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Hunter A. Hammock, Dean A. Kopsell, and Carl E. Sams

. Supplemental lighting (SL) systems play a vital role in plant research and greenhouse production. Research on spectral responses of various plant species has been limited in the past by technology and the inability to accurately provide narrowband wavelengths

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Neil O. Anderson, Mi-kyoung Won, and Dong-chan Kim

) ( Anderson and Ascher, 2001 ; Cathey, 1954 , 1957 ; Cockshull and Kofranek, 1994 ; Langton, 1977 ), HTs can cause heat delay which prevents or delays either FBI and/or FBD in greenhouse production under black out or black cloth (used to induce SD

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Joshua K. Craver, Krishna S. Nemali, and Roberto G. Lopez

With the development of light-emitting diodes (LEDs) and advancements in environmental control technologies, indoor production using sole-source lighting (SSL) is a potential alternative to traditional greenhouse production for many high

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Richard M. Klein

In order to determine whether the concentration of floral petal anthocyanin pigments could be increased, ultraviolet radiations in the UV-A and UV-B wavelength bands were presented to a variety of flowering plants to partly restore those wavelengths filtered out by greenhouse glass. In no tested plant did the supplementary ultraviolet radiation enhance floral anthocyanin content. Supplementary UV radiation has no economic value in greenhouse production of flowering plants.

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D.W.A. Hunt, A. Liptay, and C.F. Drury

Host plant selection by Colorado potato beetle [Leptinotarsa decemlineata (Say)] was examined on tomato [Lycopersicon esculentum Mill.] transplants fertilized with varying N, P, and K concentrations during greenhouse production. In choice tests conducted with beetles in the field and the greenhouse, the insect preference for plants increased with increasing leaf tissue N concentration, but P and K concentrations had no effect. Five-day, seedling acclimatization to outdoor spring temperatures before planting reduced the insect preference for plants.

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Garry V. McDonald* and Michael A. Arnold

Previous experiments indicated that plant growth regulators applied during greenhouse production can have a negative effect on subsequent landscape performance of pansy (Viola × wittrockiana H. Gams `Crown Yellow'). Three experiments were initiated in September 2003 to determine the affects of paclobutrazol and ancymidol on production and landscape performance of ornamental cabbage (Brassica oleracea L. var. acephala A.P. deCandolle `Dynasty Pink'), calendula (Calendula officinalis L. `Bon Bon Orange'), and pansy. Seeds were germinated in plug trays (1.5 cm3 inverted cone-shaped pockets) in a growth chamber with a 12 h photoperiod at 25/21 °C day/night. Plants were sprayed with paclobutrazol (formaulated as Bonzi) or ancymidol (formulated as Arest) at plug stage (cabbage, pansy, and calendula on 25 Sept., 2 Oct., 11 Nov., respectively), at 14 days after transplant into 0.73 L containers, or at both stages. Paclobutrazol was applied at 0, 5, 10 or 15 mg·L-1 and ancymidol at 0, 2, 4, or 8 mg·L-1. Cabbage (30 Oct.), pansy (6 Nov.), and calendula (4 Dec.) were transplanted to landscape beds to assess residual effects on growth and flowering. Cabbage and calendula, showed minor differences in growth during greenhouse production due to varying rates of either paclobutrazol or ancymidol, but exhibited a greater response to application time. Only minor differences in growth occurred with pansy during greenhouse production due to rate or time of application using ancymidol, but exhibited major differences in response to both rate and time of application using paclobutrazol. Residual effects on growth and flowering during landscape performance phase will be discussed.

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Edward F. Durner

Two- to three-week-old `Sweet Charlie' strawberry (Fragaria ×ananassa Duch.) plug plants were conditioned [seven 9-hour short days without chilling (21 °C day/21 °C night) followed by seven 9-hour short days with chilling during the nyctoperiod (21 °C/12 °C night)] in September, then planted in a vertical hydroponic system for winter greenhouse production. Conditioned plugs produced significantly more fruit than did nonconditioned control plugs in January and February, but the difference was nonsignificant in March and April. Fruit yield increased linearly with height in the column (≈40 g/plant for every 30-cm increase in column height), probably because of increasing light level. When productivity is considered on an area basis (kg·m–2) and the column height effect on yield is accounted for, productivity over a 4.5-month period was 4.8 kg·m–2 for controls and 7.8 kg·m–2 for conditioned plugs. Conditioned plug plants offer the potential for increasing strawberry productivity and therefore the profitability of a winter greenhouse production system.

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Zhanao Deng and Brent K. Harbaugh

Caladium (Caladium ×hortulanum) leaves can be injured at air temperatures below 15.5 °C. This chilling sensitivity restricts the geographical use of caladiums in the landscape, and leads to higher fuel costs in greenhouse production of pot plants because warmer conditions have to be maintained. This study was conducted to develop procedures to evaluate differences among caladium cultivars for chilling sensitivity and to identify cultivars that might be resistant to chilling injury. The effects of two chilling temperatures (12.1 and 7.2 °C) and three durations (1, 3, and 5 days) on the severity of chilling injury were compared for three cultivars known to differ in their sensitivity to low temperatures. Exposure of detached mature leaves to 7.2 °C for 3 days allowed differentiation of cultivars' chilling sensitivity. Chilling injury appeared as dark necrotic patches at or near leaf tips and along margins, as early as 1 day after chilling. Chilling injury became more widespread over a 13-day period, and the best window for evaluating cultivar differences was 9 to 13 days after chilling. Significant differences in chilling sensitivity existed among 16 cultivars. Three cultivars, `Florida Red Ruffles', `Marie Moir', and `Miss Muffet', were resistant to chilling injury. These cultivars could serve as parents for caladium cold-tolerance breeding, and this breeding effort could result in reduced chilling injury in greenhouse production of potted plants, or in new cultivars for regions where chilling occurs during the growing season.

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Steven C. Adams

Seed vigor has a very subtle effect on the productivity of greenhouses producing vegetable transplants, celery, cauliflower, lettuce, etc. and on todays highly mechanized automatic or semi-automatic transplanting operations. As greenhouse production technology moves from traditional bare root to plug/tray growing systems and as automatic and semi-automatic transplanting operations increase in number, the impact of poor seed vigor is realized.

Measures to mitigate the impact of poor seed vigor in the nursery are: Seed density grading; increased growing cycle in the nursery, hand culling or replanting. Measures to mitigate the impact of poor seed vigor in automatic transplanting operations: increase the number of people following the planter to replace poor vigor plants; use hand fed transplanters.

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L-Y. Li and J.H. Lieth

Greenhouse crop production involves high rates of energy input to implement a greenhouse microclimate that results in high productivity levels, correct crop timing, and desired product specifications. Producing quality crops while maintaining low energy consumption is achievable through improved crop management and environment control strategies. In this study, greenhouse crops and their microclimate were treated as an integrated system that was driven by solar radiation and external energy input. A set of simulation models were developed to describe the greenhouse climate, the crop, and their dynamic interactions. The temperature and light regimes were simulated using the greenhouse energy budget under typical weather patterns. The crop model simulated growth and development of several ornamental greenhouse crops. Coupling the crop model with the greenhouse energy model resulted in a system that allows determination of optimal strategies for crop management and environmental control. This greenhouse/crop system can be used to assist growers with formulating strategies of greenhouse production management.