Yesterday we bought a “seedless” watermelon at Sams Club.
Cut it open today, and it’s full of seeds! 75% are the white seeds, the rest are black. Also, they are about 1/2 the size of normal watermellon seeds, but they are still there. The white ones are soft enough to eat and not notice, but not the black ones, they have to be picked or spit out. Anyway, this is definately NOT seedless. What gives?
Mendel’s laws. It was probably not at true hybrid, but grew from old seeds from the previous season. It happens a lot in melon country, and there’s special herbicides to kill the seeds between plantings.
I might have to explain a little more. By “old seeds”, We don’t mean the ones we planted, but refer to the ones that come from melons that break or spoil and drop the white seeds, which are fertile if surrounded by sufficient protecting pulp.
FWIW, the white seeds are aborted baby watermelons. IIRC, seedless watermelons have an odd ploidy - that is, they have 3, 5, 7, etc, copies of each gene. I’m thinking triploid, but I could be wrong. Anyway, when that happens, during meiosis I, pairing between homologues gets screwed up, and the seed dies. Occasionally, the odd chromosomes out will get successfully segregated, and you’ll get a normal seed. But there’s not much that can be done to get more seedless, except outright genetic manipulation.