no milho. No entanto, considerando a complexidade da dinâmica do N no solo, e todas as modificações que ocorrem durante a ontogenia desta cultura, outros parâmetros podem ser úteis para auxiliar na decisão sobre o manejo da adubação nitrogenada em cobertura. Vários parâmetros de planta têm sido estudados como indicadores do nível de N no tecido. Dentre estes, destacam-se o teor de nitrato no colmo, o teor e o acúmulo de N na folha e/ou planta e o teor relativo de clorofila na folha. A estimativa do teor de clorofila na folha pelo clorofilômetro tem sido bastante estudada nos últimos anos, em função da sua rapidez, precisão e baixo custo. Esta revisão visa abordar parâmetros de planta que podem ser utilizados como indicadores do nível de N na planta para predizer a necessidade de adubação nitrogenada em cobertura na cultura do milho, objetivando aumentar a eficiência de uso do nutriente e reduzir o impacto ambiental do N aplicado.

Leaf relative chlorophyll content as an indicator parameter to predict nitrogen fertilization in maize

The development of a portable chlorophyll meter (SPAD 502), that takes instantaneous measurements of greenness without leaf destruction, has emerged as a new tool to assess plant N status. This trial was carried out to determine the adequate SPAD readings to predict maize nitrogen needs in four growth stages. The experiment was conducted in the state of Rio Grande do Sul, southern Brazil, during the 1998/99 growing season. Treatments were two maize hybrids (Pioneer 32R21 and Cargill 901) and nine side-dressed nitrogen levels (0, 50, 100, 150, 200, 300, 400, 500 and 600kg ha-1). Nitrogen was side-dressed at the soil surface in four equal doses, according to the levels established on each treatment. The first, second, third and fourth applications were made in the stages of three to four, six to seven, 10 to 11 and 14 to 15 fully expanded leaves, respectively. Urea was used as the N source. Since there was no difference in the SPAD readings among maize hybrids, average values at each stage were used. Readings were carried out in the stages of three to four, six to seven, 10 to 11 fully expanded leaves and at silking. Chlorophyll evaluation samples were taken at two-thirds of the distance from the leaf tip towards the stem. The two upper leaves were sampled on each growth stage before maize flowering. The index leaf (first leaf below the ear) was evaluated during silking. Chlorophyll meter readings above 45.4, 52.1, 55.3, and 58.0 represented the adequate values for the stages of three to four, six to seven, 10 to 11 expanded leaves and at silking, respectively, to achieve high grain yield. The variation in SPAD readings were highest in the early stages of plant growth.

Evaluation of a portable chlorophyll meter to estimate chlorophyll and nitrogen contents in sugar maple ( Acer saccharum Marsh.) leaves

Portable, non-destructive chlorophyll meters could be a valuable tool for forest managers and researchers. The ability of such meters to assess both chlorophyll and nitrogen content has been well established for many agricultural species, but not well-studied for North American forest tree species. The objective of this study was to evaluate the ability of a portable chlorophyll meter to estimate chlorophyll (CHL) and nitrogen (N) content in sugar maple ( Acer saccharum Marsh.) leaves by testing correlations between chlorophyll content index values (CCI) and extractable CHL and N in large heterogeneous samples. Significant correlations were observed between CCI and CHL ( P ≤ 0.001, r 2 = 76%) and CCI and N ( P ≤ 0.001, r 2 = 64%). These data indicate that the meter tested can be an effective tool for estimating relative chlorophyll and nitrogen content in sugar maple leaves.

Insecticides from Five Chemical Classes Differentially Affect the Plant Growth and Development of Chrysanthemum (Dendranthema grandiflora Tzvelev var. Charm)

This research focused on the influence of insecticides on plant growth, gas exchange, rate of flowering, and chlorophyll content of chrysanthemum (Dendranthema grandiflora Tzvelev cv. Charm) grown according to recommended procedures for pot plant production. Five insecticides were applied at recommended concentrations at three different frequencies: weekly (7 days), bi-weekly (14 days), or monthly (28 days). A separate treatment was applied weekly at 4× the recommended concentration. Insecticides used were: acephate (Orthene®) Turf, Tree & Ornamental Spray 97), bifenthrin (Talstar®) Flowable), endosulfan (Thiodan®) 50 WP), imidacloprid (Marathon®) II), and spinosad (Conserve®) SC). Phytotoxicity occurred in the form of leaf burn on all acephate treatments, with the greatest damage occurring at the 4× concentration. Photosynthesis and stomatal conductance were influenced primarily by the degree of aphid and/or spider mite infestation—except for acephate and endosulfan treatments (weekly and 4×), which had reduced photosynthesis with minimal insect infestations. Plants receiving imadacloprid monthly had the greatest leaf dry mass (DM). Plants treated with acephate had lower leaf and stem DM with bi-weekly and 4× treatments. Spinosad treatments at recommended concentrations had reduced stem DM, in part due to aphid infestations. The flower DM was not significantly different among treatments. There were treatment differences in chlorophyll content as measured with a SPAD-502 portable chlorophyll meter.

Disponibilidade de água no solo e crescimento de artemísia

Plantas de artemísia (Tanacetum parthenium L. Schultz-Bip.), cultivadas em vasos com substrato mantido na capacidade de campo, a 90%, a 70% e a 50% da capacidade de campo foram comparadas quanto à altura, acúmulo de massa fresca na parte aérea, teor relativo de clorofila e teor de prolina. O teor relativo de clorofila foi estimado por meio do clorofilômetro SPAD-502, enquanto o teor de prolina foi determinado por colorimetria. Verificou-se reduções de 16% na altura e de 22,5% no acúmulo de massa fresca nas plantas crescidas a 50% da capacidade de campo, em relação àquelas crescidas a 90% da capacidade de campo. O teor relativo de clorofila nas folhas, em quaisquer dos níveis hídricos, decresceu com o tempo, indicando tendência à senescência. Apesar da redução contínua nos níveis de clorofila, as plantas mantidas a 50% da capacidade de campo tiveram, durante todo o tempo acompanhado, teor relativo de clorofila cerca de 30% mais alto comparado às plantas mantidas a 90% da capacidade de campo. O teor de prolina também foi maior nessas plantas, indicando ocorrência de estresse por deficiência hídrica e ajuste osmótico. O maior teor relativo de clorofila e de prolina nas folhas expandidas das plantas sob deficiência hídrica pode ser utilizado como indicativo de estresse.

Doses e épocas de aplicação de nitrogênio e teores foliares deste nutriente e de clorofila em feijoeiro

O presente trabalho foi desenvolvido na região de Selvíria (MS) e teve como objetivo avaliar o efeito de diferentes doses e épocas de aplicação de N sobre o teor de clorofila e de N nas folhas do feijoeiro, bem como estabelecer correlações com a produtividade. O delineamento experimental foi de blocos ao acaso, em esquema fatorial 3 x 5, constituído pela combinação de três épocas de aplicação (15, 30 e 15 + 30 dias após a emergência) do fertilizante nitrogenado (uréia) em cobertura e em cinco doses (0; 35; 70; 105 e 140 kg ha-1 de N). Avaliaram-se os teores de clorofila e N das folhas no florescimento pleno e a produtividade. A concentração de clorofila correlacionou-se positivamente com o teor de N nas folhas e com a produtividade de grãos, e o medidor portátil de clorofila mostrou-se promissor para avaliar o estado nutricional do nitrogênio no feijoeiro.

Sample Size Determination for Chlorophyll Meter Readings on Maize Hybrids with a Broad Range of Canopy Types

The portable chlorophyll meter [Soil Plant Analysis Development (SPAD)] has been used successfully for measuring leaf‐nitrogen (N) of several crops. Determination of the appropriate sample size, in terms of number of plants to be sampled within each plot, has recently become a matter of concern. An insufficient sample size does not allow for the detection of small, but real differences between treatment means, whereas an excessively large sample size constitutes a waste of time and resources. In this study, SPAD meter data were collected at two sites. Each of these two field experiments was organized following a split‐plot design with three blocks and two treatment factors: four nitrogen levels (main plot factor) and six maize (Zea mays L.) hybrids (subplot factor), selected to represent a broad range of canopy types. The approach followed in collecting SPAD meter readings for the determination of an appropriate sample size consisted of sampling one leaf per plant and taking a single reading per leaf. Confidence intervals for the mean of SPAD meter readings and the associated required sample sizes for the variability observed were generated using a standard procedure. Taking a single reading per leaf near the midpoint of the leaf blade, a sample size of 15 to 20 plants provided a level of precision of 5% (about ± 2.8 SPAD meter units). The variability among and within hybrids was highest at the zero N fertilization level (kg ha−1), for which the leafy and non‐leafy reduced stature and leafy normal stature hybrids showed the largest required sample sizes at both sites. At the Ottawa site, where an N fertilization effect was observed, required sample sizes at the 0 N level were larger than at any other level, including the recommended 170 N level. In summary, a relationship between sample size and precision level is presented for maize researchers using the SPAD technology.

Nondestructive and rapid estimation of hardwood foliar nitrogen status using the SPAD-502 chlorophyll meter

The utility of a portable chlorophyll meter (SPAD-502, Minolta Camera Co. Ltd., Japan) for rapidly and nondestructively assessing foliar N status of hardwood species was evaluated in two experiments. In experiment one (established near Raleigh, North Carolina), 0, 56, 168, or 336 kg N/ha (ammonium nitrate) was applied in June 1998 to sycamore ( Platanus occidentalis L.), sweetgum ( Liquidambar styraciflua L.), green ash ( Fraxinus pennsylvanica Marsh.), and swamp cottonwood ( Populus heterophylla L.) to obtain foliar samples with a range of N concentrations. Significant regression equations were established between foliar N concentration (obtained through chemical analysis) and SPAD value for all four species studied in August 1998. In experiment two, the SPAD meter was further tested in 1999 on sweetgum in eastern NC to examine whether crown position and the date of measurement affect the relationship between SPAD meter readings and foliar N concentrations. The slopes of the regression lines were similar but the intercepts were variable among the dates and crown positions. The best correlations between the SPAD meter readings and foliar N concentrations were obtained for the upper crown position early in the growing season and for the lower crown position late in the growing season. The SPAD meter was demonstrated to be a useful tool for nondestructively assessing foliar N status, particularly for relative comparison purposes, and may have efficient application for field assessments in decision-making and operational nutrient management programs for hardwood species. Accurate prediction of foliar % N by the SPAD meter may be difficult giving the generally medium range correlation coefficients.