Managing The Newer Varieties
Is more calcium needed for the larger-seeded types?
By Amanda Huber
New varieties coming out of peanut breeding programs have been packed with disease resistance and other traits producers need to make it in today’s market. A result of those getting the desired traits has been a larger seed.
Now producers are asking if that seed needs to be treated differently than the standard, Georgia Green. One question is, “Do the newer, larger-seeded varieties need more calcium?”
Result Of Wanted Traits
“Basically, the varieties that had the highest yield and grade, or overall performance, also had large seed,” he says. “To a large extent, performance in yield and grade are the factors that make the decision on the release of a new variety.
“In addition, most of the new large-seeded varieties have the variety C-99R as a parent, so that created the opportunity for the new varieties to have large seed.”
Tillman says that not all of the crosses with C-99R have resulted in a large-seeded type. For example, the variety “York,” released from the Florida program, has a normal seed size and has C-99R as one parent.
End Use An Important Factor
“We have done calcium tests with varieties that range in seed size from Georgia Green to C-99R,” Tillman says. “What we found was that farmers who are growing a large-seeded type, like C-99R, for commercial production do not need to apply calcium if the calcium in their soil test is sufficient.”
Tillman says, in their research, C-99R yielded and graded the same regardless of the amount of calcium applied even when there was a mild deficiency in the calcium level.
“However,” he says, “the seed germination of C-99R was reduced when less calcium was applied.”
Standard For Seed Producers
“This should be standard practice for all farmers who produce seed.”
Similar results were found by John Beasley and Glen Harris, University of Georgia Extension peanut agronomist and Extension soil scientist, respectively.
“We conducted trials comparing Georgia Green to C-99R and saw no response by C-99R for extra calcium, except when the calcium level was marginal, about 500 pounds per acre, in the pegging zone,” Beasley says.
However, he says, cultivars like Georgia-06G, Florida-07 and Tifguard are all slightly larger than C-99R.
Need Seems Logical
“It stands to reason that since we know the larger the seed the more calcium is required that we need to make sure we don’t come up short on these varieties and end up with pops, lower grades and poor germination,” he says.
Harris says the main questions he is getting from producers are as follows: Can you use the lime method for these new large-seeded runners? Is a pegging zone sample of 500 pounds calcium per acre enough for these large-seeded varieties like it is for Georgia Green? If my pegging zone is 500 pounds per acre or less and I need gypsum even for Georgia Green, do the large-seeded runners need a higher rate of gypsum?
Does Lime Method Work?
“Dr. Beasley and I have a study in place this year to look at the lime method on these larger-seeded runners,” Harris says.
“For the second question, we have a study this year that has 500 pounds calcium per acre in the pegging zone and we are going to see if this amount is enough or if we need to go to something like 700 pounds calcium per acre, which is what we are guessing.”
As to the last question, Harris says he and Julie Howe, Auburn University, had a study last year, and at the Tifton site the beginning pegging zone calcium level was 385 pounds per acre.
“We grew Georgia Green and Georgia-06Gs, and we put out three levels of gypsum per acre: zero pounds per acre, 500 pounds per acre and 1,000 pounds per acre.
“In terms of yield, Georgia Green made better yield at 500 pounds per acre versus zero pounds per acre, but there was no additional yield increase above 500 pounds per acre gypsum.
“On the other hand,” Harris says, “Georgia-06G made more yield with the increasing gypsum rate, and it looked like it may have even responded to 1,500 pounds per acre of gypsum, if we had put it out.”
Answers In Ongoing Studies
“When you multiply yield times grade for a ‘value’ in terms of dollars per acre, Georgia Green peaked at the 500 pounds per acre gypsum rate at $974, whereas 06G went from $862 to $1,012 to $1,105 with each increasing gypsum rate.”
“Anyone growing these new varieties for seed should be interested in the germination data that shows, once again, Georgia Green leveled off at the 500 pounds per acre gypsum rate, going from 83 percent with no gypsum added to 90 percent at 500 or 1,000 pounds per acre added. Whereas, Georgia-06G went from 72 to 84 to 87 percent germination with each rate.”
Finally, Harris says, if you look at the “cold test,” where germination is tested at lower temperatures to simulate adverse planting conditions, 06G drops off with no gypsum, for 66 percent, 82 percent and 84 percent. Georgia Green’s cold test is 82 percent, 86 percent and 88 percent at the 0, 500 and 1,000 pounds per acre gypsum rates, respectively.
“We got so used to growing DPL 555 on the majority of our acres, and now we are learning how to manage the new cotton varieties differently,” he says. “Now, it looks like some of the newer peanut varieties are going to get significant acres in Georgia, and they are definitely larger in size than Georgia Green.”
Tillman says the new larger-seeded types such as Florida-07 and Georgia-06G fit into this category.
Other Needs Of Large Seeds
“First, larger-seeded types should be dried very carefully since they tend to split more than smaller types,” he says. “This means that harvest should be timely, before the peanuts dry too much, and that drying in wagons should be done slowly with temperatures that do not exceed 98 degrees F and only to about 10.5 percent moisture content.
“Secondly, calcium content is extremely important in seed production, so gypsum should be applied to all seed peanuts regardless of seed size, but it is even more important with larger-seeded types.”
Harris agrees, saying, “The bottom line is to automatically, regardless of soil test calcium levels, put gypsum on any peanut being saved for seed. With the new larger-seeded runners such as 06G, you really need to put gypsum on and not skimp below 1,000 pounds per acre.”