David Moseley, Stephen Harrison, Boyd Padgett, Trey Price, Dustin Harrell, Kenneth Gravois, Don La Bonte and Matt Foster

New row crop varieties — soybeans, wheat, rice, corn, cotton, grain sorghum, sweet potatoes and sugarcane — are released annually by private companies and university breeding programs. Each variety can vary dramatically in yield potential, agronomic traits such as maturity, and resistance to insects, diseases and environmental stress factors. It is important to note a variety with high yield potential at one location may not be competitive in another location because of a lack of adaptability to different environments, including weather patterns, soil characteristics, disease pressure and cropping systems. Furthermore, a variety achieving a high yield or quality one year may not perform as well the next year at the same location because of yearly changes in the environment, such as rainfall or disease patterns.

One of the most important decisions producers make annually is variety selection. It is difficult to recover from a failed or underperforming crop. To assist producers in variety selection, LSU AgCenter scientists have conducted variety trials across the state for more than 100 years. The variety trials consist of both randomized small-plots located on LSU AgCenter research stations and large on-farm strip demonstrations conducted in conjunction with cooperating producers and parish agents. The purpose is to screen the available varieties for each crop in different environments and under production practices. Data from these trials enable producers to make selections according to their individual situations.

Common selection characteristics among the commodities are yield, maturity, quality, stress/pest resistance and harvest efficiency. Careful consideration of the data for each characteristic should be taken before selecting a variety. For example, consider a variety that has high yield potential but is susceptible to a high soil salt content. If planted in a field containing high chloride, the variety may perform significantly worse than an average-yielding variety tolerant to high chloride.

These trials provide data that can be used to assess variety performance and stability. A variety is said to perform well if the data, such as high yield and low stress symptoms, looked good in a particular location. If a variety performs well across multiple locations and years, it is considered stable. Examining data across locations and years provides more reliable selection criteria.

Every year, the LSU AgCenter publishes variety performance data made available to stakeholders in print or online (www.LSUAgCenter.com). In most cases, there will be differences in yield and stress/pest resistance among the varieties within and across locations. When available, the yield data from previous years is also included. The number of companies and entries submitted varies across commodities. The data from the LSU AgCenter trials help producers select the most adapted and best performing varieties for their farms to maximize profitability.

The life cycle (annual versus perennial) of the row crop determines the methodology for variety testing. All of the Louisiana row crops but sugarcane are planted every year. Sugarcane is planted once and produces multiple crops for three to five years.

The annual crop varieties are planted each year in a crop rotation system. Depending on the participating company and university decisions, some varieties will be tested again in following years based on performance/stability.

The variety trials on research stations are planted in replicated small plots and harvested with a small plot combine or picker. Stress or pest resistance ratings and plant characteristics, such as maturity group and plant height, are taken in the field during the growing season and at maturity before harvest. For the core-block demonstrations, the annual crops are planted and harvested by producers with the help of an AgCenter county agent or extension associate.

Sugarcane variety testing occurs in the Outfield Variety Trials that are cooperatively conducted by scientists from the AgCenter, the U.S. Department of Agriculture-Agricultural Research Service and the American Sugar Cane League. The 12 locations where testing occurs are evenly distributed across the sugarcane growing region of south Louisiana, with six sites on heavy clay soils and six sites on lighter soil types. Each test is replicated three times. At harvest, a single-axle high-dump weigh wagon is brought to the site, and the grower’s combine harvester is used to cut and weigh plots to determine sugarcane yield. A 10-stalk sample is hand-cut and taken to the lab to estimate sucrose content. Each trial is harvested through either the second or third ratoon crops.

In a survey of Louisiana soybean growers conducted after the 2020 harvest season, 84% of the participants said they use the online variety preliminary data, and 90% said they use the printed version of the soybean variety production book. Given the chance to write in their top three most important research needs, 71% wrote in variety testing, and 58% indicated variety testing was the top priority.

Because of improved varieties and variety testing, average yields in Louisiana for soybeans, wheat, rice, grain sorghum, cotton, sweet potatoes and sugarcane have doubled over the past 50 years. Average corn yields have greatly improved as a result of breeding, testing and agronomic practices, averaging 43 bushels per acre in 1970 and 181 bushels per acre in 2020.

Data from multiple locations and years allow producers to select varieties with high yield potential and stress and pest resistance. With proper variety selection, producers increase their chances to be profitable and sustainable, which is critical for Louisiana’s economy.

David Moseley is an assistant professor at the Dean Lee Research and Extension Center in Alexandria; Stephen Harrison is a professor in the School of Plant, Environmental, and Soil Sciences; Boyd Padgett is a professor at the Dean Lee Research Station; Trey Price is an associate professor at the Macon Ridge Research Station in Winnsboro; Dustin Harrell is a professor at the H. Rouse Caffey Rice Research Station in Crowley; Kenneth Gravois is a professor at the Sugar Research Station in St. Gabriel; Don La Bonte is a professor in the School of Plant, Environmental, and Soil Sciences; and Matt Foster is an assistant professor at the Macon Ridge Research Station.

(This article appears in the winter 2021 issue of Louisiana Agriculture.)

Core-block demonstration distribution map.

Planting four-row small research plots at the Dean Lee Research and Extension Center in Alexandria. Photo by David Moseley

Soybean Official Variety Trial at the Dean Lee Research and Extension Center during the reproductive stage. Photo by David Moseley

Soybean Official Variety Trial at the Dean Lee Research and Extension Center in Alexandria at the mature stage. Photo by David Moseley

Harvesting soybeans at the Official Variety Trials at the Dean Lee Research and Extension Center. Photo by David Moseley