Expression of Spatial Variability in Corn (Zea mays L.) as Influenced by Growth Stage Using Optical Sensor Measurements By-Plant Prediction of Corn (Zea mays L.) Grain Yield Using Optical Sensor Readings and Measured Plant Height K.L. Martin, W.R. Raun, M.L. Stone, J.B. Solie, K.W. Freeman, B. Tubana, B. Chung, R.K. Teal, D.B. Arnall, K. Desta, S. Moges, C.J. Mack, J.W. Lawless, O. Walsh, S. Holtz, K. Lawless

Expression of Spatial Variability in Corn (Zea mays L.) as Influenced by Growth Stage Using Optical Sensor Measurements Four rows (30 m long) at each location (2 locations, 2 years) In 2004, 2 rows of low population and 2 rows of high population at each site Accumulate NDVI readings using a GreenSeeker™ hand held sensor throughout the growing season Evaluate NDVI and CV of NDVI readings over time Four rows (30 m long) at each location (2 locations, 2 years) In 2004, 2 rows of low population and 2 rows of high population at each site Accumulate NDVI readings using a GreenSeeker™ hand held sensor throughout the growing season Evaluate NDVI and CV of NDVI readings over time

Collect biomass and grain yield by harvesting each individual plant and computing yield in kg ha -1 for the entire row. Evaluate relationships between NDVI and biomass yield, grain yield, and plant spacing Evaluate relationships between CV and biomass yield, grain yield, and plant spacing Collect biomass and grain yield by harvesting each individual plant and computing yield in kg ha -1 for the entire row. Evaluate relationships between NDVI and biomass yield, grain yield, and plant spacing Evaluate relationships between CV and biomass yield, grain yield, and plant spacing

NDVI Over Time V3 V6 VT R4 V6 VT R4 V3 V6 VT R4

CV Over Time V3 V6 VT R4 V6 VT R4 V3 V6 VT R4

Relationship of NDVI and CV of NDVI with Corn Grain and Biomass Yields

By-Plant Prediction of Corn Grain Yield This bicycle was modified such that a GreenSeeker™ sensor head, power source, and shaft encoder could be used to determine distance for each NDVI reading recorded in the data file. Measure the distance of each plant’s location Calculate the area that each plant occupies Where: Di is the area occupied by the i th plant di-1,di,di+1 are the distances to the i-1, i, and i+1 plants Average NDVI of each plant Measure the distance of each plant’s location Calculate the area that each plant occupies Where: Di is the area occupied by the i th plant di-1,di,di+1 are the distances to the i-1, i, and i+1 plants Average NDVI of each plant

The unit was pushed along the corn row as illustrated White marker plates were used at the beginning and end of each row to designate the start and stop point The resulting data file included NDVI for each calibrated distance (approximately 1.1 cm) and sonar height (when sonar was used) The unit was pushed along the corn row as illustrated White marker plates were used at the beginning and end of each row to designate the start and stop point The resulting data file included NDVI for each calibrated distance (approximately 1.1 cm) and sonar height (when sonar was used)

Data Presentation Individual data points collected every 1.1 cm Average NDVI for each plant

NDVI vs. Grain Yield at all sites (2003 and 2004) INSEY vs. Grain Yield at all sites where height was recorded

Plant Height and Corn Grain Yield Prediction Plant height was used as a means of evaluating plant competition. Competition can be defined as: 1. The process by which the activity or presence of one substance interferes with or suppresses the activity of another substance with similar affinities, as of antigens. 2. The simultaneous demand by two or more organisms for limited environmental resources. 3. The simultaneous demand by two or more organisms for limited environmental resources, such as nutrients, living space, or light. Source: The American Heritage® Dictionary (2000) Plant height was used as a means of evaluating plant competition. Competition can be defined as: 1. The process by which the activity or presence of one substance interferes with or suppresses the activity of another substance with similar affinities, as of antigens. 2. The simultaneous demand by two or more organisms for limited environmental resources. 3. The simultaneous demand by two or more organisms for limited environmental resources, such as nutrients, living space, or light. Source: The American Heritage® Dictionary (2000)

Do these plants compete with one another? If they do, what above ground parameter(s) can we use to evaluate this? Does the proximity of the competitor have an impact on the level of competition? Do these plants compete with one another? If they do, what above ground parameter(s) can we use to evaluate this? Does the proximity of the competitor have an impact on the level of competition?

Plant Competition Equation In a series of five plants, the height of plant number 2 and 4 is compared to the average of the height of their neighbors to assess the competitive ability of plants 2 and 4 as compared to the plant in question, plant 3. This value generated from the first step of this process (weighted average value of plant 2 and 4 in the series) is then compared to the actual height of plant 3 to result in a weighted comparison of the competitive ability of plant 3 to its neighbors

GYest is the estimated grain yield Cadj is the competition adjustment factor D is the linear distance occupied by each plant INSEY is the in-season estimate of yield GYest is the estimated grain yield Cadj is the competition adjustment factor D is the linear distance occupied by each plant INSEY is the in-season estimate of yield The competition adjustment factor accounts for the competitive ability of the plant in question when considering its height against those that surround it. This value is then divided by the linear distance to adjust the index due to the change in proximity of the competitive plants (a closer proximity to the competitive plant will divide by a smaller number resulting in more emphasis being placed on the height comparison). The resulting value is then multiplied by INSEY to allow for an incorporation of biomass produced per day.

By-Plant Prediction of Corn Grain Yield Yield Prediction Using INSEY Yield Prediction Using GY est

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