The best way to know something about the genetics of seed color would be to conduct a genetic study in which you would cross individuals that produce different colored seeds. Generating an F1 (white x black seed) and F2 (either crossing two F1's, or selfing an F1) in a common environment would certainly tell you something about how this trait is determined.

Thanks for your answer. I know the procedure but want to know about findings by any researchers. @Sean Stankowski