Why seedless watermelon have seeds?

There is a interesting thing when you growing seedless ( triploid) watermelon.

You may find some special black big seeds in the seedless watermelon fruit.

Why ? Is it fake seeds ? It is not exactly. Let me tell you the reason.

Actually, it is not a real seed, it is actually fake seeds. Open the seeds, you will find there are no embryos. See the bellow picture.

seedless watermleon fruit full of fake seeds

Why this happen ? how to avoid ?

1. Low termperature( normally under 25 centigrade) when pollination and fruit setting. that may induce black color seeds. but the seeds without embryo.
2. Fertilizer phosphorus is a little more. The best ratio for N:P:K is 2:1:2.
3. the seedless variety is triploid. There is still a 1/1024 ratio to have a normal gamete. so that may also have real seed with embryo. but the ratio is very low.
4. If fruit setting at first or second femal flowers, also have possibility to have black seeds without embryo.

But do not worry ! if you pay attention on the reasons, it will be easy to avoid fake seeds during cultivation.