Growth Stages of Soybeans

Emergence and Cotyledon

• The first two stages of the life of a soybean involve the germination of the seed and its emergence from the ground. Emergence takes up to 10 days depending on soil temperatures while the cotyledon stage can take another 10 days. The cotyledons are the first leaves of the plant that unroll as they expand. These are called unifoliolate leaves because each leaf forms individually.

Setting Leaves

• Stages V1 through V5 represent the number of trifoliolate leaves--leaves in sets of three--which form on the plant stem. Some agronomists track the V stages to a higher number of tirfoliolate leaves depending on weather and growing conditions. The rate at which soybean plants set trifoliolate leaves is a product of the growing habits of the soybean variety and weather conditions.

Blooming

• The reproductive stage of the soybean plant begins with the appearance of the first flowers. The stage R1 indicates plants with at least one flower while the R2 stage indicates that at least 50 percent of the upper buds are blooming. Soybeans in stage R2 are fully in bloom.

Setting Pods

• Stages R3 through R8 involve the various stages of the setting and maturity of the seedpods. Stage R3 indicates the beginning of the pod formation while R4 indicates full pod formation. Stage R5 indicates the start of seed formation in the pod while R6 indicates full seed formation. Maturity is treated similarly with step R7 indicating the start of pod maturity and R8 indicating at least 95 percent of the pods are mature.