PLANT TREATMENT BASED ON A WATER INVARIANT CHLOROPHYLL INDEX

• US 20110047867A1
• Filed: 10/01/2010
• Published: 03/03/2011
• Est. Priority Date: 11/07/2003
• Status: Active Grant

• Current Assignee: Kyle H. Holland Trustee Of The Maranatha Trust
• Original Assignee: Kyle H. Holland Trustee Of The Maranatha Trust
• Inventors: HOLLAND, KYLE H.
• Granted Patent: US 9,075,008 B2
• Time in Patent Office: Days
• US Class Current: 47/1.5
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01N 2021/3155 Measuring in two spectral ranges, e.g. UV and visible
• CPC Class Codes: G01N 2021/635 Photosynthetic material analysis, e.g. chrorophyll
• CPC Class Codes: G01N 2021/8466 Investigation of vegetal material, e.g. leaves, plants, fruits
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/3563 for analysing solids; Preparation of samples therefor
• CPC Class Codes: G01N 21/55 Specular reflectivity
• CPC Class Codes: G01N 2201/1244 Ambient light detector, e.g. for invalidating

Abstract

A method and system of treating plants is provided. The method includes measuring optical properties of a plant using a plurality of spectral bands. The method further includes calculating in a computational device at least two vegetative indexes using the optical properties, each of the at least two vegetative indexes correlating to one or more plant growth parameters. The method further includes calculating in the computational device a water invariant chlorophyll index from at least two vegetative indexes using the plurality of spectral bands. The also provides for treating one or more of the plants based on the water invariant chlorophyll index.

Claims

1. A method of treating plants, comprising:

measuring optical properties of a plant using a plurality of spectral bands;

calculating in a computational device at least two vegetative indexes using the optical properties, each of the at least two vegetative indexes correlating to one or more plant growth parameters;

calculating in the computational device a water invariant chlorophyll index from at least two vegetative indexes using the plurality of spectral bands; and

treating one or more of the plants based on the water invariant chlorophyll index.

2. The method of claim 1 wherein the method is performed in real-time.

3. The method of claim 1 wherein the plurality of spectral bands comprise at least three spectral bands.

4. The method of claim 1 wherein the measuring optical properties of a plant using a plurality of spectral bands comprises:

(a) simultaneously projecting light of a first, visible wavelength from a solid-state polychromatic light source, and light of a second, infrared wavelength from the light source, modulating the first and second light sources, and setting and monitoring optical power of the first and second light sources;

(b) receiving reflected visible light originating from the light source in a reflected light receiver comprising a first photodetector sensitive to visible light, and reducing the effects of ambient light on the first photodetector in an ambient light compensation means to provide a first output;

(c) configuring the photodetectors for each of the plurality of spectral bands by applying at least one spectral selectivity means to at least one of the photodetectors, wherein the spectral selectivity means is fitted to removably attach to the photodetector;

(d) positioning a second photodetector sensitive to infrared light to receive reflected infrared light originating from the light source, and reducing the effects of ambient light on said second photodetector in an ambient light compensation means to provide a second output;

(e) distinguishing the light originating from said light source and reflected by the object from ambient light.

5. The method of claim 1 wherein the measuring optical properties of a plant using a plurality of spectral bands comprises:

(a) simultaneously projecting light of a first, visible wavelength from a solid-state polychromatic light source, light of a second, red-edge wavelength from a solid-state polychromatic light source, and light of a third, infrared wavelength from the light source, modulating the first, second and third light sources, and setting and monitoring optical power of the first and second light sources;

(b) receiving reflected visible light originating from the light source in a reflected light receiver comprising a first photodetector sensitive to visible light, and reducing the effects of ambient light on the first photodetector in an ambient light compensation means to provide a first output;

(c) configuring the photodetectors for each of the plurality of spectral bands by applying at least one spectral selectivity means to at least one of the photodetectors, wherein the spectral selectivity means is fitted to removably attach to the photodetector;

(d) positioning a second photodetector sensitive to infrared light to receive reflected infrared light originating from the light source, and reducing the effects of ambient light on said second photodetector in an ambient light compensation means to provide a second output;

(e) distinguishing the light originating from said light source and reflected by the object from ambient light.

6. The method of claim 1, wherein the step of treating comprises applying an agricultural treatment to the one or more plants with an applicator.

7. The method of claim 1 wherein the method is performed on an agricultural implement within a field.

8. A method of treating plants, comprising:

measuring optical properties of one or more plants across three or more spectral bands;

calculating in a computational device at least two vegetative indexes using the optical properties, each of the at least two vegetative indexes correlating to one or more plant growth parameters;

calculating in the computational device a water invariant chlorophyll index from at least two vegetative indexes using the plurality of spectral bands; and

treating the plants based on the water invariant chlorophyll index.

9. The method of claim 8 wherein the step of treating is performed using an applicator.

10. The method of claim 8 wherein the method is performed on an agricultural implement within a field.

11. A system for treating plants, comprising:

an optical sensing system configured to measure optical properties of one or more plants across three or more spectral bands;

an applicator for selectively applying treatment to the plants;

a controller operatively connected to the optical sensing system and the applicator and configured to (a) calculate at least two vegetative indexes using the optical properties, each of the at least two vegetative indexes correlating to one or more plant growth parameters, (b) calculate a water invariant chlorophyll index from at least two vegetative indexes using the plurality of spectral bands, and (c) control the applicator to provide for selectively applying treatment to the plants based on the water invariant chlorophyll index.

12. The system of claim 11 wherein the optical sensing system comprises a light sensor for measuring the reflectance of an object, comprising:

(a) a polychromatic light source simultaneously emitting visible light and infrared light with a modulator of the light source, and apparatus to set and monitor optical power of the light source;

(b) a reflected light receiver comprised of an array of photodetectors comprised of at least one photodetector sensitive to visible light positioned to receive reflected light originating from the light source and including ambient light compensation means for reducing the effects of ambient light on the photodetector and a first output, and at least one photodetector sensitive to nonvisible light positioned to receive reflected light originating from said light source and including an ambient light compensator for reducing the effects of ambient light on said second photodetector and a second output; and

(c) a detector for distinguishing the light originating from the light source and light reflected by the object from ambient light.

13. The system of claim 11 wherein the optical sensing system provides for measuring reflectance and reducing effects of ambient light in measuring the reflectance.

14. A method for measuring a plant'"'"'s reflectance, comprising the steps of:

(a) modulating a light source comprised of one or more LEDS that emit light in the spectral range of 350 nm to 480 nm having a phosphorescent coating, and

(b) detecting light originating from the light source reflected off of the plant in the presence of ambient light in one or more spectrally sensitive photodetectors.

15. The method of claim 14, wherein the phosphor coating comprises one or more rare earth elements selected from the group consisting of cerium, yttrium, terbium, gadolinium, and europium.

16. The method of claim 14 further comprising monitoring and stabilizing intensity of the light source.

17. The method of claim 14 further comprising calculating a vegetation index using detected light.

18. The method of claim 15 further comprising performing spectral selectivity using a narrowband optical filter.

19. The method of claim 18 wherein the narrowband optical filter is configurable.

20. The method of claim 18 further comprising reducing specular reflections using polarizing filters.

21. The method of claim 14 further comprising performing spectral selectivity using a linear variable filter.

22. The method of claim 14 further comprising performing spectral selectivity using a diffraction grating.

23. The method of claim 14 wherein the ambient light is sunlight.

24. The method of claim 14 wherein the phosphor re-emits light from an LED light source.

25. The method of claim 14 wherein the phosphor emits low color temperature white light.

26. The method of claim 14 wherein the phosophor emits green, yellow, orange, or red light.

27. The method of claim 14 further comprising mounting the light sensor on a moving vehicle.

28. A method of treating plants, comprising:

measuring optical properties of a plant using at least three spectral bands;

determining by a computational device a treatment for one or more of the plants using the optical properties; and

applying the treatment to the one or more of the plants.

29. The method of claim 28 wherein the optical properties are correlated to plant growth parameters.

30. The method of claim 28 wherein the optical properties are correlated to chlorophyll levels within the plant.

31. The method of claim 28 wherein the step of determining by the computational device the treatment is based at least in part on effects of water related stresses on the plant.

32. The method of claim 28 wherein the step of determining provides for using a first of the plurality of bands with a first index and a second of the plurality of bands with a second index.

33. A system for treating plants, comprising:

an optical sensing system configured to measure optical properties of one or more plants across a plurality of spectral bands;

an applicator for selectively applying treatment to the plants;

a controller operatively connected to the optical sensing system and the applicator and configured to control the application of the treatment based on properties of the one or more plants determined from the optical properties, and one or more indexes that relate the properties of the one or more plants to the optical properties.

34. The system of claim 33 wherein the one or more indexes include at least one index selected based on leaf area.

35. The system of claim 33 wherein a first of the one or more indexes is associated with a first of the spectral bands and a second of the one or more indexes is associated with a second of the spectral bands.

36. The system of claim 33 wherein the controller is configured to select the one or more indexes based on leaf area.

37. The system of claim 33 wherein the plurality of bands include four or more bands.

38. A method of treating plants, comprising:

measuring optical properties of a plant using a plurality of spectral bands;

calculating in a computational device at least two vegetative indexes using the optical properties, each of the at least two vegetative indexes correlating to one or more plant growth parameters, wherein a first of the vegetative indexes is used for low leaf area index and a second of the vegetative indexes is used for a high leaf area index.

39. The method of claim 38 wherein the plurality of spectral bands include three or more bands.

40. The method of claim 38 wherein the plurality of spectral bands include four or more bands.

41. The method of claim 38 wherein at least one of the plurality of spectal bands is associated with chlorophyll.

42. The method of claim 38 wherein one of the plurality of spectral bands is associated with water.