Short-day onions are grown for fresh market in the southern region of the US, and they require around 10 to 12 hours of photoperiod or 12 to 14 hours of nighttime to thrive. These onions tend to produce fewer, thinner layers and have higher moisture contents, making them susceptible to bruising. When short-day onions are harvested by machines, a small percentage of them are damaged and the rest experience bruising during the harvesting process. This leads to a focus on bulb firmness and how it can affect the reduction of bruise damage. The current study seeks to identify bulb characteristics that affect bulb firmness and their relation to the overall bruise damage in short-day onions. For this, early and main season maturity varieties were used and several bulb characteristics including bulb weight (gm), height (cm), width (cm), number of rings, firmness, growing point (single versus multiple centers), and total soluble solids (°Brix) were measured. Correlation among bulb traits was analyzed using correlation in R corrr package. In the early season, there was correlation between bulb weight and bulb width (r=0.920343), firmness and single center (r=0.504853), and single center and ring number (r=0.609349). There was no significant correlation between bulb firmness and the remaining bulb traits. A negative correlation was observed between firmness and moisture content (r=- 0.412323) and firmness and ring number (r=- 0.5084) in the main maturity season trial, but not enough to significantly impact the bulb firmness. The results suggested that in early maturity bulbs, a single center directly correlated with firmer bulbs, but in the main maturity season, firmness had a negative correlation with moisture content and ring number. Results will be validated with the second season trial during the 2024-2025 season.
