Determination of a fungal infection of a plant by chlorophyll fluorescence induced by different excitation wavelengths

• US 9,921,162 B2
• Filed: 12/17/2014
• Issued: 03/20/2018
• Est. Priority Date: 12/18/2013
• Status: Active Grant

• Current Assignee: BASF SE
• Original Assignee: BASF SE
• Inventors: Tischler, Ylva, Hartung, Eberhard, Thiessen, Eiko
• Primary Examiner(s): Jo, Taeho
• Application Number:
  US15/105,056
• Publication Number:
  US 20160349180A1
• Time in Patent Office: 1,189 Days
• Field of Search: 2504591
• CPC Class Codes: A01G 7/045 with electric lighting
• CPC Class Codes: G01N 2021/635 Photosynthetic material analysis, e.g. chrorophyll
• CPC Class Codes: G01N 2021/6419 Excitation at two or more wavelengths
• CPC Class Codes: G01N 21/6486 Measuring fluorescence of biological material, e.g. DNA, RNA, cells G01N21/6428 takes precedence
• CPC Class Codes: G01N 2201/062 LED's
• CPC Class Codes: G01N 33/0098 Plants or trees wood G01N33/46

Abstract

The present invention relates to a method for determining a fungal infection of a plant—The method comprises: emitting excitation radiation by one or more radiation sources to the plant, said radiation comprising first excitation wavelengths being within the absorption band of a compound whose content in the plant is affected by a fungal infection, in particular a phenolic compound, and second excitation wavelengths being outside the absorption band of said compound, thereby inducing chlorophyll fluorescence; detecting chlorophyll fluorescence radiation from the plant; and obtaining a value being indicative for the fungal infection of the plant, said value is dependent from the detected chlorophyll fluorescence radiation induced by excitation radiation of the first excitation wavelengths and the detected chlorophyll fluorescence radiation induced by excitation radiation of the second excitation wavelengths. Moreover, the present invention relates to a detection device, in particular a mobile detection device, for carrying out this method.

Claims

1. A method for determining a fungal infection affecting the content of a phenolic compound of a plant, comprising:

determining a change in the content of the phenolic compound of the plant comprising;

providing an excitation radiation by one or more radiation sources to the plant, said radiation comprising first excitation wavelengths being within the absorption band of the phenolic compound and second excitation wavelengths being outside the absorption band of said phenolic compound, thereby inducing chlorophyll fluorescence;

detecting only the chlorophyll fluorescence radiation from the plant; and

obtaining a variation of a value being indicative for the fungal infection of the plant, said value is dependent from the detected chlorophyll fluorescence radiation induced by excitation radiation of the first excitation wavelengths and the detected chlorophyll fluorescence radiation induced by excitation radiation of the second excitation wavelengths.

2. The method of claim 1, wherein said providing excitation radiation includes illuminating electromagnetic radiation to the plant and filtering said illuminated electromagnetic radiation to said first excitation wavelengths being within the absorption band of the compound whose content in the plant is affected by the fungal infection and to said second excitation wavelengths being outside the absorption band of said compound.

3. The method of claim 1, wherein the value is dependent from the ratio of the detected chlorophyll fluorescence radiation induced by excitation radiation of the first excitation wavelengths and the detected chlorophyll fluorescence radiation induced by excitation radiation of the second excitation wavelengths.

4. The method of claim 1, wherein said first excitation wavelengths are in a range from 200 nm to 400 nm and said second excitation wavelengths are in a range from 450 nm to 650 nm.

5. The method of claim 4, wherein said first measurement wavelength is between 670 nm and 700 nm and said second measurement wavelength is between 715 nm and 745 nm.

6. The method of claim 1, wherein the chlorophyll fluorescence radiation from the plant is detected for at least a first and second measurement wavelengths, said first and second measurement wavelengths being different.

7. The method of claim 6, wherein analyzing the detected chlorophyll fluorescence radiation at the first measurement wavelength relative to the detected chlorophyll fluorescence radiation at the second measurement wavelength thereby determining the reduction of chlorophyll concentration in the plant tissue.

8. The method of claim 1, wherein said excitation radiation comprises at least four different discrete excitation wavelengths and wherein said value is dependent from the detected chlorophyll fluorescence radiations induced by excitation radiation of said at least four discrete excitation wavelengths.

9. The method of claim 1, wherein the excitation radiation radiates one or more leaves of the plant.

10. The method of claim 1, wherein the plant is irradiated from a distance larger than 10 cm and less than 10 m.

11. A detecting device for determining a fungal infection affecting the content of a phenolic compound of a plant, comprising:

one or more radiation sources for emitting providing excitation radiation to the plant, said radiation comprising first excitation wavelengths being within the absorption band of the phenolic compound and second excitation wavelengths being outside the absorption band of said phenolic compound, thereby inducing chlorophyll fluorescence;

a detector comprising one or more optical filters that only allow wavelengths to pass that relate chlorophyll fluorescence radiation for detecting chlorophyll fluorescence radiation from the plant; and

an analyzing unit coupled with the detector for obtaining a variation of a value being indicative for the fungal infection of the plant, said analyzing unit is adapted to calculate said value in dependence from the detected chlorophyll fluorescence radiation induced by excitation radiation of the first excitation wavelengths and the detected chlorophyll fluorescence radiation induced by excitation radiation of the second excitation wavelengths.

12. The detecting device of claim 11, wherein the detector comprises one or more optical elements having an entrance pupil at infinity.

13. The detecting device of claim 11, wherein said optical elements are arranged to form a telecentric lense system.

14. The detecting device of claim 11, wherein the radiation sources are light-emitting diodes.

15. The detecting device of claim 14, wherein the light-emitting diodes emit at least four different discrete excitation wavelengths.

16. The detecting device of claim 11, wherein the detector is adapted to detect the chlorophyll fluorescence radiation for at least a first and second measurement wavelengths, said first and second measurement wavelengths being different.

17. The detecting device of claim 11, wherein said detecting device is a mobile detecting device.

18. An apparatus for determining a fungal infection of a plant comprising the detecting device of claim 11.

19. The apparatus of claim 18, wherein said apparatus is a vehicle or a satellite.

20. The apparatus of claim 18, wherein said apparatus is fixed on the plant field.