One drawback is that the study was done using unproven and unknown varieties, accumulated by the ACCI from student work over the years, so the focus now needs to be on breeding improved varieties that have been measured in terms of desired traits.
“The NWG has been tasked with putting forward a project proposal before the end of June to evaluate and start breeding cassava varieties that meet South Africa’s needs,” says Laing. Evaluations will be done in KwaZulu-Natal by the ACCI and in Mpumalanga by the ARC.
“We have a pathway of what needs to be done. First, we need cultivars to give to farmers. The goal is to have good varieties and good agronomic packages available to them within five years,” says Laing.
“It’s relatively quick to breed new varieties – about four years. You only need one perfect individual, which you then use to propagate cuttings. But we will want a number of good parents so the farmers are not vulnerable to new diseases.”
The ACCI already has some cassava germplasm, and can access more if needed, and Laing says the breeding programme will involve growing a wide range of germplasm for South African conditions. Parent material will be sought that have good traits of disease resistance, high yields, cold tolerance and earliness, which is especially important.
One of the barriers to growing cassava in South Africa in the past was that old varieties took 18 months to grow and the crop couldn’t survive through winter. ACCI students have since bred seven-month varieties, making the crop feasible here. A seven-month variety also means that farmers can harvest a crop every year.
“Once good parents have been identified, we will make crosses, plant that seed out and then look for outstanding progeny plants. We can then develop clones for doing economic trials, where we test the best progeny on a larger scale and can get a better idea of yields and performance.”
“We will actively engage with farmers, select the best of the parent material and then they can get started.”
After that, Laing says the DTI will need to get involved in setting up the industry in terms of the economics and establishing factories to process industrial starch.
He’s also applying his mind to the agricultural engineering side. “Harvesting, peeling and processing all need to be considered. How do you dig up cassava tubers? They can be big, almost a metre long and 10kg in weight, and how do you peel them? Then you also have to deal with a waste stream that’s full of cyanide compounds, which is found in cassava. How do you process that?”
The NWG has agreed that two streams of breeding will need to take place — for industrial and edible cassava.
The requirements for industrial cassava are low protein and high cyanide content, so that animals don’t eat the crop while it’s growing. This cassava will go to the factory to be converted into starch or beer.
Desirable traits for edible cassava are high levels of protein and the micronutrients, pro-Vitamin A, zinc and iron, as well as low levels of cyanide and a longer shelf life.
Laing says most of the ideas for the project have been worked out and the final budget is being drawn up. If the proposal is accepted, the ACCI will receive funding to do breeding and agronomic studies that could involve four to five PhD students working on it for a five to ten-year period.
He’s upbeat about the potential of the project.
“Cassava production could be a very good industry for South Africa. We have outstanding infrastructure here, such as roads, railways and capital, compared to our competition. And farmers need more crop diversity because crops like sugar are not doing well.”