Abstract: The relationship between net photosynthetic rate and yield formationin Soybean was studied in 1981～1983.The main results and conclusionsare summarized as follows:1.The photosynthetic rate of soybean is one important property inbreeding.The photosynthetic rate of leaves in different varieties gavedifferences on growing stages,leaf position,and changing years.Therange of varying intensity was within about 15—30 mgCo₂·dm^-2·hr^-1,and increased progressly from early developed varieties to modern varie-ties...