主题：【讨论】美国农业部发布转基因作物报告 -- 似曾相识

Over the first 15 years of commercial use, GE seeds have not been shown to increase yield potentials of the varieties.In fact, the yields of herbicide-tolerant or insect-resistant seeds may be occasion-ally lower than the yields of conventional varieties if the varieties used to carry the HT or Bt genes are not the highest yielding cultivars, as in the earlier years of adoption (Fernandez-Cornejo and Caswell, 2006; National Research Council, 2010). However, by protecting the plant from certain pests, GE crops can prevent yield losses to pests, allowing the plant to approach its yield potential.