New Standards for Watermelons:

In early spring, when there is still a chill in the air in Northern Taiwan, Wandan Township in Southern Taiwan’s Pingtung County is bathed in warm spring sunshine. After making numerous turns we finally arrive at a farm. Inside a fenced-off field are row after row of watermelons large and small, with each row being planted with a single variety. This is a variety testing site for Known-You Seed. The company’s plant breeders use instruments to measure the sweetness of the water­melons, and after tasting each one, they record data including the size of the fruit and seeds, the hardness and thickness of the rind, and the texture of the pulp.

Achievements of a “watermelon king”

Based on documentary evidence, watermelons originated in tropical Africa. Around the 1950s, 11 watermelon varieties were introduced to Taiwan from China and Japan. In 1968 Known-You began to invest in water­melon breeding, and thus far it has produced a total of more than 400 commercial varieties, accounting for more than 70% of all watermelon varieties in Taiwan and sold into more than 100 countries.

Huang Yuanman, an associate researcher at the Tainan District Agricultural Research and Extension Station, noted in an article that Taiwan is one of the world leaders in terms of the number of watermelon varieties. Known-You founder Chen Wen-yu (1925–2012), a veteran breeder, had the nickname “watermelon king,” and his grandson Chen Wei-ting, Known-You’s current chairman, says that his grandfather said he had eaten more watermelon than anyone else on the planet.

In the early days after Known-You’s founding, it was producing one out of every four commercially sold water­melon seeds in the world. There was even a time when foreign farmers came to Taiwan cash in hand and lined up to buy its seeds. 

Among Known-You’s many commercial varieties, the best known in Taiwan is ‘China Baby,’ a red-fleshed water­melon which averages 12–18 kilograms per fruit. Jaden Hsu, section chief in charge of vegetable and fruit seeds in the Domestic Department at Known-You, notes than China Baby has a more than 90% market share in Taiwan. It is preferred for its high yield and long shelf life, and at the tail end of the harvest season it can be sold to shaved ice shops to make watermelon juice, generating higher incomes for farmers.

“Watermelon king” Chen Wen-yu used to say that he had eaten more watermelon than anyone else on the planet.

Chen Wen-ting, the grandson of Known-You founder Chen Wen-yu, is working hard to promote branding of individual watermelon varieties.

Over 100 cultivars are evaluated at the watermelon tasting session.

Unfairly disparaged yellow watermelon

Yellow-fleshed watermelons initially took the market by storm, but later there was also a period when purchasers found the pulp to be too pale and the flesh flavorless. Hsu says that the main reason was that farmers were harvesting their watermelons early in order to meet public demand for fruit to use as religious offerings on the first and 15th days of each lunar month, so that the melons were underripe, with pale flesh and low sweetness. This caused people to mistakenly believe that yellow-fleshed watermelons don’t taste good, and reduced their desire to buy them. Poor sales impacted farmers’ willingness to grow these melons, creating a vicious circle.

Farmers do not lightly change the varieties they grow, so to promote new varieties seed companies have to change tack and market them to consumers. In ­order to create market differentiation, breeders improve existing varieties, as has been the case with different types of small and medium-sized watermelons.

The ‘Sweet Beauty’ variety, with its elongated oval shape, bright red pulp, high sweetness, and crisp, refreshing texture, was produced in response to changing family structures and consumer preferences. Fruits of this variety, marked by clear stripes on the rind, weigh only two to three kilograms.

If you ask Kung Chien-chen his opinion as to what makes these watermelons “beauties,” he replies: “The first standard for beauty is that the stripes must be straight, not crooked. The second is that the stripes must be darker than the background color, so they stand out.” The latest variety in the “large Sweet Beauty” category, called ‘Hanni,’ fits these criteria; moreover, it is large and has a long shelf life.

Watermelons selected via the evaluation process must be further appraised through trial cultivation before they can go into commercial production.

Taiwan’s subtropical climate, with its highly variable weather, gives the island an innate advantage in watermelon breeding.

A wake-up call

Another master stroke has been making “black” water­melons commercially viable. In the past, these did not sell well in Taiwan, perhaps because of traditional rules for religious rituals which forbid the use of black-­colored fruit as offerings. But an upmarket supermarket in Southern Taiwan imported Japanese black watermelons and sold them for over NT$1,800 a pop, causing dealers to wake up to their potential. They need not be used for religious worship, but can be given as gifts.

Chen Wei-ting, who aims to achieve market differentiation through branding, says that the most noteworthy thing about black watermelons in that they have black-green or deep-green rinds, making them instantly identifiable to consumers. In addition, all varieties are sweet and juicy.

The high-yielding ‘Skylar’ variety, which has a deep black-green rind and red flesh, can be cultivated in open fields and offers three harvests per year. Its Chinese name, Yajun, is a popular girl’s name, indicating that this variety is targeted at the mass market. Each Skylar melon weighs three to four kilograms and has a high level of sweetness; they are well suited for banquets and other gatherings, and for restaurants.

Meanwhile, the variety ‘Helen,’ with a deep black-green rind and orange flesh, has stripes on the rind but its black-green color conceals them, causing the whole fruit to look dark-hued. What is most special about Helen ­watermelons is that they have crisp, refreshing pulp and durable rinds. Researchers have found that even after nearly three weeks in a refrigerator, the texture of the pulp remains intact. These watermelons are also well suited for export, because shipping to nearby countries in Southeast Asia can be completed within the melons’ shelf life, making Helen a new fruit with great market potential.

What’s the best way to eat watermelon? Watermelon expert Kung Chien-chen suggests taking big mouthfuls because that’s the only way to fully feel the texture of the pulp.

Plant breeders use specialized instruments to measure the sweetness of fruits.

When breeders test watermelon cultivars, they measure the size of the fruit and seeds and the hardness of the rind, and also taste-test each one for flavor and texture.

‘Dark Belle 6989,’ the latest watermelon variety bred at Known-You, has a darker rind than its ancestor ‘Dark Belle.’ This dark hue puts 6989 at the top of the watermelon “black list.”

Upright cultivation, high-end market

The category of black watermelons, which are targeted at the high end of the consumer pyramid, mainly comprises novel small melons, such as ‘Miniball,’ released in 2022. About the size of a softball, with a crisp, refreshing texture and a fresh, sweet taste, each one is just the right size to make a single-person serving.

Another variation on this theme is ‘Onyx,’ with its full, round shape, which Known-You first put on the market in 2024. Its thick, jet-black rind makes a sharp contrast with the finely textured red pulp inside.

Traditionally watermelons have been grown in sandy soil, but Miniball and Onyx are both cultivated in greenhouses. The vines grow upwards along trellises in the same way that cherry tomatoes are raised. But each plant is only allowed to produce a single fruit, taking nutrition from the entire plant, and thus making them a high-cost, high-value crop. Hence they are marketed at high prices to high-end consumers.

Black watermelons have long sold well overseas. For instance, the ‘Dark Belle’ variety does particularly well in the Indian and Southeast Asian markets. This is a variety that Known-You developed to meet India’s special needs—long transport distances over poor roads—so it has a resilient rind that is flexible and resistant to splitting.

In 2024 Kung Chien-chen bred the latest variety, ‘Dark Belle 6989,’ which is not only twice as large as Dark Belle, having an average weight of four to five kilos, it is also high-yielding and has a long shelf life: it can be stored for at least a week longer than its ancestor Dark Belle. Most importantly, the rind is even darker than that of its ancestor, which first came on the market 30 years ago, putting 6989 at the top of the “black list.”

The very sweet ‘Skylar’ variety is targeted at the mass market.

‘Onyx’ has a thin but hard rind that is resistant to cracking, and its flesh has a delicate texture.

Known-You has come out with this seedless black watermelon, ‘Twilight,’ aimed at individual consumers.

The ‘Helen’ variety’s oval shape makes it easy to stack and the rind is resilient. It travels well and has a long shelf life.

Taiwan’s humidity: A competitive advantage

As for exports of watermelon seeds, after India and China, where Taiwanese seeds are widely accepted, the third-ranking region for sales is the Balkan Peninsula, followed by Ecuador, Colombia, and the Caribbean region. The best-selling varieties all have the advantages of being fast-growing, high-yielding, and heat-tolerant.

In major watermelon growing areas in the Balkans and Southern Europe, varieties with broad stripes, such as ‘Olympia,’ are preferred. Known-You has a market share of at least 10% in a number of nations, including Serbia, Croatia, Bosnia, and Montenegro, and up to 30% in some places. Travis Lu, a section chief in the Inter­national Department, says that because in recent years temperatures in Europe have been rising, varieties developed in the subtropics can meet the need for water­melons that grow under higher temperatures in early spring.

“We have been operating in the Caribbean region for at least 30 years. They also require varieties that are resistant to heat and to rain, like the variety ‘Warrior’ in the ‘Quinson Sweet’ category, which sells well in equatorial countries such as Ecuador and Colombia.” He suggests that varieties developed in subtropical Taiwan, with its highly variable climate, have an innate competitive advantage in these regions.

In emerging markets like Kazakhstan in Central Asia, fast-growing, cold-resistant varieties are popular. Because the market there has just recently been opened, there is high acceptance of a wide range of varieties. For example, the cold-resistant ‘Dark Star’ sells very well in Eastern Europe and is also marketed to Korea and Russia. However, in these places there is only one growing season annually, unlike Taiwan, which has three per year.

In his poem “Six Ways of Eating Watermelons,” the poet Lo Ching wrote that the first is just to eat it straight up.

Onyx watermelons are grown on vertical trellises in temperature-controlled greenhouses.  (courtesy of Known-You Seed Company)

Taiwan’s climate change advantage

“From farmers’ perspective, varieties that are fast-growing, easy to cultivate, and have high sweetness are the most competitive.” Especially today, when heavy rains often fall suddenly even outside the rainy season, there is a demand for varieties that tolerate wet conditions. Travis Lu believes that this is the greatest impact of climate change in the international market.

Chen Wei-ting notes that in the traditional selective breeding process using field planting, each cultivar had to pass through ten generations during its development. Today, in the face of competition from global seed companies, Known-You applies techniques from molecular biology in order to speed up the breeding process, such as using genome sequencing to identify disease resistance genes.

“It is the responsibility of breeders to do their best to develop varieties that are more resistant to adverse conditions, including heat, water, drought, and most importantly pests and diseases, which will be easier for farmers to cultivate, will require less use of agrochemicals, and will promote agricultural sustainability.” This is how Chen describes the mission of plant breeders today.

Watermelons prefer intense sunshine and high temperatures, and are vulnerable to damage from wind and rain. Given the challenge of extreme weather, we should all be grateful to plant breeders for their efforts to ensure that consumers can continue to enjoy all kinds of sweet, juicy, cooling, and refreshing watermelons. 

‘China Baby’ watermelons have the advantages of high yields and a long shelf life.