ISHS Acta Horticulturae 631: XXVI International Horticultural Congress: Issues and Advances in Transplant Production and Stand Establishment Research
CONTAINERIZED TRANSPLANTS AND SUBSURFACE DRIP IMPROVED YIELD AND QUALITY OF SHORT-DAY ONIONS |
| Authors: | D.I. Leskovar, K. Kolenda, K.S. Yoo, L.M. Pike |
| Keywords: | Allium cepa, brix, direct seeding, evapotranspiration rates, pyruvic acid, subsurface drip irrigation, trickle |
| Abstract:
A 2-year field study was conducted to determine growth, yield and bulb quality in response to stand establishment, irrigation methods, and cultivars. Containerized transplants or direct seeding were irrigated with subsurface drip (SDI) placed at 5- or 15-cm depth at water application rates of 1.0 and 0.5 ET. Two yellow cvs, ‘TG 1015Y’ and the newly developed ‘Legend’, and one white cv. ‘Texas Early White’ (TEW) were used. The initial plant population for direct seeding and transplants was 387 500 and 182 400 pl/ha, respectively. Root and shoot growth, bulb pungency (pyruvic acid level), soluble solids (brix %), and the flavonoid quercetin were monitored. At harvest, bulbs were sorted by commercial size classes. By mid development, transplants had larger bulbs with more number of leaves and roots than direct-seeded plants. After the onset of bulbing, differences in bulb quality were measured mainly in response to stand establishment and cultivars, and minimal differences due to irrigation. At harvest, pungency was lower and brix was higher for transplants than direct seeding in both years. Pungency level ranges were 2.8-3.9 μmoles/ml (Legend), 3.4-4.1 (TG1015Y) and 5.3-5.7 (TEW). Transplants had 37% (2000 season) and 42% (2001 season) higher total yields than direct seeding. The yield increase was greatest for the cv. ‘Legend’. Transplants also had larger bulb sizes and higher water use efficiency than direct-seeded plants. Containerized transplants are more costly, but can provide an immediate and complete field establishment. This work demonstrated that transplanting with efficient subsurface drip systems and superior cultivars can enhance onion flavor attributes and produce uniform high-value bulb sizes, thus increasing profit potential. | |
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