Quantifying the nonlinearity in chlorophyll meter response to corn leaf nitrogen concentration

1995 ◽  
Vol 75 (1) ◽  
pp. 179-182 ◽  
Author(s):  
L. M. Dwyer ◽  
D. W. Stewart ◽  
E. Gregorich ◽  
A. M. Anderson ◽  
B. L. Ma ◽  
...  
Keyword(s):  
Growth Stage ◽  
Nitrogen Concentration ◽  
Leaf Nitrogen ◽  
Growth Stages ◽  
Concentration Data ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Non Destructive ◽  
Leaf N

Chlorophyll meters have been used to provide a rapid non-destructive method to estimate corn leaf nitrogen (N) concentration, although meter readings plateau at high leaf N levels. Paired chlorophyll meter and leaf N concentration data were obtained for ear level leaves at growth stages ranging from 3 wk before anthesis to 5 wk after anthesis over a 2-yr period at Ottawa, Ontario. Separate quadratic-plus-plateau models best represented chlorophyll meter response to leaf N concentration for pre-anthesis, early grain-fill and late grain-fill stages; chlorophyll meter readings corresponding to the beginning of the plateau increased at later growth stages. Leaf N concentration was estimated well from chlorophyll meter readings up to the plateau range using growth stage specific functions (R2 ≥ 0.77) but chlorophyll meter readings beyond the plateau should not be used to estimate leaf N concentration. Key words: Chlorophyll meter calibration, maize

Effect of spad techniques and planting density on 'Y' leaf nitrogen concentration in transplanted rice

2004 ◽  
Vol 52 (1) ◽  
pp. 95-104 ◽  
Author(s):  
P. Janaki ◽  
T. M. Thiyagarajan
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Nitrogen Concentration ◽  
Planting Density ◽  
Growth Stages ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Leaf N Concentration ◽  
N Management ◽  
Leaf N

Field experiments were conducted in June-September 1998 and 1999 with rice variety ASD18 at the wetland farm of Tamil Nadu Agricultural University, in Coimbatore, India to examine variations in 'Y' leaf (youngest fully expanded leaf) N concentration as influenced by different planting densities and N management strategies in a split plot design. The main plot consisted of three plant populations (33, 66 and 100 hills m-2) and the sub-plots treatments of five N management approaches. The results revealed that the nitrogen concentration progressively declined with growth, the decline being steep up to 35 days after transplanting, wereafter the values became almost linear up to the flowering stage in all the treatments. The mean 'Y' leaf N was found to be significantly higher at 33 hills m-2 (45.1 g kg-1), while the other two densities were on par (42.9 g kg-1). When N application was based on chlorophyll meter (SPAD) values the leaf N concentration was maintained at a level of 39.2 to 51.9 g kg-1 to produce maximum grain yield. A significant correlation was observed between the chlorophyll meter values and 'Y' leaf N concentrations at various days after transplanting (r values ranged from 0.57* to 0.83**), while the correlation was highly significant during the major physiological growth stages. Though the 'Y' leaf content was significantly higher in the treatment involving Sesbania rostrata green manuring + 150 kg N applied in splits, the grain yield produced was on par in all the N applied treatments. A highly significant correlation was observed between the grain yield and both 'Y' leaf N content and SPAD values during various growth periods.

Optical sensing estimation of leaf nitrogen concentration in maize across a range of water-stress levels

2011 ◽  
Vol 62 (6) ◽  
pp. 474 ◽  
Author(s):  
Tong-Chao Wang ◽  
B. L. Ma ◽  
You-Cai Xiong ◽  
M. Farrukh Saleem ◽  
Feng-Min Li
Keyword(s):  
Water Stress ◽  
Vegetation Index ◽  
Optical Sensing ◽  
Leaf Nitrogen ◽  
Growth Stages ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Chlorophyll Index ◽  
Plant Moisture ◽  
Leaf N

Optical sensing techniques offer an instant estimation of leaf nitrogen (N) concentration during the crop growing season. Differences in plant-moisture status, however, can obscure the detection of differences in N levels. This study presents a vegetation index that robustly measures differences in foliar N levels across a range of plant moisture levels. A controlled glasshouse study with maize (Zea mays L.) subjected to both water and N regimes was conducted in Ottawa, Canada. The purpose of the study was to identify spectral waveband(s), or indices derived from different wavebands, such as the normalised difference vegetation index (NDVI), that are capable of detecting variations in leaf N concentration in response to different water and N stresses. The experimental design includes three N rates and three water regimes in a factorial arrangement. Leaf chlorophyll content and spectral reflectance (400–1075 nm) were measured on the uppermost fully expanded leaves at the V6, V9 and V12 growth stages (6th, 9th and 12th leaves fully expanded). N concentrations of the same leaves were determined using destructive sampling. A quantitative relationship between leaf N concentration and the normalised chlorophyll index (normalised to well fertilised and well irrigated plants) was established. Leaf N concentration was also a linear function (R2 = 0.9, P < 0.01) of reflectance index (NDVI550, 760) at the V9 and V12 growth stages. Chlorophyll index increased with N nutrition, but decreased with water stress. Leaf reflectance at wavebands of 550 ± 5 nm and 760 ± 5 nm were able to separate water- and N-stressed plants from normal growing plants with sufficient water and N supply. Our results suggest that NDVI550, 760 and normalised chlorophyll index hold promise for the assessment of leaf N concentration at the leaf level of both normal and water-stressed maize plants.

scholarly journals Indirect Estimations of Lentil Leaf and Plant N by SPAD Chlorophyll Meter

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Hossein Zakeri ◽  
Jeff Schoenau ◽  
Albert Vandenberg ◽  
Mohammadreza Tayfeh Aligodarz ◽  
Rosalind A. Bueckert
Keyword(s):  
Leaf Nitrogen ◽  
Plant Age ◽  
Rbf Neural Networks ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Independent Variable ◽  
Relationship Of ◽  
The Relationship ◽  
Leaf N

A Soil Plant Analysis Development (SPAD) chlorophyll meter can be used to screen for leaf nitrogen (N) concentration in breeding programs. Lentil (Lens culinarisL.) cultivars were grown under varied N regimes, SPAD chlorophyll meter readings (SCMR) were recorded from the cultivars leaves, and leaf N concentration was measured by combustion. Linear regression and the nonlinear Radial Basis Functions (RBF) neural networks models were employed to estimate leaf N concentration (LNC) based on the SCMR values. The closest estimates of LNC were obtained from the multivariate models in which the combination of plant age, leaf thickness, and SCMR was employed as the independent variable. In comparison, SCMR as the single independent variable in both models estimated less than 50% of LNC variations. The results showed significant effects of soil moisture and plant age on the association of LNC –SCMR as well as the relationship of LNC with plant N, grain yield, and days to maturity. However, the effect of cultivar on the measured variables was negligible. Although lentil N can be diagnosed by comparing SCMR values of the crop with those from a well-fertilized (N fixing) plot, the results did not support using SPAD chlorophyll meter for screening lentil LNC.

Monitoring leaf nitrogen in wheat using canopy reflectance spectra

2006 ◽  
Vol 86 (4) ◽  
pp. 1037-1046 ◽  
Author(s):  
Yan Zhu ◽  
Yingxue Li ◽  
Wei Feng ◽  
Yongchao Tian ◽  
Xia Yao ◽  
...  
Keyword(s):  
Nitrogen Concentration ◽  
Leaf Nitrogen ◽  
Reflectance Spectra ◽  
Nutrition Status ◽  
Nitrogen Accumulation ◽  
Canopy Reflectance ◽  
Leaf Nitrogen Concentration ◽  
Non Destructive ◽  
N Status ◽  
Leaf N

Non-destructive monitoring of leaf nitrogen (N) status can assist in growth diagnosis, N management and productivity forecast in field crops. The objectives of this study were to determine the relationships of leaf nitrogen concentration on a leaf dry weight basis (LNC) and leaf nitrogen accumulation per unit soil area (LNA) to ground-based canopy reflectance spectra, and to derive regression equations for monitoring N nutrition status in wheat (Triticum aestivum L.). Four field experiments were conducted with different N application rates and wheat cultivars across four growing seasons, and time-course measurements were taken on canopy spectral reflectance, LNC and leaf dry weights under the various treatments. In these studies, LNC and LNA in wheat increased with increasing N fertilization rates. The canopy reflectance differed significantly under varied N rates, and the pattern of response was consistent across the different cultivars and years. Overall, an integrated regression equation of LNC to normalized difference index (NDI) of 1220 and 710 nm of canopy reflectance spectra described the dynamic pattern of change in LNC in wheat. The ratios of several near infrared (NIR) bands to visible light were linearly related to LNA, with the ratio index (RI) of the average reflectance over 760, 810, 870, 950 and 1100 nm to 660 nm having the best index for quantitative estimation of LNA in wheat. When independent data were fit to the derived equations, the average root mean square error (RMSE) values for the predicted LNC and LNA relative to the observed values were no more than 15.1 and 15.2%, respectively, indicating a good fit. Our relationships of leaf N status to spectral indices of canopy reflectance can be potentially used for non-destructive and real-time monitoring of leaf N status in wheat. Key words: Wheat, leaf nitrogen concentration, leaf nitrogen accumulation, canopy reflectance, spectral index, nitrogen monitoring

scholarly journals Estimating Plant Nitrogen Concentration of Maize Using a Leaf Fluorescence Sensor across Growth Stages

2020 ◽  
Vol 12 (7) ◽  
pp. 1139
Author(s):  
Rui Dong ◽  
Yuxin Miao ◽  
Xinbing Wang ◽  
Zhichao Chen ◽  
Fei Yuan ◽  
...  
Keyword(s):  
Precision Agriculture ◽  
Fluorescence Sensor ◽  
Accurate Estimation ◽  
Growth Stages ◽  
Fluorescence Sensors ◽  
N Application ◽  
N Concentration ◽  
Leaf N Concentration ◽  
N Status ◽  
Leaf N

Nitrogen (N) is one of the most essential nutrients that can significantly affect crop grain yield and quality. The implementation of proximal and remote sensing technologies in precision agriculture has provided new opportunities for non-destructive and real-time diagnosis of crop N status and precision N management. Notably, leaf fluorescence sensors have shown high potential in the accurate estimation of plant N status. However, most studies using leaf fluorescence sensors have mainly focused on the estimation of leaf N concentration (LNC) rather than plant N concentration (PNC). The objectives of this study were to (1) determine the relationship of maize (Zea mays L.) LNC and PNC, (2) evaluate the main factors influencing the variations of leaf fluorescence sensor parameters, and (3) establish a general model to estimate PNC directly across growth stages. A leaf fluorescence sensor, Dualex 4, was used to test maize leaves with three different positions across four growth stages in two fields with different soil types, planting densities, and N application rates in Northeast China in 2016 and 2017. The results indicated that the total leaf N concentration (TLNC) and PNC had a strong correlation (R2 = 0.91 to 0.98) with the single leaf N concentration (SLNC). The TLNC and PNC were affected by maize growth stage and N application rate but not the soil type. When used in combination with the days after sowing (DAS) parameter, modified Dualex 4 indices showed strong relationships with TLNC and PNC across growth stages. Both modified chlorophyll concentration (mChl) and modified N balance index (mNBI) were reliable predictors of PNC. Good results could be achieved by using information obtained only from the newly fully expanded leaves before the tasseling stage (VT) and the leaves above panicle at the VT stage to estimate PNC. It is concluded that when used together with DAS, the leaf fluorescence sensor (Dualex 4) can be used to reliably estimate maize PNC across growth stages.

scholarly journals LEAF TOTAL NITROGEN CONCENTRATION AS AN INDICATOR OF NITROGEN STATUS FOR PLANTLETS AND YOUNG PLANTS OF EUCALYPTUS CLONES

2015 ◽  
Vol 39 (4) ◽  
pp. 1127-1140 ◽  
Author(s):  
Eric Victor de Oliveira Ferreira ◽  
Roberto Ferreira Novais ◽  
Bruna Maximiano Médice ◽  
Nairam Félix de Barros ◽  
Ivo Ribeiro Silva
Keyword(s):  
Total Nitrogen ◽  
Block Design ◽  
Nitrogen Concentration ◽  
Soil N ◽  
Total N ◽  
Chlorophyll Meter ◽  
N Concentration ◽  
Total Nitrogen Concentration ◽  
N Status ◽  
Leaf N

The use of leaf total nitrogen concentration as an indicator for nutritional diagnosis has some limitations. The objective of this study was to determine the reliability of total N concentration as an indicator of N status for eucalyptus clones, and to compare it with alternative indicators. A greenhouse experiment was carried out in a randomized complete block design in a 2 × 6 factorial arrangement with plantlets of two eucalyptus clones (140 days old) and six levels of N in the nutrient solution. In addition, a field experiment was carried out in a completely randomized design in a 2 × 2 × 2 × 3 factorial arrangement, consisting of two seasons, two regions, two young clones (approximately two years old), and three positions of crown leaf sampling. The field areas (regions) had contrasting soil physical and chemical properties, and their soil contents for total N, NH+4-N, and NO−3-N were determined in five soil layers, up to a depth of 1.0 m. We evaluated the following indicators of plant N status in roots and leaves: contents of total N, NH+4-N, NO−3-N, and chlorophyll; N/P ratio; and chlorophyll meter readings on the leaves. Ammonium (root) and NO−3-N (root and leaf) efficiently predicted N requirements for eucalyptus plantlets in the greenhouse. Similarly, leaf N/P, chlorophyll values, and chlorophyll meter readings provided good results in the greenhouse. However, leaf N/P did not reflect the soil N status, and the use of the chlorophyll meter could not be generalized for different genotypes. Leaf total N concentration is not an ideal indicator, but it and the chlorophyll levels best represent the soil N status for young eucalyptus clones under field conditions.

scholarly journals Evaluation of Three Portable Optical Sensors for Non-Destructive Diagnosis of Nitrogen Status in Winter Wheat

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5579
Author(s):  
Jie Jiang ◽  
Cuicun Wang ◽  
Hui Wang ◽  
Zhaopeng Fu ◽  
Qiang Cao ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Optical Sensors ◽  
Accurate Estimation ◽  
Growth Stages ◽  
N Accumulation ◽  
N Nutrition ◽  
N Concentration ◽  
Non Destructive ◽  
N Status ◽  
Leaf N

The accurate estimation and timely diagnosis of crop nitrogen (N) status can facilitate in-season fertilizer management. In order to evaluate the performance of three leaf and canopy optical sensors in non-destructively diagnosing winter wheat N status, three experiments using seven wheat cultivars and multi-N-treatments (0–360 kg N ha−1) were conducted in the Jiangsu province of China from 2015 to 2018. Two leaf sensors (SPAD 502, Dualex 4 Scientific+) and one canopy sensor (RapidSCAN CS-45) were used to obtain leaf and canopy spectral data, respectively, during the main growth period. Five N indicators (leaf N concentration (LNC), leaf N accumulation (LNA), plant N concentration (PNC), plant N accumulation (PNA), and N nutrition index (NNI)) were measured synchronously. The relationships between the six sensor-based indices (leaf level: SPAD, Chl, Flav, NBI, canopy level: NDRE, NDVI) and five N parameters were established at each growth stages. The results showed that the Dualex-based NBI performed relatively well among four leaf-sensor indices, while NDRE of RS sensor achieved a best performance due to larger sampling area of canopy sensor for five N indicators estimation across different growth stages. The areal agreement of the NNI diagnosis models ranged from 0.54 to 0.71 for SPAD, 0.66 to 0.84 for NBI, and 0.72 to 0.86 for NDRE, and the kappa coefficient ranged from 0.30 to 0.52 for SPAD, 0.42 to 0.72 for NBI, and 0.53 to 0.75 for NDRE across all growth stages. Overall, these results reveal the potential of sensor-based diagnosis models for the rapid and non-destructive diagnosis of N status.

Altitudinal effects on leaf traits and shoot growth of Betulaplatyphylla var. japonica

1995 ◽  
Vol 25 (11) ◽  
pp. 1881-1885 ◽  
Author(s):  
Gaku Kudo
Keyword(s):  
Shoot Growth ◽  
Leaf Size ◽  
Leaf Traits ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Leaf Life Span ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Lower Site ◽  
Leaf N

Leaf demography, shoot growth, and seasonal changes of leaf size, specific leaf area, and leaf nitrogen (N) concentration of Betulaplatyphylla var. japonica Hara were compared at two altitudes (140 and 700 m above sea level). At the higher site, where the length of growing season was restricted, leaf life-span was shorter and leaf N concentration was higher throughout the growing season than at the lower site. Leaf size did not differ between sites. Production of short-lived and high N concentration leaves was considered adaptive under the condition of short growing season. At the higher site, N was translocated from senescing early leaves to late leaves in mid-September, whereas a significant increase in late leaf N concentration was not observed at the lower site. There were no differences in shoot growth, bud size, late leaf number on long shoots between sites, probably because of effective N use at the higher site.

scholarly journals Down-Regulation of Photosynthesis to Elevated CO2 and N Fertilization in Understory Fraxinus rhynchophylla Seedlings

Forests ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1197
Author(s):  
Siyeon Byeon ◽  
Kunhyo Kim ◽  
Jeonghyun Hong ◽  
Seohyun Kim ◽  
Sukyung Kim ◽  
...  
Keyword(s):  
Elevated Co2 ◽  
N Fertilization ◽  
Leaf Nitrogen ◽  
N Availability ◽  
Down Regulation ◽  
Leaf Production ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Regulation Of Photosynthesis ◽  
Leaf N

(1) Background: Down-regulation of photosynthesis has been commonly reported in elevated CO2 (eCO2) experiments and is accompanied by a reduction of leaf nitrogen (N) concentration. Decreased N concentrations in plant tissues under eCO2 can be attributed to an increase in nonstructural carbohydrate (NSC) and are possibly related to N availability. (2) Methods: To examine whether the reduction of leaf N concentration under eCO2 is related to N availability, we investigated understory Fraxinus rhynchophylla seedlings grown under three different CO2 conditions (ambient, 400 ppm [aCO2]; ambient × 1.4, 560 ppm [eCO21.4]; and ambient × 1.8, 720 ppm [eCO21.8]) and three different N concentrations for 2 years. (3) Results: Leaf and stem biomass did not change under eCO2 conditions, whereas leaf production and stem and branch biomass were increased by N fertilization. Unlike biomass, the light-saturated photosynthetic rate and photosynthetic N-use efficiency (PNUE) increased under eCO2 conditions. However, leaf N, Rubisco, and chlorophyll decreased under eCO2 conditions in both N-fertilized and unfertilized treatments. Contrary to the previous studies, leaf NSC decreased under eCO2 conditions. Unlike leaf N concentration, N concentration of the stem under eCO2 conditions was higher than that under ambient CO2 (4). Conclusions: Leaf N concentration was not reduced by NSC under eCO2 conditions in the understory, and unlike other organs, leaf N concentration might be reduced due to increased PNUE.

scholarly journals Feasibility Study of Using Absolute SPAD Values for Standardized Evaluation of Corn Nitrogen Status

Nitrogen ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 298-307
Author(s):  
Abdelaziz Rhezali ◽  
Abdellah El Aissaoui
Keyword(s):  
Zea Mays L ◽  
Growth Stages ◽  
Plant Analysis ◽  
N Concentration ◽  
Fertilizer Recommendations ◽  
Leaf N Concentration ◽  
The Mean ◽  
High Yields ◽  
Spad Meter ◽  
Leaf N

Nitrogen fertilizer recommendations for corn (Zea mays L.) should ensure high yields using adequate N doses. Soil–plant analysis development (SPAD) meter technology using absolute SPAD values, might be more reliable than relative SPAD values in helping corn producers making timely decisions about N applications. This study aimed to develop a relationship between absolute SPAD values and leaf N concentration, and to determine optimal leaf N concentrations at early corn growth stages (V6, V8, V10, and V12). Three experiments were conducted during two summer seasons (2014 and 2015) using six N treatments applied at early corn growth stages. In parallel, two experiments were carried out in a high residual N environment to establish the optimum corn leaf N concentration. Results showed a significant linear relationship between corn leaf N concentrations and absolute SPAD values (R2 = 0.80, p < 0.05). The mean optimum corn leaf N concentration decreased over corn growth stages. It is of great importance to make the absolute SPAD method accessible for farmers, but more research is required to perform standardized reading of absolute SPAD values data.

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