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Jean Masson, Nicolas Tremblay, and André Gosselin

This experiment was initiated to determine the effects of supplementary lighting of 100 μmol·s-1·m-2 (PAR) in combination with four N rates (100, 200, 300, and 400 mg N/liter) on growth of celery (Apium graveolens L.), lettuce (Luctuca sativa L.), broccoli (Brassica oleracea italica L.), and tomato (Lycopersicon esculentum Mill.) transplants in multicellular trays. Supplementary lighting, as compared with natural light alone, increased shoot dry weight of celery, lettuce, broccoli, and tomato transplants by 22%, 40%, 19%, and 24%, and root dry weight by 97%, 42%, 38%, and 21%, respectively. It also increased the percentage of shoot dry matter of broccoli and tomato, leaf area of lettuce and broccoli, and root: shoot dry weight ratio (RSDWR) of celery and broccoli. Compared with 100 mg N/liter, a N rate of 400 mg·liter-1 increased the shoot dry weight of celery, lettuce, broccoli, and tomato transplants by 37%, 38%, 61%, and 38%, respectively. High N fertilization accelerated shoot growth at the expense of root growth, except for tomato where a 16% increase of root dry weight was observed. High N also reduced percentage of shoot dry matter. Supplementary lighting appears to be a promising technique when used in combination with high N rates to improve the production of high quality transplants, particularly those sown early.

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Laurie Hodges, Entin Daningsih, and James R. Brandle

Field experiments were conducted over 4 years to evaluate the effects of antitranspirant (Folicote, Aquatrol Inc., Paulsboro, N.J.) and polyacrylamide gel (SuperSorb, Aquatrol Inc., Paulsboro, N.J.) on early growth of transplanted muskmelon grown either protected by tree windbreaks or exposed to seasonal winds. A randomized complete block design (RCBD) with split plot arrangement was used with wind protection (sheltered and exposed) areas as the main treatment and use of an antitranspirant spray or gel dip as subtreatments. Based on destructive harvests in the field, treatments and subtreatments did not affect dry weight or leaf area index in the first 2 years. Specific contrasts, however, showed that gel application significantly increased fresh weight, dry weight, and leaf area index over that of the untreated transplants whereas the spray application tended to reduce these factors during the first 3 weeks after transplanting. Significant differences between gel and spray subtreatments disappeared by 5 weeks after transplanting. Shelterbelts ameliorated crop microclimate thereby enhancing plant growth. Significantly, wind velocity at canopy height was reduced 40% on average and soil temperatures were about 4% warmer in the sheltered plots compared to the exposed plots during the first 5 weeks post-transplant. Muskmelon plants in the sheltered areas grew significantly faster than the plants in the exposed areas in 2 of the 3 years reported, with the 3-year average fresh weight increased by 168% due to wind protection. Overall transplanting success and early growth were enhanced the most by wind protection, followed by the polyacrylamide gel root dip, and least by the antitranspirant foliar spray. We conclude that microclimate modification by wind speed reduction can increase early muskmelon plant growth more consistently than the use of polyacrylamide gel as a root dip at transplanting or the use of an antitranspirant spray. A polyacrylamide gel root dip generally will provide more benefit during early muskmelon growth than the use of an antitranspirant spray.

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Brian R. Poel and Erik S. Runkle

. During commercial seedling production, a minimum DLI of 10–12 mol·m −2 ·d −1 has been recommended to achieve suitable seedling quality and reduced time to flower after transplant ( Lopez and Runkle, 2008 ; Pramuk and Runkle, 2005 ). Commercial

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Regina P. Bracy

Field studies were conducted in Spring 1991, 1992, and 1993 to determine if stand deficiencies of 10%, 20%, or 30% affected bell pepper (Capsicum annuum L.) yield and fruit size. Subsequent replanting to a 100% stand and timing of replanting also were evaluated for effects on fruit yield. Stand deficiencies of up to 30% and replanting to a complete stand 2 or 3 weeks after initial transplanting did not affect yield per acre and average weight per fruit of bell pepper plants grown on polyethylene-mulched beds during 3 years of tests. Bell pepper plants grown in 10%, 20%, or 30% deficient stand had greater marketable yield per plant than plants grown in 100% stand. Replanting to a complete stand 3 weeks after initial transplanting decreased early marketable yield and production per plant over replanting 2 weeks after initial transplanting.

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Daniel I. Leskovar and Daniel J. Cantliffe

Shoot and root growth changes in response to handling and storage time in `Sunny' tomato (Lycopersicon esculentum Mill.) transplants were investigated. Transplants, 45 days old, were stored either in trays (nonpulled) or packed in boxes (pulled) for 0, 2, 4, 6, or 8 days at 5 and 15C. Also, 35-day-old nonpulled and pulled transplants were kept in darkness at 20/28C for 0, 1, 2, or 3 days. At SC, pulled transplants had longer and heavier stems, a higher shoot: root ratio, higher ethylene evolution, and lower root dry weight than nonpulled transplants. At 15C, pulled transplants had more shoot growth than nonpulled transplants. Nonpulled, initially 35-day-old transplants had heavier shoots and roots and higher (7.0 t·ha-1) yields of extra-large fruit than pulled transplants (4.1 t·ha-1), but there were no differences in the total yields of marketable fruits.

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D.S. NeSmith

Greenhouse and field experiments were conducted to determine the influence of transplant age on growth and yield of `Dixie' and `Senator' summer squash (Cucurbita pepo L.). Dry weight and leaf area measurements indicated that 28- to 35-day-old greenhouse-grown transplants grew more slowly after transplanting than plants that were 10, 14, or 21 days old. Older transplants flowered earlier; however, earlier flowering did not result in higher early yields. Transplants of varying ages did not differ greatly in yield and yield components in the field, although all transplants had higher early yields than the directly seeded controls. Results from these experiments suggest that 21 days may be a reasonable target age for transplanting summer squash. If transplanting were delayed by adverse planting conditions, 21-day-old transplants would likely have at least a 10-day window of flexibility before yields would be reduced notably by additional aging.

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Yuqi Li and Neil S. Mattson

is one of the most desirable traits for bedding plants ( Hu et al., 2012 ). Tomato is one of the most widely grown vegetables in the world ( Passam, 2008 ). Tomato transplants in a retail setting also often suffer from inadequate watering. Increasing

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Andreas Westphal, Nicole L. Snyder, Lijuan Xing, and James J. Camberato

produced with a transplant system on plastic mulch ( Hochmuth et al., 2001 ). Seedlings are produced in peatmoss-based, soilless potting mixes in plastic trays. This production system allows for early and rapid establishment of 1-month-old transplants into

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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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Lawrance N. Shaw

The use of containerized transplants will increase in the future because of greater survival rates and improved yields. Many transplant operations are already mechanized. Fully automatic field transplanting is highly feasible in the future for several vegetable crops and may become a common practice with most commercial crops. Technology is developing that uses the greenhouse growing trays as magazines to be loaded into the transplanting machines. Automatic field transplanters will then set plants into the soil at rates of 3 to 4 per second. To accomplish this, the following are required: highest quality uniform seedlings; greater seedling tolerance to handling stresses; no dead or missing plants in transplant trays; standardized cell containers; and precise cell arrangement to allow whole rows of plants to be mass removed simultaneously to reach the highest transplanter machine capacity. Plant production and greenhouse growing systems need to be modified to facilitate automatic field transplanting.