However, there are still some unsettled key issues in GE maize cultivation which remain to be addressed, such as if GE technology improves the grain quality in terms of nutritional value and toxin content (including mycotoxins) 21, 22, and if it affects important agro-ecosystem services including soil organic matter decomposition. To date, a few meta-analyses have been performed on GE maize at farm and field level addressing questions concerning yield, production cost and gross margin terms 14, 15, 16, pesticide use 16, and effects on non-target (NT) invertebrates 17, 18, 19, 20. However, these studies, mostly literature reviews, do not allow us to draw univocal conclusions. Numerous attempts have been carried out to synthesize the huge literature on agronomic and economic performance and environmental impact of GE maize ( e.g., 6, 7, 8, 9, 10, 11, 12, 13). This is due to its comparatively low rate of adoption (30% of the global maize in 2015) and its huge cultivated area 4. Moreover, among GE crops, maize has the highest potential of expansion. The global value of GE maize is estimated at US$ 8.1 billion 4. Thirty-three million ha were grown in USA, while GE maize planted in Brazil, Argentina, and Canada accounted for 17.4 million ha. In 2015, 53.6 million ha of GE maize were cultivated on a global scale, representing almost 1/3 of the 185 million ha of maize planted worldwide. In 2016, the different GE traits introduced into major crops (soybean, maize, canola, and cotton) consist of herbicide tolerance (HT) which comprise 95.9 million hectares of GE crops (53% of the total GE area) insect resistance (IR) at 25.2 million hectares (14% of the total GE area) and both HT and IR stacked in one crop, at 58.5 million hectares (33% of the total GE area) 4.ĭespite the extensive cultivation of GE crops and a considerable number of scientific reports, the concerns about their safety has led 38 countries worldwide, including 19 in Europe, to officially prohibit their cultivation, though allowing the import of food and feed derived from or consisting of GE plants 4.Īmong GE crops, maize ( Zea mays L.) has the highest number of approved events (single and stacked traits) and is the second largest crop, after soybean, in terms of global adoption 5. GE crop cultivation has increased from 1.7 million hectares in 1996 to 185.1 million hectares in 2016, representing about 12% of the global cropland, 54% of which are found in developing countries 4. Since their first commercialization in 1996 1, 2, genetically engineered (GE) crops have been rapidly adopted in many countries 3 becoming the fastest adopted crop technology in the world 4.
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Furthermore, the reduction of the parasitoid of the target and the lack of consistent effects on other NTOs are confirmed. The results support the cultivation of GE maize, mainly due to enhanced grain quality and reduction of human exposure to mycotoxins. Biogeochemical cycle parameters such as lignin content in stalks and leaves did not vary, whereas biomass decomposition was higher in GE maize. The NTOs analyzed were not affected by GE maize, except for Braconidae, represented by a parasitoid of European corn borer, the target of Lepidoptera active Bt maize.
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Results provided strong evidence that GE maize performed better than its near isogenic line: grain yield was 5.6 to 24.5% higher with lower concentrations of mycotoxins (−28.8%), fumonisin (−30.6%) and thricotecens (−36.5%). This meta-analysis aimed at increasing knowledge on agronomic, environmental and toxicological traits of GE maize by analyzing the peer-reviewed literature (from 1996 to 2016) on yield, grain quality, non-target organisms (NTOs), target organisms (TOs) and soil biomass decomposition.
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Despite the extensive cultivation of genetically engineered (GE) maize and considerable number of scientific reports on its agro-environmental impact, the risks and benefits of GE maize are still being debated and concerns about safety remain.