Based on farm field plot level survey data and laboratory test, Prof. HUANG Jikun and his team from Institute of Geographic Sciences and Natural Resources Research (IGSNRR)，Chinese Academy of Sciences, examine the determinants of the expression of Bt toxin in China’s Bt cotton production.

The results show that the expression of Bt toxin differs significantly among varieties. Even for the same variety the expression of Bt toxin also varies substantially among villages and among farmers in the same village. Econometric analyses show that after controlling for the effects of varieties and locations (or villages), farm management, particular applications of phosphate and potash fertilizers, and manure, has significant positive effects on Bt toxin expression in farmer’s fields.

In contrast to previous studies which showed that nitrogen fertilizer has a positive impact on expression of Bt toxin, this study shows that nitrogen fertilizer has no significant impact on expression of Bt toxin in farmer’s fields. On the other hand, the expression of Bt toxin has a positive relationship with phosphate fertilizer, potash fertilizer and manure application.

The related study has been published in the journal of Transgenic Research(Jikun Huang, Jianwei Mi, Ruijian Chen, Honghua Su, Kongming Wu, Fangbin Qiao & Ruifa Hu. Effect of farm management practices in the Bt toxin production by Bt cotton: evidence from farm fields in China, Transgenic Research (2014) 23:397-406 DOI 10.1007/s11248-013-9775-7).