Carolyn Frost
South Africa is the world’s 10th-largest exporter and 13th-largest producer of sugar cane, but a group of scientists at the University of Stellenbosch hope their research will help push the country up the rankings.
Although South Africa is the third most productive grower of sugar cane, sugar yields have plateaued since the 1960s at a ceiling of approximately six tonnes a hectare.
The “yield decline hypothesis” is that conventional production techniques and means had been maximised, and the only way to improve productivity is through the quantum jump of genetic engineering.
Professor Frikkie Botha, the sugar guru of the Institute for Plant Biotechnology, believes his team has made that jump. They have been looking for “a magic gene in sugar cane that will allow more sugar to be harvested from existing crops”. By introducing new genes into sugar cane from other biological systems such as plants and bacteria, they’ve managed to significantly increase the sucrose yield.
To date the research has been conducted in controlled laboratory conditions. But there are plans to introduce the genetically engineered plants into strictly controlled field studies in KwaZulu-Natal next year.
Botha believes his team is “one of the best in the world”. It has been awarded an evergreen or rolling contract with the South African Sugar Association Industry.
Rather than being renegotiated every year, the partnership is now only reviewed every two years, and there is a three year termination period. This enables the institute to take on more postgraduate and PhD students since it has a guaranteed minimum of three-years’ funding .
Although sugar cane is one of South Africa’s biggest agricultural export commodities, our sugar cane-growing regions are considered “fairly hostile” for the crop, because of their distance from the equator. Sugar cane likes a hot, wet environment. It is grown predominantly in KwaZulu-Natal and Mpumalanga, were almost 80% of the sugar cane is rain-fed. Botha predicts that the industry will soon start expanding north to countries outside South Africa’s borders. Countries like Mozambique offer hotter, wetter growing environments and the land is usually flatter, which is better for practices such as mechanical harvesting.
In the most southern growing regions in South Africa, with lower temperature and water the sugar cane is grown on an 18-month cycle compared to a 12-month cycle under optimal conditions. Due to our specific needs sugar cane development in South Africa is aimed at resistance to harsh dry conditions. Whereas other countries such as Australia have the problem of excessive water and so look at developing sugar cane resistant to water logging.
An estimated 47 000 small growers make a sustainable income from sugar cane, and there are about 2 000 commercial farmers.
Although the evidence is there that the sucrose yields have been dramatically increased, Botha insists the work is “fundamental still on the way to being application”.
If growers can obtain more tonnes a hectare, it would result in a reduced input cost and make them more competitive. He estimates that just a 2% increase in sucrose production could yield an extra R500-million for the industry. “The potential is there especially with anticipated increasing demand from other countries in Africa.” Botha says that an expected rise in average income throughout the continent should go with higher demand for sucrose, because sweetened food items tend to be a luxury that gets priority in people’s lives.
ENDS