Harvest date effect on yield and controlled-atmosphere storability of short-day onions

This study was undertaken to evaluate the effect of harvest date on yield and storage of short-day onions in controlled-atmosphere (CA) storage conditions. In general, harvest yields increased with later harvest dates. Yields of jumbo (>7.6 cm) onions primarily showed a quadratic or cubic response to harvest date, first increasing and then showing diminished or reduced marginal yields. Medium (>5.1 to less than or equal to7.6 cm) onions generally showed diminished yield with later harvests as jumbos increased. Neither days from transplanting to harvest nor calculated degree days were reliable at predicting harvest date for a particular cultivar. Cultivars (early, midseason, and late maturing) performed consistently within their harvest class compared to other cultivars for a specific year, but could not be used to accurately predict a specific number of days to harvest over all years. Only three of the eight statistical assessments of percent marketable onions after CA storage were significant with two showing a linear increase with later harvest date and one showing a cubic trend, first increasing, then decreasing, and finally I increasing again based on harvest date.