WANG Kang-xu, ZHANG Ke-rou, CAO Cou-gui, JIANG Yang

Journal of Integrative Agriculture; Available online 10 January 2023

Abstract

Transgene escape could lead to genetically modified rice establishing wild populations in the natural environment, where they would compete for survival space with weeds. However, whether the expression of Bacillus thuringiensis (Bt) gene in rice will alter the relationship between transgene plants and weeds and induce undesirable environmental consequences are poorly understood. Thus, field experiments were conducted to investigate the weed competitiveness and assess the ecological risk of transgenic Bt rice under herbicide-free and lepidopterous pest controlled environment. Results showed that weed-rice competition in direct seeding field (DS) was earlier and more serious than that in transplanting field (TP), which resulted in the significant decrease of biomass and yield in DS. However, the yield between conventional Bt and non-Bt rice was not significant difference. The weed number, weed coverage ratio and weed diversity of conventional Bt rice were significantly higher than those of non-Bt rice at the early growth stage and mature stage, especially in DS plots, suggesting that Bt traits did not increase the weed competitiveness of transgenic rice and had no negative effect on weed diversity. Grain yield and weed number varied between different hybrid rice lines, but those differences were not significant between Bt and non-Bt rice. The number of insects increased with the increase of weeds in hybrid rice plots, whereas the insect number and diversity did not display a significant difference between Bt and non-Bt rice. Therefore, the ecological risk of transgenic Bt rice is comparable to non-Bt rice.

See https://www.fao.org/newsroom/detail/as-the-pace-of-urbanization-quickens-in-asia-pacific-so-too-does-the-threat-of-urban-food-insecurity-un-agencies-report/en

Fig. 3 Non-metric multidimensional scaling (NMDS) analysis of Bt and non-Bt rice in 2018 (A) and 2019 (B). A, red circles and blue triangles represent Bt hybrid t rice and non-Bt hybrid rice, respectively. B, p(T1/T2) indicates the significant analysis between the treatment of direct-sowing (T1) and treatment of transplanting (T2); p(B/C) indicates the significant analysis between Bt rice (B) and Ck non-Bt rice (C); red circle and the green diamond represent Bt rice and non-Bt rice in the treatment of direct-sowing, respectively; orange squares and blue triangles represent Bt rice and non-Bt rice in the transplanting treatment, respectively.