Rice yields could be reduced by global warming, shows a rice research conducted by an international team headed by a Chinese agronomist at the International Rice Research Institute (IRRI).
Field studies conducted at IRRI headquarters in the Philippines over the past dozen years along with weather data showed rice yields declined by 10 percent for every one degree Celsius increase in the mean daily temperature, Peng Shaobing Wednesday told Xinhua by telephone.
"We analyzed weather data at the International Rice Research Institute Farm from 1979 to 2003 to examine temperature trends and the relationship between rice yield and temperature by using data from irrigated field experiments conducted at the International Rice Research Institute Farm from 1992 to 2003," Peng said.
He said researchers noted that annual mean maximum and minimum temperatures have increased by 0.35 Celsius and 1.13 Celsius, respectively, for the period 1979-2003 and a close linkage between rice grain yield and mean minimum temperature during the dry cropping season (January to April).
Grain yield declined by 10 percent for each one degree Celsius increase in growing-season minimum temperature in the dry season, whereas the effect of maximum temperature on crop yield was insignificant, he added.
The finding provides a direct evidence of decreased rice yields from increased nighttime temperature associated with global warming, Peng said.
"These findings are important for predicting the effects of global warming on food security because rice is the staple food for two billion people, or about one-half of the human population," IRRI said earlier.
The next challenge for the researchers was to develop new rice varieties that can still yield well despite any increase in temperatures in rice growing areas, IRRI said.
The research result was published online this week in the Proceedings of the National Academy of Sciences and a study paper co-worked by the nine-member research team headed by Peng will appear on the July 6 edition.
(People's Daily July 1, 2004)
