Results reported by Buzzell (1974) were not conclusive as to whether or not E3 (daylength response) and Ep (seedcoat peroxidase) are independent or loosely linked. Palmer et al. (1984) has shown that Ep is linked with Frl in linkage group 12. Using F2 plants of 'Minsoy' x 'Hark' previously reported (Palmer et al., 1984) for seedcoat peroxidase and root fluorescence, we tested for linkage of E3 with Ep and Frl by testing F3 material for response under a daylength extended to 20 h with cool white fluorescent light.