1. Research Associate, Dept. of Agricultural and Biological Engineering, Univ. of Florida, Gainesville, FL 32611-0570.
2. Associate Professor, Dept. of Agricultural and Biological Engineering, Univ. of Florida, P.O. Box 110570, Gainesville, FL 32611-0570 (corresponding author).
3. Professor, Dept. of Crop Science, North Carolina State Univ., Raleigh, NC 27695.