Critical N concentration can vary with growth conditions in forage grasses: implications for plant N status assessment and N deficiency diagnosis

The efficient utilization of nitrogen (N) in grass production is essential to reduce the risks of water and air pollution, and the costs of production. Recent findings in grass physiology and agronomy should help in developing new tools to improve N utilization efficiency. A model of N dilution describing the decrease in plant N concentration with increasing shoot biomass under non-limiting N supply is used to define a critical N concentration in grasses required to reach maximum shoot growth and yield. The index of N nutrition (INN) is then calculated as the measured N concentration in a given situation divided by the critical N concentration. The INN is a diagnostic tool to quantify the level of N deficiency during growth cycles, and can also be used in crop modelling and in the interpretation of results from studies conducted over many sites and years. The "universality" of the model of N dilution is based on the increased proportion of structural to metabolic components during crop growth combined with the fact that the structural component has a lower N concentration. Inter- and intra-species differences in N concentration at a given shoot biomass can be related to differences in the proportion of leaves which are assumed to be equivalent to the metabolic component. Under N-deficient conditions, the reduction in grass growth is due to a reduction in the interception of solar radiation primarily through reduced leaf extension, and to a reduction in the conversion efficiency of intercepted radiation into shoot biomass primarily through an effect on biomass partitioning between roots and shoots. The concept of the critical N concentration based on the relationship between plant N concentration and shoot biomass is used to derive general and synthetic expressions of the effect of plant N nutrition on crop growth and crop growth processes. These recent findings on the relationship between N nutrition and the growth of forage grasses should result in the improvement of the efficiency of N utilization by a more precise fertilizer management and the development of more N efficient cultivars. Key words: Physiology, growth, photosynthesis, leaf, partitioning, model

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

Remote Sensing ◽

10.3390/rs12071139 ◽

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.

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

Revista Brasileira de Ciência do Solo ◽

10.1590/01000683rbcs20140689 ◽

2015 ◽

Vol 39 (4) ◽

pp. 1127-1140 ◽

Cited By ~ 4

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.

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A new approach for determining rice critical nitrogen concentration

The Journal of Agricultural Science ◽

10.1017/s0021859611000177 ◽

2011 ◽

Vol 149 (5) ◽

pp. 633-638 ◽

Cited By ~ 13

Author(s):

R. CONFALONIERI ◽

C. DEBELLINI ◽

M. PIRONDINI ◽

P. POSSENTI ◽

L. BERGAMINI ◽

...

Keyword(s):

Nutritional Status ◽

Cropping Systems ◽

Nitrogen Concentration ◽

Simulation Models ◽

Crop Models ◽

N Concentration ◽

Alternative Approach ◽

Using Data ◽

The University ◽

Critical N Concentration

SUMMARYA reliable evaluation of crop nutritional status is crucial for supporting fertilization aiming at maximizing qualitative and quantitative aspects of production and reducing the environmental impact of cropping systems. Most of the available simulation models evaluate crop nutritional status according to the nitrogen (N) dilution law, which derives critical N concentration as a function of above-ground biomass. An alternative approach, developed during a project carried out with students of the Cropping Systems Masters course at the University of Milan, was tested and compared with existing models (N dilution law and approaches implemented in EPIC and DAISY models). The new model (MAZINGA) reproduces the effect of leaf self-shading in lowering plant N concentration (PNC) through an inverse of the fraction of radiation intercepted by the canopy. The models were tested using data collected in four rice (Oryza sativaL.) experiments carried out in Northern Italy under potential and N-limited conditions. MAZINGA was the most accurate in identifying the critical N concentration, and therefore in discriminating PNC of plants growing under N-limited and non-limited conditions, respectively. In addition, the present work proved the effectiveness of crop models when used as tools for supporting education.

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ALTERNATIVE EQUATIONS FOR CRITICAL N-CONCENTRATION IN CABBAGE

Acta Horticulturae ◽

10.17660/actahortic.1999.506.16 ◽

1999 ◽

pp. 123-128 ◽

Cited By ~ 6

Author(s):

H. Riley ◽

G. Guttormsen

Keyword(s):

N Concentration ◽

Critical N Concentration

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Diagnostic nitrogen concentrations for tomatoes grown in sand culture

Australian Journal of Experimental Agriculture ◽

10.1071/ea9880401 ◽

1988 ◽

Vol 28 (3) ◽

pp. 401 ◽

Cited By ~ 3

Author(s):

DO Huett ◽

G Rose

Keyword(s):

Critical Values ◽

Sand Culture ◽

Nutrient Concentrations ◽

Total N ◽

Nitrate N ◽

N Concentration ◽

Leaf N Concentration ◽

Petiole Sap ◽

N Status ◽

Leaf N

The tomato cv. Flora-Dade was grown in sand culture with 4 nitrogen (N) levels of 1.07-32.14 mmol L-1 applied as nitrate each day in a complete nutrient solution. The youngest fully opened leaf (YFOL) and remaining (bulked) leaves were harvested at regular intervals over the 16-week growth period. Standard laboratory leaf total and nitrate N determinations were conducted in addition to rapid nitrate determinations on YFOL petiole sap. The relationships between plant growth and leaf N concentration, which were significantly affected by N application level, were used to derive diagnostic leaf N concentrations. Critical and adequate concentrations in petiole sap of nitrate-N, leaf nitrate-N and total N for the YFOL and bulked leaf N were determined from the relationship between growth rate relative to maximum at each sampling time and leaf N concentration. YFOL petiole sap nitrate-N concentration, which can be measured rapidly in the field by using commercial test strips, gave the most sensitive guide to plant N status. Critical values of 770-1 120 mg L-I were determined over the 10-week period after transplanting (first mature fruit). YFOL (leaf + petiole) total N concentration was the most consistent indicator of plant N status where critical values of4.45-4.90% were recorded over the 4- 12 week period after transplanting (early harvests at 12 weeks). This test was less sensitive but more precise than the petiole sap nitrate test. The concentrations of N, potassium, phosphorus, calcium and magnesium in YFOL and bulked leaf corresponding to the N treatments producing maximum growth rates are presented, because nutrient supply was close to optimum and the leaf nutrient concentrations can be considered as adequate levels.

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Use of a Chlorophyll Meter for Nondestructive and Rapid Estimation of Leaf Tissue Nitrogen in Macadamia

HortTechnology ◽

10.21273/horttech04276-19 ◽

2019 ◽

Vol 29 (3) ◽

pp. 308-313 ◽

Cited By ~ 2

Author(s):

Russell Galanti ◽

Alyssa Cho ◽

Amjad Ahmad ◽

Javier Mollinedo

Keyword(s):

Linear Regression ◽

Leaf Tissue ◽

Sampling Period ◽

Concentration Data ◽

Total N ◽

Chlorophyll Meter ◽

N Concentration ◽

Important Concern ◽

N Management ◽

N Status

Nitrogen (N) management in macadamia (Macadamia integrifolia) orchards is an important concern for growers. Leaf tissue analysis is the accepted method for determining N status in macadamia; however, this process is expensive and time-consuming. The chlorophyll meter has been used in other crops to estimate N status in plants through estimation of the amount of chlorophyll in leaf tissue. The use of the chlorophyll meter in two macadamia cultivars (Kakea and Kau) at two locations in Hawai’i (Kapa’au and Pahala) and five time periods (12 Apr. 2017, 13 June 2017, 15 June 2017, 18 Dec. 2017, and 20 Feb. 2018) was assessed. Leaf samples were collected based on a tissue-sampling protocol, chlorophyll meter (SPAD) values were collected, and leaves were analyzed for total N concentration. Data were analyzed statistically using linear regression. Leaf tissue N concentration had a positive monotonic relationship to SPAD values for both macadamia cultivars, both locations, and all sampling periods. The sampling period of Apr. 2017 for ‘Kakea’ macadamia had the greatest R2 value for the linear regression at 0.85. The Feb. 2018 sampling period had an R2 value for the linear regression of 0.74. ‘Kau’ macadamia had the greatest R2 value for the linear regression of 0.24 in the Dec. 2017 sampling period. The slopes of the two macadamia cultivars for June 2017 were different from each other, suggesting that N recommendations need to be customized for specific macadamia cultivars if sampled in summer. The chlorophyll meter can be used for general estimation of tissue N in macadamia. Additional methods need to be considered and researched to refine procedures for direct estimation of total N concentration when using the chlorophyll meter.

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

Sensors ◽

10.3390/s21165579 ◽

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.

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(347) Identifying Common Reflectance Properties in Diverse Ornamental Species to Nondestructively Determine Nitrogen Status

HortScience ◽

10.21273/hortsci.40.4.1060c ◽

2005 ◽

Vol 40 (4) ◽

pp. 1060C-1060

Author(s):

Jonathan M. Frantz ◽

Dharmalingam S. Pitchay ◽

Glen Ritchie ◽

Heping Zhu

Keyword(s):

Gray Mold ◽

Production Cycle ◽

Strongly Correlated ◽

N Concentration ◽

Derivative Analysis ◽

Leaf Chlorosis ◽

N Deficiency ◽

Whole Plants ◽

Ornamental Species

Nitrogen (N) is often supplied to plants in excess to minimize the possibility of encountering N deficiency that would reduce the plant quality due to leaf chlorosis and necrosis. This is not only costly, but it can reduce the quality of plants, predispose the plants to biotic stress such as Botrytisgray mold, and extend the production cycle. Several tools can be used to identify N deficiency in plants, and most are based on chlorophyll reflectance or transmittance. While sensitive when plants are experiencing N deficiency, spectral signals can saturate in an ample N supply and make it difficult to discern sufficient and supra-optimal N nondestructively. Three diverse ornamental species (begonia, Begoniacea×tuberhybrida; butterflybush, Buddlejadavidii; and geranium, Pelargonium×hortorum) were grown with a broad range of N supplied (1.8 to 58 mm) in three separate studies that resulted in a range of 1.8% to 6% tissue N concentration. Using a spectroradiometer, we measured reflectance from the whole plants twice over a period of 3 weeks. A first-derivative analysis of the data identified six wavebands that were strongly correlated to both begonia and butterflybush tissue N concentration (r2 ∼ 0.9), and two of these also correlated well to geranium N concentration. These wavebands did not correlate to chlorophyll peak absorbance, but rather blue, green, red, and far-red “edges” of known plant pigments. These wavebands hold promise for use as a nondestructive indicator of N status over a much broader range of tissue N concentration than current sensors can reliably predict.

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Nitrogen Nutrition of Containerized Citrus Nursery Plants

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.119.2.195 ◽

1994 ◽

Vol 119 (2) ◽

pp. 195-201 ◽

Cited By ~ 32

Author(s):

B.E. Maust ◽

J.G. Williamson

Keyword(s):

Citrus Sinensis ◽

Dry Weight ◽

Leaf Expansion ◽

Poncirus Trifoliata ◽

Growth Stages ◽

The Third ◽

N Concentration ◽

Total Plant ◽

Cleopatra Mandarin ◽

Critical N Concentration

Experiments were conducted with `Hamlin' orange [Citrus sinensis (L.) Osb.] budded on Cleopatra mandarin (Citrus reticulata Blanco) or Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.] seedling rootstocks to determine minimum container solution N concentrations required for optimum growth and fertilizer uptake efficiency at various growth stages. Plants were fertigated daily with 1 liter of N solution at either 0, 12.5, 25, 50, 100, or 200 mg·liter-1 from NH4NO3 or 0, 3.13, 6.25, 12.5, 25, or 50 mg·liter-1 from NH4NO3 dissolved in a complete nutrient solution, respectively. Percentage of N in the mature plant tissues increased as N concentration in the medium solution increased. Shoot length and leaf area increased as N concentrations increased up to a critical concentration of 15 to 19 mg·liter-1. The critical N concentration for root, shoot, and total plant dry weight was ≈18 mg·liter-1 for `Hamlin'-Cleopatra mandarin nursery plants and 15 mg·liter-1 for `Hamlin'-Carrizo nursery plants. The critical N concentration for relative total plant dry weight accumulation (percentage) for the two experiments was 16.8 mg·liter-1. In a separate experiment, plants were given labeled fertilizer N (FN) (15NH415NO3) at one of five growth stages: A) in the middle of rapid shoot extension of the third flush, B) immediately following the cessation of the third flush shoot extension but during leaf expansion, C) immediately following leaf expansion, D) before the fourth flush, or E) in the middle of rapid shoot extension of the fourth flush. Labeled FN recovery increased during rapid shoot extension of the fourth scion flush compared to the other labeling periods. FN uptake per gram of total plant dry weight was greatest during rapid shoot extension (A and E) and lowest during the intermediate labeling periods (B-D). FN supplied 21% to 22% of the N required for new growth during rapid shoot extension.

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