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Warren Roberts, Jim Duthie, and Wes Watkins

Wet soils can prevent growers from transplanting tomatoes at the ideal size and age. Experiments were conducted to determine the length of time that transplants can be held before yield is reduced Also, different techniques for holding and hardening plants were compared. Seven ages of `Sunny' tomato plants (4, 5, 6, 7, 8, 9, 10 weeks old at transplanting) were either grown normally, grown with limited water, or grown with limited fertilizer. Plants were grown in trays containing 128 cells, with each cell approximately 3.2 by 3.2 by 11 cm. Water was applied for 3 minutes either once a day or twice a day. Fertilizer (20-20-20) was applied either once a week or once during the entire seedling production period. Transplants were later planted in the field. The experiment was conducted in 1990, 1991, and 1993. The yield response to transplant age was quadratic, with maximum yield occurring with 6, 7, and 8 week old transplants. In general, the greatest yield occurred when water was withheld, and the lowest yield occurred when fertilizer was withheld from the transplants

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J.E. Brown, R.P Yates, C. Stevens, and V.A. Khan

Effects of planting methods and rowcover on the production of yellow crookneck squash, Cucurbita pepo L. var. melopepo Alef., were evaluated over 2 years at the E.V. Smith Research Center, Shorter, Ala. Summer squash was direct-seeded or transplanted in the field with or without black plastic mulch and grown with or without rowcover. Yield of transplanted squash was significantly increased over the same squash direct-seeded. Neither plastic mulch nor rowcover had an effect on summer squash production. Transplants matured 8 to 10 days earlier than the direct-seeded plants.

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Regina R. Melton and Robert J. Dufault

`Sunny' tomato (Lycopersicon esculentum Mill.) seedlings were pretransplant nutritionally conditioned (PNC) in 1988 and 1989 with factorial combinations of N from 100 to 300 mg·liter-1 and P from 10 to 70 mg·liter-1. In 1988, all conditioned seedlings were exposed to 12 hours of 2C for eight consecutive nights before transplanting. In 1989, half of the conditioned plants were exposed to a low-temperature treatment of 8 days with 12-hour nights at 2C and 12-hour days in a warm greenhouse (19C/26C, night/day). In both years, as N PNC increased to 200 mg·liter-1, seedling growth increased. Increasing P PNC from 10 to 40 mg·liter-1 increased seedling growth, but only in 1988. In both years, P PNC did not affect yields. Low-temperature exposure in 1989 decreased seedling growth in comparison to those held in a warm greenhouse (19C/26C, day/night). In 1988, first harvest yields were not affected by N PNC; however, in 1989, as N increased to 200 mg·liter-1, early yields increased. In 1988, total yields increased wit h N PNC from 100 to 200 mg·liter-1 and in 1989 with N at 50 to 100 mg·liter-1 with no further increases from 100 to 200 mg·liter-1. Low-temperature exposure had no effect on earliness, yield, or quality. A PNC regime combining at least 200 mg N/liter and up to 10 mg P/liter should be used to nutritionally condition `Sunny' tomato seedlings to enhance yield.

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Richard L. Parish

This article is a review of the current status in planting and transplanting equipment and practices for vegetable crops. A review of horticultural and agricultural engineering literature is supplemented by information from an informal survey of members of American Society of Agricultural Engineers (ASAE) committee PM-48, Fruit and Vegetable Production Engineering, and other engineers and horticulturists working in this field. Areas covered include precision seed metering, seed placement, and high-speed transplanting with automated plant handling.

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S. M. Olson and Salvadore J. Locascio

Four experiments were conducted to evaluate the influence of transplant age and container size on `Green Duke' broccoli production. Transplant ages (weeks from seeding) were 3, 4, and 5 weeks in Exp. A, 4, 5, and 6 weeks in Exps. B and D and 3, 4, 5, and 6 weeks in Exp. C. Cell sizes were 2.0 cm (width) × 3.2 cm deep (2.0 cm), 2.5 cm × 7.2 cm deep (2.5 cm), and 3.8 cm × 6.4 cm deep (3.8 cm) with each transplant age. With the smallest container size (2.0 cm), yields were significantly lower in 3 of 4 experiments as compared to the 3.8 cm container size. In 2 of 4 experiments, yields were lower with the 2 cm size as compared to the 2.8 cm container size. In Exps. A and B transplant age did not influence yield, but use of the oldest transplants in Exp. C resulted in reduced yields while use of the oldest transplants in Exp. D resulted in the highest yields Generally, head weights followed similar patterns to the yields.

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Daniel I. Leskovar, Daniel J. Cantliffe, and Peter J. Stoffella

Tomato, cv. `Sunny' containerized transplants produced either with overhead (SP1) or sub (flotation) (SP2) irrigation were established in the field in fall, winter, and spring. Leaf area (LA), root volume (RV), and dry weights of shoots (SDW) and roots (RDW) were measured weekly before and after transplanting. In fall 1987, SP1 with 44 cm2 LA, 275 mg SDW, 68 mg RDW, and 0.9 ml RV at transplanting (T0) had 33% more fruit yield than SP2 transplants with 20 cm2 LA, 236 mg SDW, 62 mg RDW, and 0.6 ml RV at T0. In spring and winter 1988, SDW, RDW, and RV increased uniformly in both SP1 and SP2 plants, and yields did not differ significantly. In spring 1989, at T0, SP1 had 182 mg SDW and 7.8 shoot/root ratio (S:R) and SP2 had 92 mg SDW and 4.6 S:R, thereafter SDW and S:R ratios were not different and yields were unaffected. In fall 1989, SP1 total fruit yeild (52.3 t.ha-1) did not differ significantly from that of SP2 (47.4 t.ha-l) plants. Sub irrigated transplants may have similar fruit yields than overhead irrigated transplants provided plants are kept with minimum stress before establishment.

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Warley M. Nascimento

The growing of transplants in plug cell trays is the primary method of producing brassica transplants in many countries. Seed quality is an important aspect to achieve success in transplant production. Seed size may affect seed performance, seedling growth and development of brassica transplants. Seeds of cauliflower (`Vitoria de vero') and cabbage (`Unio') from Embrapa Vegetables were used in this study. During seed conditioning, seeds were classified using round screens generating three (>1.5, 1.5-2.0, and 2.0-2.5 mm) and four (>1.5, 1.5-2.0, 2.0-2.5, and < 2.5 mm) seed size categories, for cauliflower and cabbage, respectively. The original seed lot was used as control. Seed weight increased with seed size. Seed germination (laboratory) and seedling emergence (greenhouse) were not affected by seed size. In both species, root and shoot weight, and leaf area, measured 30 days after seeding, in greenhouse conditions, increased with seed size. Also, transplants from larger seed size resulted in a significantly higher root weight, shoot weight, and leaf area relative to the original (control) seeds. The results indicate that, overall, an adequate seed conditioning improve brassica transplant quality.

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William Terry Kelley and Darbie M. Granberry

Bell pepper (Capsicum annuum) has traditionally been transplanted to the top of the root ball or to the cotyledons of the transplant. Recent studies have shown increased and earlier yields are obtained by transplanting pepper deeper. Thus, a study was initiated to investigate effects of transplanting depth on pepper yield and plant growth. Pepper was transplanted to the top of the rootball, the cotyledons, and the first true leaf in two locations in 1994. `Camelot' hybrid and `Jupiter' (open pollinated) cultivars were planted into bare ground on Mar. 24 in Tifton, Ga. Only `Camelot' was transplanted into a plastic mulch with drip irrigation on Mar. 28 in Cool Springs. Plots consisted of single rows of seven plants with data collected from the internal five plants. Treatments were replicated three times. Normal cultural and pest control practices were used at both locations. Plant measurement data were taken 5 weeks after transplanting. Yield data were collected at harvest. Total weight per plant of three harvests was significantly greater with peppers planted to cotyledons and first true leaf than those planted to the rootball in `Jupiter'. There was no significant effect of planting depth on `Camelot', although there was a distinct trend toward greater yield with deeper planting on plastic. The same trend was evident for average weight per plant and average number of fancy-grade peppers per plant. Average stem diameter, plant height, and length of largest leaf were all greater among deeper planted peppers. Deeper planting seems to have a positive effect on yield and plant growth, particularly with hybrid pepper planted into a plastic mulch.

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Wayne C. Porter

Four bed covers (black polyethylene, perforated clear polyethylene, double-slitted clear polyethylene, and spunbonded polyester) and a bare soil control were evaluated for their effect on the number, size, and harvest time of sweetpotato [Ipomoea batatas (L.) Lam. cv. Travis] transplants. The perforated and double-slitted bed covers increased the weight and number of sweetpotato transplants compared with the control or with black polyethylene at the first harvests 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 numbers of transplants among black polyethylene, or perforated or double-slitted clear polyethylene treatments in 1986. Total transplant count and weights from plots covered with spunbonded polyester were lower than those from plots with any other bed covers.

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David A. Bender

Two cultivars of onions, `New Mexico Yellow Grano' and `Midstar' were seeded in single bed plots in mid-October 1985 and 1987 for overwinter transplant production. Plots were covered with spunbonded polyester (POL) or tunnels of clear polyethylene (CLR) or microperforated polyethylene (PER) (1985 only) in early November and compared to uncovered controls. Temperatures were monitored 5 cm above the soil surface under the covers in each plot with three parallel-wired thermocouples. Heat unit (HU) accumulation (number of degrees by which the daily mean temp exceeded 0°C) was recorded for each plot and compared with onion plant size. HU accumulation by mid-February 1986 under CLR, POL and PER was 139%, 131% and 113%, respectively, of that over bare ground. In mid-March 1988 cumulative HU under CLR and POL were 192% and 125% of those over bare ground. Plant diameter varied with variety but increased linearly with cumulative HU for all varieties. `New Mexico Yellow Grano' reached the minimum 4 mm size for transplanting at about 1800 HU while `Midstar' required only 1500 HU. CLR produced useable transplants by early March and the other covers by late March. Numbers of useable transplants per meter of bed in mid-March ranged from 3-6 in uncovered plots to 102-153 under PER tunnels, 185-203 under POL and 263-301 under CLR tunnels. CLR tunnels appear to provide sufficient HU accumulation to produce onion plants for transplanting in early March in West Texas.