Some considerations to take into account and can catch up on the subject:
In principle the new transgenic plants should pose the same environmental risks as new plants generated by traditional breeding.
In practice, it may prove that the risks from some transgenic novelties will considerably exceed the risks of the conventionally bred plants. Transgenes may be able to produce larger nd quicker jumps in adaptation
For instance, there is the possibility, whenever farmers employ the new GM seeds, there is a certain amount of risk of hybridization with trans gene infiltration into related weed and/or wild species of plants, that are occupying agricultural and /or disturbed sites and/or alteration of natural gene frequencies in these species.
Weeds that are presently inconsequential could become invigorated to the point that they become a more serious problem.
In the UK for example, Raybould and Gray 1993 examined the probability of introgression from crops into wild species, (both introduced wild weeds and indigenous species) and noted a range of probability from minimal to very high, depending on the particular crop and its wild relatives.
Weeds that are already very successful may become even more of a problem, once these changes occur.
So when you examine the Canadian farmers problem with the new superweeds, most of which I know of that came from the use of Gm rapeseed, then you realize that the fears of those early activists against Gm crops have been right all along.
Never forget for a minute that much of what constitutes the various methods and blueprints for creating Gm seeds came from e majoprity of researchers who were steeped in the mythology of the fact that a good deal of the DNA of a plant species is "empty DNA." That theory, of the junk-i-ness of the "empty" section of DNA, raged along all through the nineteen eighties and nineties. When it was finally discovered that the DNA portion considered to "be empty" actually contained no specific instructions for a specific part of a plant (or human being for that matter0 but instead, the vast "blank" DNA areas were all about the overall programming of the entity, then you realize why Gm seeds, crop and foodstuffs are such a terrible problem.