Technical Abstract: Fructans are the primary soluble carbohydrate in onion (Allium cepa L.) bulbs and show significant correlations with dry weights and pungency. In this research, we estimated the genetic effects and interactions between two chromosome regions associated with higher amounts of soluble carbohydrates in onion bulbs. Two segregating inbred families from BYG15-23 by AC43 were grown in field trials over three years and bulbs were evaluated 30 and 90 days post-harvest for dry weights and soluble carbohydrates. Fructan concentrations decreased significantly between 30 and 90 days after harvest, consistent with loss of bulb dormancy over this period. Dry weights were negatively correlated with fructose and positively correlated with sucrose and fructans. Analyses of variance and interval mapping revealed that one region on chromosome 5 primarily affected bulb dry weight, while one region on chromosome 8 significantly affected both dry weights and fructan concentrations. Regions on chromosomes 5 and 8 from BYG15-23 show dominance for increased DW and/or soluble solids. Interactions between regions on chromosomes 5 and 8 were significant only for sucrose and the fructan neokestose, indicating that these regions independently contribute to higher amounts of soluble carbohydrates. These results indicate that onions with low concentrations of soluble carbohydrates were developed by selecting for relatively few recessively inherited chromosome regions.