Soybean South


New Soybean Lines

High seed yield and unique resistance to nematodes and several diseases are the key qualities of new soybean lines developed by the Agricultural Research Service (ARS) and the Tennessee Agricultural Experiment Station in Knoxville.

The release of soybean lines JTN-5303 and JTN-5503 was announced in Jackson, Tenn., during a ceremony hosted jointly by ARS and the experiment station.

According to Prakash R. Arelli, a geneticist at the ARS Nematology Research Unit in Jackson, the new lines have broad resistance to multiple races of soybean cyst nematode (SCN). This is the most destructive soybean pest in the United States, causing an annual estimated loss of $1.1 billion.

Soybean cyst nematode
Stephen R. Koenning, Extension plant pathologist, North Carolina State University, says nematodes generally are microscopic round worms.

The soybean cyst nematode is a parasite that can reproduce on only a few hosts, such as soybeans and snap beans, and can’t reproduce on crops such as corn, cotton, peanuts, tobacco or wheat, Koenning says. Nematode eggs hatch from April through June, and juvenile nematodes migrate through the soil.

“When soybeans are planted and start to germinate, the roots exude substances that stimulate more hatch and attract juveniles to the root systems,” the pathologist explains. “Cyst juveniles penetrate the roots, migrating in the root until they locate a feeding site.

“This first event, penetration of the root system, may cause considerable damage to the soybean plant,” Koenning says.

As for resistant varieties, he notes that when they are available, they are an economical means of managing SCN. However, the resistant variety must be “matched to the race of SCN to which it is resistant and then used judiciously,” Koenning adds.

High-yielding lines
According to the ARS, JTN-5303 is a cross between the cultivars Caviness and Anand, while JTN-5503 is a cross between Fowler and Manokin.

Traditional breeding techniques and marker-assisted selection were used to track the resistance genes.

Both lines have yields significantly higher than the popular cultivars Hartwig, Fowler and Anand and have Hartwig-type resistance to widespread nematode populations.

Both lines were also selected for resistance to several fungal pathogens, including Sudden Death Syndrome, stem canker and frog-eye leaf spot, with moderate resistance to charcoal rot. Previous soybean lines have never had this unique combination of resistance to both SCN and pathogens.

Good fit for the Mid-South
The new releases are in maturity Group V. Maturity groups are used to designate which soybean varieties are best suited for production in specific geographic regions. The new lines named here are well adapted to production in the Mid-South.

Arelli developed the new soybean lines with Vince Pantalone and Fred Allen, geneticists at the University of Tennessee. They were assisted by ARS scientists Lawrence Young, Arelli’s research leader, and Alemu Mengistu, a soybean pathologist.

These lines are expected to be ideal choices for breeders for use as parents in developing cultivars in early maturity groups that reduce soybean yield losses.

The ARS is the USDA’s chief scientific research agency.