The number of chromosomes in a normal watermelon are doubled with the use of the chemical colchicine, which turns a normal diploid watermelon into a tetraploid plant that has four sets of chromosomes.  When the tetraploid is pollinated by a diploid, the resulting plant is a seedless, sterile triploid.  However, if I understood correctly (and I’m kind of out of my league here, so correct me if I’ve misinterpreted), growing seedless watermelon involves throwing out a relatively large proportion of wasted fruit (the seeded fruit grown from the female parent line), distinguishable by its gray rind, a trait that has been bred into the variety for ease of recognition.  According to the USDA, though, over 80% of the watermelons grown in California are seedless.  How is that possible?  Do they mean over 80% of the watermelons sold in California are seedless?  I still haven’t figured out the answer to that one.

The seed cost of producing a seedless watermelon tetraploid plant is 10 to 100 times more than that of standard, open-pollinated varieties, because it only produces 5-10% as many seeds.  Additionally, about one third of the plants in the garden must be of the standard, ‘pollinator’ variety.  A typical field of seedless watermelon will result in regular seedless watermelons (from pollinator plants), true seedless melons, and light-green tetraploid melons that produce a limited number of seeds.  Bees are critical to pollination, as the plants cannot pollinate themselves.  In other words, there is no way to grow an entire field of seedless watermelons.  Better choose a distinguishable cultivar, or there’s no way of knowing whether you’ve got a seedless one without busting the fruit open.

We forget that growing seedless fruit is essentially cloning.  Given their lack of diversity, clones are at risk of succumbing to disease, like potatoes did in Ireland during the Irish potato famine, when a single variety of potato was overexploited to tragic ends.  “At the moment, we have to expend a great deal of effort to fight black Sigatoka, which attacks the banana plant’s leaves,” says a spokesperson for the International Network for the Improvement of Banana and Plantain (that’s INIBAP to you).  “Plantations are sprayed intensively with pesticides to keep the disease at bay.  More than a third of the price of a banana goes to pay for these pesticides.”  

INIBAP was actually founded after an attack of black Sigatoka nearly devastated banana farms in Africa and South America.  The cultivated bananas we eat today are seedless, sterile hybrids of the founder species, and crossing them will not produce new banana varieties that can resist the pests.  So far, fungicides seem to be the only way to keep them at bay. 

What’s wrong with eating fruit that has seeds in it?  Doesn’t anyone like to spit anymore?

Nathalie Jordi's appetites keep her bouncing between between County Cork, New York, London and the French Alps.  When not slinging curd or interviewing farmers, she writes for Travel&Leisure, Conde Nast Traveler, Gastronomica, and her blog at www.autobiogeography.com.  Her dreams of a life spent baking, drinking margaritas, and sitting in the sun are gathering steam during her current stint as a waitress in New York City.