Bt抗虫棉秸秆还田对土壤养分特征的影响

【目的】研究转基因作物秸秆或残茬还田可能对土壤养分特性造成的影响。【方法】以不同抗虫水平Bt棉花和常规棉花(泗棉3号)为研究材料,分别在经过一、二个生长周期后将秸秆机械粉碎后原位还田,40 d后测定分析土壤中Bt蛋白含量及肥力相关的养分含量变化。【结果】Bt棉秸秆还田后,所有品种棉花土壤中Bt蛋白含量与还田前无显著增加,且转Bt基因棉与非转基因棉还田对土壤Bt蛋白含量的影响并无显著差异。同时,棉秸秆还田可显著提高土壤有机质、速效磷、碱解氮、速效钾、全氮、全磷和全钾含量,提升土壤pH值;增加幅度在不同抗虫水平Bt棉花间及与非转基因常规棉花品种间皆无显著性差异。【结论】秸秆还田对土壤肥力的提升与Bt棉的抗虫水平无关。“转Bt基因”不成为Bt棉秸秆还田提高土壤肥力的限制性因素,其秸秆还田不会对土壤肥力质量产生负面影响,可使土壤养分含量增加,有效提升土壤肥力。秸秆原位还田简单、无害又提升肥力,有条件作为转Bt基因植物秸秆无害化处理的理想方式。

Effects of returning Bt cotton straw on soil nutrient characteristics

Aim] To study the impact of returning residues of genetically modified crops to soil on fertility characters.Method] Several Bt cotton varieties with different resistance to insect and non-transgenic conventional cotton (Simian no. 3) were used as research materials in this study. All the plants were mechanically smashed and returned in site after one or two growth cycles. 40 days later, Bt protein content and the nutrient contents in soil were detected and analyzed to reveal the effects of Bt cotton straw returning on the soil fertility characters.Result] The results showed that straw returning would not distinctly result in the increasing of Bt protein contents in soil for all cotton species. And moreover, there was no significant difference between Bt transgenic cottons and non-transgenic cotton in content variation of soil Bt protein. The amount of organic matter, available phosphorus, alkali-hydrolyzed nitrogen, available potassium, total nitrogen, total phosphorus and total potassium can be significantly increased by cotton straw mulching, and the soil pH value can be improved too. No significant differences in change scope were found between Bt cotton and non-transgenic cotton. The above results are further confirmed by the grey relation analysis, and the effect of straw returning on soil fertility was not related to the insect resistance of Bt cotton.Conclusion] The improvement of soil fertility by straw mulching had nothing to do with the insect resistance of Bt cotton. "Bt gene" does not become a restrictive factor for Bt cotton straw returning to improve soil fertility. The soil fertility quality was not adversely affected by the straw returning. Instead, it can increase soil nutrient content and effectively improve soil fertility. In sum, straw returning is so simple and harmless that could be used as a potential optimal choice for transgenic plants disposal.