Development of a suite of onion varieties for the subtropical region of the Lockyer Valley in SE Queensland, Australia

Approximately 80% of Queensland's annual onion production of 20 000 t is produced in the subtropical environment of the Lockyer Valley in S.E. Queensland. Here, short to medium daylength onions can be produced over an extended period. Over the past three years varieties supplied by seed companies, local seed producers and selections developed at Gatton Research Station have been evaluated over a series of planting dates commencing in February and ceasing in June. In years one and two, varieties were planted at fortnightly intervals and at monthly intervals in year three. In early season plantings (February-March) locally developed open-pollinated lines including Early Lockyer White and Brown and Golden Brown were the highest yielding. Wallon Brown, Golden Brown and Cavalier hybrid were the most successful varieties in April plantings. In May, the hybrids Diamond White and Cavalier and the open-pollinated Wallon Brown were dominant. Hybrid varieties including Gladiator, Omega and SPS 846 were outstanding in June plantings. Average yields for the best three varieties in the early and late season plantings were 54-56 t/ha, 70-84 t/ha for the best three varieties in the April plantings and 60-63t/ha for May plantings. Observations were recorded on the incidence of doubles, bolting and shell development at harvest throughout the trial series. Generally the production of doubles was greatest in the March/April plantings and then declined until the June planting when a slight increase was observed. Bolting was more of a seasonal occurrence with very little in year one compared to year two. It was generally absent in all late season plantings. The development of 2-3 complete skins at harvest was remarkably constant throughout the season and from year to year. The program has identified a suite of well adapted varieties for the extended production of fresh, low pungency onions in a subtropical environment.