1. Indirect Measurement of Plant Height in Cotton (Gossypium hirsutum) Pam Turner Oklahoma State University

2. M-5000/95 Conical Beam Angle 8 o Min. Distance 1 ft Max. Distance 13 ft Output units 20 mAmps Operating temp. -20 o C to 65 o C ‘MassaSonic’ Ultrasonic Sensor

3. 1)Measure and record height from ground to face of sensor 2)Place sensor over plant. It must be 4 – 40 inches from the plant. 3)Record reading provided by sensor (mAmps). Fifty readings are taken at each growth stage. 4)Convert mAmps to inches. = 3.7809 x Voltage Reading - 3.1698 5) Value subtracted from sensor height to give plant height. Sonar Measurement Methods

4. Hand Measurement 1)Measure and record the distance between plant and face of sensor. 2)Using Microsoft Office Excel, subtract height of sensor from hand measured height to get plant height. Methods

5. Growth Stage: 17 Leaf Sensor Height: 47.25 in. (120 cm) from ground View Diameter 6.59 cm

6. Growth Stage: Square Growth Midpoint Sensor Height: 41.5 in. (105.4 cm) from ground View Diameter 5.79 cm

7. Growth Stage: White Bloom Sensor Height: 43 in. (109.2 cm) from ground View Diameter 5.99 cm

8. Growth Stage: Flowering 5-7 Days Sensor Height: 43 in. (109.2 cm) from ground View Diameter 5.99 cm

9. Growth Stage: Developing Boll Sensor Height: 42.5 in. (107.9 cm) from ground View Diameter 5.92 cm

10. Growth Stage: Developing Boll Sensor Height: 55 in. (139.7 cm) from ground View Diameter 7.67 cm

11. Cotton Sonar Height y = 0.96x + 4.39 R 2 = 0.95

12. Plant Development 2006 17 Leaf Square Growth Midpoint Developing Boll

13. Conclusions Where OSU cotton research is going… Establish relationship between measuring plants by hand and measuring plants with ultrasonic sensor Develop a benchmark setting for cotton to look at plant or target biomass NDVI Establish a method for yield prediction