Gene A Giacomelli

Tollefson, S. J., Curlango-Rivera, G., Huskey, D. A., Pew, T., Giacomelli, G., & Hawes. M.C. (2014). Altered Carbon Delivery from Roots: Rapid, Sustained Inhibition of Border Cell Dispersal in Response to Compost Water Extracts. Plant and Soil. doi: 10.1007/s11104-014-2350-z.

Abstract:

Under two combinations of roof and side vent openings of a semiarid greenhouse located in Tucson, Arizona, U.S.A, air and leaf temperatures, relative humidity, ventilation rate and water use (fog injection and plant water uptake) were measured. The natural ventilation rate was continuously measured by using SF6 as the tracer gas. Plant water uptake rate was measured using a sap flow gage. When the roof and side vents open, the inside temperature and ventilation rate were larger than when only the roof vent open. The inside air temperature increased with increasing ventilation rate. Converse responses were found for inside relative humidity and leaf temperature. Therefore, it follows that the vertical distribution of inside air temperature and relative humidity were increased with increasing ventilation rate. Water use in the greenhouse was reduced with decreasing ventilation rate and increasing internal relative humidity. Future work will be to develop the fog and vent control method to make air temperature and relative humidity uniform in the greenhouse and to reduce water use.

Abstract:

Floor heating is a promising technique to heat greenhouses using low quality energy. The large thermal inertia of floor heating systems requires some form of predictive control. To analyze the effectiveness of feedforward logic, first a prediction model has been developed and then an experiment using a controlled-environment chamber has been conducted. Basic control logic has been established and verified for controlling air temperature by energy input only to the floor. The combination of feedforward and feedback control should be the next step.

Abstract:

Transplanting tests with commercially grown seedling plugs were conducted using a Sliding-Needles with Sensor (SNS) gripper operated by a SCARA type robot. A total of 11 plug trays, with 600 cells each, were tested. Many mechanical and horticultural factors were found to affect the percentage of successful transplanting, which were analyzed to understand their influence on the effectiveness of the gripper. The mechanical factors were 1) the angles of gripper needles; 2) plug extraction acceleration; and 3) the sensor sensitivity. The horticultural factors included 1) empty cells on the plug trays; 2) plant species; 3) root connections; 4) adhesion between roots and cell walls; 5) root zone moisture; and 6) the number of seedlings in one cell.

Abstract:

An overview of the design considerations and the operational characteristics for production of tomato in a greenhouse in a semi-arid region is provided. The integration of the automation, culture and environment requires an understanding of the production needs of the crop, and the specialized weather conditions of the Arizona climate. The demand on the plant imposed by the greenhouse climate, including air temperature and humidity, or atmospheric vapor pressure deficit (VPD), leaf temperature, and solar radiation must be balanced with the water availability within the plant root zone, as affected by the electrical conductivity of the nutrient solution and the irrigation frequency. The crop production system requires that nutrient delivery be automated to provide a consistent availability of nutrient formulation and concentration in proportion to the general daily fluctuating water demand. An automatic means to determine water demand that will vary the irrigation frequency and the nutrient concentration is important to provide the desired stress for crop production. The climate control includes monitoring and feedback mechanisms to firstly, minimize the potentially harsh diurnal fluctuating desert conditions of low air humidity, high solar radiation, and water quality with high salts, and then, to secondly, alter the plant microclimate to match the stage of plant growth and its production condition. The greenhouse structure should be of sufficient height for buffer volume needed to offset the large daily environmental fluctuations. The structure system must also offer air exchange capacity, shading, and evaporative cooling to help maintain the desired air temperature and relative humidity for crop production. Experiences and research studies within each of these areas of production system, climate control and greenhouse structure will be presented, including: production of greenhouse tomatoes within a high-wire, continuous production system; modulating plant vegetative or reproductive tendency with a combination of root zone and aerial microclimates; improving fruit market quality; and greenhouse structure design variations for improved cooling and reduced water utilization.