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Response To A Poster Titled "Tolerance Of Transgenic Soybean To Heat Stress", Presented By J. M. Gertz, Jr., W. K. Vencill, And N. S. Hill At The 1999 Brighton Conference

Response to a poster titled "Tolerance of Transgenic Soybean (Glycine max) to Heat Stress", presented by J. M. Gertz, Jr., W. K. Vencill, and N. S. Hill at the 1999 Brighton Conference. In this paper, the authors suggest that their laboratory research shows Roundup Ready® soybeans may be more susceptible to heat stress than conventional varieties. On millions of acres of Roundup Ready soybeans grown in North and South America over a four-year period, as well as in a variety of research trials, we and others have seen no significant differences in performance of Roundup Ready soybean varieties compared with conventional varieties under a wide range of climatic conditions.

RAPID ADOPTION OF ROUNDUP READY SOYBEAN TECHNOLOGY REFLECTS SIGNIFICANT GROWER BENEFITS

• Roundup Ready soybean use in the United States has grown to 54% of the 73 million soybean acres planted in 1999, a fast and considerable increase from the one million acres planted in the U.S. in 1996, when they became commercially available. The rapid adoption of this technology suggests the Roundup Ready soybean system (Roundup Ready seed and Roundup® herbicide) provides producers attributes and value not offered by alternative weed control programs and production systems. Similar rapid adoption of Roundup Ready soybeans has occurred in Canada and Argentina where growers also have achieved significant benefits. This level of market growth is the result of growers' experience with good yields, agronomic performance, management flexibility and profitability.

• Field data from a range of sources clearly demonstrate that Roundup Ready soybean varieties have the same (or better) yield potential as comparable conventional varieties. This has been demonstrated in side-by-side tests in the U.S., Argentina and Brazil. There is no basis to claims that Roundup Ready soybeans suffer crop loss or yield reductions of 40% when grown under elevated temperatures.

• The yield of Roundup Ready soybeans was studied and reported in a peer-reviewed paper in the journal Crop Science in 1995 (Delannay, et al. vol. 35, pgs. 1461-1467, 1995). This paper looked at Roundup Ready soybean yield potential over a three-year period at nearly 60 sites and found no significant difference in yield between the Roundup Ready soybean and parental non-transgenic variety. Independent data from the USDA Economic Research Service¹ and the University of Georgia² have confirmed that Roundup Ready soybeans perform as well as or better than conventional soybean varieties in a wide range of environments tested.

²University of Georgia 1998 Soybean Variety Performance Trials, Research Report No. 658 (www.griffin.peachnet.edu/swvt/1998/fc98sybn.htm)

THE CONDITIONS OF THIS STUDY DO NOT REFLECT NORMAL FIELD GROWING CONDITIONS

• The University of Georgia investigation was conducted in growth chambers using environmental conditions that are rarely, if ever, experienced in the field. This included subjecting the seedlings to high day and night temperature regimes for an entire month. Stem splitting was not observed under more typical or realistic temperatures for any of the varieties tested, whether Roundup Ready or conventional. Only at extremely elevated temperature (113/86 Fº or 44/35 Cº for 32 days) were differences noted. Results showed unacceptable levels of damage for both conventional and Roundup Ready soybean varieties.

The following table contains the 30-year monthly average summer temperatures for four NOAA weather stations in Georgia.

PRODUCER SATISFACTION

• Market research conducted in September, 1999, by Marketing Horizons, Inc., sampled 858 Roundup Ready soybean users, including 250 growers from southern soybean producing states. Overall, 97% of the national sample were either very satisfied (73%), or somewhat satisfied (24%), with Roundup Ready soybean technology. Extremely high satisfaction among producers using Roundup Ready soybean varieties would not be achievable if heat stress or other agronomic challenges were creating problems for producers using this technology.

Roundup Ready soybeans have been rapidly adopted in both North and South America because they provide growers with superior and cost-effective weed control, excellent crop safety, a flexible management tool and the opportunity to employ more sustainable farming practices. Heat stress has not been identified by growers as an issue. We will continue to work with independent researchers, as well as conduct research internally, to evaluate the performance of Roundup Ready soybeans.