Effects of Cold Temperatures on a Soybean Crop Nearing Maturity

Every September, as the warm weather of summer transitions to cooler fall temperatures, farmers start to ask, “What happens if we get an early frost”?  The quick response is “it depends”.

Soybean plants respond to shortening days which pushes them to maturity. Soybean seeds, like corn kernels, need warmth and wind to dry down once reaching full maturity (R8 growth stage). Some growing seasons are long while others end abruptly with a killing frost.  Three main factors can affect yield potential from an early cold event:

Temperature and Time

Temperature and time work together and ultimately determine what parts of the soybean plant may be left to photosynthesize. Light frost (32° F) could damage the top leaves of the canopy but preserve the main stem and lower leaves and allow the plant to continue growing. Heavy frost (28° F or less) for a period of 4 hours will kill the plant at its current maturity stage.

Row Configuration

Narrower rows and bushier canopies can trap heat, which can reduce some of the effects of freezing temperatures on the plants. If the middle and lower part of the canopy are preserved, the plants can continue to photosynthesize until maturity or another frost

Growth Stage of the Plants

The closer plants are to maturity the less susceptible the seed is to damage from frost (Table 1).

 

Table 1. Soybean growth stages and predicted yield loss after a frost1

Growth Stage

Percent Yield Loss

Beginning Seed (5.0)

65.4

Beginning Seed (5.5)

51.0

Full Seed (6.0)

37.1

Full Seed (6.5)

23.9

Beginning Maturity (7.0)

11.4

Beginning Maturity (7.5)

0.0

Full Maturity (8.0)

0.0

Source: Saliba. et al. Crop Sci. 22:73-78, As found in Staggenborg, S., Dhuyvetter, K., Fjell, D. and Vanderlip, R. 1996. Fall freeze damage in summer grain crops. Kansas State University Extension. MF-2234

For more information, please see Channel Advice, Late Season Frost Damage to Soybean.

John Goeden

Technical Agronomist

Sources:

1Saliba, M.R., Schrader, L.E., Hirano, S.S., and Upper, C.D. 1982. Effects of freezing field-grown soybean plants at various stages on podfill on yield and seed quality. Crop Science, Vol. 22.

Berglund, D. Assessing frost damage in soybeans. North Dakota State University Extension. http://www.ag.ndsu.edu.

Staggenborg, S., Dhuyvetter, K., Fjell, D. and Vanderlip, R. 1996. Fall freeze damage in summer grain crops. Kansas State University Extension. MF-2234. https://www.bookstore.ksre.ksu.edu/.

Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.

ALWAYS READ AND FOLLOW GRAIN MARKETING AND ALL OTHER STEWARDSHIP PRACTICES AND PESTICIDE LABEL DIRECTIONS. Channel® and the Arrow Design® and Seedsmanship At Work® are registered trademarks of Channel Bio, LLC. ©2020 Bayer Group. All rights reserved.

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