The lack of a suitable screening technique for photoperiod response has prevented the identification of photoperiod-insensitive (PI) genotypes. In an F2 population, each plant has a specific genotypic constitution. To determine the photoperiod response, each F2 plant should be subjected to at least two different photoperiods.
Shanmugasundaram, S. and Wang, C. C.
"Research Notes: Decapitation Technique to screen for photoperiod insensitivity
in Soybean. Glycine max,"
Soybean Genetics Newsletter: Vol. 4
, Article 5.
Available at: http://lib.dr.iastate.edu/soybeangenetics/vol4/iss1/5