By George Boyhan
University of Georgia

Watermelons are still a summer favorite, and Georgia is still one of the nation's top producers. With summer right around the corner, look for some new watermelons on the market. They'll cost more. But they'll be worth it.

Melons come in many shapes and sizes, and seed companies keep coming up with new varieties.

One way seed companies have spurred new demand is by developing seedless varieties. Seedless watermelons aren't really seedless. But the seeds don't develop completely. They remain soft and edible.

More recently, larger seedless melons in the elongated 20- to 25-pound class have been released. These long melons will often have a dark rind with a narrow, light green or yellow stripe. Often called an Allsweet type, these larger seedless melons should quickly become a favorite with shoppers.

Smaller, too

Small watermelons (less than 10 pounds) have been around for many years, too. They've often been sold in roadside and local markets. They come with names like Sugar Baby, Minilee and Mickilee.

These small melons were called icebox types because they could fit in a refrigerator. Recently, seed companies have been offering something called personal melons. These new small melons have the added benefit of being seedless.

The personal melons don't generally produce as well as larger melons, so farmers are reluctant to grow them. After all, they're paid by weight.

The seed companies have overcome this, though, by contracting with farmers to grow them. They're handling marketing and sales directly as well.

To know how seedless watermelons are grown, you need to understand basic genetics.

Chromosomes

All higher organisms start out with two complementary pairs of chromosomes. During reproduction, the number is halved to one, so it can mate with a complementary chromosome. This is called sexual reproduction. It's essentially the same in all higher organisms.

In watermelons, it's possible to double the number of chromosomes from one pair to two pairs, or four chromosomes. During reproduction, halving the chromosomes leaves two instead of one. When this is mated with a normal watermelon, the resulting seeds have three sets of chromosomes.

Growers plant these seeds, and when the plants are pollenized, the reproductive cells have one and a half chromosomes, which aren't capable of mating properly with the one chromosome from the normal pollen. So the seeds then never develop.

Triploids

These seedless varieties are properly called triploids. Triploid watermelons have been around for years, usually as small, round melons in the 10- to 20-pound range.

A watermelon innovation that won't affect shoppers directly is how triploids are grown. Triploid melons don't produce viable pollen, so up to one-third of a field has to be planted with normal watermelons to have pollen available for the triploids to grow.

Seed companies are working on pollenizer plants that are small enough to be interplanted in a field. This means a grower can have an entire field planted to triploids and get dramatically more of these popular melons.

One-third of Georgia farmers' vegetable acreage is used to grow watermelons. There are still plenty of the traditional, seeded melons. But if the new seedless types appeal to you, look for them as summer arrives.

(George Boyhan is an Extension Service horticulturist with the University of Georgia College of Agricultural and Environmental Sciences.)