不同生育期转基因抗草甘膦抗虫棉花对草甘膦的耐受性

Glyphosate tolerance of transgenic glyphosate/insect-resistant cotton during different growth periods

为明确转基因抗草甘膦抗虫棉田草甘膦的使用适期，于棉花子叶期、3～4片真叶期和花铃期喷施不同浓度的草甘膦，比较药害发生情况、棉花产量和纤维品质。棉花子叶期、3—4片真叶期和花铃期喷施1640～9840g／hm。（有效成分，下同）草甘膦后，施药初期棉花均表现出一定的药害症状，药后4～8d药害株率和药害指数达最大值，药后12d药害症状逐渐减轻或消失。棉花子叶期和3～4片真叶期喷施草甘膦，对棉花产量无显著影响，但棉花花铃期喷施2460～9840g／hm。草甘膦后，棉花产量显著降低，降幅达35．0％～63．3％。3个时期喷施苹甘膦均不影响棉花的纤维品质。研究表明，转基因抗草甘膦抗虫棉田草甘膦的使用适期为棉花苗期。

To determine the suitable spraying time of glyphosate in the transgenic glyphosate/insect-re- sistant cotton field, glyphosate application with different rates was performed at the cotyledon stage, 3 -4 true leaf stage and blooming and boll forming stage, respectively. The injury of glyphosate to cotton, cot- ton yield and fiber quality among treatments were compared. The results showed that glyphosate applied during different cotton growth stages with 1 640 -9 840 g/hm2 generally caused cotton injury in the early days after spraying. Both cotton injury ratio and injury index reached the peak value at 4 -8 days after spraying. About 12 days after glyphosate application, symptoms of cotton injury gradually reduced or dis- appeared. There was no difference in cotton yield among glyphosate treatments at the cotyledon and 3 -4 true leaf stages. However, at the blooming and boll forming stage, cotton yield significantly decreased by about 35.0% - 63.3% under 2460 - 9 840 g/hm2 glyphosate application. No effect on cotton fiber quali- ty was observed after all glyphosate treatments. In conclusion, the optimal application time of glyphosate in the glyphosate-insect resistant cotton field was at the cotton seedling period.