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.

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

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 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 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.

scholarly journals Machine Learning in Evaluating Multispectral Active Canopy Sensor for Prediction of Corn Leaf Nitrogen Concentration and Yield

2021 ◽  
Vol 14 (1) ◽  
pp. 120
Author(s):  
Razieh Barzin ◽  
Hossein Lotfi ◽  
Jac J. Varco ◽  
Ganesh C. Bora
Keyword(s):  
Machine Learning ◽  
Grain Yield ◽  
Vegetation Index ◽  
Growth Stages ◽  
Fertilizer N ◽  
Red Edge ◽  
Leaf N Concentration ◽  
Different Growth Stages ◽  
N Status ◽  
Leaf N

Applying the optimum rate of fertilizer nitrogen (N) is a critical factor for field management. Multispectral information collected by active canopy sensors can potentially indicate the leaf N status and aid in predicting grain yield. Crop Circle multispectral data were acquired with the purpose of measuring the reflectance data to calculate vegetation indices (VIs) at different growth stages. Applying the optimum rate of fertilizer N can have a considerable impact on grain yield and profitability. The objectives of this study were to evaluate the reliability of a handheld Crop Circle ACS-430, to estimate corn leaf N concentration and predict grain yield of corn using machine learning (ML) models. The analysis was conducted using four ML models to identify the best prediction model for measurements acquired with a Crop Circle ACS-430 field sensor at three growth stages. Four fertilizer N levels from deficient to excessive in 50/50 spilt were applied to corn at 1–2 leaves, with visible leaf collars (V1-V2 stage) and at the V6-V7 stage to establish widely varying N nutritional status. Crop Circle spectral observations were used to derive 25 VIs for different growth stages (V4, V6, and VT) of corn at the W. B. Andrews Agricultural Systems farm of Mississippi State University. Multispectral raw data, along with Vis, were used to quantify leaf N status and predict the yield of corn. In addition, the accuracy of wavelength-based and VI-based models were compared to examine the best model inputs. Due to limited observed data, the stratification approach was used to split data to train and test set to obtain balanced data for each stage. Repeated cross validation (RCV) was then used to train the models. Results showed that the Simplified Canopy Chlorophyll Content Index (SCCCI) and Red-edge ratio vegetation index (RERVI) were the most effective VIs for estimating leaf N% and that SCCCI, Red-edge chlorophyll index (CIRE), RERVI, Soil Adjusted Vegetation Index (SAVI), and Normalized Difference Vegetation Index (NDVI) were the most effective VIs for predicting corn grain yield. Additionally, among the four ML models utilized in this research, support vector regression (SVR) achieved the most accurate results for estimating leaf N concentration using either spectral bands or VIs as the model inputs.

Effects of strobilurin fungicide programmes and fertilizer nitrogen rates on winter wheat: severity ofSeptoria tritici, leaf senescence and yield

2011 ◽  
Vol 150 (4) ◽  
pp. 411-426 ◽  
Author(s):  
S. ISHIKAWA ◽  
M. C. HARE ◽  
P. S. KETTLEWELL
Keyword(s):  
Winter Wheat ◽  
Plant Height ◽  
Leaf Senescence ◽  
Field Experiments ◽  
Fertilizer Nitrogen ◽  
N Concentration ◽  
Progress Curve ◽  
Strobilurin Fungicide ◽  
Leaf N Concentration ◽  
Leaf N

SUMMARYFour field experiments were conducted over 3 years to study whether adding a strobilurin fungicide to a triazole fungicide programme for disease control in winter wheat had any influence, in combination with different rates of fertilizer nitrogen (N), on the severity of foliar diseases, the degree of leaf senescence and consequently on yield.Septoria triticiwas the dominant foliar disease observed in all experiments. The area under the disease progress curve (AUDPC) tended to be greater for untreated plots than those treated with fungicides; however, the performance of the programme containing a strobilurin fungicide did not always exceed that of the triazole-only programme. Fitting a quadratic equation to relationships between leaf N concentration and the proportion of leaf area covered withS. triticion a relative scale across the four experiments indicated a possibility that there could be an optimum N concentration in host plants forS. triticito develop, rather than a simple increase or decrease with a rise in plant N concentration. Plant height tended to be reduced following an application of a mixture of epoxiconazole and trifloxystrobin; however, it was not clear whether there was any association between plant height and the severity ofS. tritici. S. triticicaused a reduction in mean grain weight (MGW) in most of the experiments. It was concluded that an optimum leaf N concentration may exist forS. triticiin winter wheat.

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.

scholarly journals Optimal Nitrogen Concentration and Rapid Nutritional Diagnosis of Nitrogen Requirement for Container Production of Malabar Chestnut

2015 ◽  
Vol 25 (5) ◽  
pp. 602-607
Author(s):  
Yung-Liang Peng ◽  
Fang-Yin Liu ◽  
Rong-Show Shen ◽  
Yu-Sen Chang
Keyword(s):  
Plant Growth ◽  
Dry Weight ◽  
N Fertilization ◽  
Chlorophyll Meter ◽  
Leaf Chlorophyll ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Leaf Dry Weight ◽  
N Requirement ◽  
Leaf N

Nitrogen (N) is a major element required for crop cultivation and an important factor affecting plant growth and development. Malabar chestnut (Pachira macrocarpa) is an important ornamental potted plant crop whose N requirement has been studied, and a rapid monitoring method to manage N fertilization during its commercial production is yet to be established. Malabar chestnut seedlings were fertilized weekly with 0, 4, 8, 16, or 24 mm N. After 12 weeks, 16 mm N was found to yield the greatest plant growth such as plant height, number of nodes, and total leaf area. Measurements of chlorophyll meter readings, leaf chlorophyll concentration, leaf N concentration, and leaf dry weight all indicated that the optimal level of N fertilization was 16 mm N. A chlorophyll meter can be used to monitor nondestructively whether sufficient N has been supplied to support optimal plant growth. In this study, a chlorophyll meter reading of 46.1 corresponded with a critical leaf N concentration of 2.65%, defined as the leaf N concentration when the leaf dry weight was at 90% of saturation point. Additional N supplied beyond this critical level increased foliar chlorophyll content and improved the rate of net photosynthesis. Therefore, chlorophyll meter readings, which are convenient and nondestructive can serve as a reliable reference for commercial production in monitoring N requirement for optimum growth of malabar chestnut. Weekly fertilization of malabar chestnut with 16 mm N and maintaining leaf chlorophyll meter readings between 46.1 and 58.4 are recommended.

Effect of N management approaches and planting densities on nitrogen accumulation by transplanted rice

2005 ◽  
Vol 53 (4) ◽  
pp. 405-415 ◽  
Author(s):  
P. Janaki ◽  
T. M. Thiyagarajan
Keyword(s):  
Grain Yield ◽  
Uptake Rate ◽  
Aboveground Biomass ◽  
N Uptake ◽  
Planting Density ◽  
Transplanted Rice ◽  
The Mean ◽  
N Uptake Rate ◽  
Management Approaches ◽  
N Management

Field experiments were conducted during 1998 and 1999 in June-September with rice variety ASD18 at the wetland farm, Tamil Nadu Agricultural University, Coimbatore, India to find out theeffect of N management approaches and planting densities on N accumulation by transplanted rice in a split plot design.The main plot consisted of three plant populations (33, 66 and 100 hills m-2) and the sub-plot treatments of five N management approaches. The results revealed thatthe average N uptake in roots and aboveground biomass progressively increased with growth stages. The mean root and aboveground biomass Nuptake were 26.1 to 130.6 and 6.4 to 17.8 kg ha-1, respectively. The N uptake of grain and straw was higher in theSesbania rostratagreen manuring + 150 kg N treatment, but it was not effective in increasing the grain yield. The mean total N uptake was found to be significantly lower at 33 hills m-2(76.9 kg ha-1) and increased with an increase in planting density (100.9 and 117.2 kg ha-1at 66 and 100 hills m-2density). N application had a significant influence on N uptake and the time course of N uptake in all the SPAD-guided N approaches. A significant regression coefficient was observed between the crop N uptake and grain yield. The relationship between cumulative N uptake at the flowering stage and the grain yield was quadratic at all three densities. The N uptake rate (µN) was maximum during the active tillering to panicle initiation period and declined sharply after that. In general, µNincreased with an increase in planting density and the increase was significant up to the panicle initiation to flowering period.thereafter, the N uptake rate was similar at densities of 66 and 100 hills m-2.

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