It turns out that three seeds per row-foot is still the best way to maximize cotton yields in Virginia.

At this year’s Virginia Cotton Growers annual meeting at the Paul D. Camp Community College in Franklin, Dr. Hunter Frame, Virginia Tech Extension cotton specialist, shared the results of two trials conducted at the Tidewater Research and Extension Center in Suffolk in 2017,  comparing a seeding rate of one, two or three seeds per row-foot. The goal was to find out if growers could reduce their seeding rates to save money yet still maintain yields.

The bottom line: three seeds per row-foot is still the best planting rate for achieving maximum cotton yields in Virginia. Three seeds per row-foot is Virginia Tech’s official recommended seeding rate for cotton. “Both trials showed lint response to increased seeding rates. The higher seeding rates generated more yield.  However, yield potential is still determined by variety,” Frame said. “Varieties  responded similarly in terms of their plant architecture and yields across seeding rate, which is a good thing. You don’t have to look so hard at fine tuning seeding rates for different varieties."

Choosing the correct planting date is critical for maximizing yield. Frame said considering the environmental conditions three or four days after you plant is important.

Frame’s first trial was planted May 9 and the maximum and minimum air temperatures dropped and the soil temperature dropped as well. “We saw a pretty good cut in our emergence rate in that environmental condition, just from having nighttime temperatures drop into the mid-50s and lows into the low-40s. We saw a good reduction in terms of our final plant population,” Frame said.

The second trial was planted exactly one week later on May 16.

“There were warming temperatures and warming soil temperatures, and the cotton jumped out of the ground. We got higher plant population with the same seeding rate in that trial. Environmental conditions around planting play an important role in seeding rate determinations if you’re going to adjust your seeding rate,” Frame said.

In the first trial, lint yield was 1,533 pounds per acre at one seed per row-foot. At three seeds per row-foot, lint yield was 1,777 pound per acre, or a 240 pound increase. “That’s a pretty substantial increase even if the seed cost is high,” Frame said.

“As we increase seeding rates, we saw vegetative composition of yield decrease from 37 percent of your yield at one seed per row (foot) to 14 percent at three seed per row (foot). That’s significant,” Frame said, emphasizing the importance of protecting first-position bolls.

“As you increase your seeding rate, protecting those first-position bolls becomes a premium because 65 to 70 percent of your yield is coming from that first-position fruit. If you have anything that is going to affect that first-position fruit during that bloom period and you see knocking off of bolls, you’re probably going to have quite a bit of yield loss because two-thirds of your yield is relying on that first position fruit," he said.

In short, plant population and seeding rates impact plant architecture with more reliance of increased seeding rates coming from first position fruit. The research showed no statistical difference of seeding rates on second-position fruit.

“Second-position fruit didn’t really care if you had one, two or three seeds per row foot in terms of yield composition,” Frame said.

“A final stand or plant population of two to three plants per row foot is sufficient to achieve maximum yields,” he said.

Frame said Virginia Tech will do the study again this year but will look at seeding rates up to four seeds per row-foot and also add more varieties to see how they perform across different seeding rates.

A big crowd filled the hall at the Paul D. Camp Community College in Franklin on Feb. 6 for the 19th annual Virginia Cotton Growers Association meeting and annual statewide cotton production meeting.