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Plant analysis as a tool to determine crop nitrogen status

towards leaf area based measurements

Ekbladh, Göran (2007). Plant analysis as a tool to determine crop nitrogen status. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:109
ISBN 978-91-85913-08-4
[Doctoral thesis]

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An effective plant nutrient management strategy optimises nitrogen (N) use efficiency for minimised environmental impact, while ensuring an optimum N status of the crop for good product quality and maximum growth. Soil or plant analysis can be used to evaluate the strategy; however the use of plant analysis for this purpose has been limited. One reason is lack of reliable reference values for the critical concentration needed for optimal growth. This study builds on theories that relate ontogenetic changes in the critical N concentration to changes in the relation between mass and surface area of the entire plant and of individual leaves. Through the establishment of critical N concentrations on the basis of these theories, some of the drawbacks hitherto experienced with plant analysis, such as difficulties in defining growth stage or plant part to sample, can be avoided. The aim of this thesis was to establish critical N concentrations for white cabbage (Brassica oleracea L. var. capitata L. f. alba D.C.) on the basis of these theories. Multi-N-rate and multi-harvest experiments were conducted in the field and in a climate chamber. The results showed that the critical N concentration declined at the same rate (-0.33) as the plant's leaf area ratio (leaf area divided by plant mass), which is in agreement with the 2/3-Power rule or "skin-core" hypothesis. The critical N concentration (% of DM) on a whole plant basis was estimated to 4.5 (W<1.5 t ha-1) and to 5.1W-0.33 (W>1.5 t ha-1), where W is weight per unit area of plant dry matter exclusive of roots. Moreover, it was concluded that the unshaded horizontally orientated leaves of cabbage can be used for leaf area based plant analysis of individual leaves. The critical N concentration of these leaves expressed on an area basis was found to be 3.7 g N m-2, while that for the whole plant N on a leaf area basis was 4.7 g N m-2. The ratio of these two critical concentrations, 0.8, was similar to the leaf N ratio (leaf N/whole plant N) of young plants before self shading occurs.

Authors/Creators:Ekbladh, Göran
Title:Plant analysis as a tool to determine crop nitrogen status
Subtitle:towards leaf area based measurements
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:50
ALLI. Göran Ekbladh, Ernst Witter, Tom Ericsson, 2007. Ontogenetic decline in the nitrogen concentration of field grown white cabbage – Relation to growth components. Scientia Horticulturae, 112, 149-155. II. Göran Ekbladh, Tom Ericsson, Ernst Witter. Ontogenetic changes in the nitrogen concentration of white cabbage — I. Relation to relative growth rate and its components (Manuscript) III. Göran Ekbladh, Tom Ericsson, Ernst Witter. Ontogenetic changes in the nitrogen concentration of white cabbage — II. Leaf-area-based assessments on individual leaves (Manuscript) IV. Göran Ekbladh, Ernst Witter. Determination of the critical nitrogen concentration of white cabbage (Manuscript)
Place of Publication:Uppsala
Associated Programs and Other Stakeholders:Z - SLU - Library > Odla mera
ISBN for printed version:978-91-85913-08-4
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:brassica oleracea capitata, vegetable crops, leaves, tissue analysis, leaf area, nitrogen content, chemical composition, plant nutrition
Keywords:critical nitrogen concentration, ontogenetic decline, leaf area ratio, leaf nitrogen ratio, specific leaf nitrogen
Permanent URL:
ID Code:1621
Department:(NL, NJ) > Dept. of Soil Sciences (until 081001)
Deposited By: Göran Ekbladh
Deposited On:08 Nov 2007 00:00
Metadata Last Modified:22 Mar 2015 15:13

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