1. Graduate Research Assistant, Agricultural and Biological Engineering Dept., Univ. of Florida, P.O. Box 110570, Gainesville, FL 36211-0570.
2. Assistant Professor, Agricultural and Biological Engineering Dept., Univ. of Florida, P.O. Box 110570, Gainesville, FL 32611-0570 (corresponding author).
3. Associate Professor, Environmental Horticulture Dept., Univ. of Florida, P.O. Box 110570, Gainesville, FL 32611-0570.