Rumor: The ripening watermelon has a short ripening time, the pulp of the watermelon is red but the seeds are flat and white. Such white-seeded watermelon is harmful to health.
Truth: Watermelon white seeds are not pollinated and have nothing to do with ripening.
In fact, these white seeds are actually undeveloped embryos (unfertilized [eggs]).
The greenhouse watermelon cultivated in early spring does not have enough temperature to pollinate normally during flowering. Fruit growers will use plant growth regulators to help it set fruit.
The sweetness and taste of these watermelons may indeed be different from those of conventional watermelons, but it cannot be said that they are harmful.