Theoretical Determination of a Critical Nitrogen Dilution Curve Based on the Carrot Case Study

Eli Shlevin, Arkadi Zilberman, Jiftah Ben-Asher

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The objectives of the present study were to: (a) formulate a general dilution equation for a critical nitrogen percentage in a leaf (Nc); (b) monitor dilution function of carrot as a case study; (c) demonstrate applicability of digital color imaging to monitor total nitrogen (Ntot) in crops. Carrot (Daucus carota) was grown on loess soil at five Ntot application rates. Ntot weight (kg/ha) was obtained by standard laboratory analysis and by image processing. Total yield of the treatments was the sum of canopy and roots dry matter. A new logistic decay curve Nc = a/[1 + (W/W0)b] agreed with experimental data. Nc (g/kg) is the critical nitrogen level, a and b are coefficients, and W/W0 is the relative dry matter biomass. Values of Nitrogen Nutrition Index (NNI) ≥ 1.0 indicated that there was no nitrogen deficiency in treatment larger than 100% application of Ntot. The weight of nitrogen in form of multiplication of the dry leaves weight (W) and N percent is suitable for the determination of nitrogen status. The availability of image-based data for N percent is faster, timely and less expensive than that of laboratory test. Applicability of digital color camera to monitor Ntot in crops instead of laboratory test was successfully demonstrated.

Original languageEnglish
Pages (from-to)239-244
Number of pages6
JournalAgricultural Research
Issue number2
StatePublished - 1 Jun 2018
Externally publishedYes


  • Color imaging
  • Days after planting
  • Dry matter weight
  • Nitrogen Nutritional Index (NNI)
  • Slow release fertilizer

ASJC Scopus subject areas

  • Food Science
  • Agronomy and Crop Science
  • Plant Science


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