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Toyoki Kozai and Tadashi Ito

Commercial transplant production in Japan has been increasing rapidly since 1985. Transplant production began with plug seedlings for bedding plants, followed by carnation and Chrysanthemum plug transplants vegetatively-propagated using cuttings. Next, production more recently includes plug seedlings of lettuce and cabbage, and micropropagated tubers of potato plants and grafted transplants of tomato, eggplant, cucumber, and watermelon plants. The reasons for the rapid increase in commercial production of transplants will be reviewed. The current “cutting edge” practices include hardening before shipping or planting. The pros and cons of current transplant production systems in Japan will be discussed. Recent research advances in production of micropropagated, grafted and seedling transplants are reviewed with special reference to environmental control for hardening or acclimatization. Research on robotic or automated systems for micropropagation, grafting, and transplanting currently developed in Japan are described.

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Albert Liptay

Air circulation, generally an integral part of environmentally-controlled plant growth chambers, retarded tomato (Lycopersicon lycopersicum Karstens) seedling growth seismomorphogenetically. Continuous air movement at a speed of 0.5 to 0.7 m·s-1 inhibited growth by about 40%. Growth inhibition was noticeable with as little as 15 min of daily exposure to the air circulation; a continuous exposure gave the greatest amount of growth inhibition. The retarding effect of air on seedling growth was transient and required a continued daily exposure to air movement. Continuous aeration of seedlings inhibited growth to such an extent that in a two factor experiment, ie aeration and water stress, the water stress effects were completely masked in the aerated chamber by the aeration effect. The results have important implications for plant growth experiments in chambers equipped with air circulation: seedling growth may be affected more by the air circulation in the growth chamber than by an experimental treatment.

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Jiffinvir Khosa, Robyn Lee, Srishti Joshi, Martin Shaw, John McCallum, and Richard Macknight

Bulb onion (Allium cepa L.) is a challenging subject for experimental studies because of its slow growth, genetic heterogeneity, and sensitivity to environmental and biotic stresses. Sharing of common germplasm and controlled propagation practices has underpinned research on model plants, such as Arabidopsis and tomato, but not in onion. To encourage wider evaluation of onion for physiological and molecular studies in controlled environments, we describe the growing practices we have developed over two decades of research on adaptive and nutrient assimilation traits. Key aspects covered include choice of germplasm, propagation media, nutrition, and environmental control. Adopting common onion genetics and cultivation techniques across laboratories will allow researchers to answer deeper research questions and increase the reproducibility of the research.

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Gary R. Bachman and Margaret J. McMahon

`Celebrity White' hybrid petunia plants (Petunia ×hybrida Hort. Vilm-Andr.) were grown either in chambers constructed of CuSO4-filled panels acting as spectral filters removing the far-red light (-FR) or in environmental control chambers under temperature treatments of 24 °C day/18 °C night (+DIF) or 18 °C day/24 °C night (-DIF). Growth responses for plants grown under CuSO4 filter (-FR) or -DIF temperatures were similar in that both treatments resulted in decreased internode length, increased stem diameter, and decreased cell length and cell diameter in epidermal, cortical, and pith tissues. Reduced cortical cell length contributed the largest percentage to internode length reductions compared to epidermal and pith tissue for the -FR treatment while reductions in cell length of all three tissues contributed to internode reduction of -DIF-treated plants. Chlorophyll a increased for plants grown under -FR, but decreased for plants grown in -DIF when compared to the appropriate controls.

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Otho S. Wells and J. Brent Loy

Crop growth is enhanced with the use of relatively inexpensive rowcovers and high tunnels. Even though these structures do not provide the same degree of environmental control as greenhouses, they modify the climate sufficiently to lengthen the growing season from 1 to 4 weeks in the spring and 2 to 8 weeks in the fall. Rowcovers generally remain over a crop for 2 to 4 weeks, whereas a high tunnel may function for an entire growing season. Both systems require a relatively low capital investment, provide a good return on investment, and improve the ability of new growers to succeed in the crop production business. The selection of either rowcovers or high tunnels will depend on the management program of a grower; however, both growing systems potentially are economically viable means of season extension.

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David L. Bubenheim

The role of spectral quality and CO2 concentration in environmental control of lignin synthesis in spring wheat is being studied by the NASA Controlled Ecological Life Support System Program (CELSS). Wheat cultivars were exposed to four different spectral environments provided by 1) metal halide lamps (MH), 2) high pressure sodium lamps (HPS), 3) low pressure sodium lamps (LPS; almost monochromatic, 589 nm), or 4) LPS plus low irradiance blue light (5 μmol m-2 s-1; LPS + Blue) at equal photosynthetic photon flux. Stem lignin content was suppressed 25% under the LPS compared with the MH and HPS; blue addition (LPS + Blue) resulted in 25% greater lignin content compared with the LPS alone and 8% suppression compared with MH and HPS. CO2 studies compared lignin content of wheat grown in the field, greenhouse at 350 μmol mol-1 CO2, and growth chambers at 350 and 700 μmol mol-1 CO2, Lignin content was greatest and equal in the field and growth chamber at 700 μmol mol-1 CO2. Lowest lignin content was measured in the growth chamber at 350 μmol mol-1 CO2; lignin content in the greenhouse was intermediate between that measured in the field and growth chamber at 350 μmol mol-1 CO2, Additional CO2 studies in controlled environments will be discussed.

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George M. Greene, Alvan G. Gaus, and Laura J. Lehman

A grant from the Pa. Dept. of Agriculture has allowed Penn State University to increase postharvest physiology research of fruit, vegetables, and mushrooms. One part of this program is a CA storage research facility described herein. An insulated pole barn (26m × 18m with 5m ceilings) houses the facility. Three coolers (6m × 7m with 10cm insulation) provide environmental control for the CA systems (-2 to 10C ±0.5C). A laboratory within the building (6m × 7m × 3m) provides space for product evaluation and for CA control equipment. A total of 239 steel drums (208-liter), fitted with 28 cm round plexiglass windows, are the CA chambers. Gas pumps provide flow to: each chamber, the gas analysis system, and the CO2 scrubbing system. A David Bishop Instruments Oxystat 2, analyzes O2 and CO2 and provides control signals. High CO2 can be removed either by lime scrubbing or by flushing with gases containing N2 and the desired O2 level. Several large experiments involving 7.8 MT of apples were started and preliminary results will be presented.

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Richard G. Snyder

A successful greenhouse tomato crop depends on the optimization of several factors; among these factors are water, nutrition, and all facets of environmental control. Good pollination, however, is one of the most important requirements for the production of fruit of high yield and quality. Poor pollination causes fruit that are smaller, angular, or puffy, due to reduced seed numbers and poor gel fill in the locules. In Spring 1993, two 7.3 × 29.3 double plastic-covered greenhouses were used to compare the conventionally used electric pollinator to bumblebees for effective pollination; replicated variety trials were performed within each. In one greenhouse (12 replications, RCBD), `Trust' performed better than `Caruso' in yield and quality, although it was smaller in fruit size. In the other greenhouse (four replications, RCBD), `Match' and `Switch' were better than all others (`Belmondo', `Capello', `Laura', and `Rakata') for most yield and quality variables. Means across varieties were similar for the two pollination techniques, with marketable weights identical. For gutter-connected greenhouse ranges of 0.1 ha or larger, bumblebees are an economically viable option for pollinating hydroponically grown tomatoes.

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Harry W. Janes, Seenithamby Logendra, and Sitheswary Logendra

It was proposed to study and develop a system for producing salad vegetables on a space station. To this end a `Salad Machine' was designed to act as a controlled environment growth chamber within which various plants will be grown on a continuous and predictable basis such that crew members will periodically have available the ingredients of a “normal” salad. Within this framework we studied the enclosed environment production of tomatoes.

Forty-five tomator cultivars were screened in a greenhouse and four were selected for further evaluation. The criteria for selection were total plant yield, fruit size, fruit quality and the total weight of the fruit on the main stem as compared to the axillary branches. The four selected cultivars were grown in an environmentally controlled chamber (`Salad Machine') at 6 plants/m (volume rather than area is important here). The data collected included: weekly plant height, total daily yield, water use and nutrient uptake.

The continuous production of tomatoes in a small volume using a selected cultivar will be discussed.

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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.