I read a lot about the simple test of seed viability by placing a handful of seeds into water, those that float are sterile and those that sink can be germinated. Can someone give me a more specific explanation of what is happening?
It doesn't always apply, but the principle is based on that many seeds develop their seed outer shell before the seed itself starts to grow; and unpollinated, non-viable seeds then fail to grow to fit the shell, leaving an empty air-filled seed shell which is very light in weight and so floats.
That rule about sinking seeds probably only applies to separating viable from sterile fresh seeds, and then only some of them. Older seeds lose viability with age, not necessarily by drying out. This year, I planted some corn seeds that I bought in 2007; and not one of them sprouted. They look and feel just like newer corn seeds that had close to 100% germination; and they sink like stones.
Some seeds will not sink but rather seem designed to float as streams take them to their new home. Soaking older seeds in GA3 can improve germination rates.
