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Matthew Rogoyski, Alvan Gaus, Byron McNew, Israel Broner, and Thomas Mourney

A simulator of a control system for evaporative cooling of crop canopies was developed. This development, prior to implementation of an irrigation/cooling system, allowed for experimentation before committing resources to the field system. The project provided insight into problems of modeling interaction between biological, mechanical, and digital systems and demonstrated how specialists from diverse areas can solve these problems. The object orientation methodology and the C++ programming language were tools for development of this simulator. A communication mechanism was devised to facilitate interactions between software entities representing both concrete and abstract objects corresponding to the problem domain. The object-oriented approach to the system development allowed for better communication between team members, irrespective of their background in software engineering. The modular and polymorphic nature of the object-oriented code made it possible to plan for code reuse in future projects. Simulator development using the object-oriented paradigm was found to be preferable over the procedural model used by team members in other projects in the past.

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Michael D. Dukes, Lincoln Zotarelli, and Kelly T. Morgan

Perry (2006) showed that uniformity of a variable rate control system was not different from a traditional control system on two typical center pivot/linear move irrigation systems used in the southeastern United States. However, the problem of

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Kelly T. Morgan, Lincoln Zotarelli, and Michael D. Dukes

Florida is the most important center of processed citrus (Citrus spp.) production in the United States, and all of the crop is irrigated. Irrigation systems include low-volume microirrigation, sprinkler systems, and subsurface irrigation. This review details the relative irrigation efficiencies and factors affecting irrigation uniformity such as design and maintenance. A wide range of soil moisture sensors (e.g., tensiometers, granular matrix, and capacitance) are currently being used for citrus in the state. The use of these sensors and crop evapotranspiration estimation using weather information from the Florida Automated Weather Network in irrigation scheduling are discussed. Current examples of scheduling tools and automated control systems being used on selected fruit crops in Florida are provided. Research data on the effect of irrigation scheduling, soluble fertilizer injection, and soil nutrient movement, particularly nitrate and the use of reclaimed water in Florida, are also reviewed. Concluding this review is a discussion of the potential for adoption of irrigation scheduling and control systems for citrus by Florida growers and future research priorities.

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S. Shukla, C.Y. Yu, J.D. Hardin, and F.H. Jaber

Continuous monitoring of hydraulic/hydrologic data for managing water for horticultural crops has been a challenge due to factors such as data loss, intensive resource requirements, and complicated setup and operation. The use of state-of-the-art wireless spread spectrum communication technology and wireless data acquisition and control (WDAC) systems for agricultural water management is discussed in this paper. The WDAC technology was applied to a research project where lysimeters were used for water quantity and quality studies for vegetables. Two types of WDAC networks, master–slave and peer-to-peer WDAC networks, are discussed. The WDAC system linked the wireless dataloggers to a network to make real-time data available over the Internet. The use of WDAC made it possible to collect real-time data and control the experiment (e.g., frequency of data collection) remotely through the Internet. The WDAC system for the lysimeter study was compared to a commonly used manual system with regard to potential instrument damage, data loss, ease of data collection and analyses, and total cost of monitoring. The advantages of the WDAC include: reduced equipment losses from natural disasters (e.g., lightning), improved equipment maintenance, reduced data loss from faulty equipment, higher project personnel efficiency, and real-time involvement by a dispersed team. The total cost of the WDAC system ($65,750) was about half that of the manual system ($130,380). The WDAC system was found to be an effective tool for agricultural water management projects.

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Kazuhiro Fujiwara, Toshinari Sawada, Yoshikatsu Kimura, and Kenji Kurata

A light-emitting diode (LED)-low light irradiation (LLI) storage system was developed for suppressing the change in dry weight and maintaining the quality of green plants during long-term storage. In this system, the carbon dioxide (CO2) exchange rate was maintained at zero by automatically adjusting the photosynthetic photon flux density (PPFD) with a proportional-integralderivative (PID) controller. The voltage supplied to the LEDs was controlled by the difference between the inflow (400 μmol·mol-1) and outflow CO2 concentrations in the storage case. Grafted tomato (Lycopersicon esculentum; scion = `House Momotaro'; rootstock = `Anchor T') plug seedlings were stored at 10 °C for 35 days under four different LLI conditions as a system operating test: fixed red light irradiation at 2 μmol·m-2·s-1, PID-controlled red light irradiation with no blue light, and PID-controlled red light irradiation with blue light at 0.2 or 1.0 μmol·m-2·s-1. The results showed that the automatic PPFD control during LED-LLI helped suppress changes in dry weight during storage as expected. Furthermore, it was found that addition of a low percentage of blue light improved the morphological appearance of the seedlings and reduced the PPFD required to suppress the change in dry weight.

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Chung-Liang Chang and Ming-Fong Sie

evolution analysis. However, to integrate and design a control system with a crop growth model can be difficult as a result of diversity of plant growth factors, comprising internal, external (environmental factors), and biological factors. Internal factors

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Gene A. Giacomelli

as well as a greenhouse with climate control systems for heating, cooling, shading, etc. However, they do offer improved crop protection from adverse weather conditions compared with the open field or plasticulture techniques such as row (low) tunnels

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Abby ShalekBriski, B. Wade Brorsen, Jon T. Biermacher, Charles T. Rohla, and Will Chaney

the least for the control system with no irrigation (None) and greatest in the sprinkler systems (R5 and R10) as well as the LI2 system. Besides the nonirrigated trees, the SI2 and LI4 systems had no statistical difference in concentration of B, and

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Robert C. Morrow

photodiode. LEDs turn on instantly and do not require warmup time. They also turn off instantly. Because they are solid-state devices, LEDs are easily integrated into digital control systems. This allows complex control options not generally available

Open access

Lloyd L. Nackley, Elias Fernandes de Sousa, Bruno J.L. Pitton, Jared Sisneroz, and Lorence R. Oki

( de Lima et al., 2015 ; Marin et al., 2016 ; Nemali and van Iersel, 2008 ). Optimized irrigation management requires properly quantifying the water volume to maximize plant growth without wasting this critical resource. Sensor-based control systems