Gene A Giacomelli

Abstract:

The transplanting of seedlings from high density plug trays into low density growing flats, as currently practiced in the bedding plant production systems, was the operation studied within a prototype workcell utilizing a Selective Compliance Assembly Robot Arm (SCARA) type robot. The concept of a multi-stop local work trajectory surrounding each seedling was incorporated into the workcell design consideration. The trays and flats were envisioned to flow across each other's path at different heights within the workcell. A straight-line robot wrist motion was used between the locations on a tray and a flat. A computer program for checking the interactions of the workcell layout, the robot motions and the flows of materials was developed. The average robot wrist horizontal travel distance per transplanting (AHT) for a given workcell could be readily calculated using this computer program. The AHT was evaluated for its use as an indication of the performance of any given workcell design. For the 12 cases studied, the AHT ranged from 0.381 m to 0.993 m which was found to correlate well with the average cycle time per transplanting.

Abstract:

Design and operation of a greenhouse for plant production are challenging tasks even for the most experienced growers or designers, primarily because they are a highly complex system of biological and mechanical subsystems. These subsystems are deeply interrelated and must function together to provide successful crop production. With fundamental understanding and a desire to develop integrated crop production systems, the design of future greenhouses may become less guesswork, less design by "experience", and more methodical and reliant on information databases. The specific greenhouse structure, the crop production system, the environmental control and the labor/management procedures, directly affect the ability of the greenhouse manager to successfully produce high quality crops within the greenhouse. The greenhouse design requires the selection of many individual component systems, within the three primary areas of automation, culture and environment. Having selected the crop or crops, thereby knowing the culture requirements, it becomes necessary to select a water/nutrient delivery system, which when housed within a greenhouse structure, will efficiently incorporate labor requirements and environmental control. The complexity of the dynamic greenhouse system requires that problem solving and planning should not occur with the daily management decisions, but during the design stage of the greenhouse, prior to implementation. A logical procedure of design steps needs to be developed, in order to avoid the trial and error methodologies typically utilized, and whose success or failure depends totally on the past experiences of the designer, with too little input from the grower. Although a detailed design procedure does not currently exist, the basis for its development will be considered in this paper.

Abstract:

Greenhouse crop production systems have been established throughout the world, including arid and semi-arid regions, to fulfill a market demand of locally grown produce consistently through the year. In these particular regions while they have the advantage of sunshine year-round, production during the summer is a challenge due to elevated air temperatures. Fog systems have proven to be a good economical alternative for evaporative cooling while potentially providing a more uniform environment when compared to fan and pad systems. High-pressure fogging systems equipped with variable frequency drives can be operated at different pressures to meet the varying cooling demands during the day. This feature adds the flexibility of varying the fog flow rate by operating at lower pressures or by changing the number of working fog lines accordingly to the cooling demands. These systems may offer the potential advantage of energy and water saving by operating at a low frequency while providing the proper amount of fog accordingly to the cooling loads. A variable pressure fogging systems operating in the range of 4.8 to 10.3 MPa (700 to 1500 psi) was recently installed in a greenhouse at the University of Arizona Controlled Environment Agriculture Center (UA-CEAC) for the purpose of developing advanced control strategies for optimum greenhouse environments. This study experimentally evaluated the dynamics of air and canopy temperatures, crop evapotranspiration rates, and climate uniformity in the greenhouses working under various fogging system operational pressures and greenhouse side/roof vent opening configurations.

Abstract:

Controlled environment, greenhouse cultivation of Sweet Charlie strawberries is technically an effective method to target niche winter markets. Supplemental lighting can help to accelerate fruit maturation, and to encourage a greater number of smaller fruit earlier in the season. Unless yield per plant can be drastically increased, achieving an economically viable system will require a planting density approaching 30 plants m^-2.

Abstract:

Balancing plant growth between vegetative and reproductive status is crucial for producing high quality greenhouse tomatoes while maintaining high productivity. The ability to change plant growth characteristics often associated with vegetative or reproductive growth status was demonstrated. Two greenhouse canopy environments were selected for inducing reproductive growth [high vapor pressure deficit (VPD) (2 kPa) and 27°C / 18°C day-night air temperature], and vegetative growth [low VPD (0.8 kPa) and 24°C / 22°C day-night air temperature]. Plant responses from the treatment environments were contrasted with those from a standard commercial greenhouse environment (24°C / 19°C). All environmental treatments were associated with two electrical conductivities (EC) of the nutrient solution: 2.5 dS m-1 (EC 2.5) and 8 dS m-1 (EC 8). Plants were grown under one of two treatment environmental conditions, until significant differences in plant growth characteristics were observed. Out of the five plant growth characteristics monitored, stem diameters were the most responsive to canopy environment and EC treatments. The major factor in changing plant growth responses was EC, for the range of VPD and day-night air temperature differences achieved in the present study, while canopy environment affected the magnitude of the change. Mean stem diameters (SD) were significantly higher under EC 2.5, than for plants growing under EC 8. IN5 cm and SD 15 cm are the plant growth responses most affected by EC treatments and canopy environment. Single leaf gas exchange measurements had significantly reduced transpiration rate at EC 8 under all canopy environments, while net photosynthetic rate was not affected. This suggests that decreased plant growth responses observed under high salinity treatments resulted from reduced water and nutrient uptake due to suppressed transpiration rate.