The importance of variety selection

CHOOSING A VARIETY with high fiber quality potential is the biggest factor affecting the lint. Varietal selection is one of the earliest and most important decisions a cotton grower makes every season. A grower must live with this single decision all year long, from emergence to marketing.

The variety decision will begin to establish profit potential before a seed is ever planted. Considerations are personal for each producer, encompassing not only yield and quality but also variety characteristics and management practices relevant to the region where it's planted.

General components of profit potential are yield potential, fiber quality, response to management, consistency and market acceptance. Region-specific components may include crop maturity, disease resistance, insect resistance, stress tolerance and harvestability. Management components will include herbicide tolerance and insect resistance offered through transgenic varieties.

According to FiberMax Sales and Marketing Manager Lee Rivenbark, FiberMax varieties have shown consistent yield and quality performance in the areas to which they are adapted. New varieties have been introduced to help meet the demand for quality, yield and transgenic requirements. Those growers who have identified herbicide-tolerant and insect-resistant traits as a high priority now have more options to choose from with the introduction of new FiberMax transgenic varieties.

“Under a commercial agreement with Monsanto finalized in March 2001, FiberMax varieties with the Roundup” Ready and Bollgard “traits are now available,” says Rivenbark. “Immediately available are FM 989BR, FM 989RR, FM 991RR and FM 832B. In all tests, fiber properties of the transgenic varieties were equal to the properties of their most closely related conventional parent.”

Tests in both the U.S. and Australia indicate that new FiberMax transgenic varieties will address grower demand for insect-resistant and herbicide-tolerant traits while maintaining the fiber quality for which the FiberMax germplasm is known.

“When these varieties were bred, intense selection pressure for yield and quality traits was applied throughout the backcrossing procedure with the intention of maintaining excellent yield and quality attributes in the FiberMax germplasm,” says Jane Dever, Ph.D., global coordinator, cotton breeding and product development for Aventis CropScience.

FM 989BR and FM 989RR are expected to be as widely adaptable as their conventional parents, with a strong fit in the Southwest, West and Southeast. Both the conventional and transgenic varieties have excellent fiber quality attributes.

FM 832B is well adapted to the South Delta and Southwest. The Bollgard trait for worm protection should prove critical, especially in areas such as Louisiana. Since this is an okra leaf variety, it also promises to be very water-use efficient. The conventional FM 832 is known for excellent performance and the same is expected from FM 832B.

FM 991RR offers another option for Roundup Ready technology, while maintaining excellent fiber quality traits. This is a true full-season variety that should be adaptable to California, South Carolina and Georgia.

Tests conducted in the USA in 2000 indicate that these varieties are similar in yield potential and maturity to their recurrent parent with equivalent fiber characteristics. The currently available transgenic FiberMax varieties are relatively long-season varieties and should perform best in regions where their recurrent parents are adapted. They have fiber length, strength, micronaire and uniformity that are consistently better than the crop average in the region grown.

However, those growers who are looking for the high yield and quality potential of FiberMax without the transgenes also have two more conventional varieties to choose from.

“Recently, two new varieties, FM 958 and FM 966, have been released in the Mid-South,” says Rivenbark. “Currently, the germplasm is available only in conventional varieties. These two varieties have performed well in state trials in Tennessee, Arkansas, Missouri and Mississippi, demonstrating the earlier maturity required in this region. Yield results were good, while the varieties produced some of the longest and strongest fiber in the tests.”

In the Tennessee cotton variety test results in 2000, two varieties with high fiber strength and long staple length, FM 958 and 966, also had the highest mean yields across locations.

The FiberMax germplasm, which is selected from one of the world's largest germplasm pools, comes from the Commonwealth Scientific Industrial Research Organization in Australia (CSIRO). However, Aventis is expanding its breeding program and has established three breeding stations in the U.S. Two stations are set up as part of the joint breeding venture with Cotton Seed International called Aventis Cotton Seed International (ACSI), located in Sellers, S.C., and Leland, Miss. The third station is an Aventis site located in Lubbock, Texas. This growing breeding and product development program with its Australian relationship allows Aventis to bring products to market with access to leading biotechnology. Namely, in the pipeline is Liberty® cotton, which is a herbicide-tolerant system containing Aventis proprietary technology.

The Aventis breeders are committed to local development of varieties to address the needs of the regions in which they are grown. Early results from the ACSI breeding programs indicate the importance of selection in the target environment.

ACSI breeders selected and yield tested sister lines from advanced generation CSIRO material. Twelve improved lines from FM 819 and 11 improved lines from FM 966 were selected. This is strong evidence that a local breeding effort can achieve further improvement in germplasm.

Three strains developed in the ACSI program at Mississippi by Dr. Jeff Gwyn were entered into state official variety trials this year. These potential varieties in the pipeline, averaged over 9 locations, had significant yield increases over the most widely grown competitive variety in the Delta. Fiber length, strength and micronaire were better than ST 474.

“We expect our seed supply to improve with local production,” says Rivenbark. “By utilizing both the U.S. and Australian production sites, we can assure growers of a good seed supply. We expect to meet the growing demand for conventional and transgenic FiberMax seed for the upcoming season.”

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