Research on the relationship between temperature and yields of various rice varieties suggests that warming temperatures negatively affect rice yields.

The study uses 50 years of weather and rice-yield data from farms in the Philippines.

Recent varieties of rice, bred for environmental stresses like heat, showed better yields than both traditional rice varieties and modern varieties of rice not specifically bred to withstand warmer temperatures.

But the study, published in the American Journal of Agricultural Economics, finds that warming adversely affected crop yields even for those varieties best suited to the heat. Overall, the advantage of varieties bred to withstand increased heat was too small to be statistically significant.

One of the top 10 countries globally in rice production, the Philippines is also a top 10 rice importer, as domestic supply cannot meet demand.

Teasing out the effects of temperature on rice yields is important to understand whether rice-breeding efforts have helped address the environmental challenges faced by modern society, such as global warming, says corresponding author Roderick Rejesus, a professor and extension specialist of agricultural and resource economics at North Carolina State University.

“Taken all together, there are two main implications here,” Rejesus says. “The first is that, at the farm level, there appears to be a ‘yield gap’ between how rice performs in breeding trials and on farms, with farm performance of recent varieties bred to be more tolerant to environmental stresses not being statistically different relative to the older varieties.

“The second is that rice breeding efforts may not have reached their full potential such that it may be possible to produce new varieties that will statistically perform better than older varieties in a farm setting.”

Read the full article about rice-breeding methods by Mick Kulikowski at Futurity.