Glucoraphanin level in broccoli seed is largely determined by genotype

Broccoli (Brassica oleracea L., Italica Group) seed and resulting sprouts can contain high levels of glucoraphanin, a glucosinolate, which can be converted to sulforaphane, a compound with cancer protective and antioxidant properties. This observation has stimulated interest in broccoli seed production. In this study, inbred lines, which produce relatively high yields of homogeneous, selfed-seed across different environments in the absence of insect pollinators, were used to evaluate the relative importance of genotype versus environment as a determinant of glucoraphanin concentration in broccoli seed. Glucoraphanin and glucoiberin were measured in broccoli seed lots generated from ten broccoli inbred lines grown in two greenhouse and two screen cage environments. Typically, seed glucoraphanin level ranged from 5 to 100 μmol·g^-1 seed and glucoiberin ranged from 0 to about 40 μmol·g^-1 seed, regardless of the environment in which seed was produced. Analysis of variance indicated that genotype was the most significant factor influencing levels of the two glucosinolates. Although significant environmental and genotype x environment effects were observed for glucoraphanin and a significant genotype x environment effect was observed for glucoiberin, these effects were small compared to the genotype effects. Results indicate that it is possible to identify broccoli inbreds that consistently produce relatively high yields of seed with a high glucoraphanin content across different environments.