Dr Sebinasi Dzikiti obtained his undergraduate degree in physical sciences from the University of Zimbabwe. He says he was interested in water from the start. “There was a lot of irrigation in Zim, and I was keen on getting into the sector and applying physics there.”
His MSc was in agricultural meteorology, which bridges physical and agricultural sciences.
He enrolled at Ghent University in Belgium for his PhD, but his fieldwork was in Zimbabwe, studying the transpiration dynamics of citrus. Dzikiti explored the plant response to partial rootzone wetting and drying and soon encountered problems.
“The results were not what I expected,” he recalls. “The signals were just too noisy. I was very worried.”
When Dzikiti consulted his study leaders in Belgium, he created a stir because he was the first person to identify stomatal oscillation under natural conditions and to show that these oscillations occur across the entire transpiration stream from roots to leaves.
Stomatal oscillation is the stomata’s cyclical opening and closing during the day, even under well-watered conditions. It was discovered in sunflowers in the 1960s, but researchers didn’t have the technology to study it in detail back then.
“This oscillation is simply a question of supply and demand,” explains Dzikiti. “The plant doesn’t take up water fast enough to meet the water requirements of the canopy, so it develops transient water deficits, even when the rootzone is fine. When water in the canopy is in short supply, the stomata close, and as soon as it’s replenished, they open.”
His work on citrus led him to connect with Citrus Research International and a post-doctoral position in the Department of Horticultural Sciences at Stellenbosch University. In 2008, Dzikiti moved to the Western Cape with his family, and they have lived here ever since.
After his post-doctoral position, he joined the CSIR but kept his ties to the University and forged new ones with the Water Research Commission and Hortgro. He was at the CSIR for a decade before returning to the Department of Horticultural Sciences as a senior lecturer, where he currently works on deciduous and subtropical fruit and citrus.
Dzikiti misses Zimbabwe and hopes to return there. But he says he is grateful for the career opportunities he and his wife, a clinical epidemiologist, have enjoyed in South Africa. “The environment here is very safe, and the people are amazing,” he adds. “I can only say good things about South Africa.”