SA breeder's new cultivar sparks fresh love for passion fruit

Mpumalanga-based granadilla breeder Darryn Stoltz has developed a delicious new passion fruit cultivar that offers several advantages over previous varieties. One of these is longer shelf life, enabling the export of better-quality fruit. He spoke to Lindi Botha.

Lindi Botha

There can be few fruit cultivars whose origins are as unusual as that of the new passion fruit variety, Silesia.When drought struck North West in the mid-2010s, game breeder Darryn Stoltz, who farmed in the province, began to look for a nutritious source of food for his herds. He was advised to plant passion fruit, as the sweet pulp was said to satisfy the animals.

Unhappy with the low yield and pulp content of the two commercially planted varieties, Ester and Edulis, Stoltz began breeding for a new, juicier variety of passion fruit, using his knowledge of crossbreeding. In 2017, after two years of trial and error, he ended up producing Silesia, a cultivar that was nearly double the size of the conventional passion fruit, sweeter and faster-growing.

While Stoltz was pleased with the result, his game were less than impressed, leaving him with a harvest and no takers. Rather than waste the produce, he set off for the market with the fruit in an effort to interest buyers. He was in luck: a buyer from Switzerland immediately showed interest, and Stoltz realised the potential of the cultivar.

He initiated a rapid expansion project, which began with registering plant breeder’s rights on the new cultivar and purchasing land near White River in Mpumalanga on which to produce the cultivar commercially. He later bought land in Limpopo as well.

Stoltz also entered into partnership with Charles Rossouw, owner of Roslé Boerdery near Groblersdal in Mpumalanga, to form Roslesia, and production was ramped up. Today, the business produces more passion fruit than that grown by the rest of South Africa’s farmers combined. Eight varieties are bred under the Silesia name, ranging in size, colour and application, from fresh produce to fruit for juicing and pulping.

Roslesia began exporting fruit in 2018, and Asia, Europe and the Middle East have become established markets for the cultivar.

PAINSTAKING BREEDING

Stoltz recalls the long and arduous journey that is well known by breeders everywhere.

“The plant material needs to be crossbred, grown out, tested and then multiplied to ensure you get the same results over and over from a plant. It has now been six years and I’m still making tweaks here and there, but overall I’m very satisfied with what we have.”

Stoltz specifically looked at traits that increased fruit size, flavour and resistance to pests. Breeding for disease-resistance was also a key consideration, as most of the commercially planted varieties are highly prone to disease.

He and his team managed to achieve a 60:40 ratio of pulp to peel (a ratio reversed in other cultivars), as well as a considerably sweeter fruit.

“We get a Brix value ranging between 16 and 22, which is substantially more than the Brix of the Ester and Edulis cultivars.

“[Conventional] varieties don’t provide a good eating experience. They’re sour, and the amount of pulp is minimal. I was shocked at the high prices and quality of passion fruit in supermarkets in Europe, so I knew that having a superior product would mean fitting into a market where there was already demand at high prices,” he says.