Climate change threatens to roast kūmara crops
A Kiwi favourite could disappear from dinner tables as climate change puts the heat on kumara crops, scientists say. Peruvian researchers tested 1973 kumara (sweet potato) strains , including six from New Zealand, and found just 132 were heat-tolerant. None of the New Zealand kumara were judged likely to cope with higher temperatures. "Heat and drought stresses are among the most important climatic events aggravated by climate change that affect sweet potato productivity," the researchers said. READ MORE: * PM's chief science adviser urges 'overarching umbrella' for Antarctic science sector * Climate change is about to make your beer more expensive * Maori horticulture: growing kumara and other crops the traditional way * Unicef NZ: Climate change and preparing for the coming storm "The increase in intensity and frequency of heat waves represents a serious threat to crop production worldwide." The researchers, from the International Potato Centre in Peru, suggested the heat-tolerant kumara could be used in breeding programmes to help crops adapt to predicted temperature increases of up to six degrees Celsius by 2070. New Zealand has about 50 commercial kumara growing operations, most of them in Northland and Northern Wairoa, producing red, gold and orange varieties. In 2019, a 24,000-tonne kumara crop was harvested for the domestic market, with a sales value of $55 million. Plant and Food Research scientist Dr Steve Lewthwaite said climate change presented opportunities and challenges for commercial kumara production in New Zealand. The ecology of future fields with changes in weed, pest and disease make-up would vary with changing temperatures and available moisture, he said. Although the plants were sensitive to water shortage during their establishment and to water surplus later in their life cycle, they were fairly hardy to surviving drought. As a tropical crop, kumara was also well adapted to hot conditions but production issues could occur without an adequate water supply, he said. Current sweet potato production is largely reliant on rain-fed systems, so extreme and erratic changes to the seasonal distribution of natural rainfall will be problematic, and may require the industry to adapt in non-conventional ways. "The research conducted by the International Potato Centre underlines the importance of genetic diversity in acting as a buffer within the intersection of ever-changing physical and biological challenges." Although domesticated in Peru about 8000 years ago , kumara has a long history of cultivation in New Zealand. Several varieties of small bush kumara about the size of a finger arrived with early Maori settlers and were widely grown. Modern kumara were imported in the early 1850s and evolved from a larger American variety.