摘要:随着转基因的快速发展，大量转Bt棉秸秆的合理利用和处理是不可忽视的重要课题之一。为明确Bt棉秸秆还田利用的可行性和安全性，本研究以不同抗虫转Bt基因棉和常规棉花‘泗棉3号’为研究材料，在分别种植1、2年后将秸秆机械粉碎后原位还田，测试土壤中Bt蛋白残留量、土壤酶活性及养分含量的变化，分析Bt棉秸秆原位还田对土壤肥力特性的影响。研究结果表明，秸秆还田40 d后，Bt棉样地土壤中Bt残留蛋白检测值较低，均与非转基因棉样地无显著性差异。棉秸秆还田后，土壤脲酶、蔗糖酶、蛋白酶、多酚氧化酶、过氧化氢酶、碱性磷酸酶活性皆较秸秆还田前增加，但土壤纤维素酶活性较之前降低。棉秸秆还田使土壤中有机质、有效磷、碱解氮、速效钾和全氮等养分含量及pH明显增加，而Bt抗虫棉与常规棉秸秆还田后对土壤肥力的影响不存在显著差异。对土壤综合肥力指数评价结果表明，秸秆还田对土壤肥力提升与Bt棉抗虫水平无关，土壤肥力指数在两年间由Ⅲ级水平上升至Ⅱ级水平。综上，Bt棉花秸秆还田不会造成土壤综合肥力降低，相反能有效提升土壤肥力；同时还田利用措施可对转基因植株有效灭活，与转基因植物秸秆利用和无害化处理要求相契合。生产中用于Bt转基因棉花秸秆利用和处理在一定程度上是安全可行的。
关键词:转Bt基因棉/
秸秆还田/
转基因植物/
Bt蛋白残留/
土壤肥力
Abstract:With the rapid development of genetically modified organisms, how to use and deal with a large amount of Bacillus thuringiensis (Bt) transgenic cotton straw is an important issue. To study and clarify the feasibility and safety of straw incorporation of transgenic Bt cotton into the field, four kinds of Bt cotton with different levels of insect resistance and one non-transgenic conventional cotton (Simian no. 3) were analyzed. After one or two years of planting, all the cotton straws were mechanically crushed and returned to the field in situ. The content of residual Bt protein, activities of several soil enzymes, and nutrient contents in soil were detected and the changes were further analyzed. The effects of Bt cotton straw returning on nutrient characteristics and fertility of soil were analyzed. The Bt protein residues in soils were very few and almost undetectable after 40 days of straw recycling of transgenic Bt cotton with different insect resistance levels, and there was no significant differences between the transgenic field plots and non-transgenic ones. After cotton straws were returned into the field, the activities of urease, sucrase, protease, polyphenol oxidase, catalase, and alkaline phosphatase in soil obviously increased, while the activity of cellulose did not increase. The activity of soil cellulase was lower than that before cotton planting. The amounts of organic matter, available phosphorus, available nitrogen, available potassium, and total nitrogen in soil increased remarkably both for the first year and for the second year of cotton planting, and so did the pH value. Similarly, there were not any significant differences in variations of all nutrient content between Bt transgenic treatments and non-transgenic ones. The soil comprehensive fertility index resulted by straw recycling was calculated and the effect on the fertility suitability was evaluated. The fertility index rose from level Ⅲ to level Ⅱ in two years, which was not related to the insect resistance level of Bt transgenic cotton. The soil fertility was not adversely decreased but increased, in fact, by straw returning treatment of Bt cottons. Returning Bt cotton straw to the field could effectively improve the soil fertility index. In addition, this straw recycling scheme could effectively kill transgenic plants, and would meet the disposal requirements of transgenic plants. The collective data confirmed that returning treatment, to a certain extent, should be feasible and safe for dealing with mass residues of Bt transgenic cotton in practice.
Key words:Bacillus thuringiensis transgenic (Bt) cotton/
Straw returning/
Transgenic plant/
Residual Bt protein/
Soil fertility
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