Agronomic Evaluation of Transgenic Cotton Varieties

Four field tests were conducted at three Arizona locations in 1999 to evaluate the performance of transgenic cotton varieties in Arizona. We included a total of 34 varieties in one or more of these tests. Across locations and varieties, Bollgard (BG) and stacked BG and Roundup Ready (BGRR) varieties produced about 7 to 8% greater lint yields than the conventional varieties from which they were derived. Across all varieties and all tests, the average lint yield of the Roundup Ultra sprayed RR or BGRR treatments was 1569 lb./A, while the average yield of the unsprayed RR or BGRR treatments was 1580 lb./A. Roundup Ready (RR) varieties produced lint yields similar to the conventional varieties with a couple of exceptions. Roundup Ready varieties tended to be taller and more vigorous than the conventional parent. Transgenic varieties were often different from the conventional parent in one or more traits, such as fiber quality, lint percent, boll weight, or maturity, but the variation was not associated with a particular transgene