What are the applications of genetic engineering in crop improvement?

Could you please elaborate on the various applications of genetic engineering in crop improvement? I'm particularly interested in understanding how it can enhance crop resistance to diseases and pests, as well as improve nutritional value. Additionally, could you discuss the potential risks and challenges associated with the use of genetic engineering in agriculture? How does it compare to traditional breeding methods? I'm also curious to know if there are any environmental concerns or ethical considerations surrounding the utilization of genetic engineering in crop improvement. Thank you for your insights.