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SUMMARYA prototype robot for picking citrus is described which utilized real-time, color machine vision to vision-servo the robot on a targeted fruit. A programming technique is presented which simplified development of the task-level, robot control program. An economic evaluation of robotic harvesting in Florida determined that robotic harvesting would be approximately 50 percent more expensive than conventional hand harvesting. Harvest inefficiency was identified as the most influential factor affecting robotic harvesting economics. Field trial performance is summarized and the potential of commercial robotic harvesting discussed.

Callus Suspension Cultures of Ipomea batates Poir. cv. White Star were grown in an airlift bioreactor. A machine vision system was used to monitor nondestructively callus growth during a 10 day culture period. Growth data obtained with this system included the overall reactor population and population estimates for the 200-1200-microm fractions at 200-microm intervals. A model of callus growth was developed to explain the mechanics of callus enlargement. The model was based on the assumptions that (1) the calli could not subdivide or shrink, (2) there was a fixed percentage of the initial population for each fraction that was nonviable, and (3) growth rates did not vary with time during the culture period. It was determined that the growth rates and nonviable ratios decreased as fraction size increased.

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Somatic embryos of Ipomoea batatas Lam. (sweet potato cv. 'White Star') were produced in an airlift bioreactor. This work describes the optimization of the embryogenic system on semisolid medium, followed by transfer of the system to liquid cultures and ultimately to the airlift bioreactor. The physiological age of embryogenic callus influenced the number and overall morphology of the embryo population in both semisolid and liquid medium. Maximum mature embryo production (35 embryos 10 mg-~ inoculum) was obtained from six-week-old callus at 30°C. Somatic embryogenesis occurred in liquid cultures containing 20 mM NH4NO3 and 30 mM KC1. Globular embryos formed and continued development in suspension producing viable, mature cotyledonary embryos by day 14. Embryo formation and development was limited in the bioreactor. Although shear stress was responsible for some embryogenic damage, the effect of purging the system with fresh air needed to be investigated. To isolate aeration effects from shear stress effects, atmospheric determinations were performed on shaker flask cultures. Initially the gas composition within the Erlenmeyer headspace was that of room air. Ethylene increased to a maximum of 6.4 ppm (day 16), maximum CO2, 21.2%, was also evident on day 16, and oxygen was depleted to a minimum of 8.1% by day 14. Purging the cultures with fresh air reduced the number of embryos formed; however, they were significantly longer than those formed in closed flasks. The gas response model of Ipomoea batatas will enable atmosphere replenishment in the bioreactor mimicking that of the shaker flask environment. Once the damaging effects of shear stress have been overcome, the regulation of bioreactor gasses should allow somatic embryo formation in the bioreactor comparable to that in shaker flasks.

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