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Transgenic cotton varieties in Arizona were compared to the conventional variety from which they were derived in four field tests at three Arizona locations in 1999 and three tests at the same three locations in 2000. We included a total of 31 transgenic varieties and 11 conventional parents in one or more of these tests. Bollgard (BG) and stacked (BGRR) varieties produced lint yields that were equal to or significantly greater than lint yields of their respective conventional parents, while Roundup Ready (RR) varieties produced lint yields that were similar to their conventional parent. Only one transgenic variety (DP5690RR) produced significantly lower yields than the conventional parent in these tests. Pollen sterility ratings, one measure of heat tolerance, indicated that some transgenic varieties were more heat tolerant, most were similar to, and some were less heat tolerant than their conventional parent. Differences in fiber quality were also observed in these trials, but the variation was not associated with a particular transgene. Our results showed that most transgenic varieties were similar to, but not the same as, their respective conventional parent. Furthermore, our results indicated that differences in non-target traits between transgenic and conventional varieties were most likely the result of breeding and selection during the backcross conversion of the conventional variety, and were not a result of the direct effects of the transgene. |
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©National Cotton Council, Memphis TN |
Document last modified XXXXXX, XXX XX 2001
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