Providing continuous light (24-h photoperiod) at a relatively low photosynthetic photon flux (PPF) is one possible way to reduce both initial and operational costs for lighting and cooling during transplant production with an artificial light. However, physiological disorders (i.e., chlorosis and necrosis) are often observed in several species under continuous light with a constant temperature. The objective of this study was to find an effective air-temperature regime under the continuous light to avoid such physiological disorders, and simultaneously enhance floral development, using tomato [Lycopersicon esculentum Mill.] as a model. The seedlings with fully expanded cotyledons were grown for 15 d at a PPF of 150 μmol·m–2·s–1, a relative humidity of 70%, and a CO2 concentration of about 380 μmol·mol–1 (atmospheric standard). Leaf chlorosis was observed when the air temperature was constant regardless of average air temperature (16, 22,or 28 °C). Neither leaf chlorosis nor necrosis was observed when the air temperatures were alternated [periods of high (28 °C) and low (16 °C) air temperatures of 16/8, 12/12, and 8/16 h·d–1]. Faster floral development was observed in the seedlings grown at lower average air temperatures. These results indicated that physiological disorders of tomato seedlings grown under continuous light could be avoided, and at the same time floral development could be enhanced, by lowering the average air temperature through modification of the periods of high and low air temperatures.
Katsumi Ohyama, Yoshitaka Omura, and Toyoki Kozai
Charles S. Vavrina and William Summerhill
Thirty-four operators produced > 1.15 billion vegetable transplants in Florida in the 1989-90 season. Sales, concentrated in the winter and spring, were estimated at $30 million. Firms in the industry also made additional sales of ornamental and agronomic plants. Nine large firms accounted for 88% of all transplants produced. More than 109 acres (44 ha) of greenhouse area are allocated to containerized vegetable production. The majority (83%) of Florida s vegetable transplants were from three crops--tomatoes (45%), peppers (28%), and cabbage (10%). Only 36% of the transplants produced in the state were shipped out-of-state. This report discusses various facets of production, marketing, labor, and general business conditions of the containerized vegetable transplant industry.
Gregory E. Welbaum, Jonathan M. Frantz, Malkanthi K. Gunatilaka, and Zhengxing Shen
in part by Southern States Cooperative, Richmond, Va. We thank Arthur Pfister for help with field plot preparation and transplanting. Mention of a trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by
Shinsuke Agehara and Daniel I. Leskovar
Vegetable transplant production in high-density plug trays can induce excessive stem elongation as a result of shade avoidance responses ( Marr and Jirak, 1990 ; Smith, 1994 ). The resulting spindly transplants are generally considered unsuitable
Joshua R. Gerovac, Roberto G. Lopez, and Neil S. Mattson
bedding plants transplanted during week 14 in HTs to a GH revealed that dianthus ( D. chinensis ), petunia ( Petunia × hybrida ), and pansy ( Viola ×cornuta ) could be produced in an HT with little to no delay in time to flower. For example, dianthus
Marc van Iersel
Auxins are commonly used to induce root formation during in-vitro culture of higher plants. Because transplanting is often accompanied by root damage and loss of small roots, auxins also could be beneficial in minimizing transplant shock. Vinca (Cataranthus rosea) seeds were germinated in a peat-lite growing mix and transplanted into pots (55 mL) filled with a diatomaceous earth (Isolite) 10 days after planting. Pots were then placed in a tray containing 62.5 mL of auxin solution per pot. Two different auxins [indole-acetic acid (IAA) and naphtylacetic acid (NAA)] were applied at rates ranging from 0.01 to 100 mg/L. Post-transplant growth was slow, possibly because of Fe+2-deficiencies. Both IAA (1–10 mg/L) and NAA (0.01–10 mg/L) significantly increased post-transplant root and shoot growth. As expected, NAA was effective at much lower concentrations than IAA. At 63 days after transplant, shoot dry mass of plants treated with 0.1 mg NAA/L was four times that of control plants, while 10 mg IAA/L increased shoot dry mass three-fold. High rates of both IAA (100 mg/L) and NAA (10–100 mg/L) were less effective. The highest NAA rate (100 mg/L) was phytotoxic, resulting in very poor growth and death of many plants. These results suggest that auxins may be a valuable tool in reducing transplant shock and improving plant establishment.
Charles E. Barrett, Xin Zhao, and Alan W. Hodges
Sorribas, 2008 ). However, grafting in the United States has not yet reached its full potential as a control for soil-borne pathogens and nematodes. It has been estimated that 40 million grafted vegetable transplants are currently used in the United States
Commercially produced bare-root onion (Allium cepa L.) transplants may not be uniform in size and require a period following planting in which to begin regrowth. There is little information on how, when established in the field, plants developed from greenhouse grown onion transplants differ from those that develop from bare-root transplants. Development and yield for onions grown from bare-root transplants were compared to plants produced from transplants grown in single cells with volumes of 36 or 58 cm3 in seedling production trays in a greenhouse. `Texas Grano 1015Y' and `Walla Walla' onions were established in the field with commercially available bare-root transplants or with greenhouse grown transplants produced in trays. Bare-root transplants were heavier than 8-week-old greenhouse grown transplants. Fresh weights of transplants produced in 58-cm3 cells were heavier than those from 36-cm3 cells, but dry weights were similar. From when about 20% of onion tops were broken over, onion bulb diameters did not increase sufficiently to justify delaying harvest until 50% of tops had broken over. Yields of `Walla Walla' were better than those of `Texas 1015 Y' and yields from plants developed from seedlings grown in 58-cm3 cells were similar to those from plants developed from bare-root transplants and better than those from plants developed from seedlings grown in 36-cm3 cells. Individual bulb weights of `Texas 1015 Y' were not affected by transplant type and averaged 162 g. Individual bulbs for `Walla Walla' from plants developed from bare-root transplants and those produced in 58-cm3 cells were similar in weight (averaged 300 g) and were heavier than those from plants developed from transplants grown in 36-cm3 cells (240 g). Greenhouse transplants produced in trays with the larger cells may provide an alternative to the use of bare-root transplants, if transplant production costs are comparable.
Shinsuke Agehara and Daniel I. Leskovar
Vegetable transplants grown for commercial producers need an ideal size to minimize damage during shipping and transplanting operations and to enable successful establishment in the field ( Agehara and Leskovar, 2015 ). However, vegetable
Charles S. Vavrina, Stephen Olson, and J.A. Cornell
Total fruit yield of watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] in Florida field tests was unaffected by transplant age (3, 4, or 5 weeks from seeding) or modular cell size (18.8, 30.7, or 60.5 cm3), but was affected by trial year. A further study revealed that early and total fruit yields at two field sites were unaffected by transplant age, ranging from 3 to 13 weeks, when grown in the same modular cell size (34 cm3), but were affected by field trial site. We conclude that transplant age or modular cell size is of little importance relative to post-transplanting conditions (site or year) in influencing watermelon fruit yield.