As government representatives negotiate ways to strengthen the international response to global warming at the United Nations Climate Change Conference COP23, in Bonn, Germany, scientists around the world are working on technologies to help farmers produce food and generate income in a warming world.
The CGIAR Research Program on Roots, Tubers and Bananas (RTB) is coordinating varied efforts to meet the challenges of climate change that include an initiative to assess the risks of crop pests and diseases under future climate scenarios, and help government institutions prepare for them: innovations to accelerate the breeding of resilient root, tuber and banana varieties; and deployment of climate-smart technologies such as the ‘Triple S’ seed system for sweetpotato, which will help farmers produce planting material as dry seasons become longer.
Root and tuber crops have the potential to play a more important role in food security, but more resilient varieties will be needed as climate change advances. Cassava, for example, is drought tolerant, but climate change is causing increasingly erratic rainfall, which affects the starch content of cassava roots, since sudden rain before harvest can result in new foliage growth and reduced starch content in roots. Cassava breeders at the International Center for Tropical Agriculture (CIAT) are thus developing varieties with more stable starch yields under variable rainfall.
As banana is sensitive to drought, scientists at the International Institute of Tropical Agriculture (IITA) are concentrating on breeding drought-tolerant varieties. However, as IITA banana breeder Dr. Rony Swennen explains, bananas don’t wilt, so protocols to screen effectively for drought responses are being developed.
Sweetpotato is also relatively drought tolerant, and because its storage roots develop underground, they often survive tropical storms, providing vital food after winds or flooding destroy other crops. Scientists at the International Potato Center (CIP) sweetpotato breeding program in Mozambique, led by Dr. Maria Andrade, have developed 15 drought-tolerant, pro-vitamin A, orange-fleshed sweetpotato (OFSP) varieties that were released in 2011 and an additional four varieties released in 2016. These varieties now account for one-third of the sweetpotato produced in Mozambique, and some of them are also being grown in Madagascar, Ivory Coast and Abu Dhabi, or are being used as parents for breeding programs in other countries.
CIP potato breeders have also developed varieties that tolerate drought, heat and soil salinity, some of which have been released in Africa, Asia and South America. These include the heat- and drought-tolerant variety Sarnav, which is being grown in three regions of Uzbekistan, and the salt- and heat-tolerant variety BARI Alu-72, which is being grown in coastal lowland areas of Bangladesh that suffer seawater intrusion. One variety developed and released in Peru under the name Tacna was later released in China under the name Jizhangshu 8, and by 2008, it was being grown on over 20,000 hectares there.
Potato and sweetpotato were included among the stress-tolerant crop varieties to counter climate change in a working paper entitled 10 best bet innovations for adaption in agriculture: A supplement to the UNFCCC National Adaption Plan Technical Guidelines. A project of the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), that paper was written to support governments in the elaboration of their National Adaption Plans.
Dr. Jan Low, a Principal Scientist at CIP, contributed to that working paper and participated in two COP23 side events organized by CCAFS. She explains that in addition to breeding for tolerance to drought and other environmental stresses, CIP breeders are developing potato and sweetpotato varieties that mature early. Since 2009, 40 early-maturing sweetpotato varieties, which can be harvested within 90-120 days after planting, have been released in sub-Saharan Africa. Early maturity allows farmers to better avoid high stress environments and provides them with more flexibility to fit the crop into optimal growing seasons. Low adds that another top priority for CIP breeders is that potato and sweetpotato varieties have high levels of micronutrients.
“The idea is to combine varieties that can perform well under stress, in drought conditions, and at the same time provide excellent nutrition, particularly vitamin A,” says Low. “We need to ensure the quality of the food as well as the ability to produce food under difficult conditions.”
In order to help root, tuber and banana breeding programs speed up the development of climate-smart varieties, RTB has made a significant investment in genomic research, which has included the DNA sequencing and field tests of thousands of plant accessions. Scientists at RTB centers and partner organizations are using the resulting data to identify genetic markers associated with specific crop traits – such as heat or drought tolerance – that can be used to accelerate the breeding process. Researchers at IITA, for example, are studying gene expression changes in response to drought in banana, in order to understand the genetic basis of drought tolerance. RTB genomic research is being complemented by field research to ensure that new varieties being developed have the traits that men, women and youth want.
“Given the pressing nature of climate change, I think significantly increased investment in breeding will be required to meet the challenges,” observes Dr. Graham Thiele, Director of RTB. “There are indications that progress is possible and some encouraging examples in the RTB portfolio, but overall, tackling climate change needs a step change in longer term funding. We need to have targets for improving traits which take on board future climates. To achieve these targets, breeding programs need to become more focused and product and demand driven, if they are going to rise to the challenge. One important development is support and funding for the Excellence in Breeding Platform, with which RTB is actively partnering.”