Dinh Tran Nguyen, a senior student of agriculture and applied biotechnology, has been researching the growth of the square melon since he was a freshman.

The square fruit was first produced in Japan, several years ago. Last October, Tesco, Britain’s leading supermarket chain, started selling it in stores across the UK. The retailer claimed the melons were the first of their kind sold in the country. In Japan they were sold for 10,000 yen (about US$82) a piece.

In Viet Nam, people have been prepared to pay VND500,000 ($32) for a pair of the melons.

Nguyen and his school friends have sold the dark green and yellow-skinned square melons at local markets in their home city of Ninh Kieu. The melons were particularly popular during the lead-up to the lunar New Year.

Nguyen also entered the square melons in the national science and technology contest for young people in Hue last March, and won first prize.

Dinh Tran Nguyen spends a lot of time on his melon farm. — VNS File Photo

In the Vietnamese culture, watermelon is an indispensable offering to ancestors during Tet, the lunar New Year. In Vietnamese ancient philosophy, the square shape represents the earth, and the round shape the sun. Having a pair of round and square melons to offer ancestors is therefore a perfect match.

Nguyen said the square fruit also had less seeds, more flesh and were much easier to transport and store. Last Tet, he sold about 50 pairs.

He is planning to supply about 500 melons for the coming New Year celebrations. He said two to three times that many plants would be grown on 1,000 sq.m at Song Hau Farm in Can Tho Province, where he has previously grown successful crops.

In 2004, Nguyen was fascinated when he saw a television programme about the sale of square-shaped melons in Japan. Surfing the Internet, the freshman found an on-line forum on square melons posted on Can Tho University’s website. Discussion was high on what technology the Japanese had used to grow the melons, or if the fruit was genetically modified.

Nguyen embarked on researching methods to reshape the melon, which he said had not been previously tried in Viet Nam.

But to no avail; Nguyen could not find a clue. All he got was that the scientists probably placed wooden boxes around the growing fruit, which naturally swells to fill the surrounding shape.

Nguyen discussed it with his scientist parents, and they encouraged him by putting a small sum of money towards his experiment.

Nguyen started with 30 melons. When it came time to harvest them, only four had reached maturity, and those were tiny — cubes with 14cm sides.

Nguyen wasn’t put off by the failure. He applied for, and won, an assistantship for student research projects at Can Tho University.

With a meagre VND5 million ($350), Nguyen bought the material to make the moulds he needed and asked farmers to co-operate with him on the experiment.

They followed the melons every day, adjusting their conditions until they got the desired shape.

The result was that 14 out of the 50 melons grown were successfully shaped.

"The other melons failed due to technical problems when they were put into the ‘cells’ during their growth," Nguyen said. "That also explains the high cost of the melons, which are sold for $80 each in Japan."

Nguyen’s melons sold out at Xuan Khanh Market in Can Tho city, even at the hefty price of VND500,000 a pair. He refused to sell the last pair, even after getting offers of VND650,000, for fear of losing the seeds needed to produce more melons.

Trial and error

Growing the square melons is a trial of both skill and patience because a high success rate has still not been reached.

For every 10 melons grown, about six turn out correctly, he said. Even to get that meagre 60 per cent success rate, Nguyen had to trial dozens of melon fields, during different seasons, over the last three years.

Using the F1 Yellow and Thang Long seeds favoured by farmers, Nguyen was able to produce fruit weighing about 2kg each.

"But I care more about the quality," he said, adding "Weight does not tell all."

Nguyen said aluminium-framed glass boxes were placed over the melons at 43 days after planting, or when the melons were 11 or 12cm in diameter, forcing the fruit to take the shape of the boxes as they grew to full maturity.

Nguyen had to ask friends for help, as all the boxes had to be placed over the fruit on one particular day.

He used aluminium-framed boxes instead of wooden ones because the latter blocked the sun out and caused the fruit to bear an undesired colour.

Wooden moulds also provided favourable conditions for insect infestations, he added.

Nguyen said he himself placed the moulds on the melons and followed them every single day.

"Moulding the melon is a kind of art, the more skilful the artist, the better the product will be," he said.

Like the popular saying "practice makes perfect," Nguyen’s advise for other farmers is, the more you try, the better your melons will grow.