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Stephen M. Olson, George J. Hochmuth, and Robert C. Hochmuth

Studies were conducted at the NFREC, Quincy, and AREC, Live Oak, Fla., to compare watermelon {Citrullus lanatus [(Thumb.) Matsum & Nakai]} plant establishment by transplanting and direct-seeding. Cultivars used were `Charleston Gray' in 1984, 1985, 1986, and 1989; `Jubilee' in 1988 and 1989; and `Crimson Sweet' in 1987 to 1990. Early yields were greater with transplants for all three cultivars in all years. With `Charleston Gray', total yields with transplants were higher in 1985 and 1989, but not in 1984 or 1986. The average fruit weights with transplants were also greater in 1985 and 1989 than in 1984 or 1986. With `Jubilee', total yield with transplants was higher in 1989, but not in 1988. Average fruit weight with transplants was greater in 1989 than in 1988. With `Crimson Sweet', total yields were higher with transplants in 1989 and 1990, but not in 1987 or 1988, but fruits were larger with transplanting compared to direct-seeding only in 1990. In all experiments, yields with transplants were never less than those with direct-seeded plants.

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J.G. Robb, J.A. Smith, R.G. Wilson, and C.D. Yonts

The Paperpot system provides a relatively flexible approach to commercial transplanting of crops. Around the world, most of the research and application of this system has been on sugar beets. Compared to traditional hand-transplanted, field-grown, bare-root onions, there are several potential advantages of the Paperpot system, including reduced labor requirements, accuracy of placement, and fewer imported insect and disease problems. Comparison of three transplanters—carousel, BST, and chain-type—indicated the chain-type transplanter had lower labor inputs and a higher transplanting capacity than the other models. The BST transplanter was capable of placing 65% of the plants within a 3- to 5-inch plant spacing. The chain-type and carousel deposited 36% and 14%, respectively, within this same spacing. Yield was higher when onions were transplanted with the BST machine. This was attributed to the more-accurate placement of the onion plants. A four-row BST transplanter was capable of transplanting 0.4 acres/h of onions in field-scale trials.

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José A. Franco and Daniel I. Leskovar

Containerized `Lavi' muskmelon [Cucumis melo L. (Reticulatus Group)] transplants were grown in a nursery with two irrigation systems: overhead irrigation (OI) and flotation irrigation (FI). Initially, root development was monitored during a 36-day nursery period. Thereafter, seedling root growth was monitored either in transparent containers inside a growth chamber, or through minirhizotrons placed in the field. During the nursery period, OI promoted increased early basal root growth, whereas FI promoted greater basal root elongation between 25 and 36 days after seeding (DAS). At 36 DAS leaf area, shoot fresh weight (FW) and dry weight (DW), and shoot to root ratio were greater for OI than for FI transplants, while root length and FWs and DWs were nearly the same. Total root elongation in the growth chamber was greater for FI than for OI transplants between 4 and 14 days after transplanting. Similarly, the minirhizotron measurements in the field showed a greater root length density in the uppermost layer of the soil profile for FI than for OI transplants. Overall, muskmelon transplants had greater root development initially when subjected to overhead compared to flotation irrigation in the nursery. However, during late development FI transplants appeared to have a greater capacity to regenerate roots, thus providing an adaptive mechanism to enhance postplanting root development and to withstand transplant shock in field conditions. At harvest, root length density and yield were closely similar for the plants in the two transplant irrigation treatments.

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Jonathan M. Frantz, Gregory E. Welbaum, Zhengxing Shen, and Ron Morse

“Float-bed” (FB) is a simple hydroponic system used by the tobacco industry for transplant production. “Ebb-and-flood” (EF) is a modified FB system with periodic draining of the bed to limit water availability and control plant growth. Field-bed cabbage (Brassica oleracea L. gp. Capitata) transplant production was compared with FB, EF, and overhead-irrigated plug-tray greenhouse systems. Plants were produced in May and June and transplanted in a field near Blacksburg, Va., in June and July of 1994 and 1995, respectively. Beds for FB and EF production consisted of galvanized metal troughs (3.3 × 0.8 × 0.3 m) lined with a double layer of 0.075-mm-thick black plastic film. In 1994, both EF and FB seedlings were not hardened before transplanting, were severely stressed after transplanting, and had higher seedling mortality compared with plants from other systems. Plug-tray transplants showed the greatest increase in leaf area following transplanting and matured earlier than seedlings produced in other systems. In 1995, EF- and FB-grown cabbage plants were hardened by withholding water before transplanting, and seedlings had greater fresh mass and leaf area than plug-tray or field-bed seedlings 3.5 weeks after transplanting. Less succulent cabbage transplants were grown in EF and FB systems containing 66 mg·L-1 N (40% by nitrate) and 83 mg·L-1 K. Compared with the FB system, the EF system allowed control of water availability, which slowed plant growth, and increased oxygen concentration in the root zone. Both EF and FB systems are suitable for cabbage transplant production.

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Jonathan M. Frantz, Gregory E. Welbaum, Zhengxing Shen, and Ron Morse

“Float-bed” (FB) is a simple hydroponic system used by the tobacco industry for transplant production. “Ebb-and-flood” (EF) is a modified FB system with periodic draining of the bed to limit water availability and control plant growth. Field-bed cabbage (Brassica oleracea L. gp. Capitata) transplant production was compared with FB, EF, and overhead-irrigated plug-tray greenhouse systems. Plants were produced in May and June and transplanted in a field near Blacksburg, Va., in June and July of 1994 and 1995, respectively. Beds for FB and EF production consisted of galvanized metal troughs (3.3 × 0.8 × 0.3 m) lined with a double layer of 0.075-mm-thick black plastic film. In 1994, both EF and FB seedlings were not hardened before transplanting, were severely stressed after transplanting, and had higher seedling mortality compared with plants from other systems. Plug-tray transplants showed the greatest increase in leaf area following transplanting and matured earlier than seedlings produced in other systems. In 1995, EF- and FB-grown cabbage plants were hardened by withholding water before transplanting, and seedlings had greater fresh mass and leaf area than plug-tray or field-bed seedlings 3.5 weeks after transplanting. Less succulent cabbage transplants were grown in EF and FB systems containing 66 mg·L-1 N (40% by nitrate) and 83 mg·L-1 K. Compared with the FB system, the EF system allowed control of water availability, which slowed plant growth, and increased oxygen concentration in the root zone. Both EF and FB systems are suitable for cabbage transplant production.

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Ricardo Hernández and Chieri Kubota

production of vegetable transplants because cucumber growth rate decreased with the increased of blue PF under low solar DLI (5.2 ± 1.2 mol·m −2 ·d −1 ) ( Hernández and Kubota, 2014a ). To advance the use of LEDs as a supplemental lighting technology in

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Sherrod A. Baden and Joyce G. Latimer

A brushing system for vegetable transplants that is adjustable, easy to use, and provides uniform brushing action was designed and constructed. Using this system, the height of several species and cultivars of vegetable transplants was reduced 15% to 50%. Quality and uniformity also were improved, and edge effects on growth were reduced.

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Albert Liptay, Peter Sikkema, and William Fonteno

The theme of this review is modulation of extension growth in transplant production through restraint of watering of the seedlings. The purpose of the modulation is to produce transplants of 1) appropriate height for ease of field setting and 2) adequate stress tolerance to withstand outdoor environmental conditions. Physiological responses of the plant are discussed in relation to the degree of water deficit stress and are related to the degree of hardening or stress tolerance development in the transplants. Optimal stress tolerance or techniques for measuring same have not been fully defined in the literature. However, stress tolerance in seedlings is necessary to withstand environmental forces such as wind and sand-blasting after the seedlings are transplanted in the field. It is also imperative that the seedlings undertake a rapid and sustained rate of growth after outdoor transplanting. Water deficit stress applied to plants elicits many different physiological responses. For example, as leaf water potential begins to decrease, leaf enlargement is inhibited before photosynthesis or respiration is affected, with the result of a higher rate of dry matter accumulation per unit leaf area. The cause of the reduced leaf area may be a result of reduced K uptake by the roots with a concomitant reduction in cell expansion. Severe water deficits however, result in overstressed seedlings with stunted growth and poor establishment when transplanted into the field. In transplant production systems, appropriate levels of water deficit stress can be used as a management tool to produce seedlings conducive to the transplanting process.

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Wayne C. Porter

Black polyethylene, perforated clear polyethylene, double-slitted clear polyethylene, spunbonded polyester, and a bare soil control were evaluated for their effect on the number, size, and distribution of production of sweet potato transplants. The perforated and double-slitted bed covers increased the weight and number of sweet potato transplants compared with the control or with black polyethylene at the first harvest in 1986 and 1987, Seed roots covered with the spunbonded polyester bed cover produced more plants of greater weight than seed roots covered with bare soil at the first harvest in 1986 only. Black polyethylene treatments produced the greatest weight and number of transplants at the second harvest (8 to 12 days later) in both years. There were no significant differences in total weight and number of transplants among black polyethylene, perforated or double-slitted clear polyethylene treatments in 1986. Total transplant number and weight from plots covered with spunbonded polyester were lower than those from plots with any other bed covers.

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Kristine M. Lang, Ajay Nair, and Alexander G. Litvin

Grafted tomato transplants ( Solanum lycopersicum ) have become an important production tool for vegetable growers within the United States ( Grieneisen et al., 2018 ; Masterson et al., 2016a ; Meyer, 2016 ; Rivard and Louws, 2008 ). Vegetable