Are Yellow-Fleshed Watermelons and Seedless Watermelons Genetically Modified? A Look at Cultivation Methods and Prices

Yellow-fleshed watermelon, commonly known as “Heibengjin”, is mostly grown in coastal and plain areas; seedless watermelon is triploid, has no reproductive capacity, and has no seeds. So are they genetically modified? How are they grown? How much do they cost per jin?

Are yellow-fleshed watermelons and seedless watermelons genetically modified?

1. In fact, the yellow flesh is not caused by hormones, and of course, it does not use transgenic technology either. Whether wild watermelons or cultivated watermelons, the flesh color ranges from white, pale yellow, bright yellow, pink, orange-red to bright red, there is everything one could wish for; that being so, there is naturally no need to go to the trouble of researching transgenic technology to change the color.

2. Seedless watermelons are not genetically modified; they are merely ordinary hybrid watermelons that make use of special parent materials.

There are two kinds of seedless watermelons. One is triploid seedless watermelon, which is produced by crossing a tetraploid watermelon as the female parent with a diploid watermelon as the male parent (the detailed breeding principle has already been introduced above); the other is chromosomal translocation seedless watermelon, which is produced by crossing a translocation homozygote as the female parent with an ordinary diploid as the male parent.

Genetic modification is a new biotechnology for creating innovative breeding materials. In the future, this technology may also be used to improve the parents of seedless watermelons, and by then there may also be genetically modified seedless watermelons.

How are yellow-fleshed watermelons and seedless watermelons grown?

1. The watermelon fruit is a pepo, formed by the fertilized development of the ovary. The entire fruit consists of three parts: the rind, the flesh, and the seeds. Among these, the rind develops from the ovary wall, the flesh develops from the placenta, and the seeds develop from the fertilized ovules. Different varieties of watermelon show a wide variety of shapes, sizes, skin colors, patterns, and flesh colors. These characteristics are commonly used as the main basis for identifying varieties.

2. The seeds needed to cultivate seedless watermelons are triploid watermelon seeds. Triploid watermelon seeds have the thick, hard seed coat of tetraploid seeds, with a high degree of suberization, especially at the beak, which is particularly thick and tightly closed. The seed embryo is not fully developed, and the weight of the seed embryo is relatively low, with embryo weight accounting for only 38.5% of seed weight (the embryo of diploid seeds accounts for 50% of seed weight), and embryo volume accounting for 60—70% of the inner cavity of the seed coat, while there is also a considerable proportion of deformed embryos, such as large and small embryos and folded embryos. For the above reasons, under natural germination conditions, the radicle of triploid seeds is not easy to drill out of the seed coat, so the germination rate is relatively low. In order to overcome the above difficulties, measures need to be taken to promote germination.

How much do yellow-fleshed watermelons and seedless watermelons cost per jin?

1. Seedless watermelons are among the more expensive melons on the market, reaching about 7.5 yuan/kg, but because they are relatively large, they are not very popular with consumers.

2. The market price of yellow-fleshed watermelons is more expensive than red-fleshed ones, generally 3 to 4 yuan per jin. In fact, twenty or thirty years ago, yellow-fleshed watermelons were fairly common; at that time, melon farmers mostly saved their own seeds and planted them themselves, and yellow-fleshed melons could always be found mixed in among the piles of melons.

Appendix: How to select watermelons

1. Look at the rind: for striped-rind melons, the stripes should be clear, with a distinct contrast between dark and light; for black-rind melons, the skin color should be pitch black with a luster.

2. Look at the head and tail: one with both ends well-proportioned, with the navel and the stem end relatively deeply sunken and the surroundings plump, is a good melon; one with a big head and small tail, or a pointed head and thick tail, is a lower-quality melon.

3. Look at the stem: a green one is a ripe melon; one that is black-brown, with the fine hairs fallen off, curved and brittle, and with the tip of the tendril turned yellow and withered, is a melon picked before it was ripe; if the stem has already dried up, it is a “dead vine melon” of poor quality.

4. The higher the degree of ripeness of a watermelon, the lighter its weight. Generally, among watermelons of the same size, the lighter one is better, while an overly heavy one is an unripe melon.

5. Hold the watermelon in your hand and gently tap it with your finger: if it gives a crisp “dong, dong” sound and the hand holding the melon feels a slight vibration, it is a ripe melon; if it gives a “tu, tu” sound, it reflects a relatively high degree of ripeness; if it gives a “pu, pu” sound, it is an overripe melon; if it gives a “da, da” sound, it is an unripe melon.