The obvious question, Heiniger points out, is can we get plant populations up and still build seed weight?

The answer is yes, he says.

Soybean plants have the capability to translocate carbons and don’t have to depend solely on nutrients fixed by leaves during the R1 through R5 growth stages. Soybean plants can store sugar from photosynthesis for later use.

“Ideally, we want all the sugar possible to go to the seed to produce higher seed weights. To get this extra energy to the plant, we have to find a way to store sugar, in the form of starch, then get it to the plant when it gets to the R4 to R5 stage and begins pod development,” Heiniger says.

To get consistently high yields, whether it be in corn or soybeans, early growth is important to set the stage for translocation of nutrients to seed development.

And, getting as much light into the canopy during these critical growth periods is essential to improving yields, the North Carolina State researcher adds.

It appears it will be critical to begin fixing and storing sugars before the R1 growth stage. By increasing leaf surface early in the season, it can produce more than is needed by the plant. It can then store it for future use at the R1-R5 seed development stage of growth.

Light is the key, Heiniger says.

“One of the problems with getting adequate light into the canopy of grain crops is the tendency to grow big plants.

“In many cases bigger is not better when it comes to high yielding grain crops. Obviously, if plants get too tall and/or foliage is too dense to allow light penetration, there will be limitations on how much the plant can build seed weight and thus produce ultra-high yields.”

There are other limiting factors to grain yields.

Insects are a significant factor. Damage from insects or diseases can damage foliage and significantly impact seed weight in a negative way. 

Clearly, Heiniger says, future efforts to increase and sustain grain crop yields in the Southeast must include a good pest management program.

Some of the strobilurin fungicides labeled for use on corn and soybeans have shown some capabilities to increase photosynthesis.

Finding the optimum use for fungicides on soybeans is an ongoing hot research topic for researchers across the country.

North Carolina typically produces about 1.5 million acres of soybeans annually. Last year growers set a statewide yield record of 39 bushels per acre.

The 2013 crop has been plagued by historic rainfall and was planted a month to six weeks late, especially double-crop beans that make up about half the state’s acreage.

Yields will likely take a big hit from the prolonged cool, wet weather, but the future is bright.

“We are getting translocation of sugars in our soybeans in North Carolina, which means we do have a means of building seed weights and to produce ultra-high yields of soybeans comparable to those being grown by Kip Cullers in Missouri,” Heiniger says.