Soybean temperature requirements – how can temperature impact soybeans?

Soybean temperature requirements are different from corn. It is something worth taking into consideration as you manage your soybean crop.

I would like to share an article written by Kyle Poling of DuPont which was published in Ohio’s Country Journal. You can view the full article here.

Here are a few excellent points made by Mr. Poling in his article:

  • If air temperature exceeds 85 degrees F, soybeans will experience heat stress that can impact yield potential. This is often compounded by a lack of soil moisture. Heat stress can result in a decreased number of pods set, while temperatures above 99 degrees F severely limit pod formation.
  • Compared to corn, soybeans are less sensitive to high nighttime temperatures. In fact, soybeans like it warmer in the evening so that they can “burn” (respire) the stored energy (photosynthates that are stored as starch) and grow.
  • Several factors affect the rate at which crops develop — photoperiod, heat, moisture, and fertility.
  • Because of their long flowering period, soybeans can often compensate for short periods of stress, but its ability to make up ground dwindles as it approaches R5.
  • Elevated temperatures at the R5 growth stage (beginning seed fill), has the greatest negative impact on soybean yield. During seed fill, daytime temperatures greater than 85 degrees can cause decreased soybean weight while temperatures 91 to 96 degrees can result in fewer seeds per plant. During this period, pods are filling at a maximum rate, making the plant more susceptible to stresses and causing it to move nutrients from other areas. Moving those nutrients will weaken it and open it up to invasion by diseases through the roots and foliage.
  • A string of nighttime temperature less than 60 degrees can result in reduced pod set, seed formation, and seed size.
  • Studies have shown greatest growth rate for soybeans at mid-80 degree daytime and 72 degree nighttime temperature resulting in good seed size and no delay in maturity.

Depending on the season, we may not always have the optimum soybean temperature requirements. However, there are other things which can be done to minimize stress and maximize the plant’s nutrition during that critical R5 growing stage. For more information on intensively managing your soybeans, contact me.

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