In 'Biloxi' soybeans the trifoliolate leaves are essential to perceive the photoperiodic inductive conditions and to cause the initiation of flower primordia (Borthwick and Parker, 1935). To respond to photoinduction, some plants have to reach "ripeness to flower" or pass the "juvenile phase" (Lang, 1965). "Juvenile phase" is distinct in some soybean cultivars, such as Acc. G 2120, while in the day-neutral soybean Acc . G 215 it is not clear whether there is a "juvenile phase" (Shanmugasundaram and Tsou, 1978).
Shanmugasundaram, S. and Lee, M. S.
"Research Notes : Flowering of Glycine max (L.) Merr. with cotyledonary
and unifoliolate leaves,"
Soybean Genetics Newsletter: Vol. 7
, Article 33.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol7/iss1/33