Containerized Onion Transplants: A Management System to Enhance Growth, Yield, and Quality

Abstract

In the United States, most short-day onions are direct seeded. With this method, plant stands can be reduced because of extreme temperatures, weed pressure, and soil-borne diseases. Containerized transplants offer an alternative method of stand establishment with less seedling losses while producing uniform bulb sizes and high marketable yield. However, the use of transplants is not a widespread commercial practice because of the high cost of production. This study aims to select the best transplant strategies to improve onion crop performance in semiarid regions of southwest Texas or similar environments. Three sequential transplanting dates of early, mid, and late season (14 Nov., 8 Dec., and 9 Jan.) and two seedling densities of one seed per cell (T1) and three seeds per cell (T3) were evaluated on growth, yield, bulb quality, and phytonutrient content of three onion cultivars, two yellow (‘Caramelo’ and ‘Don Victor’), and one red (‘Lambada’). During early development, late-transplanted onions had an increase in plant height and greater leaf elongation rate than early and midtransplanted onions, whereas early plantings required more days to reach maturity than mid and late plantings. Overall, early and midtransplanting dates resulted in higher yields than late plantings. Although increasing seedling density (T3 vs. T1) did not significantly reduce marketable yield in early plantings, T1 produced a higher number of jumbo and colossal bulb sizes than T3. Onion quality was mostly affected by cultivar and not by transplant strategies. The technique of establishing onions from transplants grown from one plant per cell (T1) or multiple plants (T3) from early November to early December provides a practical and economical alternative to achieve earlier crops, while reducing the length of the production season, as planting date is delayed.