NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
May 4, 2000
Variety selection may make the difference between success and failure of a soybean crop on alkaline soil, warns a soil scientist at North Dakota State University.
Soybeans are sensitive to alkaline, poorly drained soils. The result is often stunted, yellow plants, a condition called iron deficiency chlorosis, according to Jay Goos, professor of soil science at NDSU.
No soybean varieties are as resistant to iron chlorosis as crops like barley, but there are differences among soybean varieties. With the support of the North Dakota Soybean Council, Goos has been screening varieties for resistance to iron chlorosis.
"Our goal is to screen 80 to 100 varieties per year, so farmers can know which varieties are the most resistant to this problem," Goos says. "We simply want to help farmers avoid the terrible situation where large portions of fields are stunted on chlorosis-producing soils."
Unlike many other nutrient deficiencies, iron chlorosis affects the younger parts of the plant first. Once the younger leaves are stunted and necrotic, regrowth is difficult. Under these conditions it is not uncommon for soybean yields to be cut by 60 to 80 percent.
The soybean variety screening trials are performed in the greenhouse, using a very alkaline soil from near Leonard, N.D., and soil water content adjusted to give a moderate and severe chlorosis. The chlorophyll levels of the leaves are measured and calculated as a percentage of Traill, one of the most resistant varieties grown in North Dakota. The varieties Council and Glacier are also included in every greenhouse run.
"In general we feel that varieties with chlorophyll levels greater than 90 percent of Traill have a very good level of chlorosis resistance," says Goos. Varieties for chlorosis-prone soils should have ratings at least as good as the variety Council, which usually has a chlorophyll content about 80 percent of Traill in the screening trials, he says.
Goos and his research crew have evaluated 92 varieties.
"We have conducted seven screening trials, and Traill always comes out on top," Goos says. "If Traill can't be successfully grown on a field because of chlorosis, the field is probably unsuited for soybean production."
Goos stresses that any soybean variety can turn chlorotic if the conditions are bad enough. Under the worst conditions a resistant variety can turn yellow also, but recovery is usually much better with a resistant variety.
Evaluated varieties with a chlorophyll rating at least 90 percent of Traill include Jim, Minnesota 301, Traill, Garst Ex9112RR, Gold Country Sonora, Kaystar X0990RR, Mustang 0958, Peterson Farm Seeds Thor, Pioneer 9007, Pioneer 9071, and Thunder 0997.
"You can walk into the greenhouse and immediately see that these are greener than the rest," says Goos. "Out of 92 varieties, this is a very short list."
Varieties with chlorosis resistance levels at least as high as Council include Barnes, Council, Daksoy, Lambert, Surge, Asgrow 0801RR, Asgrow 0902, Firstline 9804, Gold Country Durbin. Golden Harvest 1103, Hyland RR Rattler, Hyland RR Rugged, Kaystar 0350RR, Land O'Lakes 983, Midwest Seed Genetics 0906, Novartis X9904R, Ostlund 3092, Ostlund 3098, Ostlund 3117RR, Payco 9809, Peterson Farm Seeds 0006RR, Peterson Farm Seeds 0009RR, Peterson Farm Seeds Ole, Stine 1096-4, and Wensman 3139N.
"These varieties do show some yellowing in our greenhouse screening trials but are still significantly better than a weak variety like Glacier," Goos says. "Taken together, these two lists represent roughly the top third of the 92 varieties we have tested to date."
Goos points out that this list is not exhaustive and that there are many good varieties that haven't been tested yet. He says growers with chlorosis problems should talk to their seed dealers and insist on varieties with high levels of resistance.
Goos' list of varieties from his screening trials is updated every one to two months and is available from the Department of Soil Science at NDSU or from the North Dakota Soybean Council in Fargo.
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Source: Jay Goos (701) 231-8581
Editor: Gary Moran (701) 231-7865