Primed Acclimation

Apply this concept to prime plants to be more efficient users of water

By Amanda Huber

In production agriculture, water is still the most limiting factor – no matter where you are or what crop you grow. But what Wilson Faircloth, research agronomist at the National Peanut Research Laboratory in Dawson, Ga., has been telling producers this spring is that peanuts do not need as much water as you may think. More accurately, at certain growth stages, irrigation can be reduced from what is currently applied, saving money while still making the yield.

Faircloth and Diane Rowland, who was formerly with NPRL and is now at the University of Florida, plus other researchers at NPRL study water management constantly, and recently through these studies the concept of primed acclimation was born.

“Primed acclimation is the intentional, but regulated, use of mild drought stress to change plant water-use efficiency,” says Faircloth, who describes the concept as being similar to someone getting a flu shot.

“When you get a vaccine, you are actually exposed to a small portion of the flu so that when you come into contact with it again, your body is prepared for it and will know what to do.

“With primed acclimation, you are exposing the plant to intentional, regulated drought stress so that it changes the physiology of the plant and changes its growth habits, such as causing it to have deeper rooting,” Faircloth says.

Rowland says, “It changes a lot of things about the plant and makes it become a more efficient user of water.”

Screen Shot 2014-12-04 at 1.33.55 PM‘When’ Is Always Most Important
The key to primed acclimation is knowing when to reduce water applied through irrigation.

“From planting until we get a good stand, peanuts have a high susceptibility to drought early in the season because you have to get those peanuts out of the ground,” Faircloth says. “If you have stand problems, that will plague you for the rest of the season, and it opens the door to other problems such as TSWV.

“From early vegetative growth through the beginning of flowering and pegging, peanuts have low drought susceptibility. During fruiting, it goes back to a high susceptibility to drought as the peanut finishes flowering, the pegs develop into pods and the pods begin to fill out. This is when we know there is a high water need and high susceptibility to drought. During pod maturation, the water requirement tapers off some, but it is not as low as in early vegetative.”

Updating Water-Use Data
Faircloth says they determined that during the early vegetative growth stage was the time for potential for water savings. However, much of the water-use data the researchers had to go on was very outdated.

“This was data from the 60s and 70s based on Florunner and its predecessors. Therefore, collecting data on these newer varieties was part of the study, as was studying varying amounts of water on fields.

“Fully irrigating peanuts is not always the best economic option,” Faircloth says. “Often our best yields are somewhere between 100 percent irrigation and 66 percent irrigation. We often see that in cotton as well.”

Faircloth says their research has found that newer varieties have a higher water need for emergence, but, after this, the newer varieties have a lower water requirement for a longer period of time than previous varieties. At flower, the water requirement increases again for flowering through pod fill.

Once this was determined, he says, they knew the early vegetative stage offered the potential to cut back on irrigation for water and cost savings.

Cut Water Application In Half
In their studies, they applied irrigation at 100 percent of the crop’s requirement, 50 percent, 25 percent and then no water applied.

“We actually found that we got the best yields when applying 50 percent and even 25 percent of the water requirement for that five-week period after emergence and stand establishment,” Faircloth says.

Instead of putting out an inch, they would only put out half of an inch at the 50 percent application rate.

“Once you get past early flowering, into peak flowering and pegging, you have to put the maximum water on the crop. But for five weeks before that, if you cut back 50 percent of your water use, you could save three or four inches of water, and at a cost of $10 per acre-inch for electric and even more than that for diesel, that’s considerable savings on the farm.”

Make The Plant Work Harder
Faircloth says to test the primed acclimation concept, they again stressed the plants at about 75 days after planting for about three weeks and then observed the recovery.

“That’s when we knew this concept would work,” he says. “Looking at photosynthesis data, we could see where we changed the whole physiology of the plant by how it processed nutrients, water and sunlight.

“By making the plant work harder, we are getting more out of it.”

Faircloth says the primed acclimation produces effects that last season long. “Who wouldn’t want to make two tons of peanuts and only apply water six or seven times, verses 11 or 12?” he says.

Rowland says it works in cotton as well, and a large-scale field trial in Florida this year will combine primed acclimation with conservation tillage for peanuts and cotton in the hopes of achieving a significant yield boost and water savings with the combination of schemes. PG

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