Question

why are floating seeds not used for sowing

Answer 1

 Seeds may float because they lack viable embryos or nutrient stores, making them less dense than “good” seeds that sink. Or, they may float because they have air pockets inside, which don't always affect seed vigor or viability. The only sure way to test germination is to use the coffee filter method.

Answer 2

Floating seeds are not used for sowing as tgey are damaged. Before sowing, they put seeds in water and remove the floating seeds, as they may not have a proper yield.