Differentiation and Development of Floral Organs at Each Node and Raceme Order in an Indeterminate Type of Soybean

Abstract

SummaryDifferentiation and development of floral organs of soybean ( Glycine max (L.) Merr. cv. “Touzan 69”) were classified into nine stages ; pre-differentiation (I), floral differentiation (II), calyx formation (III), petal formation (IV), stamen formation (V), pistil formation (VI), ovule-anther formation (VII), pollen-embryo sac formation (VIII), and flowering (IX). The floral organs differentiated from the lower to higher nodes on the main stem. The developmental rate was higher at stages II∼VI than at stages VII∼IX, and at a higher node. At the same node, the floral organs differentiated first in the basal raceme followed by the secondary and tertiary racemes in this order and the developmental rate was the highest in the tertiary raceme. The floral organs differentiated first in the secondary raceme at the 4th node. However, most of the floral primordia that had differentiated in the secondary or tertiary racemes did not develop into flowers. The factors determining the floral organs are unknown, but this indicates that the sink-capacity in each node of soybean plant is extremely large.