Mechanical conditioning is an excellent means of regulating the growth of vegetable transplants and some ornamental bedding plants. It improves the stature, appearance, handling characteristics, and overall quality of treated plants. The application procedures reported for transplants have included wind, shaking, brushing, and more recently impedance; all of which result in physical displacement of the growing points. Brushing has been most commonly studied for mechanical conditioning in high density transplant production. Brushing reduces plant height, increases stem and petiole strength, improves insect resistance in the greenhouse, tends to improve stress tolerance and enhance stand establishment in the field, and has no effect on crop yield. Although growers using the technique have been very pleased with the quality of brushed vegetable transplants, widespread commercial application of brushing is limited by a lack of automation.
Joyce G. Latimer
M. A. L. Smith, J. Reid, A. Hansen, Z. Li, and D. L. Madhavi
Industrial-scale cultivation of plant cells for valuable product recovery (e.g. natural pigments, pharmaceutical compounds) can only be considered commercially-feasible when a fully-automated, predictable bioprocess is achieved. Automation of cell selection, quantification, and sorting procedures, and pinpointing of optimal microenvironmental regimes can be approached via machine vision. Macroscopic staging of Ajuga reptans callus masses (ranging between 2-6 g FW) permitted simultaneous rapid capture of top and side views. Area data used in a linear regression model yielded a reliable, non-destructive estimate of fresh mass. Suspension culture images from the same cell line were microscopically imaged at 4x (with an inverted microscope). Using color machine vision, the HSI (hue-saturation-intensity) coordinates were used to successfully separate pigmented cells and aggregates from non-pigmented cells, aggregates, and background debris. Time-course sampling of a routine suspension culture consistently allowed pigmented cells to be detected, and intensity could be correlated with the degree of pigmentation as verified using spectrophotometer analysis of parallel samples.
Many small and part-time commercial vegetable growers in Alabama rely on rainfall to provide irrigation for their crops. This, coupled with limited financial resources, creates situations where poor-quality produce and low yields are common. Working cooperatively with county extension agents, growers that met a series of criteria and that could benefit from drip irrigation were identified. An on-farm result demonstration and educational program was developed to help combat this problem by emphasizing the importance of irrigation and introducing affordable drip irrigation systems for these growers. County agents and growers participated in an educational program, which involved a daylong course covering the basics of drip irrigation and hands-on training with all components of the drip system. Necessary background information on each site was collected and a drip irrigation system was designed for each site. Next, each grower was provided with all of the necessary materials and equipment needed to install the system. The overall flexibility in the basic design was stressed and several growers modified their systems with items that provided various levels of automation, or the capacity to fertigate. Fifteen on-farm demonstrations in 14 counties were developed ranging from 0.08 to 0.60 ha in size. Cost for this equipment (layflat, fittings, drip tape, regulators, filter) was ≈$230 per site. Success of each demonstration varied. Overall, growers were positive about using drip irrigation and that it was affordable. Most planned on continuing or expanding its use next season.
Kent D. Kobayashi*
How do we enhance students' learning experience and help them be aware of current and emerging technology used in horticulture? An undergraduate course on “Computer Applications, High Technology, and Robotics in Agriculture” was developed to address these needs. Its objectives were to familiarize students with the ways computers, high technology, and robotics are used in agriculture and to teach students how to design, build, and run a robot. The diverse topics included computer models and simulation, biosensors and instrumentation, graphical tracking and computer scheduling, new methods in plant ecology, automation and robotics, Web-based distance diagnostic and recommendation system, GIS and geospatial analysis, and greenhouse environmental control. An individual speaker presented one topic each week with students also visiting some speaker's labs. The students did active, hands on learning through assignments on computer simulations (STELLA simulation language) and graphical tracking (UNH FloraTrack software). They also built, programmed, and ran robots using Lego Mindstorms robotic kits. The course was evaluated using the Univ.'s CAFE system. There were also open-ended questions for student input. On a scale of 1 (strongly disagree) to 5 (strongly agree), mean scores of the 20 CAFE questions ranged from 3.71 to 4.75 with an overall mean of 4.22. When comparisons to other TPSS courses were possible, this course had a higher mean score for four out of seven questions. Course evaluations indicated this special topics course was important and valuable in helping enhance the students' learning experience.
Donald J. Merhaut and Dennis Pittenger
A survey of wholesale nurseries in the United States was conducted in 1999, with 169 of the 806 nurseries surveyed responding from the state of California. The survey, consisting of 29 questions related to production practices, products, sales, and marketing, was sent to a random group of nurseries. Based on these results, over 50% of the new nursery businesses in California have been established within the last two decades. While most of the nurseries have computerized business practices, only 21% have implemented the use of computers or other automation in their production practices. Horticulturally, containerized plant production (80% of the industry) is still the primary method of growing and shipping plants in California, and most (90%) of these products are sold within the state. Nevada, Arizona, Oregon, Washington, and Texas are the primary destinations for plant material that is exported out of state. The factors that nursery owners feel influence sales the most include market demand, weather unpredictability, and water supply, while governmental and environmental regulations are perceived to have the least impact. The factors that influence product price include cost of production, market demand, and product uniqueness.
Krishna S. Nemali and Marc W. van Iersel
We have developed a completely automated irrigation system that measures and maintains substrate volumetric water content (θ) at a target level for any length of time. Advantages of this system include complete automation of irrigation and simulation of precise levels of drought stress for potted plants. This system uses ECH2O moisture sensors interfaced with a CR10X datalogger and solenoid valves connected to the datalogger by a SDM CD16 AC/DC controller. The datalogger measures the θ of the substrate hourly. When the θ of the substrate drops below the set point, the datalogger opens the solenoid valves, which results in irrigation. Substrate θ is maintained at a constant level as the datalogger is programmed to increase θ by 2% to 3% during each irrigation. When the system was validated for its accuracy, we determined that the θ measured in the substrate within the range of 0.15 to 0.35 m3·m-3 was close (2% to 3%) to the θ determined by the conventional volumetric analysis. The daily average θ maintained in the substrate was slightly higher (within 3%) than the target level. Using this system, we were able to maintain four distinct levels of substrate θ for a prolonged period (40 days), regardless of differences in plant size and environmental conditions. Significant increases in number of irrigations, total water-use, and transpiration rate of impatiens, salvia, vinca, and petunia were noticed with increasing target θ of the substrate. For all species, highest and lowest water-use efficiency (WUE) were seen at 0.09 and 0.32 m3·m-3, respectively, while WUE was not different between 0.15 and 0.22 m3·m-3.
Gioia D. Massa, Jeffery C. Emmerich, Robert C. Morrow, C. Michael Bourget, and Cary A. Mitchell
Electrical cost, primarily for lighting, is one of the largest factors inhibiting the development of “warehouse-based” controlled environment agriculture (CEA). In a jointly sponsored collaboration, we have developed a reconfigurable LED lighting array aimed at reducing the electrical energy needed to grow crops in controlled environments. The lighting system uses LED “engines” that can operate at variable power and that emit radiation only at wavelengths with high photosynthetic activity. These light engines are mounted on supports that can be arranged either as individual intracanopy “lightsicles” or in an overhead plane of lights. Heat is removed from the light engines using air flow through the hollow LED strip mounts, allowing the strips to be placed in close proximity to leaves. Different lighting configurations depend on the growth habit of the crops of interest, with intracanopy lighting designed for planophile crops that close their canopy, and close overhead lighting intended for erectophile and rosette crops. Tests have been performed with cowpea, a planophile dry bean crop, growing with intracanopy LED lighting compared to overhead LED lighting. When crops are grown using intracanopy lighting, more biomass is produced, and a higher index of biomass per kW-h is obtained than when overhead LEDs are used. In addition, the oldest leaves on intracanopy-grown plants are retained throughout stand development, while plants lit from overhead drop inner-canopy leaves due to mutual shading after the leaf canopy closes. Research is underway to increase the energy efficiency and automation of this lighting system. This work was supported in part by NASA: NAG5-12686.
James Polashock and Nicholi Vorsa
We have used RAPDs (Randomly Amplified Polymorphic DNAs) to successfully fingerprint cranberry. Although this method is simple and inexpensive, disadvantages include limited reproducibility in other labs and it is not easily computer-analyzed. RAPDs can also be labor-intensive because multiple primers are required to adequately fingerprint a single sample. As an alternative, we have utilized a method called SCARs (Sequence Characterized Amplified Regions). Clear polymorphic RAPD markers were cloned and sequenced. Primers were designed to amplify each polymorphic band and contained the original 10-mer RAPD primer sequence and 10 to 12 additional “clone-specific” bases. Primer sets were tested on eight common cranberry cultivars to determine if the desired polymorphic marker was amplified. The success rate of developing ëgoodí primer sets was ≈25%. The most common problem was loss of polymorphism, suggesting that selectivity was contained within the original 10-mer RAPD primer. The amplification of many similarly sized markers, suggesting the primer set amplified a repeat region, was another problem. Useful primer sets were multiplexed in PCR reactions to establish a “fingerprint.” The SCARs system we developed to fingerprint cranberry is powerful enough to distinguish individual clones in both crosses and selfed progeny. To further simply the system, computer automation for detection and analysis using fluorescently labeled primers is underway. One problem we are addressing is reduced product in the labeled multiplex reactions. Reduced product yield is presumably because the dye molecule (Cy5) is very large and may reduce primer binding and/or polymerization efficiency. This problem has been somewhat alleviated using a patented form of Taq DNA polymerase.
Niels B. Bredmose
The cut rose, grown as a single-stemmed crop, resembles a potted plant and can be adapted to transportable bench systems. Potentially, this cultivation method could increase control of rose development, flexibility of production and produce, and automation of difficult or laborious cultural operations. Synchronous growth and flowering is considered important. The effects of increased quantum irradiation integral and plant density on shoot growth, fresh biomass production, and bloom quality were studied as single-stemmed rose plants (Rosa hybrida L.) `Kordapa' Lambada, `Tanettahn' Manhattan Blue, `Tanorelav' Red Velvet, and `Sweet Promise' Sonia grown under 20 hours photoperiods at 23 °C average air temperature. Plants were grown in rockwool cubes on ebb and flood benches irrigated with a complete nutrient solution, and were supplied with carbon dioxide at 1000 μmol·mol-1. Increased the daily quantum integral from 17.8 to 21.0 mol·m-2·d-1 increased fresh biomass efficiency, stem diameter, and specific fresh mass while number of nodes, number of five-leaflet-leaves, plastochron value, and stem length at anthesis decreased. Fresh mass at anthesis was not affected by the treatments. Increasing plant population density from 100 to 178 plants/m2 increased stem length at visible flower bud, and reduced both fresh biomass efficiency and specific fresh mass. These effects are suggested to be related to assimilate supply and translocation, and light perception of the roses. High quantum integral slightly reduced flower diameter but in general, quantum integral or plant density did not affect bloom quality or vase life. Use of preservative floral solution generally improved rose flower diameter and vase life. In Lambada increased light quantum integral prolonged vase life, but use of preservative solution did not. The cultivars Sonia and Red Velvet required 19 to 20 days from cutting/planting until onset of bud growth, 29 to 34 days until visible flower bud, and 39 to 49 days until anthesis. Red Velvet roses were ≈60 cm long at anthesis, and had larger stem diameter and growth rate, accumulated more fresh biomass, were most efficient producing fresh biomass, and had higher specific fresh mass among the cultivars. Light quantum integral is suggested to be used as a means to synchronize single-stemmed rose plant development.
, Sterling, and Welder with productivity and other attributes suitable for table wine production. Socioeconomic Impact of Automation on Nurseries and Greenhouses Nurseries and greenhouses in Mississippi, Louisiana, and Alabama reported that 20% of all the