Soybeans and Hot Weather
When temperatures get up to 95 degrees or more, soybeans tend to:
- Close their stomates to conserve moisture within the leaf. They can't move enough water through the plant to keep up with that high an evapotranspiration demand. Soil moisture levels, therefore, have little to do with it.
- Stop producing photosynthate, since carbon dioxide can't get in through those closed stomates either.
- Abort flowers. Not a big deal, since soybeans can replace those flowers, and they don't seem to care much which flowers become pods.
- Abort small pods. This is a little more serious, but the plants may well have enough pods left anyway. If a pod was about half full size or bigger, it probably did not abort.
- Abort seeds within larger pods if the seeds were still pretty small.
- Produce smaller seeds if the seeds were very big already.
Remember that soybeans typically produce more pods than the combine will ever find, and produce way more flowers than the combine will find as pods. That's one of the major ways they survive adversity like this. The net result will probably be not much worse than losing a few days of potential production. I wouldn't expect any lasting effect of this response to high temperatures.
