Effect of harvest date on onion yield in a northern climate

Timing of harvest is an essential factor affecting the quantity, quality an d storability of onion yield. This study aimed to establish when no further yield increase is to be expected and to determine the relationship between maturity stage and yield development. Experiments on 4-6 harvests at 9-14 d intervals were conducted at several locations in southern Finland in 1996 -1999. Generally little, if any, yield increase was recorded after plants h ad reached 100% maturity, but in some cases bulb growth continued after com plete fall-down of leaves. On the other hand, harvesting before 100% maturi ty resulted in a yield loss of 0-45% of final yield. Weight loss, and thus energy consumption during drying, was still reduced after complete leaf fal l-down. Therefore, it may be concluded that delaying harvest up to 100% mat urity, or even longer, ensures that highest yield and lowest drying costs.