A Comparison Study on Productivity and Bulb Quality of Organically and Conventionally Grown Bulb Onion

Vegetable consumption is associated with health benefits. Organic vegetables are thought to have higher contents of nutrition, although they produce lower yield compared with conventional ones. The objective of this work is to compare crop growth, bulb productivity, and quality between conventionally and organically grown onions (Allium cepa). Samplings were performed from 8 organic certified farmers’ fields and their neighboring conventional ones. Fresh bulb weight of organic and conventional onion was 2.7 g/plant and 6.2 g on 4 April, 41.0 g/plant and 74.4 g on 7 May and 176.6 g/plant and 220.2 g at harvest, respectively. The difference in bulb weight between organic and conventional onion was larger at the early growth stage than at the late growth stage. The marketable bulb yield in organic onions was 55.8 ton/ha, which was significantly lower than that in conventional onions with 71.5 ton/ha. Organic onion produced 11.7 ton/ha of large-size yield, 35.2 ton/ha of medium-size, and 9.0 ton/ha of small-size, while conventional onion produced 30.0 ton/ha of large-size yield, 39.4 ton/ha of medium-size, and 2.3 ton/ha of small-size. Number of scales, scale thickness, and number of centers at harvest was not significantly different between organic and conventional onion bulbs.