Nitrogen Distribution Within a Lucerne Canopy During Regrowth: Relation With Light Distribution

Lemaire, G.; Onillon, B.; Gosse, Ghislain; Chartier, Michel; Allirand, Jean Michel

doi:10.1093/oxfordjournals.aob.a088286

Cited by 144 publications

(71 citation statements)

References 12 publications

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“…Given these hypotheses and factors, there are complicated mechanistic models to quantitatively describe the vertical profiles of nitrogen distribution within plant canopies which employ the Beer-Lambert law with an exponential function. However, these models tend to contain numerous parameters, such as cumulative LAI from the top of the canopy, the total LAI of the canopy, the coefficient of light extinction, the depth from the top of the canopy, the intercepted photosynthetically active radiation (IPAR), and the nitrogen content per unit leaf area at the top [47,[49][50][51][52]. These models can only provide explanations for some phenomena and are difficult to be implemented in practical applications due to the unavailability of numerous parameters in the models.…”

Section: Discussionmentioning

confidence: 99%

Estimating the Total Nitrogen Concentration of Reed Canopy with Hyperspectral Measurements Considering a Non-Uniform Vertical Nitrogen Distribution

Luo

Feng

et al. 2016

Remote Sensing

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Abstract:The total nitrogen concentration (NC, g/100 g) of wetland plants is an important parameter to estimate the wetland health status and to calculate the nitrogen storage of wetland plants. Remote sensing has been widely used to estimate biophysical, physiological, and biochemical parameters of plants. However, current studies place little emphasis on NC estimations by only taking nitrogen's vertical distribution into consideration, resulting in limited accuracy and decreased practical value of the results. The main goal of this study is to develop a model, considering a non-uniform vertical nitrogen distribution to estimate the total NC of the reed canopy, which is one of the wetland's dominant species, using hyperspectral data. Sixty quadrats were selected and measured based on an experimental design that considered vertical layer divisions within the reed canopy. Using the measured NCs of different leaf layers and corresponding spectra from the quadrats, the results indicated that the vertical distribution law of the NC was distinct, presenting an initial increase and subsequent decrease from the top layer to the bottom layer. The spectral indices MCARI/MTVI2, TCARI/OSAVI, MMTCI, DCNI, and PPR/NDVI had high R 2 values when related to NC (R 2 > 0.5) and low R 2 when related to LAI (R 2 < 0.2) and could minimize the influence of LAI and increase the sensitivity to changes in NC of the reed canopy. The relative variation rates (R v , %) of these spectral indices, calculated from each quadrat, also indicated that the top three layers of the reed canopy were an effective depth to estimate NCs using hyperspectral data. A model was developed to estimate the total NC of the whole reed canopy based on PPR/DNVI with R 2 = 0.88 and RMSE = 0.37%. The model, which considered the vertical distribution patterns of the NC and the effective canopy layers, has demonstrated great potential to estimate the total NC of the whole reed canopy.

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Section: Discussionmentioning

confidence: 99%

Estimating the Total Nitrogen Concentration of Reed Canopy with Hyperspectral Measurements Considering a Non-Uniform Vertical Nitrogen Distribution

Luo

Feng

et al. 2016

Remote Sensing

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“…RUE total ) seems a logical adaptation strategy for lucerne in the early stages of regrowth. The subsequent recover of photosynthetic capacity can be explained by the translocation of nitrogen from shaded senesced leaves (at the base of the canopy) to photosynthesizing leaves in the upper canopy (Lemaire and Gastal, 1997;Lemaire et al, 1991) at the same time when the absolute N uptake is increasing (Kim et al, 1991). These patterns support the rationale of a functional equilibrium between shoots and roots in which the balance between supply and demand for assimilates (C and N) within the whole plant determine growth of each organ (Lemaire and Millard, 1999).…”

Section: Physiological and Modelling Implicationsmentioning

confidence: 99%

Defoliation frequency and season affected radiation use efficiency and dry matter partitioning to roots of lucerne (Medicago sativa L.) crops

Teixeira

Moot

Brown

2008

European Journal of Agronomy

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ranged from 1.3 to 3.1 g DM/MJ PAR i in response to air temperature and defoliation treatment. The lowest RUE total in mid summer for the treatment defoliated every 28 days was related to a 20% decline in the leaf photosynthetic capacity measured at 1000 μmol photons/m 2 .s (Pn 1000 ) and at saturating light (P max ). In turn, the reduction in Pn 1000 was related to differences in specific leaf nitrogen (SLN), through changes in specific leaf weight (SLW) rather than the leaf N concentration of 4 to 6% DM. Agronomic treatments that result in sub optimal N reserves post grazing can be expected to produce conservative canopy characteristics but reduced photosynthetic capacity of the first 5 main stem leaves. Beyond this development stage, canopy expansion may be reduced with more conservative leaf N.

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“…Pour des associations présentant une structure en rangs alternés, la comparaison des teneurs en azote peut être effectuée sur la base de la biomasse foliaire par mètre linéaire d'un rang (Cruz et Lemaire, 1986b) (Gastal et Saugier, 1986 (Charles-Edwards et al, 1987 ;Lemaire et al, 1991 ;Soussana et al, 1995b). Une augmentation de l'éclairement moyen pourrait donc s'accompagner d'une moindre dilution de l'azote foliaire chez le ray-grass associé.…”

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Impact de l'association sur le niveau de nutrition azotée et la croissance du ray-grass anglais et du trèfle blanc

Soussana¹,

Arregui²

1995

Agronomie

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Nitrogen Distribution Within a Lucerne Canopy During Regrowth: Relation With Light Distribution

Cited by 144 publications

References 12 publications

Estimating the Total Nitrogen Concentration of Reed Canopy with Hyperspectral Measurements Considering a Non-Uniform Vertical Nitrogen Distribution

Estimating the Total Nitrogen Concentration of Reed Canopy with Hyperspectral Measurements Considering a Non-Uniform Vertical Nitrogen Distribution

Defoliation frequency and season affected radiation use efficiency and dry matter partitioning to roots of lucerne (Medicago sativa L.) crops

Impact de l'association sur le niveau de nutrition azotée et la croissance du ray-grass anglais et du trèfle blanc

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