A new poster titled “Soybean Growth and Development” has just been published by K-State Research and Extension. The poster can be seen at: https://www.bookstore.ksre.ksu.edu/pubs/MF3339.pdf
This publication was supported by the United Soybean Checkoff and Kansas Soybeans.
The poster lists the primary growth and development stages of soybeans, with illustrations of each stage. It describes the growth stage, and discusses some of the significant management considerations of each stage.
The author of the poster is Ignacio Ciampitti, K-State Crop Production and Cropping Systems Specialist. The following excerpts for some of the early season growth stages are from the poster:
During germination and emergence, the cotyledon pokes through the soil and primary and lateral root growth begins. Functional root hairs develop shortly after planting. Root hairs are essential to nutrient uptake and water absorption when the plant is at this early stage.
Scout for proper emergence; check final stand and uniformity. Optimum seed placement varies from 1 to 2 inches deep. Deeper planting depth (greater than 2 inches) and lower soil temperatures jeopardize final emergence. If the stand is poor, replanting may be needed.
Unifoliate leaves expand (leaf edges are not touching). The cotyledons are the main nutrient reservoir for the young soybean plants (7 to 10 days after emergence). Damaged cotyledons can lower yields.
Scout for proper emergence. Weed control is important before and after soybeans emerge. If stand is poor, replanting may be needed.
First Trifoliate (V1)
Trifoliate leaf unrolls (fully developed leaves at the unifoliate nodes). The plant becomes self-sustaining as newly developed leaves carry out photosynthesis. From this point onward, new nodes appear every 3 to 5 days until V5 stage (five-node stage), and then every 2 to 3 days until the last vegetative node.
Scout for early-season weeds, insects, and diseases.
Second Trifoliate (V2)
Two trifoliates unroll (fully developed trifoliate leaves at node above the unifoliate node). Check for effective nodulation. Nodules have been initiated on the roots at this stage and nitrogen fixation continues until late reproductive stages. Effective nodulation results in higher yields and more seed protein when compared with a non-nodulated soybean plant.
Scout for early-season weeds, insects, and diseases. Apply postemergence herbicides if needed. If nodulation has been established effectively, nitrogen fertilization is not recommended, and, if applied in large quantities, will inhibit nitrogen fixation activity.
Special Topics: Nitrogen Fixation and Pod Formation
A hard copy of the 20x30 inch poster can be ordered from K-State at no charge. There is a limited supply. To order, see: http://www.bookstore.ksre.ksu.edu/Category.aspx?id=2&catId=286
Ignacio Ciampitti, Crop Production and Cropping Systems Specialist