Precision Agriculture

, Volume 7, Issue 4, pp 281–293

Distinguishing nitrogen deficiency and fungal infection of winter wheat by laser-induced fluorescence

  • Iryna I. Tartachnyk
  • Ingo Rademacher
  • Walter Kühbauch
Article

DOI: 10.1007/s11119-006-9008-7

Cite this article as:
Tartachnyk, I.I., Rademacher, I. & Kühbauch, W. Precision Agric (2006) 7: 281. doi:10.1007/s11119-006-9008-7

Abstract

One of the most important tasks in precision farming is the site-specific application of fertilisers and pesticides in heterogeneous large-area fields. For such site-specific crop management, effective remote sensing methods for the detection of crop diseases and nutrient deficiencies are required. The aim of the present work was to compare laser-induced fluorescence (LIF) parameters from nitrogen-deficient and pathogen (rust and mildew)-infected winter wheat (Triticum aestivum L.) plants and to assess the potential of LIF to detect and discriminate between these types of stress. Both long term nitrogen deficiency and pathogen infection resulted in an increase of the ratio of fluorescence at 686 and 740 nm (F686/F740) accompanied by a reduction of leaf chlorophyll content to approximately 35 μg cm−2. A linear negative correlation between chlorophyll content and F686/F740 ratio (r= 0.78) was found for leaves with chlorophyll content ranging between 17 and 52 μg cm−2. Since chlorophyll breakdown appeared an unspecific symptom to both nitrogen deficiency and pathogen infection, it was not possible to discriminate between these types of stress only by means of the F686/F740 ratio. Specific for the pathogen-infected leaves was a large heterogeneity in the records of their spectral parameters caused by inhomogeneous, discrete lesions of fungi infection. Nitrogen-deficient plants with homogeneous reduction in chlorophyll content showed, in contrast, more uniform readings of the spectral parameters. Thus, mildew- and rust-infected plants, grown under sufficient nitrogen fertilisation could be distinguished from those grown under reduced nitrogen supply by the higher variance of their spectral readings. The simultaneous scanning multipoint mode measurements of LIF and laser light reflection characteristics with parallel estimation of their heterogeneity is proposed for the discrimination between nitrogen deficiency and pathogen infection under field conditions.

Keywords

LIFChlorophyllRustMildewNitrogen deficiency

Abbreviations

LIF

laser-induced fluorescence

PS

photosystem

F686, F740

fluorescence intensity at 686 nm and 740 nm

RL633

intensity of laser light reflection at 633 nm

Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • Iryna I. Tartachnyk
    • 1
  • Ingo Rademacher
    • 1
  • Walter Kühbauch
    • 1
  1. 1.Department of Crop and Horticultural Sciences, Institute of Crop Science and Resource ConservationUniversity of BonnBonnGermany