fraksken , 7 hours ago

the plants are cross bred for generations. Each time the seeds of the plants with the best desired properties are kept.

the seeds can also be treated (see "feminizing marijuana seeds) with chemicals to produce certain traits.

the producers of these seeds (like monsanto, bayer, basf, …) have large R&D groups where the dna of the seeds can be further tracked and modified if required.

these producers have large green houses just for breeding the plants and collecting the desired seeds.

these seeds are patented. The plants produce fruits to specifications. To protect the intellectual property, patents and business, they are made not to produce further offspring, so the farmer needs to buy the seeds year after year.

another trait that’s being developped in the plants, for example, is making the plant immune to glyphosate, allowing the farmer to wastefully spray the herbicide on the field. It will kill all plants except for the desired crops.

source: used to work in for one of the above mentioned companies in the cropscience division.