This is a bit misleading. You only need to treat the first generation of 2n watermelon with colchicine (which inhibits the movement of chromosomes during metaphase) to produce a 4n watermelon.
Once you have a 4n watermelon, subsequent generations do not require colchicine treatment.
This is a bit misleading. You only need to treat the first generation of 2n watermelon with colchicine (which inhibits the movement of chromosomes during metaphase) to produce a 4n watermelon. Once you have a 4n watermelon, subsequent generations do not require colchicine treatment.