Bulb onions: the challenge of reducing dependence on imported onions

摘要

The PNG Department of Agriculture and Livestock has set out to promote the production of bulb onions in PNG as a means of reducing dependence on imported onions. From 1988 to 1995, trials were carried out in a number of locations in the dry lowlands, the wet lowlands and the highlands of PNG. In all locations it is possible to produce bulb onions. In the dry lowlands, good crops of onions could be grown from sowings between February and June. These crops were produced under irrigation during the dry season. In the wet lowlands, production is extremely risky as the crop is easily damaged by heavy rain. In the highlands, all trials were grown as rainfed crops. It was clear that good onions could be produced, but results were not consistent. In wet weather, disease problems, especially purple blotch (Alternaria porri), affected the crop. However, the crop could be produced year-round in the highlands, if excessively wet conditions did not occur. Wet weather during harvesting was liable to cause soft rots and make drying of the crop difficult. Irrigated dry season production of bulb onions in the highlands needs to be investigated. In the dry lowlands, smallholder farmers successfully grew crops of bulb onions using selected varieties (Gladalan Brown and Superex). In the highlands, some farmers have also managed to grow satisfactory crops of bulb onions, but onions are a more difficult crop to grow than many other vegetables. To date, there has been no significant reduction of imports as a result of local production. The varieties adapted to PNG conditions ('short day' varieties) also tend to store less well than the long day imported varieties. While PNG can successfully produce bulb onions both in the dry lowlands and the highlands, the crop requires careful management and year-round production may not be possible due to excessively wet weather during the rainy season and also to the photoperiodic sensitivity of the crop. If production is targeted at selected parts of the country and at optimal planting dates, then local production still has the potential to contribute significantly to the PNG onion supply.