Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/29/2004
Publication Date: 10/15/2004
Citation: Russo, V.M. 2004. Greenhouse grown transplants as an alternative to bare-root transplants for onions. HortScience. 39:1267-1271.
Interpretive Summary: One means by which onions are established in the field is with bare-root transplants. These transplants are sometimes variable in size and this may affect plant development and yield. Production of seedlings in individual cells in greenhouses has been used in the establishment of various vegetables. There is little information on how this type of onion seedling production affects plant development and yield. Bare-root transplants and seedlings produced in seedling production trays with cells having volumes of 30- or 55-cm3 were established in the field in early spring. Bulbs produced by plants developed from bare-root transplants were 12% heavier than those produced from plants developed from seedlings grown in trays in the greenhouse. It was determined that yield and distribution of bulbs among size classes was not consistently affected by transplant type. The producer does have options in which type of transplants to use and much of that choice will be determined by the economics of production of transplants.
Technical Abstract: 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 greenhouse grown onion transplants respond when established in the field. Development and yield for onions grown from bare-root transplants were compared to plants produced from transplants grown in single cells with volumes of 30- or 55-cm3 in seedling production trays in a greenhouse. The cvs. 'Texas Grano 1015Y' and 'Walla Walla' were established in the field as commercially available bare-root transplants or as greenhouse grown transplants produced in trays. Bare-root transplants were generally heavier than greenhouse grown transplants which, for both cvs., were similar in weight regardless of tray cell size. From about 20% breakover onion bulb diameters did not increase sufficiently to justify delaying harvest. On average individual bulbs from plants developed from bare-root transplants were heavier (291.5 g) than those from plants developed from transplants grown in trays (256.3 g). Yields for plants developed from transplants produced in trays were not clearly better than for plants developed from bare-root transplants.